Bibliometric Analysis of Nasopharyngeal Carcinoma in SCI Database (19992012)
Yu Lin; Xiaofei Mao
Journal of Nasopharyngeal Carcinoma Editorial Office, E18, 3/f, Yongda building, Wen Xian Tung street 97, Sheung Wan, Hong Kong
Corresponding author: Xiaofei Mao. Journal of Nasopharyngeal Carcinoma Editorial Office, E18, 3/f, Yongda building, Wen Xian Tung street 97, Sheung Wan, Hong Kong. Email: xiaofeimao@asiapress.asia
Citation: Yu Lin, Xiaofei Mao. Bibliometric Analysis of Nasopharyngeal Carcinoma in SCI Database (19992012). J Nasopharyngeal Carcinoma, 2015, 2(3): e23. doi:10.15383/jnpc.23. Competing interests: The authors have declared that no competing interests exist. Conflict of interest: None. Copyright:2015 By the Editorial Department of Journal of Nasopharyngeal Carcinoma. This is an openaccess article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. 
Abstract Objective: To understand the development of nasopharyngeal carcinoma researches in worldwide, and to study the development feasibility of professional journal on nasopharyngeal carcinoma. Methods: The literatures on nasopharyngeal carcinoma were systematically retrieved from databases of SCI (Science Citation Index) from 1999 to 2012, and the data of publishing time, journal title, article type, language, research area, first author, correspondence author, district, and fund, etc were collected and bibliometricly analyzed. Results: An increasing trend of paper publication was detected, corresponding with linear and exponential growth pattern. Journal distribution was accordance with Bradfords' Law; the literatures of nasopharyngeal carcinoma were assembling and parting distribution. The first author and corresponding author with high academic influence are mainly distributed in China (hindex top ten accounts for eight). Besides, the first author distribution conformed to Lotka' s law; whereas, the correspondence author distribution did not. Mainland China, Hong Kong and Taiwan occupied an important position in respect of first author, correspondence author and fund. Conclusion: Nasopharyngeal carcinoma study needs professional journals bearing a larger number of scientific research achievements, and journals run in China, where the Nasopharyngeal carcinoma incidences was reported the highest in the world, may promote the development of this subject. Keywords: Nasopharyngeal carcinoma; Scientific outcome; Bibliometrics; Periodica 
Introduction
Nasopharyngeal carcinoma has unique racial/ethnic and geographic distribution, and is endemic in Southeast Asia, East Africa and Arabia, with China Guangdong province and Hong Kong reporting some of the highest incidences in the world[1,2,3,4].
To understand the research development of nasopharyngeal carcinoma in worldwide, we used the bibliometric methods to retrieve the literatures of nasopharyngeal carcinoma from electronic databases of SCI (Science Citation Index) from 1999 to 2012, which will provide reference for scientific and clinical research.
Methods
Data collection
The SCI (Science Citation Index) published by ISI (Institute for Scientific Information) is a world famous journal and literature retrieving tool.
This article was conducted by retrieving literatures in the electronic reading room of Sun Yatsen University libraries in 4th January, 2014. We chose the online edition of the SCI containing two types of database (SCIExpanded, SCIE and Social Sciences Citation Index, SSCI) as retrieving resources for statistics.
Retrieving terms were as follows:
Topic = (Nasopharyngeal Carcinoma)
Time span = 19942012
Database = SCIEXPANDED, SSCI, CPCIS, CCREXPANDED, IC
Retrieving results: there were 23,383,484 records in total, in which 7,413 records matched the search logic. In addition, by eliminating 1 record of 1994, 1 record of 1996, 2 records of 1997, 737 records of 2013 and 6 records of 2014, finally, 6666 records from 1999 to 2012 were obtained.
Data Analysis
Price's law
Price proposed an exponential interrelated expression in 1963 including the parameters of literature growth and time: N(t)= N_{0}že^{bt}, where N(t) is the literature cumulant at time t, N_{0} is the literature initial cumulant, b is the continuous growth rate of the literature[5]. Given the limitation of the exponential model, scholars proposed many other models subsequently. At present, the growth law of exponential model, linear model and logistic model is only suitable for the development of a subject at a certain time[6]. This article tested whether the literature growth conformed to the exponential model, linear model and logistic model[6,7].
