iSearch collects literature from a number of sources including PubMed and multiple preprint servers. PubMed, which is the source for peer-reviewed publications, also includes some preprints as well. If a preprint does come from PubMed, an RCR is able to be calculated, and these metrics can be seen within the literature dataset within integrated iCite. Preprints sourced from preprint servers do not currently have RCR or NIH-linked metrics calculated.
A number of papers will also have two versions, a preprint and a more recent, peer-reviewed publication. This will be denoted by the "Published As" field. This shows the later DOI where a preprint has a later version, either a newer preprint, or a peer reviewed publication. The later version may or may not have a PMID/be in PubMed.
Because the majority of preprints do not have bibliometric data around citations, the Bibliometrics section in the record view will only include fields used to calculated the APT score. However, you can download RCR and other citations fields from export, and see some of this data in the Topic Explorer (see below).
Preprints sourced from PubMed:
https://analytics.nih.gov/results/publications?ID=33d7c9e4-2291-4f15-9f38-87a8ceb59add
Literature (preprints) with Published As data:
https://analytics.nih.gov/results/publications?ID=90c32b75-923d-4efe-9801-c3c8539e3b83
Preprint Bibliometrics seen in record view
Export options for all literature records (preprint and publications)