共查询到18条相似文献,搜索用时 93 毫秒
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落叶松(larix gmelinii R.)阿拉伯半乳聚糖(AG)具有免疫、抗肿瘤等药理活性,对其提取及纯化方法的研究具有重要意义.不同分离方法各具特色,综述了落叶松中AG的不同提取及纯化方法,以期为该糖的提取及纯化提供一定参考.其中温水抽提法效率较低,但由于抽提条件温和至今仍有较多应用;闪式提取、超声及微波辅助提取法... 相似文献
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以兴安落叶松(LarixgmeiniiRupr.)木材的加工剩余物为原料,采用超声波法提取阿拉伯半乳聚糖。根据前期单因素试验确定的主要影响因素,采用正交试验研究了不同参数对超声波法提取阿拉伯半乳聚糖提取率的影响,另外组合对试验结果有最大影响的各因素为追加试验的工艺参数。较佳工艺参数为:原料粒度60~80目的兴安落叶松木粉5.0g,超声波功率160W,料液比1∶30,提取时间50min,阿拉伯半乳聚糖粗糖收率19.47%。通过红外光谱和紫外光谱分析鉴定其结构。 相似文献
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以兴安落叶松(Larix grneinii Rupr.)木材的加工剩余物为原料,采用超声波法提取阿拉伯半乳聚糖。根据前期单因素试验确定的主要影响因素,采用正交试验研究了不同参数对超声波法提取阿拉伯半乳聚糖提取率的影响,另外组合对试验结果有最大影响的各因素为追加试验的工艺参数。较佳工艺参数为:原料粒度60—80目的兴安落叶松木粉5.0g,超声波功率160W,料液比1:30,提取时间50min,阿拉伯半乳聚糖粗糖收率19.47%。通过红外光谱和紫外光谱分析鉴定其结构。 相似文献
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兴安落叶松木素化学结构特性的研究 总被引:3,自引:0,他引:3
从兴安落叶松的边材、心材和经0.1mol/NaOH抽提过的心材中分离出二氧六环木素,用化学分析和光谱分析研究了分离木素的化学结构特性.结果表明兴安落叶松的边材和心材术素都是典型的针叶材木素,三种分离木素的元素组成、官能团含量和光谱性质没有显著差异,心材多酚类化合你又少与木素存在化学连接,只是心材木素的缩合程度略高,分子量低于边材术素.兴安落叶松边材、心材和经0.lmol/NaOH抽提的心材的二氧六环木素C9单元式分别为C9H8.80O3.06(OCH3)0.96C9H8.80O3.14(OCH3)0.93和C9H8.55O3.03(OCH3)0.96,与马尾松二氧六环木素十分相似。 相似文献
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定量~(13)C-NMR谱表征蔗渣碱木素结构 总被引:4,自引:0,他引:4
从蔗渣纸浆黑液中制出纯蔗渣碱木素,然后测定其定量13C-NMR谱.图谱分析表明,蔗渣碱木素主要由紫丁香基,愈创木基和对羟苯基三种丙烷结构单元组成,其中未绩合的紫丁香基、愈创木基和对羟羊基含量比为2.2:1.0:1.4.蔗渣碱术素结构单元间主要以β-O-4烷基芳基醚键连接,也有一定量的非环状α-醚键存在.蔗渣碱木素中,相当部分对香豆酸类结构并非通过酯键而是通过醚键或碳双键连接于芳核上. 相似文献
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白腐菌Panus conchatus降解稻草木素机理研究──(二)木素降解产物高分子部分的结构特征 总被引:5,自引:1,他引:4
用定量(13)C-NMR技术研究了稻草经白腐菌Panusconchatus降解后木素的高分子部分的结构特征变化。与未经生物作用的木素相比较,发现发酵稻草木素的13C-NMR谱图出现新的吸收峰以及某些吸收峰的强度有明显变化。这些变化证实了在生物作用过程木素大分子中形成了醌类以及α-羟基酸的结构,这些类型的结构特别有利于木素进一步降解。并同时证实木素生物降解过程中发生β-O-4;Cα-Cβ及Cβ-Cγ键的断裂及Cγ的氧化。定量分析结果表明,经生物降解后木素大分子的甲氧基和羧基含量增加,愈疮木基和对羟基苯基结构单元优先降解,推断出此白腐菌对稻草的作用首先进攻纤维胞间层,其结果与电子显微镜所得的结果相一致。分析结果同时表明,生物降解优先发生于木索非缩聚结构单元。 相似文献
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Yang L Sun X Yang F Zhao C Zhang L Zu Y 《International journal of molecular sciences》2012,13(4):5163-5178
Ionic liquid based, microwave-assisted extraction (ILMAE) was successfully applied to the extraction of proanthocyanidins from Larix gmelini bark. In this work, in order to evaluate the performance of ionic liquids in the microwave-assisted extraction process, a series of 1-alkyl-3-methylimidazolium ionic liquids with different cations and anions were evaluated for extraction yield, and 1-butyl-3-methylimidazolium bromide was selected as the optimal solvent. In addition, the ILMAE procedure for the proanthocyanidins was optimized and compared with other conventional extraction techniques. Under the optimized