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Ming-Juan Qi 《Tetrahedron》2007,63(42):10415-10424
Reactions of salicyl N-tosylimines with methyl vinyl ketone, ethyl vinyl ketone or phenyl vinyl ketone proceeded smoothly under mild conditions to give the corresponding chromanes or aza-Baylis-Hillman adducts in moderate to excellent yields in the presence of phosphine or nitrogen Lewis base. 相似文献
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利用遗传算法,并结合线性回归和交叉验证方法,对一系列43个苯并呋喃/噻吩联二苯类PTP1B抑制剂作了二维定量构效关系的研究.计算得到了一组效果较好的定量构效关系模型.模型不仅具有好的回归能力,而且还具有很好的预测能力.同时,通过分析在遗传优化过程中参数在精华种群中所占的比例,还得到了可能对活性影响较大的成分.计算结果表明,分子的4个参数:lgP(分配系数)、Area(表面积)、MW(分子量)以及Dip(偶极距)是影响化合物活性的最重要的参数,这对抑制剂的设计和改造提供了指导. 相似文献
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1INTRODUCTIONBis N,N’(dithiodi 2,1 phennylene)benzamidehasbeenwidelyusedinpro cesingofrubberaspeptizerforproducingfreeradical... 相似文献
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苯酚和苯胺类化合物对鲁米诺电致化学发光的增强和抑制作用 总被引:1,自引:0,他引:1
系统研究了不同pH下的NaHCO3-Na2CO3和NaOH缓冲介质中, 36种苯酚和苯胺类化合物对鲁米诺电致化学发光(Electrochemiluminescence, ECL)体系的影响. 发现苯酚和苯胺类化合物的抑制和增强作用与化合物的结构、氧化电位和介质的pH有直接的关系: 具有较高氧化电位的苯酚和苯胺类化合物对鲁米诺的ECL没有影响; 而具有较低的氧化电位、苯环上有两个处于对位的-OH(或-NH2)或苯环上有多个相邻的-OH的化合物, 在较低的pH下有增强作用, 在较高的pH下具有抑制作用; 其它的化合物则呈现抑制作用, 抑制作用的大小与化合物的结构有关. 通过研究化合物的氧化半峰电位、ECL光谱、荧光光谱等, 提出了增强和抑制作用的可能机理: 各种有机物的电氧化产物如醌、酮及具有醌、酮结构的聚合物等能够淬灭激发态3-氨基邻苯二甲酸根阴离子(3-AP2-*)的发射, 导致了鲁米诺的ECL的降低; 同时, 反应过程中生成的半醌自由基中间体或 会促进鲁米诺的发光反应, 呈现增强作用. 相似文献
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建立检测车前草中总黄酮含量的高效液相色谱法,探索车前草黄酮苷的水解条件.通过水解车前草黄酮提取物,将黄酮苷水解成苷元,再用HPLC法测定水解后车前草黄酮苷元含量.以Shim-pack VP-ODS (150L×4.6,10μm)为分析柱,流动相为甲醇-0.1%磷酸水溶液梯度洗脱,流速为1.0mL/min,检测波长为360nm,柱温30℃,采用峰面积外标法计算含量.通过比较水解前、后黄酮苷元的检测量,发现水解后检测到黄酮量高.此法测得车前草中槲皮素的含量为1.36mg/g,木犀草素的含量为0.35mg/g,黄芩素的含量为0.89mg/g,3种苷元的含量之和为2.60mg/g.首次以水解后的车前草总黄酮苷元作为车前草黄酮含量的评价指标,首次建立了水解-HPLC法检测车前草黄酮含量,为测定车前草及其提取物中黄酮类化合物的含量提供了灵敏、准确和快速的测定方法,为不同品种和产地的车前草及其提取物质量监控提供依据. 相似文献
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The most severe problem of a two-way "plug-and-play" (p & p) quantum key distribution system is that the source can be controlled by the eavesdropper. This kind of source is defined as an üntrusted source". This paper discusses the effects of the fluctuation of internal transmittance on the final key generation rate and the transmission distance. The security of the standard BB84 protocol, one-decoy state protocol, and weak+vacuum decoy state protocol, with untrusted sources and the fluctuation of internal transmittance are studied. It is shown that the one-decoy state is sensitive to the statistical fluctuation but weak+vacuum decoy state is only slightly affected by the fluctuation. It is also shown that both the maximum secure transmission distance and final key generation rate are reduced when Alice's laboratory transmittance fluctuation is considered. 相似文献
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在40 Hz~11 MHz频率范围测量了聚苯乙烯膜以及混入聚吡咯粒子的聚苯乙烯膜和电解质溶液构成的体系的介电谱, 发现了特异的弛豫现象: 纯的和掺入导电性聚吡咯后的聚苯乙烯膜分别显示出单一弛豫和双弛豫的不同模式的介电谱. 在Maxwell-Wagner界面极化概念基础上解释了该弛豫机制: 高、低频弛豫分别由膜-液界面极化和膜相本身的不均一性引起的. 将体系进行了模型化, 并利用Hanai理论方法对谱进行了解析, 获得了内部电性质的诸多参数. 对不同聚吡咯掺入量的膜/溶液体系的介电测量和解析结果表明, 电解质溶液的种类、浓度以及膜中混入聚吡咯的量都影响着膜相的介电响应. 这些结论为利用加入导电粒子改善绝缘高分子聚合物的电性质的研究以及制备既具有导电功能又使基体的力学性能得到提高的高分子复合物提供了重要的线索. 相似文献
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Chemiluminescent reactions induced by gold nanoparticles 总被引:2,自引:0,他引:2
The reaction of gold nanoparticles with a potassium periodate-sodium hydroxide-carbonate system undergoes chemiluminescence with three emission bands at 380-390, 430-450, and 490-500 nm, respectively. It was found that the light intensity increased linearly with the concentration of the gold nanoparticles, and the CL intensity increased dramatically when the citrate ions on the nanoparticle surface were replaced by SCN(-). The shape, size, and oxidation state of gold nanoparticles after the chemiluminescent reaction were characterized by UV-visible absorption spectrometry, transmission electron microscopy (TEM), and X-ray photoelectron spectrometry (XPS). Gold nanoparticles are supposed to function as a nanosized platform for the observed chemiluminescent reactions. A chemiluminescent mechanism has been proposed in which the interaction between free CO(3)(*-) and O(2)(*-) radicals generated by a KIO(4)-NaOH-Na(2)CO(3) system and gold nanoparticles results in the formation of emissive intermediate gold(I) complexes, carbon dioxide dimers, and singlet oxygen molecular pairs on the surface of the gold nanoparticles. This work is not only of great importance for gaining a better understanding of the unique optical and surface properties and chemical reactivity of nanoparticles but also of great potential for developing new biosensing and immunolabeling technologies. 相似文献