Funding for this research was provided by:
National Natural Science Foundation of China (51337002)
Text and Data Mining valid from 2018-12-14
Received: 17 September 2018
Accepted: 26 November 2018
First Online: 14 December 2018
Compliance with ethical standards
: The authors declare that they have no competing interests.
: Informed consent was obtained from all individual participants included in the study.