Funding for this research was provided by:
National Natural Science Foundation of China (61272285)
National High-Technology Program of China (2014AA012301)
National Key Technology Support Program of China (2014BAH24F02)
Program for Changjiang Scholars and Innovative Research Team in University (IRT13090)
Program of Shaanxi Province Innovative Research Team (2014KCT-17)
National Natural Science Foundation of China (61373077)