相关基金:Project supported by the National Natural Science Foundation of China (Grant Nos 90606023, 10574003 and 20731160012), a National 973 Project (Grant No 2007CB936202 and 2009CB623703) and MOST from China's Ministry of Science and Technology and Hong Kong's NSFC/RGC Joint Research Scheme (Project No N_HKUST615/06).