Article 255 human 240 controlled study 221 Humans 204 metabolism 186 nonhuman 160 male 129 genetics 115 unclassified drug 115 female 109 enzyme linked immunosorbent assay 97 enzyme activity 89 Animals 88 Male 85 adult 85 animal 83 chemistry 83 Biology, life sciences 80 Female 78 protein expression 74 animal experiment 60 human cell 59 Research & information: general 58 gene expression 56 drug effect 55 middle aged 54 major clinical study 49 mouse 48 Middle Aged 47 animal model 46