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Objective@#To investigate the status and trend of low vision of junior and senior high school students in Beijing from 2009 to 2018, and to provide evidence for myopia prevention.@*Methods@#Data came from the results of physical examination of eyesight in 2009-2018 in Beijing, which were cdlected among juncor and senior high school students in March every year. Detection rate of low vision of students and the difference across different districts and counties were analyzed.@*Results@#From 2009 to 2018, the rate of low vision of high school and college entrance examination students in Beijing was on the rise, with the average rate of low vision of 86.07% and 76.36% respectively. Similar trend was found in the rate of high myopia(16.39% and 18.64%,respectively), while that of light and medium myopia tends to be stable. The highest rate of low vision among junior middle school students was in Xicheng (84.75%) District and Chaoyang District (84.03%), and for high middle school students,the highest rate of myopia was found in Fengtai District (91.17%) and Dongcheng District (89.92%).@*Conclusion@#In Beijing, the detection rate of low vision of middle school and college entrance examination students increased steadily, especially the high myopia. The health education of eyesight protection is of great significance to students. It is necessary to strengthen the extensive intervention of eyesight protection in middle and college entrance examination students.
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This study is aiming to establish an efficient metabolite extraction method for exploration of molecular mechanisms of desiccation tolerance of the resurrection plant Boea hygrometrica using a metabolomics approach. The extracts of metabolite in B. hygrometrica using methanol solution (method A) and methanol-chloroform-water solution (method B) were analyzed by gas chromatography-mass spectrometry (GC-MS). The total numbers of chromatographic peaks, extraction efficiency, retention time and the peak stability were compared. The results showed that for fresh materials, the total chromatographic peak number of method B is more than that of method A; the extraction efficiency of nine representative metabolites by method B is higher than that by method A; the comparison of 10 random chromatographic peaks revealed that the relative standard deviation (RSD) values of the retention time are less than 1% for both methods, whereas the RSD values of the extraction efficiency is different. The percentage of peaks that owned RSD values of the extraction efficiency higher than 10% is 50% for method A and 100% for method B. In addition, method B was also efficient for dry materials from B. hygrometrica. The number of chromatographic peaks, RSD value of retention time and extraction efficiency of dry materials was similar to that of fresh materials using method B, but decreased sharply using method A. Putting together, our study provided evidence that method B is an efficient extraction method for further analysis of metabolites from this resurrection species.