Funding for this research was provided by:
National Natural Science Foundation of China (21977026, 21702052)
Text and Data Mining valid from 2020-01-07
Received: 15 October 2019
Accepted: 25 December 2019
First Online: 7 January 2020
Ethics approval and consent to participate
: All the authors have read and agreed the ethics for publishing the manuscript.
: The authors approved the consent for publishing the manuscript.
: The authors declare that they have no competing interests.