Funding for this research was provided by:
National Natural Science Foundation of China (51665033, 51661021)
Gansu Science and Technology Department (18YF1GA061)
The financial support of the Natural Science Foundation of Gansu Province in China (1606RJZA161)
Text and Data Mining valid from 2018-09-28
First Online: 28 September 2018
Compliance with Ethical Standards
: The authors declare no conflicts of interest.