Web of Science

Thompson Reuters:

Web of Science ® provides researchers, administrators, faculty, and students with quick, powerful access to the world’s leading citation databases. Authoritative, multidisciplinary content covers over 10,000 of the highest impact journals worldwide, including Open Access journals and over 110,000 conference proceedings. You’ll find current and retrospective coverage in the sciences, social sciences, arts, and humanities, with coverage available to 1900.
Overcome information overload and focus on essential data across 256 disciplines.