Funding for this research was provided by:
NSF of China;Natural Science Foundation of Gansu Province (11501269, 11731005)
NSF of China;Natural Science Foundation of Gansu Province (1506RJYA207)
NSF of China;the Fundamental Research Funds for the Central Universities (11371179, lzujbky-2017-ot09)
the Fundamental Research Funds for the Central Universities (lzujbky-2017-it60)
Article History
Received: 25 September 2017
Revised: 12 August 2019
First Online: 26 October 2019