nonhuman article 2,695 priority journal 2,243 controlled study 2,094 Animals 1,948 animal experiment 1,142 animal cell 1,117 unclassified drug 952 male 779 animal tissue 774 mouse 735 female 712 animal 691 Male 686 Female 670 Article 647 rat 643 Mice 640 human 639 Humans 605 metabolism 557 Rats 522 protein expression 493 animal model 466 enzyme activity 457 Animalia 434 Support, Non-U.S. Gov't 403 Animal 389 Argentina 357 physiology 325