Funding for this research was provided by:
National Natural Science Foundation of China (61702150, 61702332)
Text and Data Mining valid from 2020-04-19
Received: 15 October 2019
Accepted: 11 March 2020
First Online: 19 April 2020
Ethics approval and consent to participate
: Not applicable.
: All authors agree to publish this paper in this journal.
: The authors declare that they have no competing interests.