The RIT Library subscribes not only to databases that contain full-text, but also to indexing databases that function as a means to discover articles that can be requested with Interlibrary Loan. Unfortunately the library can't afford to subscribe to every database. As a result the library does not have knowledge of every article published in the world. There are some non-library databases that index scholarly articles which may also contain full-text. These databases are worth searching as well.
Examples: BioMed Central, Scitation, National Technical Information Service.
Some search engines such as Google have made an attempt to index information available in databases and paid content on websites. You can use Google Scholar to discover research papers in academic journals, but that doesn't mean Google can allow you to access the full-text for free! This is where the library databases and Interlibrary Loan come in.