Bradford's Law
British philologist Bradford first proposed experiential law describing literature dispersion pattern in 1934. Its expression is that one core zone and several subsequent zones are divided if the science and technology journals are ranked based on the number of papers in decreasing order and every zone publishes equal papers. Thus, the quantitative relationship between the core journal and the subsequent zones was 1:n:n^{2}...
Bradford's Law , describes how the articles in a specific area are scattered across journals, postulating a model of concentric productivity zones with a decreasing information density[8,9]. Following the proposal of Egghe the Bradford multiplier was obtained by k= (1.781žym)^1/P, where ym is the number of articles published by the most productive journal and P is the number of zones including the nucleus[10,11]. The predicted frequencies were also fitted according to Leimkuhlers formulation , obtaining the constants as A = y0/loge k and B = (k1)/r0, where y0 is the constant number of articles in each group (y0 = a/P, where a is the total number of articles and P is as defined above), k is as defined above and r0 is the expected number of journals in the core (r0 = Tž(k1)/ k^(P1) , where T is the total number of journals, and k and P are as defined above) [12]. Finally, the estimated cumulative number of articles produced by the journals of rank 1, 2, r was obtained by: R(r) = Ažloge(1+ Bžr).
Lotka's law
America scholar A.J. Lotka first proposed Lotka's law, which is also called Inverse square law, representing the scientific productivity in 1920s. It describes the relationship between the number of scientific workers and their papers: the number of authors with two papers is 1/4 of that with one paper; the number of authors with three papers is 1/9 of that with one paper; the number of authors with N papers is 1/n^{2}of that with one paper, although, the number of authors with one paper occupies about 60% of the total authors. This Law is considered firstly to reveal the relationship between the authors and the number of articles.[13]
Lotka's law was applied using the method proposed by Pao, including in the analysis both the first author and coauthors[14, 15]. According to Lotka's law the number of authors (y) with x number of articles is inversely proportional to x. This relationship is expressed by the formula:_{};
where y is the number of authors producing x number of articles in a given research field, and C and n are constants that can be estimated from the observed data set. Although many authors take a value of two as the value of the exponent, as did Lotka in his original paper[13], it is known that the n exponent can vary depending on factors such as the inclusion of coauthors in the analysis or the number of pairs included in the calculation of the exponent[14]. For the present study, the leastsquares method was used to calculate the n exponent, expressed by the formula:
Estimation of the exponent n
The value of n is calculated by the least squaremethod using the following formula:
N = number of pairs of data
X = logarithm of x, i. e. number of monographs
Y = logarithm of y, i. e. number of personal name headings
The leastsquare method is used to estimate the best value for the slope of a regression line which is the exponent n for Lotka's law. The slope is usually calculated without data points representing authors of high productivity. Lotka suggested highly productive authors be considered separately and cuts off his two data sets at the first 17 points for physics and at 30 points for chemistry distribution, his cutoff was determined visually. The best cutoff can be computed also by the following formula: _{}_{, Where }_{}_{is the total sample.}
Since values of the slope change with different number of points for the same set of data, we have made several computations of n. The median or the mean values of n can also be identified as the best slope for the observed distribution. Different values of n produce different values of the constant c.
Calculation of the constant c
For estimate of the constant c, if we accept Lotkas conclusion that the proportion of all authors making a single contribution is about 60%, then the value of c can be computed by the simple formula 6/^{2}. If n equals 2, c is the inverse of the summation of the infinite series: _{} the limit of each equals to ^{2}/6. For other nonnegative fractional values of n, the summation of the series can be approximated by a function calculating the sum of the first P terms. It is found that the error is negligible if P is set to 20.
