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1.
莪术醇进行环外双键断裂氧化和酸催化氧桥开环加成2步反应后,经硅胶柱层析分离,得到一种新型的莪术醇衍生物(2). 应用1D NMR和2D NMR测试了化合物2的1H NMR、13C NMR、1H-1H COSY、gHSQC、gHMBC,对化合物2的1H和13C化学位移进行了全归属,结合其红外光谱和质谱,推得化合物2为8-羟基-12-异丙基-2-甲基-三环[6.2.2.01,5]十二烷-10-氧杂-6,9-二酮,并比较了莪术醇,莪术醇双键断裂氧化产物(化合物1),化合物2的1H NMR、13C NMR数据变化. 相似文献
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用一维1H、13C NMR谱、DEPT 13C NMR谱、选择性远程DEPT 13C NMR、1H-1H COSY和13C-1H COSY二维核磁共振技术研究了南海海绵Dysidea fragilis中的两个倍半萜herbadysidolide(1)和furodysinin lactone(2),确认了化学结构,并对其13C NMR和1H NMR谱进行了归属.药理活性试验表明:1和2具有一定的心血管活性. 相似文献
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茶多酚及其单体结构自由基的ESR研究 总被引:2,自引:0,他引:2
通过ESR检测方法研究了邻苯三酚、茶多酚及其四种单体的自氧化醌类自由基的ESR波谱信号,系统阐明了这几种物质的内在结构联系. 相似文献
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The proanthocyanidins of the leaves of 16 taxa of the Rhododendron genus (Ericaceae) [Rhododendron 'Catawbiense Grandiflorum', Rhododendron 'Cunningham's White', Rhododendron smirnowii Trautv., Rhododendron calophytum Franch., Rhododendron dichroanthum ssp. scyphocalyx (Balf. f. & Forrest ) Cowan, Rhododendron micranthum Turcz., Rhododendron praevernum Hutch., Rhododendron ungernii Trautv., Rhododendron kaempferi Planch., Rhododendron degronianum ssp. heptamerum var. hondoense (Nakai ) H. Hara, Rhododendron fortunei Lindl., Rhododendron ponticum L., Rhododendron galactinum Balf. f. ex Tagg., Rhododendron oreotrephes W. W. Sm., Rhododendron brachycarpum ssp. brachycarpum D. Don ex G. Don, and Rhododendron insigne Hemsl. & E. H. Wilson ] were investigated qualitatively by liquid chromatography-mass spectrometry in series. Twenty-nine dimeric proanthocyanidins based on (epi)catechin and (epi)gallocatechin were detected and characterized on the basis of their unique fragmentation pattern in the negative ion mode tandem mass spectrometry spectra. All of them were extracted for the first time from these sources, and ten of them were not reported previously in nature. The position of the galloyl residue was assigned on the basis of the retro-Diels-Alder fragmentation and the dehydrated retro-Diels-Alder fragmentation; it resulted from the loss of gallic acid as a neutral loss in the negative ion mode. Furthermore, four caffeoylquinic acids, six p-coumaroylquinic acids, epigallocatechin, gallocatechin, catechin, epicatechin, epigallocatechin gallate, catechin gallate, epicatechin gallate, gallocatechin gallate, two quercetin-O-hexosides, quercetin-O-galloyl-hexoside, quercetin-O-pentoside, quercetin-O-rhamnoside, quercetin-O-pentoside-O-hexoside, quercetin-O-rhamnoside-O-hexoside, quercetin-O-feruloyl-hexoside, quercetin-O-(p-hydroxy)benzoyl-hexoside, taxifolin-O-pentoside, myricetin-O-rhamnoside, two myricetin-O-pentosides, three myricetin-O-hexosides, and two myricetin-O-galloyl-hexosides were detected and shown to possess characteristic tandem mass spectrometry spectra and were tentatively assigned on the basis of their retention time. 相似文献
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近红外光谱法快速检测绿茶中儿茶素的含量 总被引:7,自引:2,他引:5
提出了一种应用傅里叶近红外漫反射光谱分析技术快速检测茶叶中主要儿茶素含量的新方法.首先获取茶叶在10000~4000 cm<'-1>范围的近红外漫反射光谱,然后以高效液相色谱分析值作参考值.采用偏最小二乘法建立茶叶中表没食子儿茶素没食子酸酯(EGCG)、表儿茶素没食子酸酯(ECG)和表没食子儿茶素(EGC)含量的定量分析模型.通过交互验证方法来优化模型的主成分数和所采用的光谱预处理方法.EGCG、ECG和EGC三个模型预测值和参考值问的相关系数分别为0.9800、0.9763和0.9853,预测均方根误差分别为0.3509、0.1147和0.1365.研究结果表明,近红外光谱技术可成功地检测茶叶中EGCG,ECG和EGC的含量. 相似文献
