Funding for this research was provided by:
National Natural Science Foundation of China (11662008, 11262010)
Abroad exchange funding for young backbone teachers of Lanzhou University of Technology
Article History
Received: 14 April 2018
Accepted: 26 September 2018
First Online: 10 October 2018
Compliance with ethical standards
:
: The authors declare that they have no conflict of interest concerning the publication of this manuscript.