HUANG Yuan-Dong1, YAN Yan2, YAN Chun-Geng3, ZHOU Qing1
1. School of Chemistry & Chemical Engineering, Shaanxi Normal University, Xi'an 710062, China;
2. Baoji Education Institute of Shaanxi Province, Baoji 721000, China;
3. Teacher Education Development Center, Northwestern Polytechnical University, Xi'an 710072, China