青年科学基金项目No.51409013;2015重庆市研究生科研创新项目No.CYB15038;2013自然科学基金项目No.41372356;中央高校基金项目No.106112014CDJZR200008 .This work was supported by the Science Foundation for Youth 51409013,Chongqing University Postgraduates' Innovation Project CYB15038,The Natural Science Foundation of China 41372356 and The Central College Fund Project of China 106112014CDJZR200008.