ACCESS: http://www.ncbi.nlm.nih.gov/PubMed/

PubMed is a free, Web-based search service that provides access to MEDLINE, a database of over 9 million citations to articles in over 5,000 biomedical journals in many instances dating back to 1965. Many records include abstracts. MEDLINE and PubMed are created and sponsored by the National Library of Medicine. MEDLINE has long been one of the major resources for searching the health and life sciences literature and the PubMed interface provides a simple interface to harness this powerful tool. The site's designers encourage searching in a basic free text style through a basic blank box for term entry. Authors' last names, journal titles, and subject headings are among the fields included in the basic search. Because of this approach, searches using common terms can retrieve thousands of records. A simple search on "cancer" retrieved over 880,000 records. However mixed with the simple search term input is a certain amount of intelligent support. For instance, the cancer search was automatically expanded to include the official thesaurus term for cancer, neoplasms. Assistance in developing more sophisticated search strategies is available with site documentation indicating that truncation is supported, phrase searching can be imposed, and Boolean and field searching are also possible. A journal browser also assists in expanding cryptically abbreviated journal titles. The display of search results is also very flexible. The default is a brief citation display with the author's name linked to a full record display. While browsing brief displays, items of interest can be selected via a check box and a display of selected citations can be created for more effective printing. Another important feature is that of search expansion; each citation offers a link to related articles. If this link is selected, a new display is created providing articles that are selected based on a similarity measure based on word and subject term co-occurrence. Related articles may also share links to nucleotide or protein sequences in other portions of the system.

In addition to the basic mode, an advanced search mode is also available. This mode offers a pull-down field limitation option in addition to the initial empty box for term entry. The resultant display offers an opportunity to add additional terms and perform publication date limitation prior to viewing search results.

Although providing MEDLINE access could be considered PubMed's main function, access to additional information is incorporated into the system. A special pre-publication process means that PubMed includes in-process citations that are not yet available in MEDLINE and additional citations to some journals that are normally only partially indexed by MEDLINE. PubMed also supports searching of several genetic databases including Genbank's DNA and protein sequences, a database of 3-D biomolecule structures, and a complete genomes database. Numerous hyperlinks between sequence records, MEDLINE records, and even some full-text electronic journals are incorporated into the system resulting in a singular knowledge resource for genetic information.

While PubMed is a singular resource for health care professionals and biomedical researchers and a significant resource for the general public, it should be borne in mind that the information provided is mainly citations to technical literature and research data that is useful only to experts. None of the journals included in the system is written for the general reader, and consumer health information and literature other than journals are not covered. What the general reader can expect to find here is cutting-edge information about new breakthroughs in medical and basic research from the same sources that are available to doctors and researchers.

Karla L. Hahn
Agriculture and Life Sciences Bibliographer
McKeldin Library
University of Maryland
July 1997

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