The US National Library of Medicine has made its searchable MEDLINE database freely available to all Americans. This site provides searchable access to over 8.5 million MEDLINE and PreMEDLINE citations. Users can also search molecular biology databases from the National Center for Biotechnology Information's Entrez system. Entrez, integrates information from a number of databases (nucleotide sequences, protein sequences, macromolecular structures, whole genomes, and MEDLINE) at the National Center for Biotechnology Information (NCBI). Entrez provides access "to over 10 million citations in MEDLINE, PreMEDLINE, and other related databases, with links to participating online journals." Its new single search interface includes four new menus that display field limits, indexes, search history (active for one hour), and a clipboard where users can store up to 500 items for one hour.A journal browser, which allows users to find articles based on the journals they appear in, and clinical alert notices are also featured at PubMed.