国家自然科学基金41073058,40973075;广东省自然科学基金团队项目9351064101000001;高等学校博士学科点专项科研基金20100172110028;the National Natural Science Foundation of China41073058,40973075;the Natural Science Foundation of Guangdong Province,China9351064101000001;the Higher Specialized Research Fund for the Doctoral Program20100172110028