Espacenet (European Patent Office - worldwide patents)The oldest of the major international patent databases. Its home screen features a simple "Google style" search box that also allows complex Boolean and proximity command search. The top menu line links to Classification search (Cooperative Patent Classification codes and definitions) , and to Advanced search (drop down menus for all searchable fields). The browser features side-by-side frames; click in a title list to quickly display abstract, drawings, claims etc.
PatentscopeWIPO's (World Intellectual Property Organization) major international database features sharp thumbnail images, many searchable fields, side by side displays of title list with your choice of other fields, and help links to tutorials and free instruction webinars.. You can search by CPC (Cooperative Patent Classification) and IPC (International Patent Classification)
One of 4 major free international patent databases. Includes structured search with fields listed. Excellent graphic analysis and displays. Non patent literature can be included
Freepatentsonline.com*Same field codes as USPTO web databases*Search granted patents and pre-grant publications together*Includes European and WIPO patents, Japanese Patent Abstracts, and Non-Patent Literature cited in patents.*Advanced Search includes proximity search [full text search is limited to 1976-present]*Fast downloading, printing, and exporting to spreadsheets.
Derwent Innovations Index, 1963-presentFacilitates precise patent searching, letting you conduct patent and citation searches of inventions in chemical, electrical, electronic, and mechanical engineering. Also merges value-added patent information with patent citation information.
Nexis Uni Academic Patent SearchAllows proximity search, truncation; may have better OCR search than Google Patents
Includes: Combined US Patents or separate search of Utility, Design, or Plant Patents, European Patents, Japan Patent Abstracts, Patent Cooperation Treaty Applications
IEEE Xplorefull records from a search include any available patent citation links
SciencDirect has a "References" field that can be proximity searched to find patent numbers, inventors, and title words
Web of Science Core CollectionThe Web of Science Core Collection provides comprehensive coverage of the sciences, social sciences, and arts, and humanities across journals, books and conference proceedings. It indexes more than 5,700 major journals across 164 scientific disciplines. The best database for finding what papers have cited other papers. Cited references can be traced forward in time. Web of Science Training Materials available here: http://wokinfo.com/training_support/training/web-of-science