INSPEC is a great database to use for finding physics and astrophysics literature.
August 2007 Archives
When you're trying to figure out where research went next after a really great article, try the Web of Science, the web interface for the Science Citation Index. It compiles cited references from journal articles and allows you to find articles that have cited older papers as well as following the trail of citations in many other directions. It covers important journals from a wide range of scientific and engineering disciplines, and we now have access back to 1975.
If you're looking for research literature in any field of engineering, Compendex is a great place to go! It includes citations for journals, conference proceedings and papers, technical reports, books, and more from all over the world. In addition to being the premier engineering database, it covers related areas in science and management.