Funding for this research was provided by:
National Natural Science Foundation of China (No. 31500044)
Natural Science Foundation of Tianjin City (17JCQNJC09600, No. 17JCYBJC24000)
Hebei Normal University of Science and Technology (ZD2017047)
Tianjin Science and Technology Committee (15PTCYSY00020)
Text and Data Mining valid from 2018-12-18
Received: 27 July 2018
Revised: 26 November 2018
Accepted: 28 November 2018
First Online: 18 December 2018
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.