Some very useful article databases for history are:
In addition to these core databases, here are several multidisciplinary online article databases that provide indexing of articles on historical topics (note that some are useful for primary sources):
There are also several major collections of full-text online journals. In these databases you can browse individual issues of journals, or you can do a search across the entire database. Many of these collections can be used to find both primary and secondary sources. For example, JSTOR contains journals such as the Philosophical Transactions of the Royal Society of London, which began publication in 1665.