国家自然科学基金面上项目81450042;甘肃省自然科学基金1506RJZA240;甘肃省青年科技研究基金1107RJYA027;兰州市科技发展计划2014-2-27Supported by the General Program of National Natural Science Foundation of China 81450042,the Natural Science Foundation of Gansu Province 1506RJZA240,the Science and Technology Research Foundation for Youth Scholars of Gansu Province 1107RJYA027,and the Project of Science and Technology Development Plan of Lanzhou City 2014-2-27.