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白花刺参中的咖啡酰基奎宁酸成分 总被引:16,自引:0,他引:16
著名藏药白花刺参Morina nepalensis var. albaHand. Mazz.的全株的水溶性部分通过硅胶、RP-8、Sephadex LH-20柱层析分离,得到4个咖啡酰基奎宁酸1~4 ,运用光谱和波谱方法, 分别鉴定为3-O-咖啡酰基奎宁酸(1)、3,5-O-双咖啡酰基奎宁酸(2)、3,4-O-双咖啡酰基-奎宁酸(3)和4,5-O-双咖啡酰基-奎宁酸(4). 应用2D NMR图谱, 对其氢和碳的化学位移进行全归属, 并报道1, 2在氘代甲醇和氘代二-甲亚砜两种溶剂下测定1H和13C化学位移. 4个化合物都是首次分离自刺参属植物. 相似文献
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合成了两种直链醚席夫碱双水杨醛缩二甘醇二胺(SALDA)和双水杨醛缩四甘醇二胺(SALTTA)及其新配合物[Zn(SALDA)](NO3)2·4H2O和[Cu3(SALTTA)(NO3)4](NO3)2·3H2O.并以IR谱、UV谱,特别是1H和13C NMR谱等方法进行了表征,并详细地讨论了合成方法,IR谱表明SALTTA中醚氧并未全部配位. 相似文献
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通过对水与水合Fe3+配合物的二位快交换体系的纵向弛豫速率的测定,得出了在本实验条件下磁化效应与权重平均表达方式的相似性,进而得出了水合Fe3+配合物纵向弛豫速率.有助于研究水溶液中的离子配合物. 相似文献
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Caffeoylquinic acids are existed in many plant species with various biological and pharmacological activities. 3-O-caffeoylquinic acid and 4-O-caffeoylquinic acid are two isomers of caffeoylquinic acids, which may be degraded and transformed to their isomers in processing. The present paper found that the stability of 3- and 4-O-caffeoylquinic acid had decreased with the increasing solution alkalinity. 3-O-caffeoylquinic acid was more stable than 4-O-caffeoylquinic acid at the same condition. During degradation, 3- and 4-O-caffeoylquinic acid were partially converted to their isomers. Additionally, ultrasonic effects on the degradation and isomerization of 3- and 4-O-caffeoylquinic acid at different pH were studied. Ultrasound facilitated the degradation and isomerization of these compounds. The degradation kinetics were described by the Weibull equation. The protective effect of ascorbic acid and epigallocatechin gallate were also explored. Ascorbic acid and epigallocatechin gallate could alleviate the degradation of 3- and 4-O-caffeoylquinic acid under certain conditions. 相似文献
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The analytical potential energy function of HDO is constructed at first using the many-body expansion method.The reaction dynamics of O+HD(v = 0,j = 0) in five product channels are all studied by quasi-classical trajectory(QCT) method.The results show that the long-lived complex compound HDO is the dominant product at low collision energy.With increasing collision energy,O+HD → OH+D and O+HD → OD+H exchange reactions will occur with remarkable characteristics,such as near threshold energies,different reaction probabilities,and different reaction cross sections,implying the isotopic effect between H and D.With further increasing collision energy(e.g.,up to 502.08 kJ/mol),O+HD → O+H+D will occur and induce the complete dissociation into single O,H,and D atoms. 相似文献
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以磷酸三乙酯、硝酸铝和正硅酸乙酯为原料,通过它们的不完全水解制备了含有有机基团的xAl2O3-xP2O5-100SiO2(x=0.25—3)凝胶.在空气中在400℃或450℃或在氮气中从300到700℃对凝胶进行热处理,使凝胶中的有机基团炭化,从而得到含有碳纳米颗粒的xAl2O3-xP2O5-100SiO2(x=0.25—2)凝胶玻璃.利用吸收光谱和TEM对含有碳纳米颗粒的凝胶玻璃进行了表征,结果发现随着碳纳米颗粒尺寸的减小吸收边向高能边移动,这种现象是由碳纳米颗粒中电子和空穴的量子限制效应引起的.电子衍射表明凝胶玻璃中的纳米碳为非晶碳.
关键词:
溶胶凝胶法
碳
纳米颗粒 相似文献
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本文研究了用 ICP- AES法测定 Pd/Al2 O3催化剂中钯所存在的干扰问题。考察了基体及所用试剂对钯测定的影响 ,发现氧化铝基体、硫酸等对钯的测定均有负干扰 ,提出采用基体匹配法测定 Pd/Al2 O3中的钯含量。方法回收率在 96%以上 ,9次测定相对标准偏差小于 3% 相似文献