Funding for this research was provided by:
National Natural Science Foundation of China (21706163)
Department of Education of Liaoning Province (LQGD2017020)
Article History
Received: 12 December 2019
Accepted: 28 February 2020
First Online: 9 March 2020
Compliance with ethical standards
:
: The authors declare no conflict of interest. The funding sponsors had no role in the design of the study; in the analyses, writing of the manuscript, and the decision to publish the results.