PubMed is an open access database indexing literature in the biomedical sciences, a combined production of the National Center for Biotechnology Education (NCBI), the National Library of Medicine (NLM) and the National Institutes of Health (NIH). The National Institutes of Health is the largest research centre for biomedical sciences in the world. The NCBI, one of its collective units, is the national resource for molecular biology information, with a mission to develop new information technologies to aid fundamental molecular and genetic processes that control health and disease. The PubMed database is one of their projects that advance these goals. While including over nineteen million citations/abstracts for biomedical articles from Medline, the database also provides access links to free full text for many of the articles through PubMed Central and, in addition, links to publisher's websites and libraries with full text. PubMed covers most allied health fields, including medicine, nursing, dentistry, veterinary medicine, pharmacology, health care and the preclinical sciences. It actually cites more items than Medline, indexing articles in life science journals not included in that database, and also linking to relevant publisher and organizational websites as well as to other NCBI molecular biology resources.
The PubMed interface was completely redesigned in September of 2009 hence this review, but the contents remain basically the same. For those familiar with the former website, changes which will be obvious include moving limiters such as History, Limits, Details, Preview/Index, and Clipboard to the advanced search screen. However there are still limits available on the basic search page. The advance search button is in smaller print above the basic search box, visible, but it could be larger.
The basic search screen can produce huge numbers of results if care is not taken to refine the search terms. For example, a search for cord blood stem cells produced over 7,000 hits. The results list mixes full text articles with abstract‐only articles. There is a link to the right of the results list to limit to free full text and re‐search (which cut the total by ? in this case), but limiting beyond full text is not possible here. If browsing the titles without this limit, one will see either related articles or free article as a link under the PubMed number. Once a user links to an article they will see a list of related articles to the right, and results which are reviews are so marked. Authors of the article are also hot linked to citations for other articles they have written. There is thus ample opportunity to link to related material, by author or subject. For those articles not free full text, there is a Link Out feature below the abstract. This links publisher's web sites where free full text might be obtained. Below this is a Library Link Out, which provides an alphabetical list of libraries that have full text for the article. However, I linked to several of these and was taken not to the library site but to a publisher's site where I could get full text. The library link is useful if you want to check whether your library has full text, however, and you still can contact other libraries for interlibrary loans if necessary.
Given these various ways to link to articles off the basic search, it does not really provide concise hits for the researcher. The advanced search, however, provides many ways to limit searches for more exact results by supporting limiting by author, journal title, dates, full text or not, etc. The limiter for type of article is extensive, including letters to editor, reviews, and most importantly, clinical trials. Further down the list of limiters there are clinical trials subdivided into levels I through IV, conference publications, lectures, and bibliographies, among other formats. It is even possible to limit to type of research support. There is a limiter for languages and for animal/versus human studies and one which breaks down clinical studies by age of patient, from infant to geriatric. Users can also link to a form to search for a specific article. A particularly helpful limiter is Fields to Search, which allows filling in a search for a corporate author, a specific MESH subject heading, a pharmacological action, and/or a transliterated title, among other options.
In short, the new PubMed interface allows the researcher to put in as specific a search as possible to get definitive results, whatever the type of information requirement. PubMed will remain the one‐stop shop for many professionals and students in health research.