The value of the constant c is calculated using the following formula:
_{}
KolmogorovSmirnov (KS) test
Pao suggests the KS test, a goodnessoffit statistical test to assert that the observed author productivity distribution is not significantly different from a theoretical distribution[14]. The hypothesis concerns a comparison between observed and expected frequencies. The test allows the determination of the associated probability that the observed maximum deviation occurs within the limits of chance. The maximum deviation between the cumulative proportions of the observed and theoretical frequency is determined by the following formula:
_{}
F_{0}(x) = theoretical cumulative frequency
S_{n}(x) = observed cumulative frequency
The test is performed at the 0.05 or at the 0.01 level of significance. When sample size is greater than 35, the critical value of significance is calculated by the following formula:
The critical value at the 0.05 level of significance: _{}
The critical value at the 0.01 level of significance: _{}
_{}
If the maximum deviation falls within the critical value the null hypothesis that the data set confirms to Lotka's law can be accepted at a certain level of significance. But if it exceeds the critical value the null hypothesis must be rejected at a certain level of significance and concluded that the observed distribution is significantly different from the theoretical distribution[16].
hindex
The hindex is a new bibliometric methods proposed by the American physicist Hirsch. It is an index that attempts to measure both the productivity and citation impact of the published body of work of a scientist or scholar. Hirsch hindex is defined as follows: a scholar with an index of h has published h papers each of which has been cited in other papers at least h times. Hirsch believes that the hindex can accurately reflect a person's academic achievement. The higher hindex means greater academic influence[17]. Many scholars suggest that the hindex is not only a composite measure of the quantity and quality of the paper, but also a very effective indicator to evaluate individual academic achievement[18, 19, 20].
Data analysis was performed using R version 3.0.2.
Results
Distribution of publication year
There were 6666 nasopharyngeal carcinoma related literatures from 1999 to 2012 in an increasing trend with year (Table 1).
Table 1 The literatures distribution from 1999 to 2012
Published year 
Freq(n) 
Cum freq(n) 
Percentage 
1999 
265 
265 
3.98 
2000 
297 
562 
4.46 
2001 
328 
890 
4.92 
2002 
359 
1249 
5.39 
2003 
353 
1602 
5.3 
2004 
439 
2041 
6.59 
2005 
440 
2481 
6.6 
2006 
486 
2967 
7.29 
2007 
482 
3449 
7.23 
2008 
524 
3973 
7.86 
2009 
574 
4547 
8.61 
2010 
624 
5171 
9.36 
2011 
653 
5824 
9.8 
2012 
842 
6666 
12.63 
Table 2 The results of three different fittings
Model 
Fstatistic 
DF 
Pvalue 
Multiple Rsquared 
Adjusted Rsquared 
Exponential 
136.7 
12 
6.462e08 
0.9193 
0.9126 
Linear 
695.1 
12 
5.429e12 
0.983 
0.9816 
Logistic 
48.75 
12 
1.47e05 
0.8025 
0.786 
This author employed the exponential curve, linear curve and logistic curve fittings to verify whether the data conform to Price's law (Table 2). The results showed that the exponential and linear curve fittings were well, and the degree of linear curve fitting was the highest. Linear curve fitting model: N(t)=636.78+481.92^{(t1998)}
Exponential curve fitting model: N(t)=424.7242e^{0.21719(t1998)}
Distribution of source
The above 6666 articles were published in 1147 journals, and each journal published 5.81 articles on average.
The journals were arranged based on the number of published paper from more to less. The Bradford distribution graph of literature was obtained with the abscissa being the logarithm of journal cumulant, and the ordinate being the related literature cumulant.
As shown in the figure 1, the literature distribution was basically fitted with the Bradford's law: Bradford curve was an upward curve firstly, then, bent down after entering the straight part.
Figure 1. The Bradford distribution of literature
Figure 2. The scatter diagram of the authors distribution
According to the Bradford's law, the quantitative relationship among the core zone, related zones and unrelated zones is 1nn^{2}.
k=(e^0.5772*475)^(1/3)=9.4578
r0=1147*(9.45781)/(9.4578^31)=11.4806
a=6666/3/log(9.4578)=988.9452
b=(9.45781)/11.4806=0.7367
R(r)=988.9452*log(1+0.7367*r)
Table 3 The results of Bradfords law
Zone 
Expected number of journals 
Number of journals 
Number of articles 
Cumulative articles 
Estimated k 
R(r) 

