Funding for this research was provided by:
National Natural Science Foundation of China (71673169, 71673170, 71974118)
Text and Data Mining valid from 2020-01-14
Received: 12 September 2019
Accepted: 31 December 2019
First Online: 14 January 2020
Ethics approval and consent to participate
: Not applicable.
: All the authors have given consent for the publication.
: The authors declare that they have no competing interests.