PubMed User Guide & FAQs prepared by National Library of Medicine:
Single Citation Matcher is one of the popular tools people use in the legacy PubMed and it is still retained in the new PubMed, located at the bottom of the PubMed homepage where you also find other useful links such as Clinical Queries, Batch Citation Matcher, NLM Journals database, FAQ and Users Guide, etc. as shown below:
The Single Citation Matcher allows you to find a reference with partial information. Below is what the Single Citation Matcher looks like. You fill in the boxes with the information you have and let the system find the matching record. It is also a very convenient tool to verify a citation.
Clinical Queries is a tool that was designed for clinician use and allow them to search for relevant clinical literature on etiology, diagnosis, therapy, prognosis, and clinical prediction guides and filtered in three clinical research areas: Clinical Study Categories, Systematic Reviews, and Medical Genetics within a broad or narrow scope.
PubMed vs PubMed Central
Please do not confuse PubMed with PubMed Central. They are two different kinds of databases:
PMID vs. PMCID