Funding for this research was provided by:
National Natural Science Foundation of China (41504032)
Text and Data Mining valid from 2019-02-01
Received: 24 November 2018
Accepted: 21 January 2019
First Online: 1 February 2019
Compliance with ethical standards
: The authors declare that they have no conflicts of interest. Disclosure of potential conflicts of interest Research involving Human Participants.