Funding for this research was provided by:
National Natural Science Foundation of China (31660408)
Distinguished Youth innovation foundation of Bingtuan (2014CD003)
Text and Data Mining valid from 2018-01-06
Received: 2 June 2017
Accepted: 23 December 2017
First Online: 6 January 2018
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.