Zotero can help search for full text if there are items in your library that don't have PDFs attached. To configure this, open Zotero preferences and go to the advanced tab. Under "OpenURL > Resolver:" enter this URL:
With the resolver configured, you can search Fresno State's OneSearch for full text of the article by selecting an item and choosing "Library Lookup" from the "Locate" menu. If full text isn't available through the library, you'll see the usual option to request it through Interlibrary Loan.
If the full text is not available through the library, there's one other option you can try: right-click (or control-click) on the item in your Zotero library, and choose "Find Available PDF."
This feature integrates with the Unpaywall service to search for legal, Open Access copies of the item. If it finds a PDF, it will add it to the item in your Zotero library. In some cases, this PDF may be a copy of the author's accepted manuscript rather than the published version, so be sure to check any results.