animal experiment in vitro study nonhuman 209 controlled study 194 Animals 192 article 157 priority journal 146 mouse 143 rat 143 animal model 134 Female 123 animal cell 123 Male 121 Rats 121 animal 117 Mice 116 in vivo study 115 animal tissue 111 male 106 Animal 100 female 100 metabolism 91 unclassified drug 85 Article 84 human 79 protein expression 66 Humans 61 drug effect 55 human cell 55 radioisotope 54