In order to only display results which are open access, go to the bottom of the filters on the left side, and select the 'Open access' filter, by clicking on "Limit to". When this filter is applied, only publications that are open access will appear in the results list. As with all filters, this can be done with a blank search, or along with a keyword search or abstract search, to display results in a particular area, and can also be combined with other filters.

For example, to find open access publications from 2015 including the word "CRISPR", simply search with the keyword "CRISPR" in the search box, then select "2015" in the 'Publication Year' filter, and select the 'Open access' filter also.