You may use a tag if you don’t want to include any narrower terms in your search. In this case, you would use the following syntax for no explosion, [mh:noexp]. Keep in mind that citations are indexed using the most specific term available, so turning off automatic explosion might eliminate relevant articles from your results.

For example, if you want to include the MeSH term eye in your search but none of its narrower terms, then you would search eye[mh:noexp].