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以天然长叶薄荷酮[R-( )-Pulegone]为起始原料,经过一系列立体选择性化学反应步骤,成功地建立了3个手性中心,从而完成了具有抗艾滋病活性Didemnaketals类似物的关键中间体3,7-二甲基-5,6-二羟基-辛-7-烯醛中间体的合成,发现PCC与三级氧醇8-9的非对映选择性反应,使得9被完全氧化,而8以93%的产率回收,其de值高达98%。 相似文献
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本报告了采用单线圈感应法对大面积高温超导薄膜的临界电流密度进行无损伤测定的情况。此法为研究Jc及磁通钉扎提供了新手段。我们从理论上推导了电流比常数值,并将由此算得的Jc值与传统的输运法Jc结果进行了比较,然后开展了一些讨论。 相似文献
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文章着重研究了市场需求服从正态分布时参数估计误差变化对产品开发决策正确性的影响。通过实例分析,得到了处理这类问题的方法。文章进而给出了需求为有限方差与数学期望的一般随机量的处理方法,还给出了对Poisson变量的分析公式。 相似文献
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The thermodynamical quantities are usually considered as the independent ones in the case of the existence of multi-horizons. Comparing the first laws for the event horizon and cosmological horizon of Schwarzschild-de Sitter space-time, we find them share the same values of mass, charge and cosmological constant, which might imply that there exists entanglement between the two horizons. Naturally we attempt to add an extra term, which contributed to the total entropy of the black hole. We recalculate the total entropy and the effective specific heat by taking the globally effective first law and find that they will be emanative when the two horizons approach to each other. 相似文献
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By adopting a result from generalized uncertainty principles (GUP), we modify the inner bound of the membrane model to a physical fixed value and get the cut-offs naturally rather than by hand, which are both in brickwall model and membrane model, and the semi-classical quantization condition could always be valid as well. We also calculate the entropies of Schwarzschild-de Sitter black hole and find the GUP we choose qualitatively shows that the requirement of mass in this method is the same as the natural requirement of the Schwarzschild-de Sitter black hole,which means the method might be self-consistent. 相似文献
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寻找抗艾滋病活性的抚导化合物是当前药物化学研究领域中的热点之一. 相似文献
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本文报道5-氟尿嘧啶-1-乙酰天冬氨酸,5-氟尿嘧啶-1-乙酰天冬氨酸双对硝基苯酯的合成。并用5-氟尿嘧啶-1-乙酰天冬氨酸双对硝基苯酯与一系列α,ω-二胺或赖氨酸乙酯缩聚,合成了五个聚5-氟尿嘧啶-1-乙酰天冬氨酰二胺和一个聚5-氟尿嘧啶-1-乙酰天冬氨酰赖氨酸乙酯。用~1HNMR,IR,UV和元素分析表征和签定了所得的单体和聚合物。抗动物肿瘤试验结果表明:聚5-氟尿嘧啶-1-乙酰天冬氨酰戊二胺,聚5-氟尿嘧啶-1-乙酰天冬氨酰赖氨酸乙酯,对小鼠艾氏腹水癌的抑制率分别为31.85%,44.23%。 相似文献
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In this note, we recalculate the entropy of the Vaidya black hole on the event horizon by considering the generalized uncertainty principle based on the brick-wall model. The result shows that we need not impose a cut-off by hand anymore and the result satisfies the Bekenstein-Hawking law as well. 相似文献
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