In vivo gastrointestinal absorption kinetics of schizonepetin in rats Mechanism of intestinal absorption of tetrandrine in rats Studies on the absorption kinetics of baicalin and baicalein in rats‘ stomachs and intestines Absorption kinetics of dehydrocavidine in rats‘ stomachs and intestines Intestinal absorptive characteristics of andrographolide and dehydroandrographolide in extract from Andrographis paniculata in rats