Funding for this research was provided by:
Shanxi Provincial Key Research and Development Project (201603D14010)
Text and Data Mining valid from 2020-02-11
Received: 19 October 2019
Accepted: 5 February 2020
First Online: 11 February 2020
Compliance with ethical standards
: The authors declare that there are no conflict of interest.
: This research does not contain any studies with human participants or animals performed by any of the authors.