INTRODUCTION
Scholarly or scientific publications are the life blood of science (Hofman et al., 2009) . Tijssen (2007) asserted that peer-reviewed scholarly and professional journals are one of the very few internationally comparative sources of information on scientific outputs. Uthman and Uthman, (2007) stated that scholarly publications play an important role in scientific process by providing a key linkage between knowledge production and use. They are vital for knowledge sharing, dissemination of research findings and career advancement of academics. Thus, publishing in scientific journals is the most common and powerful means to disseminate new research findings (Sigoneau, 2000) . www.sljbr.com Owolabi et al. (2007) opined that scientific productivity is measured by its contribution to the body of knowledge. Although, the big and populous African countries namely South Africa, Egypt and Nigeria are the top producers of scientific publications in Africa, Rahman and Fukui (2003) noted that the decline in publications in biomedicine since the 1990s is an Africa-wide experience. Africa lags behind other regions of the world in scientific research and needs large investment to catch up with other developing countries such as India and Brazil. However, South Africa has consistently produced more biomedical research output than other African countries (Uthman and Uthman, 2007; Tijssen, 2007; Hofman et al., 2009 ).
INTRODUCTION
An examination of scientific publications can aid in determining research priorities within a country and results of such studies may be useful to policy makers in research administration, planning and collection development in libraries (Jacobs, 2001 ). Access to the contents of African journals is provided in part by the international bibliographic databases: African Index Medicus (AIM), EMBASE, MEDLINE/Pubmed, Scopus, and Web of Science (Gaillard, 1992) A number of bibliometric studies have examined scientific publications in sub-Saharan Africa as a whole (Arvantis et al., 2000; Hassan, 2001; Uthman et al., 2007; Tijssen, 2007; Hofman et al., 2009 ) and specific African countries including Malawi (Gondwe et al., 2008) , Libya (Bakoush et al., 2007) and Egypt (Afifi, 2007) . The results of these studies showed that scientific research in Africa is going through a crisis and that national scientific communities in these countries are struggling to sustain their activities. The challenges include poor infrastructure, poverty and political instability (Ondari-Okemwa, 2007) .
INTRODUCTION
In Nigeria, health researches have focused mainly on communicable and tropical diseases such as malaria, HIV/ AIDS, Tuberculosis, Onchocerciasis, Trachoma, Meningitis, Hepatitis B and C, Respiratory infections, Nutritional conditions, Maternal and prenatal conditions (Lopez et al., 2006) . Nigerian researchers have also paid attention to non-communicable diseases especially cancer (Ntekim et al., 2009) , hypertension (Okehialam, 2011; Adebiyi et al., 2011) , stroke (Ekenze et al., 2010; Desalu et al., 2011a) diabetes (Desalu et al., 2011b; Kuti et al., 2011) . These researches take place within an environment of economic constrains as in many other sub-Saharan African countries. (Uthman and Uthman, 2007; Tijssen, 2007; Ondari-Okemwa, 2007; Uthman, 2008) . Thus, it is important to carry out an assessment of Nigerian scholarly publications in order to determine research priorities in biomedical/health sciences in the country. Also, the result of this study will be useful to policy makers in research administration and to librarians for collection development in libraries.
INTRODUCTION
Although, a number of bibliometric studies (Nwagwu, 2005; Nwagwu, 2006; Nwagwu, 2007) are available that investigated the publication output of Nigerian biomedical researchers. These studies essentially covered publication output and authorship patterns in Nigerian biomedical literature. To the best of our knowledge, there is no single, comprehensive bibliographic database that indexes the scientific articles produced in Nigeria.
INTRODUCTION
There is a dearth of information on scholarly publication output of Nigerian health sciences researchers, the specific national and regional journals in where the articles were published and the publication types. Although, some scholars have documented data on biomedical research output of Nigerian authors from earlier years, this communication sought to fill the knowledge gap between 1996 to 2007 by assessing the scholarly publications of Nigerian health sciences' researchers in scientific journals accessible through MEDLINE/PubMed and the journals where they publish.
METHODOLOGY

Setting of the study
Nigeria has a population of 140 million (NPCN, 2011) , making it the most populous country in Africa.
Setting of the study
The country is endowed with rich natural resources, of which oil and gas have been the mainstay of the economy in the last few decades, providing 20% of GDP, 95% of foreign exchange earnings, and about 65% of budgetary revenues (WaterAid International, 2011) . Despite the natural and human resources Nigeria is endowed with, the country has a huge disease burden including communicable and non-communicable diseases (Lopez et al.,, 2006) .
Data Collection
For the publication output of Nigerian health sciences researchers, we obtained data by searching MEDLINE/PubMed, the premier bibliographic database of the National Library of Medicine, Bethesda, Maryland, USA. MEDLINE indexes over 5,000 medical journals worldwide and is freely accessible to all around the globe. Data collection (searches) for this study was done during the months of May and June 2008.
Search Strategy
To determine the growth trend in publication output for each year of the 12-year period: search strategies were developed using the author affiliation in the Address field combined with the Publication Date field in MEDLINE/PubMed. This was repeated for the remaining three publication types: Meta analysis, Randomized Controlled Trial, and Histories. In addition to collecting data for scholarly publications of Nigerian health sciences researchers in African journals, data were elicited from four major international journals, namely Journal of American Medical Association (JAMA), New England Journal of Medicine (NEJM), British Medical Journal (BMJ) and Lancet. These four journals were selected because they are multidisciplinary in nature, widely distributed and have high impact factor (Journal Citation Reports, 2008) .
Data Management and Analysis
The retrieved publications were changed to MEDLINE display format and imported into Endnote bibliographic management software. The data were sorted and duplicate citations were removed. The remaining citations were then exported into Microsoft Excel for analysis. The data were analyzed using frequency counts, percentages, and presented in charts and on tables. 
RESULTS

