These two databases index a wide variety of publications across disciplines, including psychology. Each has it's own thesaurus or controlled vocabulary to assist with searching.
While these two resources are more limited in scope by searching a particular publisher, both publish a large quantity of psychology articles and you are more likely to find the full-text of articles.
Collection of over 3,500 journals, mostly in science, technology, engineering, mathematics, and social sciences.
Over 1,400 online journals from ca. 1997 - present.