Web of Science

A huge database of scholarly literature across the sciences, strong in both historical and current coverage. Includes extensive citation mapping

Scopus

Another broad literature database with strengths in current scientific publications and citation mapping.

PubMed

A large database of biomedical and related literature. It's strengths are controlled subject searching and linking with other NCBI resources.  Has international coverage and content includes grey literature and material not included in other databases.

Engineering Village

Provides access to bibliographic records in engineering and physics literature from a range of trusted sources: scholarly journals, trade publications, patents, government reports, reference books and conference proceedings.  Includes the engineering index Compendex and the physics index Inspec along with many others.

Annual Reviews

Collections of critical reviews written by leading scholars in 40 focused disciplines -- mostly in scientific and social science disciplines.