controlled study human 3,783 male 2,978 Article 2,970 female 2,881 Humans 2,638 adult 2,507 Female 1,546 Male 1,538 major clinical study 1,479 article 1,300 nonhuman 1,068 Adult 1,021 middle aged 940 aged 799 Middle Aged 773 human experiment 694 clinical article 669 young adult 657 randomized controlled trial 629 procedures 597 adolescent 588 Young Adult 571 animal experiment 526 physiology 501 unclassified drug 500 priority journal 489 Aged 474 child 471 Adolescent 470