Funding for this research was provided by:
National Natural Science Foundation of China (81502410)
Text and Data Mining valid from 2019-07-15
Received: 18 December 2018
Accepted: 2 July 2019
First Online: 15 July 2019
Ethics approval and consent to participate
: Not applicable.
: All the authors give their consent for publication.
: The authors declare that they have no competing interests.