conditions, satisfactory extraction yield of the proanthocyanidins was obtained. Relative to other methods, the proposed approach provided higher extraction yield and lower energy consumption. The Larix gmelini bark samples before and after extraction were analyzed by Thermal gravimetric analysis, Fourier-transform infrared spectroscopy and characterized by scanning electron microscopy. The results showed that the ILMAE method is a simple and efficient technique for sample preparation. 相似文献
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缩聚条件对脲醛树脂结构的影响 总被引:17,自引:2,他引:15
用^13CNMR研究脲醛树脂缩聚反应结构形式特征,结果表明:在传统合成工艺条件下,与树脂化反应平行地存在一个较强烈的水解反应;二次缩聚有利于降低树脂中二亚甲基醚的含量,并可提高树脂交联程度;高温缩聚所得的树脂结构简单并有利于降低醚键的含量和提高树脂贮稳定性;降低缩聚阶段的PH值有利于提高树脂交联程度,降低了甲醛的含量。 相似文献
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Daniel J. Arriola Sergio S. Cuti David E. Henton Cynthia Powell Patrick B. Smith 《应用聚合物科学杂志》1997,63(4):439-451
A 13C-labeled crosslinker (trimethylolpropane triacrylate, TMPTA) was synthesized and copolymerized with acrylic acid while monitoring the relative rates of reaction of the crosslinker and acrylic acid by 13C-NMR. This allowed easy quantification of the concentration of the minor component (crosslinker) in the polymer and monomer mixture to levels as low as 0.02%. Polymerizations were conducted in 5 mm NMR tubes under varied temperature, percent neutralization (pH), and percent solids. Reactivity ratios were determined from the rates of incorporation of the components into the gel by use of the integrated form of the copolymerization equation, and their sensitivity to the above variables was quantified. The relative rate of incorporation of the crosslinker into the gel was exceedingly fast. The reactivity ratio, r1 for acrylic acid, varied from 0.31 (65% neutralization) to 0.77 (unneutralized). The reactivity ratio was affected by the percent solids (solvent effect), but was insensitive to temperature over the range of 55–80°C. It was observed that all of the double bonds of TMPTA were incorporated into gel network as opposed to prior models predicting only two bonds reacting. The reported inefficiency of TMPTA is postulated to be caused by a solubility problem in the monomer mixture. Very low levels of extractables were found in the products even though the crosslinker was consumed by 70% conversion. Based on these data, we propose that a major component of the gel network is graft polymer that forms late in the polymerization onto the crosslinked gel formed earlier. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 63: 439–451, 1997 相似文献
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稳定同位素13C因其具有安全、无损伤和非侵害性等特点己被广泛应用于生物医学等研究领域。尤其是应用不同的13C标记物所进行的呼气试验,更是在生物学、临床医学的诊断与研究中发挥了重要作用,应用前景广阔。 相似文献