animal experiment nonhuman 1,312 controlled study 1,018 article 1,000 Animals 964 priority journal 858 male 600 mouse 572 animal tissue 556 Male 510 female 486 Mice 482 animal model 476 animal cell 448 Female 422 animal 346 rat 336 Rats 284 protein expression 284 metabolism 252 unclassified drug 244 Article 240 Animalia 216 enzyme activity 210 physiology 174 Animal 170 Humans 170 Mice, Inbred BALB C 160 human 156 Support, Non-U.S. Gov't 152