国家自然科学基金重大项目2011YQ170067;国家自然科学基金81160293;江西省教育厅青年科学基金GJJ10067 Supported by the Major Program of National Natural Science Foundation of China2011YQ170067;the National Natural Science Foundation of China81160293;the Science Foundation for Young Scholar of Education Department of Jiangxi ProvinceGJJ10067