 This study aimed to evaluate the efficacy and safety of myeloablative double unit umbilical cord blood transplantation dUCBT in adult patients with hematologic malignancies. Two myeloablative conditioning regimens will be used in this study: 1 total body irradation TBI, cyclophosphamide, and cytarabine, or 2 thiotepa, busulfan, and fludarabine. 