Funding for this research was provided by:
National Natural Science Foundation of China (31672341)
Text and Data Mining valid from 2019-01-17
Received: 9 October 2018
Accepted: 4 January 2019
First Online: 17 January 2019
Compliance with ethical standards
: The authors declare that they have no conflict of interest.
: This article does not contain any studies with animals and human participants performed by any of the authors.