基金supported by the National Natural Science Foundation of China(21006081,20976043)Natural Science Foundation of Hu-nan Province(11JJ3024,09JJ8002)+2 种基金Scientific Research Fund of Hunan Provincial Education Department(11B122)Scientificand Technological Plan Projec tof Hunan Province(2010JT4051)Program for New Century Excellent Talents in University(NCET-10-0168)~~