human 3,387 male 2,291 Humans 2,255 female 2,122 article 2,008 adult 1,814 human experiment 1,675 controlled study 1,581 Article 1,172 Male 1,063 Female 1,051 nonhuman 827 Adult 732 animal experiment 650 physiology 583 young adult 578 major clinical study 534 Animals 499 Young Adult 497 animal 470 adolescent 409 child 398 animal model 386 clinical article 375 Education 371 psychology 358 procedures 352 Adolescent 350 TJ Mechanical engineering and machinery 348 learning 344