One way to limit your search to particular fields is by using field tags, such as [ti] to search a title word, [au] to search an author name word, [ta] to search a journal title word, etc.
Example: "food desert"[ti] searches for this phrase in the article title.
A complete list of all PubMed field tags as well as description of each is available from PubMed Help
Different results displays give you different information. Click on Summary for additional formats (above the results list).