共查询到20条相似文献,搜索用时 125 毫秒
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一维SEMDY和旋转坐标NOE差谱NMR新技术用于天然化合物中寡糖的结构研究 总被引:2,自引:0,他引:2
报告从日本续断根部的乙醇提取物中分得二个新的五糖三萜皂甙,应用一维SEMDY和旋转坐标NOE差谱等NMR新技术互相配合的方法对它们的结构进行了研究,确定为:3-O-α-L-吡喃鼠李糖(1→3)-β-D-吡喃葡萄糖(1→3)-α-L-吡喃李鼠糖(1→2)-α-L-吡喃阿拉伯糖-常春藤甙元-28-O-β-吡喃葡萄糖酯甙(1),和3-O-「β-D-吡喃葡萄糖(1→4)」「α-L-吡喃鼠李糖(1→3)」- 相似文献
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抗菌素阿莫西林荧光分析法的研究 总被引:7,自引:0,他引:7
本文提出了阿莫西林(2S,5R,6R)-3,3-二甲基-6(R-)-(1)-2-氨基2-(4-羟基苯基)乙酰氨基-7氧化-4-硫杂-1氮杂双环(3,2,0)庚烷-2-甲酸三水化合物荧光分析的方法。并对影响阿莫西林荧光性质(光谱和光谱强度)的各种因素,包括pH值、表面活性剂的增效作用、无机离子的配合作用以其他介质条件等进行了较为详细的研究。实验结果表明,阿莫西林具有良好的荧光性质,在微碱性条件下荧光 相似文献
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本文中制备了电荷转移络合物萘-I2(Nap-I2),苯乙烯-I2(Sty-I2)偶氮苯-I2(azob-I2),对二甲苯-I2(p-xyl-I2)以及吡啶-Br2(Py-Br2),以I2的共振吸收频率激发样品,在Raman散射实验中观察到了它们络合后退偏比的增强,并对退偏比的增强机理进行了讨论。 相似文献
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本文通过分析5-(2-羧基苯基)-10,15,20-三苯基卟啉(o-TPPCO2H)和苯丙氨酸乙酯的紫外-可见光谱(UV-Vis)滴定曲线以及1 H-NMR数据, 证实了o-TPPCO2H 中的吡咯氮上的氢和氨基酸酯的羰基氧之间形成的氢键 相似文献
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3-三苯基锗基-1,1-二苯基-1-丁醇类化合物的拉曼光谱和红外光谱研究 总被引:2,自引:0,他引:2
我们合成3-三苯基锗基-1,1-二苯基-1-丙醇及同系物3-三苯基锗基-1,1-二苯基-1-丁醇;3-三苯基锗基-2-甲基-1,1-二苯基-1-丙醇,这些化合物都是有机锗类化合物,是具有抗肿瘤活性的化合物3-三苯基锗基-1-二苯基-1-丙醇的类似物,它们可能具有生物活性。我们测量了它们的拉曼光谱及红外光谱。经光谱分析,指认了主要波数所对应的分子振动。在这三种化合物中,Ge-Ph的伸缩振动出现在10 相似文献
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本文综述了R-Ba-Cu-O体系,Bi-Sr-Ca-Cu-O体系,T1-Ba-Ca-Cu-O #系,T1-Sr-Ca-R-Cu-O体系以及Pb-Sr-R(Ca)Cu-O体系超导相的相关系和晶体结构,并讨论了超导相的结构特点和它们之间的相互关系. 相似文献
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N. A. Borisevich T. F. Raichenok V. A. Khripach V. N. Zhabinskii G. V. Ivanova 《Journal of Applied Spectroscopy》2008,75(1):75-79
Electronic absorption spectra of 24-epicastasterone and 24-epibrassinolide solutions have been recorded and analyzed. The
long-wavelength band in solution spectra of the former steroid with maxima in the region 292–286 nm is assigned to the electronic
nπ*-transition of a carbonyl chromophore. The latter steroid contains an O-C=O group, for which the extinction coefficient
in this spectral region is approximately one order of magnitude less. These differences can be used to identify the studied
steroids. A method to synthesize the conjugate of 24-epicastasterone with a fluorescent label, dansylhydrazine, which shows
intense fluorescence and absorption, is described. Absorption spectra of the label and conjugate in diethylether, tetrahydrofuran,
ethanol, and acetonitrile solutions are practically independent of the solvent properties. The exceptions are solutions of
the conjugate in hexane and water. All investigated solutions of label and conjugate show intense fluorescence. As the dielectric
constant of the solvent increases, the fluorescence spectra shift to long-wavelength. The fluorescence energetic and time
characteristics of both the label and conjugate are similar, which enables the conjugate to be used in developing a method
for immunofluorescent analysis of the brassinosteroid 24-epicastasterone.
