http://www.ncbi.nlm.nih.gov/entrez

U.S. National Library of Medicine (NLM) of the National Institutes of Health provides the ability to search Medline with its more than nine million citations to the biomedical literature of the world, from 1966 to the present. Abstracts are provided. Registered users can order full text documents. Other searchable databases.

AIDSLINE(r) (AIDS information onLINE)
AIDSTRIALS (AIDS clinical TRIALS)
BIOETHICSLINE(r) (BIOETHICS onLINE)
ChemID(r) (CHEMical IDentification)
DIRLINE(r) (Directory of Information Resources onLINE)
HealthSTAR (Health Services, Technology, Administration, and Research)
HISTLINE(r) (HISTory of medicine onLINE)
HSRPROJ (Health Services Research Projects in Progress)
OLDMEDLINE
POPLINE(r) (POPulation information onLINE)
SDILINE(r) (Selective Dissemination of Information onLINE)
SPACELINE
TOXLINE(r) (TOXicology information onLINE)