Screening of effective parts in Jiaoai Decoction with blood enriching function in blood deficiency model rats Enriching blood effect comparison in three kinds of blood deficiency model after oral administration of drug pair of Angelicae Sinensis Radix and Chuanxiong Rhizoma and each single herb Studies of Rehmannia glutinosa Libosch. f. hueichingensis as A Blood Tonic