Funding for this research was provided by:
National Key Research and Development Program of China (2017YFF0210200, 2017YFD0201805, 2016YFD0200804)
Text and Data Mining valid from 2019-01-11
Received: 9 October 2018
Accepted: 20 December 2018
First Online: 11 January 2019
Compliance with ethical standards
: The author(s) declare that they have no competing interest.