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Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 75, No. 1, pp. 74–78, January–February, 2008. 相似文献
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The motion and radiation of an electron moving in the field of a plane wave of elliptical polarization and a magnetic field is considered. By the methods of classical and quantum theory, the effect of the plane-wave polarization on the characteristics of the particle motion and radiation is investigated. Some particular cases are considered.Translated from Izvestiya Vysshikh Uchebnykh Zavedeniis Fizika, No. 10, pp. 70–74, October, 1978. 相似文献
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We find the most general form of a scalar density concomitant of a metric tensor and a bivector. This, together with previous theorems, gives a complete characterization of the tensor concomitants of a metric and a bivector. 相似文献
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J.M. Rickman 《Physica A》2010,389(22):5155-5162
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Ya. V. Fominov 《JETP Letters》2008,86(11):732-736
The conductance of a junction between a normal metal and a superconductor having the symmetry proposed by Berezinskii is studied
theoretically. The main feature of this symmetry is the odd frequency dependence of the anomalous Green’s function, which
makes possible the s-wave triplet superconducting state (the Berezinskii superconductor). The Andreev reflection (which links
positive and negative energies) is sensitive to the energetic symmetry; as a result, the conductance of the junction involving
the Berezinskii superconductor is qualitatively different from the case of a conventional superconductor. Experimentally,
the obtained results can be employed to test the possibility of the Berezinskii superconductivity proposed for Na
x
CoO2 and to identify the odd-ω component predicted for superconductor-ferromagnet systems. 相似文献
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In an Einstein-Yang-Mills field theory the field equations can be obtained by applying a variational principle to a Langrangian minimally coupled to a Lagrangian concomitant of a curvature form and the metric tensor. As a step in the discussion of the uniqueness of these equations, we find the general form of such a Lagrangian. 相似文献
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Ya. V. Fominov 《JETP Letters》2007,86(11):732-736
The conductance of a junction between a normal metal and a superconductor having the symmetry proposed by Berezinskii is studied
theoretically. The main feature of this symmetry is the odd frequency dependence of the anomalous Green’s function, which
makes possible the s-wave triplet superconducting state (the Berezinskii superconductor). The Andreev reflection (which links
positive and negative energies) is sensitive to the energetic symmetry; as a result, the conductance of the junction involving
the Berezinskii superconductor is qualitatively different from the case of a conventional superconductor. Experimentally,
the obtained results can be employed to test the possibility of the Berezinskii superconductivity proposed for Na
x
CoO2 and to identify the odd-ω component predicted for superconductor-ferromagnet systems.
The text was submitted by the author in English. 相似文献
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Barney Kerrighan 《General Relativity and Gravitation》1981,13(1):19-27
In the general theory of relativity the energy-momentum tensor due to an electromagnetic field is taken to be a symmetric rank-two tensor concomitant of a bivector and the metric tensor. As a step in the discussion of the possible uniqueness of this tensor we display a method for finding all tensor concomitants of a bivector and a metric in a space-time manifold. 相似文献
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We discuss a mass change that has its origin in the action of forces on an object. This phenomenon, well-known in the context of quantum field theory (mass renormalization), can be discussed systematically in both classical and quantum mechanics in a framework given by Stückelberg. We employ this framework to resolve an interesting conflict of opinions between Schopenhauer and Hegel in the mid-19th century. We show that Hegel, Kant, and Schopenhauer demonstrated remarkable prescience in their views as seen from a modern perspective. 相似文献