The PubMed collection
As stated on the PubMed homepage
PubMed is a service of the U.S. National Library of Medicine that includes over 17 million citations from MEDLINE and other life science journals for biomedical articles back to the 1950s. PubMed includes links to full text articles and other related resources.
AuthorClaim is licensed vendor of PubMed. But don’t worry, we are not selling anything, we just hold a licence that allows us to make the records available here. However, we don't hold the full records. There are about 2% of PubMed records that the NLM do not include in the PubMed distribution. Details are in the 2008 MEDLINE®/PubMed® Baseline Distribution documentation
PubMed comes as an annual baseline dataset as well as as number of patches that are released four times a week. We group records by the year in which they were created. We update the AMF data used in AuthorClaim every week.
To feed the AMF data, we use rolling updates in three lanes. Assume the current year is t The fast lane feeds the t and t−2 on Mondays and Tuesday, one year a day. The medium lane feeds the t−3 to t−6 on every Wedesday, one year every Wednesday. The slow lane feeds all remaining years, and Thursday to Saturday, one year per day, rolling over.