controlled study human Humans 1,296 article 1,242 priority journal 1,088 human cell 943 female 728 nonhuman 655 male 615 Female 603 Animals 551 adult 529 Male 498 unclassified drug 479 Article 461 protein expression 406 metabolism 399 animal cell 368 Adult 334 mouse 315 animal 279 Mice 276 signal transduction 251 clinical article 245 cell proliferation 237 animal experiment 234 genetics 232 Middle Aged 230 in vitro study 220 major clinical study 216