基金The project supported by the Natural Science Foundation of the Education Department of Anhui Province of China under Grant No. 2006kj070A, and 2006KJ057B and the Talent Foundation of Anhui University
基金The project supported by the Natural Science Foundation of the Education Department of Anhui Province under Grant Nos. 2006kj070A and 2006kj057B, and the Talent Foundation of Anhui University
基金The project supported by Natural Science Foundation of Hunan Province under Grant No. 05JJ30005, the Science Research Fund of Education Bureau of Hunan Province under Grant No. 05C756, National Naturai Science FoUndation of China under Grant Nos. 10274093 and 10474118, the Foundation for Youth Core-Teachers of Hunan Province under Grant No. 2003165, and the Science Research Fund of Hunan Institute of Humanity and Science and Technology under Grant N01 2004A014