Simply click on the title of the article to read the abstract.
If you're having trouble thinking of search terms or aren't getting the results you expect, & you do find one article that is exactly what you want, look at how that article is indexed. On the Abstract page, click on the Publications Types, MeSH Terms link below the abstract. You'll find MeSH terms that you can add to your search to improve your results.
In other databases, indexing terms (such as Emtree & Subject Headings) can be found under the article title.