elink
Look up precomputed neighbors within a database, or find associated records in other databases.
TLDR
Search pubmed then find related sequences
$ esearch -db pubmed -query "[selective serotonin reuptake inhibitor]" | elink -target nuccore
Search nucleotide then find related biosamples
$ esearch -db nuccore -query "[insulin [PROT] AND rodents [ORGN]]" | elink -target biosample
