Advanced subject heading searching
Subject headings are like the branches of a tree with, for example, “neoplasms by site” subdividing into the different areas of the body that can get cancer “abdominal neoplasms,” “bone neoplasms” and so on. Indexers are instructed to index items by using the most specific subject headings they can. By clicking on the ‘breast neoplasms’ link in Medline you can see how the subject headings are organised hierarchically. Subject headings in Embase work the same but they are displayed alphabetically.
Explode and focus
Explode means that your results will include everything given this subject heading and also any more specific subject headings. In Medline, you can see the more specific subject headings listed underneath. In Embase, look to see if there's a section called narrower terms. If so, you can click on these links to see if you want to include those headings in your search. If you do, put a tick in the explode column. In the example below, exploding the subject heading of United Kingdom means that you will also be searching for articles that have been tagged with the specific countries within the UK.
Focus means that the indexers have said that this subject heading in one of the main topics of the article. This is useful for quickly finding papers on a topic but is not recommended for more comprehensive search strategies.
If you tick both explode and focus columns then you will retrieve references that have that subject heading, or the more specific headings, as their main topic.
Subheadings
When you choose a subject heading a new page will pop up asking if you want to specify subheadings. The default option is to include all subheadings and we recommend that you do this. Subheadings narrow your search and retrieve fewer results. Subheadings allow you to indicate specific aspects of the subject heading that are of interest. For example the complications of breast neoplasms.
We recommend that you click on continue.
