1. Department of Chemistry and Chemical Engineering Jining University Qufu Shandong 273155 P. R.China
2. College of Chemistry and Chemical Engineering Qufu Normal University Qufu Shandong 273165 P. R. China
3. Laboratory of Tibetan Medicine Research & Qinghai Key Laboratory of Qinghai-Tibet Plateau Biological Resources Northwest Institute of Plateau Biology Chinese Academy of Science Xining 810001 P. R. China