Funding for this research was provided by:
National Natural Science Foundation of China (No. 81803106)
Ph.D. Foundation of North China University of Science and Technology (No. BS2017057)
Text and Data Mining valid from 2019-02-02
Received: 26 September 2018
Accepted: 17 January 2019
First Online: 2 February 2019
Compliance with ethical standards
: The authors declare that they have no conflict of interest.
: This article does not contain any studies with human participants or animals performed by any of the authors.
: This article does not contain any studies with human participants performed by any of the authors.