"pubmed"    "pubmed"
                "protein"    "protein"
                "nuccore"    "nuccore"
                "nucleotide"    "nucleotide"
                "nucgss"    "nucgss"
                "nucest"    "nucest"
                "structure"    "structure"
                "genome"    "genome"
                "assembly"    "assembly"
                "genomeprj"    "genomeprj"
                "bioproject"    "bioproject"
                "biosample"    "biosample"
                "blastdbinfo"    "blastdbinfo"
                "books"    "books"
                "cdd"    "cdd"
                "clinvar"    "clinvar"
                "clone"    "clone"
                "gap"    "gap"
                "gapplus"    "gapplus"
                "dbvar"    "dbvar"
                "epigenomics"    "epigenomics"
                "gene"    "gene"
                "gds"    "gds"
                "geoprofiles"    "geoprofiles"
                "homologene"    "homologene"
                "medgen"    "medgen"
                "journals"    "journals"
                "mesh"    "mesh"
                "ncbisearch"    "ncbisearch"
                "nlmcatalog"    "nlmcatalog"
                "omim"    "omim"
                "orgtrack"    "orgtrack"
                "pmc"    "pmc"
                "popset"    "popset"
                "probe"    "probe"
                "proteinclusters"    "proteinclusters"
                "pcassay"    "pcassay"
                "biosystems"    "biosystems"
                "pccompound"    "pccompound"
                "pcsubstance"    "pcsubstance"
                "pubmedhealth"    "pubmedhealth"
                "seqannot"    "seqannot"
                "snp"    "snp"
                "sra"    "sra"
                "taxonomy"    "taxonomy"
                "toolkit"    "toolkit"
                "toolkitall"    "toolkitall"
                "toolkitbook"    "toolkitbook"
                "unigene"    "unigene"
                "unists"    "unists"
                "gencoll"    "gencoll"
                "gtr"    "gtr"