Project51561019 supported by the National Natural Science Foundation of China;Project 1308RJYA022 supported by the Natural Science Foundation of Gansu Province,China;Longyuan Youth Innovative Support Program,China;国家自然科学基金资助项目51561019;甘肃省自然科学基金资助项目1308RJYA022;“陇原青年创新人才扶持计划”项目资助