Keyword searching (generally) works best for finding articles on a topic
If you get too many results, try limiting to a particular subject - usually there is a list of subject links on one side of the screen.
The same tricks to help you find books in the catalog, will help you find articles
(heart or cardiac)
surg* (finds surgery, surgeries, surgeon, surgical, etc.)
(orthopedic or orthopaedic) and surg*