PubMed - Medline search
Medline Search from PubMed is the National Library of Medicine's search service that provides access to over 10 million citations in MEDLINE, PreMEDLINE, and other related databases.
British Medical Journal (BMJ)
This site launched in May 1995 and contains the full text of all articles published in the weekly BMJ since January 1994. In addition, it contains material that is unique to the website. Currently access to the entire site is free.