Funding for this research was provided by:
National Natural Science Foundation of China (31670723)
Text and Data Mining valid from 2020-04-03
Received: 22 December 2019
Accepted: 31 March 2020
First Online: 3 April 2020
Ethics approval and consent to participate
: Not applicable.
: All authors consent for publication of this manuscript.
: The authors declare that they have no competing interests.