It depends on what sort of periodicals you need. If you are talking about peer-reviewed journals, then one of the best bets for a general search is Academic Search Premier (can be found under the Quick Start section of http://libguides.uah.edu/databases). If you are looking for something a little more subject specific, then at that same link, look to the left-side list of subjects and choose one that best matches the subject you are searching.