1 
11.48 
11 
1633 
1633 
 
2184.266 

2 
108.58 
109 
2698 
4331 
9.91 
4349.531 

3 
1026.94 
1027 
2335 
6666 
9.42 
6556.85 

Table 4 The information of top 11 journals
Source 
Freq 
Percentage 
2012 IF 
INTERNATIONAL JOURNAL OF RADIATION ONCOLOGY BIOLOGY PHYSICS 
475 
7.13 
4.524 
HEAD AND NECKJOURNAL FOR THE SCIENCES AND SPECIALTIES OF THE HEAD AND NECK 
153 
2.3 
2.833 
INTERNATIONAL JOURNAL OF CANCER 
153 
2.3 
6.198 
JOURNAL OF CLINICAL ONCOLOGY 
131 
1.97 
18.038 
RADIOTHERAPY AND ONCOLOGY 
127 
1.91 
4.52 
JOURNAL OF VIROLOGY 
125 
1.88 
5.076 
ORAL ONCOLOGY 
106 
1.59 
2.695 
CANCER 
102 
1.53 
5.201 
CLINICAL CANCER RESEARCH 
95 
1.43 
7.837 
LARYNGOSCOPE 
86 
1.29 
1.979 
ANNALS OF ONCOLOGY 
80 
1.2 
7.384 
From the estimated k value, the average k value was 9.67 (r0=11.48), percentage error was 4.28%, the journal distribution was basically fitted with the Bradford's law (Table 3).
Among which, the journals belonging to the core zone were the top 11 ones, occupying 0.96% of the total journals, and their published papers accounted for 24.50% of all articles (Table 4).
Distribution of document type
According to the type of published articles, there were 11 types of publication. The most were journal articles, and totally 5225, accounting for 78.83%. The second and the third types were the abstract and review, respectively, having 586 and 521 articles, accounting for 8.79% and 7.82%, respectively (Table 5).
Distribution of language
According to the language of literature, there were 11 types. The English language dominated with 6454 articles, accounting for 96.82% (Table 6).
Distribution of research area
According to the research area (one article may be related to several research areas), 89 was detected. Among which, the Oncology was the dominant, possessing 3037 articles, accounting for 45.56%. The second, third, fourth and fifth were Radiology, Nuclear Medicine & Medical Imaging, Otorhinolaryngology, Biochemistry & Molecular Biology and Surgery, respectively (Table 7).
Distribution of first author
Six thousand six hundred and sixtysix research papers of nasopharyngeal carcinoma contained meeting abstracts, books, reprint and other types of literatures. This article only focused on the 5774 journal papers and reviews (24 articles with no author were deleted) to analysis the first author. The result showed that the number of the first author was 4114, distributing in 72 countries and regions in the world. The number of the first author publishing the most articles was 30 (Figure 2). The statistical parameters about the distribution of first author are shown in Table 8.
The calculation of n value:
n=(16*8.963713.8849*17.3027)/(16*14.2880192.7902)=2.7033
The calculation of c value:
c=1/(3.5477^2.7033)+1/((2.70331)*20^(2.70331))+1/(2*20^2.7033)+2.7033/(24*(201)^(2.7033+1)))= 0.7854
Obtained:
y= 0.7854/x^{2.7}
By KS test,
Dmax=0.0160553<1.36/sqrt(4114)=0.02120346<1.63/sqrt(4114)=0.02541297, this was fitted with the Lotkas law curve.
According to the Price's law: m = 0. 794 (Nmax) 0.5, where Nmax is the number of the most productive author publishing articles; m is the number of the lowest productive author in the core authors publishing articles. Then, m was 4.348917, we set m value to 5, this meant the author having 5 or more articles was the productive author in Nasopharyngeal Carcinoma field.
Table 5 The information about the type of published articles
Document type 
Freq 
Percentage 
Article 
4993 
74.90 
Meeting Abstract 
586 
8.79 
Review 
516 
7.74 
Article; Proceedings Paper 
261 
3.92 
Letter 
103 
1.55 
Editorial Material 
96 
1.44 
Proceedings Paper 
70 
1.05 
Correction 
30 
0.45 
Review; Book Chapter 
5 
0.08 
News Item 
3 
0.05 
Article; Book Chapter 
1 
0.02 
BiographicalItem 
1 
0.02 
Reprint 
1 
0.02 
Table 6 The literature distribution according to the language
Language 
Freq 
Percentage 
English 
6454 
96.82 
Chinese 
84 
1.26 
French 
62 
0.93 
German 
41 
0.62 
Spanish 
6 
0.09 
Italian 
5 
0.08 
Japanese 
5 
0.08 
Polish 
4 
0.06 
Portuguese 
2 
0.03 
Turkish 
2 
0.03 
Icelandic 
1 
0.02 









