Wu, Kaijun
Zhang, Boping
Tian, Bin
Du, Sanshan
Lu, Huaiwei
Funding for this research was provided by:
National Natural Science Foundation of China (No. 11362008)
Youth science and technology fund plan of Gansu province (No. 1212RJZA063)
Scientific research project in colleges and universities in Gansu province (2015B-042)