8[1] Yoshita R, Sakai K, Okano T，et al.Pulsatile drug delivery sys tems using hydrogels[J].Adv Drug Del Rev，1993；11:85
9[2] Bjorn Lemmer.Circardian rhythems and drug delivery[J].J Contro lled Release,1991；16:63
10[3] Pozzi F, Furlani P, Gazzaniga A,et al.The time clocksystem a n ew oral dosage form and complete release of drug after a predetermined lag time [J].J Controlled Release,1994；31:99
