Funding for this research was provided by:
National Natural Science Foundation of China (61662021, 61363007)
Cernet Innovation Project (NGII20180607)
Text and Data Mining valid from 2020-01-10
Received: 19 September 2019
Accepted: 29 December 2019
First Online: 10 January 2020
: The authors declare that they have no competing interests.