Funding for this research was provided by:
National Key Basic Research and Department (973) Program of China (No. 2013CB329606)
National Natural Science Foundation of China (No. 71231002, 61375058)
National Natural Science Foundation of China (11571161, 11371115)
Shenzhen Sci.-Tech Fund (No. JCYJ20140509143748226)
CCF-Tencent Open Fund
Co-construction Project of Beijing Municipal Commission of Education