Science Citation Index Expanded(Web of Science)--Includes thousands of science and engineering journals. Especially good for dissertation-level bibliographies because it allows cited reference searching: that is, how many times an article has been cited by others
Mergent Online--Financial information on U.S/foreign public companies
Dissertations & Theses Online--Includes dissertations and theses, many with full text, from over 1,000 North America and European universities.
Not only articles
WorldCat--Catalog of library catalog across the U.S. (and some international libraries)
Google Scholar--Search for scholarly publications in a variety of fields. Set your preferences for access to full text and to RefWorks citation export.
National Technical Information Service--Latest U.S. government-sponsored research and worldwide scientific, technical, engineering, and business-related information; updated biweekly from 1964 to present