Funding for this research was provided by:
National Natural Science Foundation of China (31730082)
Text and Data Mining valid from 2018-10-31
Received: 3 August 2018
Accepted: 25 October 2018
First Online: 31 October 2018
Compliance with ethical standards
: The authors declare that there are no conflicts of interest.
: The authors note that this study was performed and reported in accordance with the ethical standards of scientific conduct.