1,3,5-Triazin-2(1H)-one, 4-amino-3,6-dihydro-1-.beta.-D-ribofuranosyl-, monohydrochloride 5,6-Dihydro-5-azacytidine hydrochloride 5-ACH 62402-31-7 DHAC DIHYDRO-5-AZACYTIDINE H5AC HCl NSC264880