Most theses and dissertations published in recent years have free full text online like Florida Tech's Scholarship Repository.
These open-access databases have full text:
These library databases provide citations or abstracts of theses and dissertations but do not have full text. Search for keywords and limit results to dissertations/theses under document type.
Once you have located the citation, search Google with the full title enclosed in quotation marks. If you cannot locate full text online, use Interlibrary Loan to request it.