Funding for this research was provided by:
National Natural Science Foundation of China (31501791)
Text and Data Mining valid from 2019-09-12
Received: 21 June 2019
Accepted: 5 September 2019
First Online: 12 September 2019
Compliance with ethical standards
: The authors declare that they have no conflict of interest.
: The authors declare that no human participants and animals were involved in this study.