Funding for this research was provided by:
National Natural Science Foundation of China (11661071,11761063)
Text and Data Mining valid from 2019-12-01
Received: 14 July 2019
Accepted: 25 November 2019
First Online: 10 December 2019
Ethics approval and consent to participate
: Not applicable.
: The authors declare that there is no conflict of interests regarding the publication of this paper.