Funding for this research was provided by:
National Natural Science Foundation of China (81803569)
Text and Data Mining valid from 2019-07-05
Received: 4 June 2019
Accepted: 1 July 2019
First Online: 5 July 2019
Compliance with ethical standards
: All the authors declare that they have no conflict of interest.
: This article does not contain any studies with human participants or animals performed by any of the authors.