PDF versions of law journal articles can be found on HeinOnline. If you have a citation, you can enter it into the search box, or you can go directly to HeinOnline to browse. If you cannot find the source here, try LibrarySearch or check the journal's website.
Law Journal Library One Box Citation Widget
For non-law journals, first try searching the journal title within UO Libraries Journal Search. Frequently, journals in electronic databases will be linked in the catalog and you can browse to the specific issue needed.