Funding for this research was provided by:
National Natural Science Foundation of China (81760441)
Text and Data Mining valid from 2019-04-17
Received: 14 November 2018
Accepted: 27 March 2019
First Online: 17 April 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.