JI Shuang1, SHEN Jin2, LI Na3, PAN Cheng-Jing1, WEI Rui1**, CHEN Ying4
1. College of Chemistry,Beijing Normal University,Beijing 100875, China; 2. Faculty of Education,Beijing Normal University, Beijing 100875, China; 3. Beijing Zhongguancun Middle School,Beijing 100086, China; 4. Beijing Haidian Teachers Training College,Beijing 100195, China