Table 7 The information of top 20 research area
Research areas 
Freq 
Percentage 
Oncology 
3037 
45.56 
Radiology, Nuclear Medicine & Medical Imaging 
1088 
16.32 
Otorhinolaryngology 
682 
10.23 
Biochemistry & Molecular Biology 
555 
8.33 
Surgery 
395 
5.93 
Cell Biology 
343 
5.15 
Research & Experimental Medicine 
340 
5.1 
Pathology 
333 
5 
Virology 
332 
4.98 
Pharmacology & Pharmacy 
239 
3.59 
Genetics & Heredity 
211 
3.17 
Immunology 
207 
3.11 
General & Internal Medicine 
167 
2.51 
Dentistry, Oral Surgery & Medicine 
163 
2.45 
Biophysics 
160 
2.4 
Neurosciences & Neurology 
143 
2.15 
Hematology 
138 
2.07 
Biotechnology & Applied Microbiology 
137 
2.06 
Science & Technology  Other Topics 
117 
1.76 
Chemistry 
95 
1.43 
Table 8 The statistical parameters about the distribution of first author
x = papers 
y = authors 
y/y 
(y/y) 
Ef* 
Ef 
D 
1 
3297 
0.80141 
0.80141 
0.785355 
0.785355 
0.016055 
2 
468 
0.113758 
0.915168 
0.120586 
0.905941 
0.009227 
3 
166 
0.04035 
0.955518 
0.040297 
0.946237 
0.00928 
4 
81 
0.019689 
0.975207 
0.018515 
0.964753 
0.010454 
5 
40 
0.009723 
0.98493 
0.010129 
0.974881 
0.010048 
6 
21 
0.005105 
0.990034 
0.006187 
0.981069 
0.008965 
7 
15 
0.003646 
0.99368 
0.004079 
0.985147 
0.008533 
8 
8 
0.001945 
0.995625 
0.002843 
0.98799 
0.007634 
9 
6 
0.001458 
0.997083 
0.002068 
0.990058 
0.007025 
10 
4 
0.000972 
0.998055 
0.001555 
0.991613 
0.006442 
11 
2 
0.000486 
0.998542 
0.001202 
0.992815 
0.005726 
13 
2 
0.000486 
0.999028 
0.000765 
0.99358 
0.005447 
14 
1 
0.000243 
0.999271 
0.000626 
0.994207 
0.005064 
16 
1 
0.000243 
0.999514 
0.000437 
0.994643 
0.004871 
22 
1 
0.000243 
0.999757 
0.000185 
0.994828 
0.004929 
30 
1 
0.000243 
1 
7.98E05 
0.994907 
0.005093 
The number of the first author publishing 5 or more articles was 102, accounting for 2.48% of the total first authors, and published 719 articles, accounting for 12.45% of the total articles. The authors from Hong Kong, Taiwan and Peoples'Republic of China account for 71.22% of the first authors publishing 5 or more articles (Table 9.1, Table 9.2 and Table 10).
Distribution of correspondence author
Six thousand six hundred and sixtysix research papers of nasopharyngeal carcinoma contained meeting abstract, book, reprint and other types of literatures. This article only focused on the 5715 journal papers and reviews (62 without author were deleted) to analyze the correspondence author. The result showed that the number of the correspondence author was 3129, distributing in 79 countries and regions in the world. The number of the correspondence author publishing the most articles was 56 (Figure 3). Table 11 showed statistical parameters about the distribution of correspondence author. Table 12.1 and Table 12.2 showed the information of top10 reprint authors.
Table 9.1 The information about top10 first authors
First author 
Organization 
District 
Freq 
Percentage 

Chua, DTT (Chua, Daniel T. T.) 
University of Hong Kong 
Hong Kong 
30 
0.52 

Lee, AWM (Lee, Anne W. M.) 
Pamela YoudeNethersole Eastern Hospital 
Hong Kong 
22 
0.38 

King, AD (King, Ann D.) 
Chinese University of Hong Kong 
Hong Kong 
16 
0.28 

Chan, ATC (Chan, Anthony T. C.) 
Chinese University of Hong Kong 
Hong Kong 
14 
0.24 

Chong, VFH (Chong, V. F. H.) 
National University of Singapore 
Singapore 
13 
0.23 

Ma, BBY (Ma, Brigette B. Y.) 
Chinese University of Hong Kong 
Hong Kong 
13 
0.23 

Lee, NY (Lee, Nancy Y.) 
Memorial Sloan Kettering Cancer Center 
USA 
11 
0.19 

Lin, JC (Lin, JinChing) 
Taichung Veterans General Hospital 
Taiwan 
11 
0.19 

Ahuja, AT (Ahuja, AT) 
Chinese University of Hong Kong 
Hong Kong 
10 
0.17 

Chang, KP (Chang, KaiPing) 
Chang Gung Memorial Hospital 
Taiwan 
10 
0.17 

Table 9.2 The information about top10 districts of first authors
First author district 
Freq 
Percentage 

