{'fraction_non_alphanumeric': 0.027544120072571333, 'fraction_numerical': 0.024657760184727033, 'mean_word_length': 5.20306905370844, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 2, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Cited Brazilian papers in general surgery between 1970 and 2009

OBJECTIVES To identify the most cited articles in general surgery published by Brazilian authors. INTRODUCTION There are several ways for the international community to recognize the quality of a scientific article. Although controversial, the most widely used and reliable methodology to identify the importance of an article is citation analysis. METHODS A search using the Institute for Scientific Information citation database (Science Citation Index Expanded) was performed to identify highly cited Brazilian papers published in twenty-six highly cited general surgery journals, selected based on their elevated impact factors, from 1970 to 2009. Further analysis was done on the 65 most-cited papers. RESULTS We identified 1,713 Brazilian articles, from which nine papers emerged as classics (more than 100 citations received). For the Brazilian contributions, a total increase of about 21-fold was evident between 1970 and 2009. Although several topics were covered, articles covering trauma, oncology and organ transplantation were the most cited. The majority of classic studies were done with international cooperation. CONCLUSIONS This study identified the most influential Brazilian articles published in internationally renowned general surgery journals.


INTRODUCTION
A central aspect of general surgery is the diversity of topics and domains. General surgery has become one of the most well-known medical specialties. At present, general surgery boasts remarkable developments and refinements in basic science, diagnosis and treatment that have transcended abdominal organs, touching neighboring and more distal branches of medicine. Advances in scientific surgical research have benefited the care of men and women of all ages.
A scientific article's impact is established over time. Because publications inspire future articles, a paper's scientific impact can be measured in terms of the number of citations received. 1 Increasing numbers of scientific papers in the Internet era have provided diverse information. The frequency of citations serves as a rough guide to the importance of an article. The impact factor (IF) is now generally used to measure the prestige of journals, the influence of articles published in those journals and, by extension, the authors, institutions and countries. 2 In Brazil, the national agency (CNPQ) dedicated to promoting scientific and technological research has used the IF as an indicator of the national research output and to define investment priorities. 3 In this paper, our goal was to identify the most frequently cited articles published by Brazilian authors in the most-cited international journals dedicated to general surgery. We aimed to provide an opportunity to recognize key historical advances and the evolution of surgery research in Brazil.

MATERIALS AND METHODS
To identify the most frequently cited Brazilian papers published in general surgery journals, we accessed the Thompson Web of Knowledge database (Institute for Scientific Information -ISI). 4 Inclusion criteria included articles with at least one Brazilian author and published in the 26 highly cited journals in the field of general surgery. These journals were selected based on their 2008 impact factor (Journal Citation Report). The search was limited to the period between January 1970 and June 2009.
The articles were identified and analyzed with respect to their authors, institution, year of publication, number of citations and topics.
An additional analysis was performed for articles that received more than 30 citations.

RESULTS
Of the 208,168 articles included in the study, 1,713 (0.8%) were published by Brazilian authors. Nine were cited over 100 times, and these were considered classics. 5 The 26 screened journals are listed in Table 1. Analyzing the ranking of each country's contributions, Brazilian authors achieved the 19 th overall position.
Brazilian contributions to those journals are listed by decades and presented in Table 2. Regarding Brazil's overall contribution, a rising curve was evident, with Brazil climbing from the 34 th position (0.07%) in the seventies to the 13 th position in the 2000s (1.47%). Figure 1 shows the number of Brazilian papers published in each year since 1970.
Because only nine Brazilian articles reached the classic denomination (article with more than 100 citations), we Topics covered by the "Brazilian Top 65" included oncology, transplantation, trauma and critical care, as listed in Table 4. Other topics were identified in this list, including gastrointestinal endoscopy and dentistry. The topics most frequently covered by the top 65 articles were shock and kidney transplantation at 10 articles each (15.3%), followed by colorectal tumors in 9 (13.8%) articles. Nineteen (29.2%) articles covered themes related to oncology. The second most heavily cited theme was trauma/critical care and organ transplantation, accounting for 15/65 (22.9%) articles each. Aside from these principal categories, bariatric surgery and GI endoscopy were covered in 4/65 (6.1%) papers each ( Table 4).
The 30 most-cited articles are presented in Table 5. The range of citations varied from 49 to 194, with an average of 85 citations per article. International collaboration was relevant since the earliest article to make the list, published in 1984 by       (Table 6).

