General

• Web of Science
• MicroPatent 
• Reader's Guide Retrospective
• Google Scholar

Reference

• Kirk-Othmer Encyclopedia of Chemical Technology
• Materials Safety Data Sheets (MSDS)

Chemsitry

• SciFinder Scholar
• Beilstein Crossfire

Physics & Astronomy

• ADS (NASA Astrophysics Data System)
• INSPEC

Materials & Engineering

• Compendex
• NTIS (National Technical Report Server)

Biological & Life Sciences

• Biosis
• Medline
• PDB (NCBI Protein Data Bank)