Funding for this research was provided by:
National Natural Science Foundation of China (No. 61601306)
Shenzhen Overseas High Level Talent Peacock Project Fund (No. 20150215145C)
Text and Data Mining valid from 2018-01-16
Received: 26 September 2017
Accepted: 7 January 2018
First Online: 16 January 2018
: The authors declare that they have no competing interests.