Funding for this research was provided by:
National Key R&D Program of China (2018YFC0808706)
National Natural Science Foundation of China (61601058)
Fundamental Research Funds for the Central Universities (310832173701)
Youth Talent Promotion Plan of Shaanxi Association for Science and Technology (20170508)
Article History
Received: 8 February 2018
Accepted: 20 September 2018
First Online: 10 October 2018
Competing interests
: The authors declare that they have no competing interests.
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