The two main article indexes for history are:
Also of possible interest:
Find more research tools by specific subjects on the UIUC Library's Databases A-Z list.
Below is a list of major, full-text periodical collections. Note that these sources are not comprehensive: many full text journals are only available, entirely or in part, through their publisher's websites. For example: The Sixties: a Journal of History, Politics, and Culture, Radical History Review, and Journal of Black Studies.
Journals like The Sixties, Radical History Review, and Journal of Black Studies, are indexed by America: History and Life.