Dissertations in ABI/INFORM Complete (ProQuest)
The content of ABI/INFORM has been expanded recently to include the full text of some 23,000 business and economics-related dissertations.
Searches can be limited to dissertations by clicking the More Search Options and then selecting the Publication Type of Dissertations. Another approach is to do a search by topic or author and see if any results are listed under the Dissertations tab. A search for "supply chain management" dissertations, for example, gets 197 results.