Peoples R China 
1183 
20.49 

USA 
925 
16.02 

Hong Kong 
655 
11.34 

Taiwan 
582 
10.08 

Japan 
275 
4.76 

Singapore 
178 
3.08 

England 
164 
2.84 

Germany 
158 
2.74 

Canada 
114 
1.97 

Italy 
114 
1.97 

* This contained 14 articles without author district record.
The calculation of n value:
n=(31*16.012435.1223*23.0789)/(31*44.95021233.5784)=1.9652
The calculation of c value:
C = 1/(3.5477^1.9652)+1/((1.96521)*20^(1.96521))+1/(2*20^1.9652)+1.9652/(24*(201)^(1.9652+1)))=0.5957
Obtained:
Y = 0.5957/x^{1.9652}
By KS test,
Dmax = 0.160809>1.63/sqrt (3199) = 0.0288191>1.36/sqrt (3199) = 0.02404539, this was not fitted with the Lotkas law curve.
^{ }
Table 10 The information about districts of first authors*
First author district 
Freq 
Percentage 

Hong Kong 
253 
35.19 

Taiwan 
134 
18.64 

Peoples R China 
125 
17.39 

USA 
49 
6.82 

Singapore 
44 
6.12 

Japan 
25 
3.48 

Tunisia 
12 
1.67 

Canada 
10 
1.39 

Italy 
10 
1.39 

Netherlands 
10 
1.39 

England 
8 
1.11 

Greece 
7 
0.97 

Turkey 
7 
0.97 

Denmark 
6 
0.83 

Belgium 
5 
0.7 

Morocco 
5 
0.7 

Indonesia 
4 
0.56 

France 
1 
0.14 

Saudi Arabia 
1 
0.14 

Wales 
1 
0.14 

No record 
2 
0.28 

*: This contained 2 articles without author district record.
Table 11 Statistical parameters about the distribution of correspondence author
x = papers 
y = authors 
y/y 
(y/y) 
Ef* 
Ef 
D 
1 
2420 
0.756486 
0.756486 
0.595677 
0.595677 
0.160809 
2 
376 
0.117537 
0.874023 
0.152551 
0.748229 
0.125795 
3 
156 
0.048765 
0.922788 
0.068763 
0.816992 
0.105797 
4 
75 
0.023445 
0.946233 
0.039068 
0.856059 
0.090174 
5 
47 
0.014692 
0.960925 
0.025198 
0.881258 
0.079668 
6 
26 
0.008128 
0.969053 
0.01761 
0.898868 
0.070185 
7 
18 
0.005627 
0.97468 
0.013007 
0.911875 
0.062805 
8 
18 
0.005627 
0.980306 
0.010005 
0.92188 
0.058426 
9 
7 
0.002188 
0.982495 
0.007938 
0.929818 
0.052677 
10 
4 
0.00125 
0.983745 
0.006453 
0.936271 
0.047474 
11 
7 
0.002188 
0.985933 
0.005351 
0.941622 
0.044311 
12 
7 
0.002188 
0.988121 
0.00451 
0.946132 
0.041989 
13 
6 
0.001876 
0.989997 
0.003853 
0.949985 
0.040012 
14 
1 
0.000313 
0.990309 
0.003331 
0.953316 
0.036993 
15 
4 
0.00125 
0.99156 
0.002909 
0.956225 
0.035335 
16 
2 
0.000625 
0.992185 
0.002562 
0.958787 
0.033398 
17 
3 
0.000938 
0.993123 
0.002275 
0.961062 
0.032061 
18 
2 
0.000625 
0.993748 
0.002033 
0.963095 
0.030653 
19 
3 
0.000938 
0.994686 
0.001828 
0.964923 
0.029763 
20 
1 
0.000313 
0.994998 
0.001653 
0.966575 
0.028423 
21 
2 
0.000625 
0.995624 
0.001502 
0.968077 
0.027547 
22 
2 
0.000625 
0.996249 
0.00137 
0.969447 
0.026802 
24 
2 
0.000625 
0.996874 
0.001155 
0.970602 
0.026272 
25 
3 
0.000938 
0.997812 
0.001066 
0.971668 
0.026144 
30 
1 
0.000313 
0.998124 
0.000745 
0.972413 
0.025711 
36 
1 
0.000313 
0.998437 
0.000521 
0.972934 
0.025503 
37 
1 
0.000313 
0.99875 
0.000493 
0.973427 
0.025323 
41 
1 
0.000313 
0.999062 
0.000403 
0.97383 
0.025232 
42 
1 
0.000313 
0.999375 
0.000385 
0.974215 
0.02516 
51 
1 
0.000313 
0.999687 
0.000263 
0.974477 
0.02521 
56 
1 
0.000313 
1 
0.000218 
0.974696 
0.025304 
Distribution by hindex
According to the literature of the first author, a total of 423 people have at least one literature cited not less than once. Among them, the highest hindex is 15, with an average of 1.571.35 (Table 13.1 and Table 13.2).
According to the literature of the corresponding author, a total of 357 people have at least one literature cited not less than once. Among them, the highest hindex is 25, with an average of 2.012.58 (Table 14.1 and Table 14.2).
Distribution by funding
In 6666 Nasopharyngeal Carcinoma articles, 1515 obtained funding, accounting for 22.72%, and the average of each literature obtained 2.42 project funding (Table 15). Classification and statistics according to the district of the correspondence author, 48 countries and regions obtained funding (Table 16). Among which the Peoples'Republic of China literatures obtaining funding was the most, a total of 629 literatures obtained funding, accounting for 41.57% of the total literatures obtaining funding (Table 17).
Table 12.1 The information of top10 reprint authors
Reprint author 
Organization 
District 
Freq 
Percentage 
Li, GY (Li, GuiYuan) 
Central South University 
Peoples R China 
56 
0.98 
Zeng, YX (Zeng, YiXin) 
Sun Yat Sen University 
Peoples R China 
51 
0.89 
Cao, Y (Cao, Ya) 
Central South University 
Peoples R China 
42 
0.73 
RaabTraub, N (RaabTraub, Nancy) 
University of North Carolina Chapel Hill 
USA 
41 
0.72 
Chan, ATC (Chan, Anthony TakCheung) 
Chinese University of Hong Kong 
Hong Kong 
37 
0.65 
Liu, FF (Liu, FeiFei) 
University of Toronto 
Canada 
36 
0.63 
Lung, ML (Lung, Maria Li) 
University of Hong Kong 
Hong Kong 
30 
0.52 
Chua, DTT (Chua, Daniel T. T.) 
University of Hong Kong 
Hong Kong 
25 
0.44 
Lo, YMD (Lo, Y. M. Dennis) 
Chinese University of Hong Kong 
Hong Kong 
25 
0.44 
Yao, KT (Yao, KaiTai) 
Southern Medical University  China 
Peoples R China 
25 
0.44 
Table 12.2 The information of top10 districts of reprint authors
Reprint author district 
Freq 
Percentage 

