If you are not retrieving many records with your searches, you may not be getting at the concept due to use of a less than optimal MeSH term or search strategy. One solution to this problem is to try multiple or different search approaches, so try again using a different combination of terms. Deleting search query entries may increase the number of references retrieved. There may be limited information on your topic in the database.
Entries can be upper or lower case.
Examples are given in the next two sections and in Searching for Flight Experiment Publications . Currency of the NLM records varies from a month or so after publication for leading journals such as JAMA to six months or longer for less widely circulated journals. This ID number is called the NLM Cit. ID in Internet Grateful Med. You can limit your search to NLM-derived or NASA records with the SI field.