查询词典 betulin

The effects of extraction temperature, microwave power, extraction time on betulin yield by MAE were discussed and the betulin content was determined by HPLC.

考察了提取温度、微波功率、提取时间对桦木醇收率的影响，并用高效液相色谱法测定了萃取物中桦木醇的含量。

Methods Rats were randomly divided into six groups: normal group,alcoholic liver disease model group,betulin low-dose group,betulin middle-dose group,betulin high-dose group and positive control group.

将SD大鼠随机分为6组，正常组和酒精性肝病模型组、白桦脂醇低、中、高剂量组和阳性药物对照组。

Analyzing the relations among betulin content and growth status, geographical location and climatic factors, it was found that the effect of growth status on betulin content was not significant, and betulin content was not only affected by self-provenance and heredity background but also by geographical location and climatic factor.

进一步分析可得，同龄树种的生长状况对白桦酯醇的含量影响不显著；而白桦酯醇的含量不仅受自身种源及遗传背景的影响，同时也受到其所处地理位置和气候因素的影响，即属于基因与环境互作的表现性状。

The results showed that in acetone and ethanol, solubilities of 3, 28-di-O-glutaryl-betulin were 33.52 and 22.65 times of those of betulin respectively; In water, solubility of 3, 28-di-O-glutaryl-betulin was 0.0021 g (100 mL water), and in PBS, solubility of 3, 28-di-O-glutary-betulin was 0.0015 g (100 mL PBS), the hydrophilicity of 3, 28-di-O-glutaryl-betulin was significantly increase.

结果表明，在丙酮和无水乙醇中，桦木酐戊二酸酯的溶解度是桦木醇的33.52和22.65倍；在水中，桦木醇戊二酸酯的溶解度为0.0021g（100mL水）；在PBS中，桦木醇戊二酸酯的溶解度约为0.0015g(100mL PBS)，目标产物的亲水性有了显著的改善。

To understand the difference of the betulin content in different parts and provenances in Betula platyphylla Suk., the methods to extract betulin were selected, and an accurate HPLC method to detect betulin content was used.

以白桦为研究材料，在白桦酯醇提取方法的选择下，采用高效液相色谱仪分析了白桦不同部位和种源间白桦酯醇含量的变化。

Its structure was characterized by FT-IR, 1H NMR and MS. Solubility data of betulin and 3, 28-di-O-glutaryl-betulin in acetone, ethanol, water and phosphate-buffered saline (PBS, pH value 7.4) were determined by equilibrium method.

采用FT-IR、1H NMR和MS对产物进行结构表征，并且选用平衡法测定了桦木醇和桦木醇戊二酸酯在丙酮、无水乙醇、水和磷酸盐缓冲溶液（PBS， pH值7.4，）等不同溶剂中的溶解度。

The current developments were summarized and the research contents of this thesis were described.In the second chapter, a simple procedure is described for the simultaneous extraction and determination of betulin and betulinic acid in white birch bark. To compare extraction efficiency, effect of white birch bark growing in different locations and different extract solvents on the content of betulin and betulinic acid were evaluated.

第二章建立了一种简单、准确度、灵敏度高和重现性好的RP-HPLC同时测定白桦树皮中白桦酯醇和白桦酯酸含量的方法，并用这种方法研究了提取溶剂以及产地对树皮中白桦酯醇和白桦酯酸的含量影响，确定了最佳的提取工艺。

To improve water solubility of betulin, two acyl groups were introduced at C-3 and C-28 hydroxy groups of betulin. 3, 28-di-O-glutaryl-betulin was synthesized with pyridine as solvent and DMAP as catalyst from betulin and glutaryl anhydride.

为了增强桦木醇的亲水性，对桦木醇的C-3位、C-28位羟基进行修饰，在吡啶作溶剂、二甲基氨基吡啶作催化剂的条件下，与戊二酸酐反应合成桦木醇戊二酸酯。

In the fifth chapter, a series of betulin derivatives including 28-acetoxybetulin, 28-tritylbetulin, 28-benzoylbetulin, 3-0-P-D-glucopyranoside of betulin and some betulinic acid conjugate containing amino acid were synthesized and confirmed by MS and NMR.

第五章分别合成得到了乙酰化白桦酯醇、28-苯甲酰化白桦酯醇、28-三苯甲基化白桦酯醇、3-O-β-D-glucopyranoside of betulin和一系列的白桦酯酸苷氨酸的衍生物，并分别对其进行了结构鉴定。

In the fifth chapter, a series of betulin derivatives including 28-acetoxybetulin, 28-tritylbetulin, 28-benzoylbetulin, 3-O-β-D-glucopyranoside of betulin and some betulinic acid conjugate containing amino acid were synthesized and confirmed by MS and NMR.

第五章分别合成得到了乙酰化白桦酯醇、28-苯甲酰化白桦酯醇、28-三苯甲基化白桦酯醇、3-O-β-D-glucopyranoside of betulin和一系列的白桦酯酸苷氨酸的衍生物，并分别对其进行了结构鉴定。

I am sure after a few weeks of adaptation and familiarization I will have no difficulty in functioning on a daily basis in an English speaking society or in participating fully in graduate studies.

在大学的三年的学习生活不仅给予我自身的充实，更重要的是磨练和培养了我较强的自觉能力和严谨，踏实的作风以及不怕困难的精神，对未来充满了信心！

As the first volcanoes erupted, one of the gases that bellowed out was steam.

在第一批火山喷发时，喷出的气体之一就是水蒸汽。