Number and types of publications

Publication output in Nigerian Journals
As at 2008 when the study was conducted, nine Nigerian medical/health journals were indexed in MEDLINE. The publication output of Nigerian health sciences' researchers in these journals is shown in 
DISCUSSION
The output of Nigerian health researchers increased substantially during the 12 year period covered by this study. A similar trend was observed in two previous studies among African biomedical researchers (Uthman and Uthman, 2007; Hofman et al., 2009) . With the exception of South Africa, the output of Nigerian researchers is higher compared to those of biomedical researchers from other subSaharan Africa countries (Hofman et al., 2009) . Among countries in sub-Saharan Africa, Nigeria ranked second (16%) with respect to number of scholarly publications while South Africa was at the top of the list with 40% of the output (Uthman, and Uthman, 2007) . The possible explanation for the consistent increase observed in publication output of Nigerian researchers may be due to the efforts being put into scholarly publication for visibility among peers and career advancement (Ajao and Lawoyin, 2005) . Also, the number of private and state owned universities in the country has increased substantially within the last decade (NUC, 2011) . This may explain the increase in the number of those holding academic positions who require publications in scholarly journals for career advancement.
DISCUSSION
A substantial number (31%) of articles published by Nigerian researchers appeared in African Journal of Medicine and Medical Sciences (AJMMS) . This may be a reflection of the fact that the subject of their investigation is more appropriate to the local environment and as such, the manuscripts are more relevant to the Nigerian audience. In addition, being a multidisciplinary journal, provides a platform for both behavioural and health science researchers to disseminate their research findings. The fact that this journal is owned by a premier university in Nigeria with a sizable number of researchers may also be a contributing factor to its success in attracting authors. However, most of Nigerian health sciences journals are in print with only abstracts appearing in bibliographic databases. Excluding Nigerian journals, EAMJ tops the list of African journals in which Nigerian researchers published their research findings. One of the reasons for EAMJ featured popularity is that it has remained continuously in publication for over 70 years. In addition, it is published monthly making it one of the most reliable journals on the continent. , 2011) . This has encouraged more Nigerians to publish in AHS despite the fact that it is a relatively young and upcoming journal. Publication in this journal creates high visibility for authors whose work is accessible to scholars around the world. This is one of the advantages of Public or Free Access journals, a category the AHS has now joined through African Journal Partnership Project, an initiative funded by the National Library of Medicine (Goehl and Flanagin, 2008) .
DISCUSSION
The number of publications by Nigerian health sciences researchers in the "big four" multidisciplinary international journals is low (17 citations) compared to those of their counterparts in developing countries such as Colombia (Nelson and De la Hiz-Restrepo, 2003) . While Nigerian health researchers published more than one-third (31%) of their papers in national journals, their Colombian counterparts have most publications in international journals, that are indexed in the major bibliographic databases (Nelson and De la HizRestrepo, (2003) . Like their counterparts in other sub-Saharan African countries, Nigerian researchers operate in a difficult environment where the basic infrastructures for research including laboratories are limited and power (electricity) cut is frequent. Unfortunately, these studies have had limited impact on public health because their conclusions and recommendations are rarely used for policy development.
DISCUSSION
Good quality research that brings about scientific breakthroughs requires huge financial investments which is lacking in Nigeria. Many Nigerian researchers fund their studies out of pocket, thus limiting the scope and rigour of their investigation.
DISCUSSION
Only a few Nigerian health sciences researchers published Clinical Trials and Review articles. This is similar to findings of a previous study by Ben Abdellaziz et al. (2000) on Tunisian Biomedical Journals in which Review articles and Clinical Trials constitute 3.4% and 6.9% of the citations respectively. The possible explanation is that clinical trial research involves huge capital and in most cases requires external funding through a competitive grant application. Although some research projects involving Nigerian researchers and their collaborators from the Western world are clinical trials, the principal investigators are usually their Western collaborators who appear as the first author when the results are published. However, these studies may not be easily identifiable as involving Nigerian researchers because affiliation is often retrievable only for first authors in MEDLINE databases.
DISCUSSION
Although, we have been able to provide useful information on the publication output of Nigerian health sciences researchers and the national and regional journals where they published, the study has some limitations. Only publications by Nigerian authors in journals indexed in MEDLINE/PubMed were investigated. MEDLINE is a major bibliographic database; does not index all journals and is not the only one available. In addition, the MEDLINE database has the limitation of including only the affiliation of the first author of an article. Furthermore, the coverage of Nigerian literature is limited in MEDLINE/PubMed because only nine Nigerian journals are indexed. More importantly, the use of bibliographic databases is not the only means of determining researchers' output in scientific journals and search strategy used in this study did not cover author institutional affiliation and city names as practices vary among journals in the form of address published.
CONCLUSION
Despite numerous constrains, Nigerian researchers are productive with regards to scholarly publications. The number of their publications increased substantially over the past decade. Some of the publications of the researchers were in Nigerian journals most of which are in print format with limited circulation and impact. We recommend the development of national bibliographic database to index articles published in Nigeria journals and also publication of electronic equivalent of the journals.

{'paper_id': '72143381', 'title': 'Assessment of Scholarly Publications of Nigerian Health Sciences Researchers in MEDLINE/PubMed (1996-2007)', 's2_url': 'https://api.semanticscholar.org/CorpusID:72143381', 'source': 'S2ORC'}