Funding for this research was provided by:
National Natural Science Foundation of China (51605378, 51375384)
Text and Data Mining valid from 2018-07-07
Received: 18 December 2017
Accepted: 26 June 2018
First Online: 7 July 2018
Compliance with Ethical Standards
: The authors declare no potential conflicts of interest with respect to the research, authorship and/or publication of this article.