基金National Natural Science Foundation of China (50671084 and 50875217)Natural Science Foundation of Shaanxi Province (2003E106, SJ08-ZT05)China Postdoctoral Science Foundation (20070420218)
基金Projects (50941020, 10902086, 50875217, 20903075) supported by the National Natural Science Foundation of ChinaProjects (SJ08-ZT05, SJ08-B14) supported by the Natural Science Foundation of Shaanxi Province, ChinaProject (CX200905) supported by the Doctorate Foundation of Northwestern Polytechnical University, China