Peoples R China 
1236 
21.63 

USA 
935 
16.36 

Hong Kong 
660 
11.55 

Taiwan 
631 
11.04 

Japan 
272 
4.76 

Singapore 
191 
3.34 

England 
175 
3.06 

Germany 
157 
2.75 

Italy 
141 
2.47 

France 
134 
2.34 

Discussion
1) Nasopharyngeal carcinoma has gradually become a mature subject, needing special journals to publish abundant outcomes of studies in this area, which continues to promoting the development of scientific researches of nasopharyngeal carcinoma.
Based on our analysis, the number of literatures from 1999 to 2012 presented the exponential and linear growth pattern, and is quite similar with the second and third periods of science and technology journal growth process. When in the second period, the professional theory develops rapidly, the number of the literatures increases dramatically and gradually enters into a relatively stable exponential growth phase. In the third period, with the increasingly mature of the subject, the literature growth slows down, and gradually evolves into a linear growth phase, maintaining a stable increment of literature.
According to the increase of nasopharyngeal carcinoma article and linear and exponential curve fitting situation, the current nasopharyngeal carcinoma article is in the second, third periods of article growth, which means the number of article is double every 4 years or increases by 481 papers annually.
Table 13.1 Hindex of first authors

n 
mean 
sd 
min 
q25 
q50 
q75 
max 
hindex 
423 
1.572104 
1.357401 
1 
1 
1 
2 
15 
Table 13.2 Top10 hindex of first authors
First author 
hindex 
district 
Lee, AWM (Lee, Anne W. M.) 
15 
Hong Kong 
Lin, JC (Lin, JinChing) 
10 
Taiwan 
Ma, BBY (Ma, Brigette B. Y.) 
10 
Hong Kong 
Ahuja, AT (Ahuja, AT) 
8 
Hong Kong 
Hao, SP (Hao, ShengPo) 
6 
Taiwan 
Leung, TW (Leung, ToWai) 
6 
Hong Kong 
Lu, CC (Lu, ChihChung) 
6 
Taiwan 
Qian, CN (Qian, ChaoNan) 
6 
USA 
Tsai, MH (Tsai, MH) 
6 
Taiwan 
Yoshizaki, T (Yoshizaki, Tomnokazu) 
6 
Japan 
Table 14.1 Hindex of reprint authors

