title: Nitrogen and helium "closing volumes": simultaneous measurement and reproducibility.
mesh_terms: D000328:Adult; D005260:Female; D006371:Helium; D006801:Humans; D008297:Male; D008722:Methods; D008875:Middle Aged; D009584:Nitrogen; D010507:Periodicity; D012119:Respiration; D012129:Respiratory Function Tests; D012907:Smoking; D014797:Vital Capacity
chemical_list: D006371:Helium; D009584:Nitrogen