China 
Africa 
- Adolescent depression
- Adolescent development
- Adolescent egocentrism
- Adolescent idiopathic scoliosis
- Adolescent pregnancy
- Adolescent sleep
- Adolescents
- Adoption studies
- Adoptive immunity
- Adoptive immunotherapy
- Adoptive transfer
- Adrenal adenoma
- Adrenal cancer
- Adrenal carcinoma
- Adrenal cortex
- Adrenal crisis
- Adrenal fatigue
- Adrenal gland
- Adrenal gland disorder
- Adrenal hemorrhage
- Adrenal hyperplasia
- Adrenal hypoplasia congenita
- Adrenal incidentaloma
- Adrenal insufficiency
- Adrenal medulla
- Adrenal steroids
- Adrenal suppression
- Adrenal tumor
- Adrenalectomy
- Adrenaline
- Adrenalitis
- Adrenarche
- Adrenergic
- Adrenergic agonists
- Adrenergic antagonists
- Adrenergic system
- Adrenic acid
- Adrenocortical adenoma
- Adrenocortical carcinoma
- Adrenocortical hyperfunction
- Adrenocorticotropic hormone
- Adrenodoxin reductase
- Adrenoleukodystrophy
- Adrenomedullin
- Adrenopause
- Adsorbate
- Adsorbents
- Adsorption
- Adsorption chromatography
- Adsorption isotherm
- Aducanumab
- Adult ADHD
- Adult ADHD Self-Report Scale
- Adult acne
- Adult attachment
- Adult congenital heart disease
- Adult day care
- Adult development
- Adult neurogenesis
- Adult stem cells
- Adult-onset Still's disease
- Adulterants
- Advance directive
- Advanced Therapy Medicinal Product
- Advanced airway
- Advanced airway management
- Advanced glycation end products
- Advanced glycation end-products
- Advanced life support
- Advanced maternal age
- Advanced practice nursing
- Advanced practice registered nurse
- Advanced sleep phase disorder
- Adventitia
- Adventitial cystic disease
- Adventure therapy
- Adverse childhood experiences
- Adverse drug reactions
- Adverse effects
- Adverse events
- Adverse outcome
- Advil
- Advisory Committee on Human Radiation Experiments
- Adynamia
- Aedes aegypti
- Aedes albopictus
- Aedes japonicus
- Aegopodium podagraria
- Aequorin
- Aeroallergen
- Aerobactin
- Aerobes
- Aerobic bacteria
- Aerobic capacity
- Aerobic conditioning
- Aerobic conditions
- Aerobic exercise
- Aerobic glycolysis
- Aerobic metabolism
- Aerobic respiration
- Aerobic training
- Aerobic vaginitis
- Aerobics
- Aerobiology
- Aerococcus
- Aerococcus urinae
- Aerogel
- Aerogels
- Aeromonadaceae
- Aeromonas
- Aeromonas caviae
- Aeromonas hydrophila
- Aeromonas infection
- Aeromonas salmonicida
- Aeromonas sobria
- Aerophagia
- Aerosil
- Aerosol-generating procedures
- Aerosols
- Aerotolerant anaerobes
- Aerotoxic syndrome
- Aesculetin
- Aesculus hippocastanum
- Aesculus indica
- Aesthetic dentistry
- Aesthetic medicine
- Afamelanotide
- Afatinib
- Affect
- Affect consciousness
- Affect heuristic
- Affect labeling
- Affect measures
- Affect regulation
- Affection
- Affectional bond
- Affective disorders
- Affective neuroscience
- Afferent
- Afferent arteriole
- Afferent arterioles
- Afferent neurons
- Affibody
- Affinity chromatography
- Affinity labeling
- Affinity labels
- Affinity maturation
- Affordance
- Affricates
- Afibrinogenemia