Funding for this research was provided by:
National Natural Science Foundation of China (61201421)
the Fundamental Research Funds for the Central Universities of Lanzhou University (lzujbky-2017-187)
Article History
Received: 17 June 2018
Accepted: 12 December 2018
First Online: 1 February 2019
Compliance with Ethical Standards
:
: On behalf of all authors, the corresponding author states that there is no conflict of interest.