Scirus, the free scientific information search engine provided by Elsevier, includes millions of sci-tech documents, including data for some 21 million patents obtained from LexisNexis. Here's an exact breakdown of Scirus' patent coverage:
EPO from 1978 (grants and pregrants) JPO from 1976 (pregrants, English abstracts only) UK from 1916 (pregrants) USPTO from 1790 (grants#) and 2001 (pregrants*) WIPO from 1978 (pregrants**)
# US coverage does not appear to include plant patents before 1976. * The USPTO began publishing utility and plant patent applications in 2001. ** Published PCT applications.
Many thanks to Danianne Mizzy of the Engineering Library, University of Pennsylvania for this scoop.
I'm the librarian for research services in the Engineering and Science Library at Queen's University in Kingston, Ontario. I've been working with patent information since 1991, including seven years at the U.S. Patent and Trademark Office. I believe that the dissemination of patent information is a public good and should be promoted, especially in the education of science and engineering students.