n 
mean 
sd 
min 
q25 
q50 
q75 
max 
hindex 
357 
2.005602 
2.576901 
1 
1 
1 
2 
25 
Table 14.2 Top10 hindex of reprint authors
Reprint author 
hindex 
district 
RaabTraub, N (RaabTraub, Nancy) 
25 
USA 
Zeng, YX (Zeng, YiXin) 
19 
Peoples R China 
Li, GY (Li, GuiYuan) 
16 
Peoples R China 
Lee, AWM (Lee, Anne W. M.) 
15 
Hong Kong 
Lo, KW (Lo, KwokWai) 
14 
Hong Kong 
King, AD (King, Ann D.) 
12 
Hong Kong 
Young, LS (Young, Lawrence S.) 
12 
England 
Zhang, L (Zhang, Lin) 
10 
Peoples R China 
Ma, BBY (Ma, Brigette B. Y.) 
9 
Hong Kong 
Yao, KT (Yao, KaiTai) 
9 
Peoples R China 
Table 15 The funding number of papers

Mean 
Std 
Median 
Min 
Max 
Funding number 
2.422442 
1.627788 
2 
1 
12 
Table 16 The information of top10 district of funding
Reprint district 
freq 
percentage 
Peoples R China 
629 
41.57 
USA 
176 
11.63 
Taiwan 
168 
11.1 
Hong Kong 
134 
8.86 
Japan 
38 
2.51 
Canada 
34 
2.25 
England 
30 
1.98 
Netherlands 
28 
1.85 
Malaysia 
23 
1.52 
Italy 
22 
1.45 
Table 17 The distribution of funding by year in top 5 district
Publised year 
Peoples R China 
USA 
Taiwan 
Hong Kong 
Japan 
2006 
 
 
 
1 
 
2007 
1 
1 
 
 
 
2008 
27 
10 
13 
10 
2 
2009 
90 
41 
37 
17 
7 
2010 
119 
42 
35 
35 
10 
2011 
155 
40 
43 
31 
7 
2012 
237 
42 
40 
40 
12 
The impact factor of core journals based on Bradfords Law ranges from 1.979 to 18.038, of which the published papers account for 24.50% of the total articles, suggesting the quality of nasopharyngeal carcinoma articles has been in a relatively high level.
The literature research areas, currently, are as many as 89 types, among which, the Oncology is the dominant, possessing 3037 papers, accounting for 45.56% of the total articles. The research direction not only has breadth, but also has depth.
Figure 3. The distribution of correspondence author
In the aspect of author distribution, the first author distributed in 72 countries and regions in worldwide; the correspondence author distributed in 79 countries and regions around the world. The nasopharyngeal carcinoma research has spread all over the world.
The above data show that, with the continuous development of the nasopharyngeal carcinoma research in the word, a large number of scientific research achievements need special journals to bear. Academics need such a platform; full discussion and a certain degree of thought collision consensus will promote the development of this subject, especially in SCI, the wellknown global search data platform.
2) The nasopharyngeal carcinoma research mainly focuses on China, so running journals in China will promote a better development of this subject.
On the one hand, in respect of the distribution of the first and correspondence authors, the nasopharyngeal carcinoma researchers mainly concentrate in China including Hong Kong and Taiwan. The number of the first author in China publishing nasopharyngeal carcinoma related articles accounts for 41.91% of the totality; the number of the correspondence author in China accounts for 44.22% of the totality. Additionally, the productive first author is also mainly in China, accounting for 71.22% of the total productive authors. The first author and corresponding author with high academic influence are mainly distributed in China (hindex top ten accounts for eight).
On the other hand, the number of Chinese correspondence authors obtaining funding accounts for 61.53% of the financial aid articles, which is much more than other countries and regions. There is an important relationship with a large number of science and technology project investments of Chinese areas in recent years. On this background, it directly or indirectly promotes the prosperity development of related research in Chinese areas.
To run professional journals of nasopharyngeal carcinoma in China can be more conducive to timely contact authors and obtain the latest research progress. Ultimately, it can timely publish the Chinese research achievements world widely, and to promote the development of this subject.
3) Limitation of the study
(1) This retrieval was made only by the subject words Nasopharyngeal Carcinoma, not contained any other Nasopharyngeal Carcinoma related keywords, the search results may exist deviation.
(2) Due to author name may be not unique in the SCI database, the disunity of author name, author name inputting error and correction error in the process of data collection, the statistical result deviation may exist in the analysis of number of author articles, author area and so on.
(3) Because of the timelag effect of the SCI database, there was a big difference between the retrieved and the practical articles of 2013. Hence, this study did not include the data of 2013.
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