贵州省自然科学基金批准号LKZS201228;贵州省教育厅“125”重大专项基金批准号2012015;遵义师范学院博士基金批准号2012BSJJ12资助.? Supported by the Natural Science Foundation of Guizhou Province, ChinaLKZS201228;the “125” Program of Guizhou Education Department, China2012015;the Doctoral Scientific Fund of Zunyi Normal College, China No.2012BSJJ12.