DISCUSSION
Eventually, all surgical specialties are dependent on general surgery. General surgery is a discipline encompassing clinical knowledge, operative techniques and scientific foundations, including wound healing, infection, metabolism, immunology, shock and resuscitation.
In this paper, we recognized articles that were published in the most cited general surgery journals, had at least one author with a Brazilian affiliation, were identified in the ISI Web of Knowledge database and were published during a 39-year period (1970 to 2009). In total, 1,713 items were published by Brazilian authors from more than 100 institutions. It is worth mentioning that 555 papers received 5,556 citations during this period. Therefore, 1,158 (67.6%) articles remained uncited. In fact, approximately one half of all published medical articles are never subsequently cited.
A limitation of our results is that we have no information on citations in journals not covered by the ISI bibliometric database. Undoubtedly, the results of this citation analysis could be different if more Latin American scientific journals were listed in the ISI Web of Knowledge or if another citation database, such as SCOPUS, had been selected. Another aspect that must be taken into consideration is that, until recently, only articles published in English were considered by the JCR.
The 26 screened journals were the periodicals dedicated to general surgery with the highest impact factor. These international journals receive contributions from all over the world, publishing milestone publications in experimental and clinical surgery.
Although English is not the native language in Brazil, our country has an established place in the general surgery literature. Nowadays, Brazilian authors have the 19 th overall position in terms of the number of papers published in these renowned journals. The contribution of papers from Brazilian authors in these journals is encouraging, as the proportion of the global total increased by about 21-fold, from 0.07% in the 1970s to 1.47% in the 2000s. Nonetheless, Brazil is behind small developing countries, such as Taiwan, and it just recently surmounted Turkey. The overwhelming supremacy of United States was evident, as the United States was the top contributing country in 23 of 26 screened journals, publishing more than 52% of all papers.
In the 2000s, Brazil occupied the 13 th overall position. In our point of view, this ascension can be partially attributed to the support of the Brazilian National Council, which is dedicated to promoting science in our country. In addition, more international exchange opportunities, widespread use of the internet and more surgeons dedicated to basic and clinical research could be responsible for the rising curve of publications over the years. 9 However, the English language can be a barrier, and other types of biases (bias towards nationality) can influence the approval rate. 2 We recognize that the SciELO (Scientific Electronic Library Online) database increased the visibility of Brazilian medical literature during the past decade. The SciELO will probably also contribute to increasing the impact of national journals devoted to surgery. Specific topics were highlighted in different decades. These data reflect, at least in part, the evolution of a specific surgical area. For example, a better comprehension of the physiology of obesity, transplantation and laser therapy resulted in great amounts of new information and motivated the establishment of new journals. Our study shows that many Brazilian papers are devoted to these Interestingly, international collaboration and multicenter trials seem to be needed for a paper to be highly cited because 7 of the 9 classics (> 100 citations) have authors from different countries. In the 1980s, 9/71 (12.6%) articles had inter-institutional collaboration. In the 1990s, 32/182 (17.1%) articles published by Brazilian authors had this characteristic, and after 2000, 185 of 1441 (12.8%) articles had international collaboration. Eighteen of the top 30 Brazilian articles were inter-institutional. In the top 65 articles (>30 citations), the United States was the country whose investigators most frequently collaborated with Brazilian authors (18/65; 27.7%).
General surgery is a heterogeneous medical specialty, covering different areas in men and women's health, basic science, clinical practice and operative techniques. The list of the top-cited articles covers some of the hottest topics in surgery today, such as surgical oncology, minimally invasive approaches and organ transplantation. In the 7 th most cited article, Habr-Gama et al. (USP) reviewed the complications of GI endoscopy. The same group addressed the use of radiotherapy and chemotherapy in low rectal cancer (10 th ) and more recently published two articles reporting the long-term results of operative treatment for rectal cancer following chemotherapy (14 th and 60 th ).
Although our search included the 26 most-cited general surgery journals, we are aware that restricting our search to these journals is a limitation of the present study. Some of the most cited Brazilian papers were published in more specific or general journals; these include the description of the "Jatene procedure" for the correction of transposition of the great arteries, which was published in the Journal of Thoracic and Cardiovascular Surgery in 1976; the use of hypertonic NaCl for the treatment of severe hemorrhagic shock, which was published in the American Journal of Physiology in 1980; and the first description of liver transplantation from a living donor, which was published by Raia et al. in 1989 in the Lancet. These articles have been cited 243, 258 and 262 times, respectively. [13][14][15] This analysis highlighted the academic influence and popularity of southeast institutions. Historically, Sao Paulo institutions provided financial and technological support for research. For decades, the University of Sao Paulo -Hospital de Clinicas has been the top published institution. However, highly contributing institutions are now also based in other states, such as Rio de Janeiro, Rio Grande do Sul, Minas Gerais and Parana.

CONCLUSIONS
In recent years, citation analysis, although imperfect, has become common and is considered to be the currency of journal prestige. The selected journals have always attracted the submission of advances and landmark articles in general surgery. This study is an opportunity to remember the mostcited Brazilian articles and to learn from distinguished Brazilian surgeons, recognizing the remarkable impact that these visionaries have had in national surgery.