Supported by the Natural Science Foundation of China(11161029);the Natural Science Foundation of Guangxi(2010GXNSFA013109,2010GXNSFA013106);the Natural Science Foundation of Guangxi University of Technology(1166218)
Supported by the National Natural Science Foundation of China(10661001);partially by the Guangxi Natural Science Foundation(0832275);the Natural Science Foundation of Liuzhou Teacher's College(LSZ2007A003)
Project supported by the Natural Science Foundation of China(10661001),Guangxi Science Foundation(0249002,0007002)and Innovation Pro-ject of Guangxi Graduate Education(2006105930701 M14).
Supported by NSFC (10661001); Guangxi Science Foundation(0640002);the Innovation Project of Guangxi Graduate Education(2006105930701M14);Science Foundation of Guangxi University(X061022).