washing the product with methanol and ether for several times, separating to purify, re-crystallizing, vacuum drying at room temperature and storing in a drier at -20 deg.c.
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It is meaningful and significant to take further research of these natural resourcesThe relatively mature method for purifying betulin is recrystallizing betulin in chloroform-methanol mixture solvent.
在白桦脂醇的纯化方面目前比较成熟的方法是氯仿—甲醇混合溶剂重结晶来提纯白桦脂醇，本论文通过正交设计，得到最优化的溶剂比例和用量。
参考来源 - 白桦脂醇的纯化及其衍生物的研究·2,447,543篇论文数据，部分数据来源于NoteExpress
It was also found that the tree initiation voltage increases after re - crystallizing.
同时还发现，经过重结晶后，电树的起始电压也升高了。
Addition of re may increase crystallizing temperature and improve film properties.
稀土的加入可以提高晶化温度和镀层性能。
During welding metallurgic process, re compound with surface energy separated out previously from superheating melted metal, and acted as the crystallizing nucleus of compound carbides.
具有高能表面的稀土化合物质点，在焊接冶金过程中领先析出于过热液相内，充当了包裹式碳化物颗粒的非自发晶核核心。
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