Medicine

Core medicine databases

• PubMed - The U.S. federal government's free interace for searching the Medline database
• PubMed Clinical Queries - Filter your PubMed results to the study types (RCTs, Systematic Reviews, etc.) that best answer your clinical question type (therapy, diagnosis, etc.) 
• Ovid MEDLINE (1996- ) - Contains the same Medline database as PubMed, but searchable with the Ovid interface
• Embase - Biomedical and pharmaceutical database by Elsevier which includes literature from European and Asian journals
• Cochrane Library - Includes the Cochrane Database of Systematic Reviews, and other databases to find systematic reviews, clinical trials and economic evaluations

Additional databases

• Scopus - Multidisciplinary, citation database
• Web of Science - Multidisciplinary, citation database

Web search engines

• Google Scholar - See these tips to improve your Google/Google Scholar searching

Clinical decision-making support tools

• UpToDate
• Essential Evidence Plus - contains reviews of studies (i.e., POEMs Research Summaries), diagnostic test calculators, and other decision support tools
• ACP's Pier: Physicians' Information and Education Resource
• Clinical Evidence
• TRIP Database (Turning Research into Practice) - Good for finding clinical guidelines and systematic reviews

Sources for electronic medical books

• Access Medicine - collection of medical and biology textbooks, including Harrison's Online
• STAT!Ref - collection of clinical medicine textbooks, including USMLE step 2 & 3 prep materials
• Springer E-books - over 20,000 medicine e-books
• Wiley Online Library - over 14,000 e-books
• ClinicalKey - Very good for finding clinical guidelines
• NCBI Bookshelf - open access biomedical textbooks
• McGill Classic Catalogue - used the Advanced Search to limit to e-books