From the PubMed Technical Bulletin:
A new PubMed search feature is now available that allows a search for structured abstracts in PubMed.
In a PubMed search box, type:
This search retrieves over two million citations. (Note: This search does not include citations with the status of publisher, i.e., publisher [sb].)
This structured abstract retrieval set is a subset of this search:
See Also: What is a Structured Abstract (via NLM)