Funding for this research was provided by:
National Natural Science Foundation of China (No.61673011)
Postgraduate Research & Practice Innovation Program of Jiangsu Province (No. KYCX18 0371)
Text and Data Mining valid from 2019-04-23
Received: 8 January 2019
Accepted: 10 April 2019
First Online: 23 April 2019
: The authors declare that they have no competing interests.