Funding for this research was provided by:
National Natural Science Foundation of China (21706005)
Text and Data Mining valid from 2019-03-26
Received: 1 February 2019
Revised: 12 March 2019
Accepted: 12 March 2019
First Online: 26 March 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.