Funding for this research was provided by:
Major Science Instrument Program of the National Natural Science Foundation of China under Grant (61527802)
Text and Data Mining valid from 2018-09-04
Received: 8 April 2018
Accepted: 3 July 2018
First Online: 4 September 2018
: The authors declare that they have no competing interests.
: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.