Influence of Shenmai injection on blood serum tumor necrosis factor and bone marrow CD34+ cell‘s apoptosis of chronic aplastic anemia patient Clinical efficacy and T-lymphocyte subset, serum interferon-γ(IFN-γ), tumor necrosis factor-α(TNF-α), interleukin-2(IL-2) levels on treatment of chronic aplastic anemia patients by Shenfu injection combined with stanozol and cyclosporin A