The annual journal, Mediaeval Studies, has put on-line various indexes of the journal’s run, from 1939-2003 (including, of course, articles regarding Aquinas). See the journal’s web site here. The downloadable files are in Adobe Acrobat PDF format.

Volumes 1—65 (1939—2003)
1   Articles listed by author and title (including notices in memoriam)
2   Texts edited (indexed by author/title and by incipit)
Volumes 51—65 (1989—2003)
1   Manuscripts and archival material
2   Principal subjects