With some databases, there is a way to look at an online list of titles indexed. I don't know if they all have this ability, though. For example, I went to the Ebsco website and look for promo on Academic Search Premier and found the following data that can be downloaded.

http://www.epnet.com/academic/acasearchprem.asp

I don't know if you use MEDLINE via Pubmed, but this is their list.

http://www.ncbi.nlm.nih.gov/entrez/getids_help.html#JournalLists

If you can't find it online, the vendor should be able to send it to you.  I hope this helps.

Barbara M. Pope, MLS
Reference Librarian/Archivist
O.J. Cloughly Alumni Library
St. Louis College of Pharmacy
4588 Parkview Place
St. Louis MO 63110
(314) 446-8361
fax (314) 446-8360
bpope@stlcop.edu