Filters, which can be found on the left side of the search results page, can help you focus your search appropriately. Categories include Article type, Publication date, Species, Languages, & Ages.
Some useful filters Species / Humans (unless you're looking specifically for animal research), & Languages / English. In this search, Ages / Adolescent will also be helpful.
Some filters are readily available, others are more hidden. To add languages other than English, ages other than the ones that are visible, & other types of filters, click on the Additional filters link below the filter list. Select the Types of filter, check the filters you want to add, then click the Show button to make the filters appear on the screen. Next choose the filter(s) you want to add from the list.
When you apply filters, they appear above your search results. You can clear a filter by clicking the name of the filter or the Clear link at the top of the results. Remember to clear all filters when you do a new search.
Finally, if you want to see just more recent articles or articles published within a specific date range, add a date filter.