For Psychology, both PsycINFO and PsycARTICLES offer a methodology filter. You can use this to narrow your search results to a particular type of scholarly article. This menu is located on the lower left once you run a search.

If you are studying in an area other than psychology, you can try using qualitative or quantitative as search terms, or you might exclude literature reviews. Some databases have "literature review" as a subject, as well as an option to exclude results labelled as such. From here, you'll need to read the methods section of the article to determine if it is appropriate.

If there isn't an exclude option (EBSCO databases) you can use advanced search to enter NOT literature reviews in the subject field. It's very important to select the subject field, otherwise any article that simply says the word literature review (or cites one) might be excluded.