基金Supported by National Natural Science Foundation of China(30560119)Supported by Natural Science Foundation of Guangxi(0991030)+3 种基金Innovational Plan Project for Guangxi Postgraduate Ed-ucation(2008105930817M46)Project of Science Research Project of Guangxi Education Department([2006]26),Project of Science Research Project of Guangxi Education Department(200708LX180)Scientific Researc-hing fund project of Guangxi University(X081020)Fund Project for Guangxi Young People(0832008)~~