PubMed was created as the free public search interface to the Medline database. All Medline records appear in it. It is an excellent place to search for health resources, although it does not supply full text itself. Any full-text article referenced in PubMed will actually reside elsewhere. Its scope is huge, with very high quality indexing, helping you focus your search more effectively (way better than Google Scholar, for example).
PubMed also carries all records for PubMed Central (or PMC as its known). This is an additional database of full text open access resources that you can freely access.
Records in PubMed come in three types (click the examples to see them in more detail). Its worth knowing a little about this to properly appraise any sources you want to include in your work. The first type to look out for are records that are ‘in process’. These records are not yet fully indexed in Medline. They don’t yet have a Medical Subject Heading (MeSH), or the full indexing required. Searching with MeSH won’t yet find such a record.
The second type are records ‘as supplied by Publisher’. These may or may not be ‘extra’ to Medline (they have not been properly processed yet). They could ultimately be out of Medline’s scope altogether. Even though its a high impact journal, this individual record won’t be found in subscription access to Medline via OVID or EBSCO. Searching in PubMed however, will find such records.
The final type are the complete records that appear in Medline, and have a MeSH heading and full indexing, making them highly ‘findable’ in Medline and other databases. These always exist within Medline.
PubMed can also help you scrutinise any results you find in other places as well. Year on year, many more journal titles are being published. A quick search in Journals in NCBI databases will confirm whether – and to what extent – a journal title is being indexed in Medline, or PubMed, or both. You can then better assess its impact as a resource.
So if you find an article in Google Scholar or WorldWideScience.org, you can use NCBI to check the journal title it appears in. If it appears in NCBI, its an indication of quality. Simple.
With thanks to Steve Glover (Library Services Head, Central Manchester University Hospitals NHS Foundation Trust).