Funding for this research was provided by:
National Natural Science Foundation of China (31960054, 31560069)
Text and Data Mining valid from 2020-02-26
Received: 18 December 2019
Accepted: 9 February 2020
First Online: 26 February 2020
Ethics approval and consent to participate
: Not applicable.
: All authors consented to the publication of this work.
: The authors declare no competing interests.