Funding for this research was provided by:
National Natural Science Foundation of China (No.31672561)
Text and Data Mining valid from 2019-06-07
Received: 29 January 2019
Revised: 9 May 2019
Accepted: 9 May 2019
First Online: 7 June 2019
Compliance with ethical standards
: 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.