animal experiment article nonhuman controlled study 646 priority journal 561 Animals 560 male 358 animal tissue 356 female 333 animal model 316 mouse 315 Male 304 Female 288 Mice 272 animal cell 268 rat 252 Rats 218 protein expression 158 Animalia 148 unclassified drug 127 enzyme activity 112 Rats, Sprague-Dawley 106 Animal 99 animal 92 Mice, Inbred BALB C 91 Humans 88 Support, Non-U.S. Gov't 83 crab 74 drug effect 73 human 71