5,7,8位取代的喹诺酮类化合物定量构效关系的量子化学研究

５，７，８位取代的喹诺酮类化合物定量构效关系的量子化学研究俞庆森，朱龙观，林瑞森，蔡国强（浙江大学化学系杭州３１００２７）关键词：氟喹喏酮类，定量构效关系，ＣＮＤＯ／２氟喹诺酮类是一类重要的抗感染化疗药物￣［１］，近十年对其研究进展神速￣［２］，结构...     

喹诺酮类N1位定量构效关系研究

氟隆诺酮类化合物是抗菌药中的重要一类，由于它的许多突出特点，已引起越来越多的研究者的关注山．这类化合物骨架见图1．我们对该类化合物进行过一些研究［’‘l自发现诺氟沙星＊以后，几位取代基在寻找高效、广谱峻诺酮类化合物方面起重要作用，但在发现环丙基（1983年）、特丁基（1989年）以后，一直未发现新的有意义的取代基·在NI位定性与定星构效关系的研究中有二种观点：（1）古贺弘等k’］提出的由立体效应决定的观点；（z）Domagala［71、Chu问等主张的立体与电子效应共同起作用的观点·3D－QSAR研究中的比较分子力场分析（Co…     

Interactions of Some Amino Acids with Aqueous N,N-Dimethylacetamide Solutions at 298.15 and 308.15 K: A Volumetric Approach

The apparent molar volumes, V _φ , of glycine, L-alanine and L-serine were obtained in aqueous 0 to ∼4 mol⋅kg⁻¹ N,N-dimethylacetamide (DMA) solutions from density measurements at 298.15 and 308.15 K. The standard partial molar volume, V _φ ^o, and standard partial molar volumes of transfer, Δ_tr V _φ ^o, were determined for these amino acids. It has been shown that hydrophilic-hydrophilic interactions between charged groups of the amino acids and the —CON= group of DMA are predominant in the case of glycine and L-serine, but for L-alanine the interactions between its side group (—CH₃) and DMA are predominant. An increase in temperature increases the standard partial molar volumes but decreases the transfer volumes of the amino acids. The results have been interpreted in terms of cosphere overlap model.     

Enthalpic interactions of -alanine and -serine in aqueous urea solutions

The enthalpies of dilution of -alanine and -serine in various aqueous urea solutions have been determined by flow microcalorimetry at 298.15 K. The homogeneous enthalpic interaction coefficients over the whole range of aqueous urea solutions have been calculated according to the excess enthalpy concept. The results were interpreted from the point of view of solute–solute interactions moderated by solvent effects.     

Transfer Volumes of Glycine, L-Alanine and L-Serine in Glycerol-Water Mixtures at 25°C

Densities of solutions of glycine, L-alanine, and L-serine have been measured by an oscillating-tube densimeter at 25^°C in glycerol–water mixtures with glycerol mass fractions ranging from 0 to 0.50. Apparent molar volumes and limiting partial molar volumes of each amino acid have been calculated. The trends of transfer volumes have been interpreted by the cosphere overlap model. The results show that the presence of glycerol in water decreases the electrostriction caused by the amino acid zwitterion.     

The estimate and measurement of longitudinal wave intensity

Quasi-longitudinal waves are one type of structural waves, which are important at high frequencies. This paper studies the estimate theory and measurement technique of quasi-longitudinal waves, analyzes the bias error due to the effect of bending waves. In a two-dimensional quasi-longitudinal wave field, the intensity vector is the sum of the effective intensity vector and the intensity variation vector. Its axial component is proportional to two imaginary parts of cross spectral densities and in the measurement, it is measured by a pair of two-transducer arrays. In a onedimensional quasi-longitudinal wave field, the intensity variation is zero, the intensity is proportional to only one imaginary part of a cross spectral density and it can be measured using a two-transducer array. If bending and quasi-longitudinal waves coexist and the contribution from bending waves cannot be eliminated or reduced to a certain extent, the measured quasi-longitudinal wave intensity will contain a large error. The results measured on the three-beam structure show that quasi-longitudinal wave intensity can be accurately measured using the intensity technique when bending waves are negligible in comparison with quasi-longitudinal waves. The project supported by the National Natural Science Foundation of China     

机械阻抗测量的一种新方法

本文介绍了一种新的机械阻抗测量方法－声强法，由定义出发将机械阻抗表为功率流和加速度响应谱的函数，应用结构声强技术测量功率流，声强法不需要测量作用力信号，可以用于测量任意结构中的各类机械阻抗，实验结果表明，声强获得的测量值与直接获得的测量值相近，声强法能较准确地测量一维和二维匀质结构中机械阻抗。     

Bending wave intensity in a thick beam

I.IntroductionMeasurementSofbendingwaveintensityinoneortwodimensi0na1structuresbecomequitepopularandgetavarietyofindustria1app1icati0ns.Theexistingintensitytheory['-']wasderivedbasedontheclassicaIBernou11i-Eu1ertheorywhichisanapproximatetheoryforana-lyzingstructuralvibration.Inthe1ow-frequencylimitwherebendingwavelengthsaremuchlongincomparisonwiththethicknessofthestructurealongwhichtheypr0pagate(i.e.,thinstructurcs),theuse0ftheclassica1theorywi1lresu1tinanegligiblyerro/`].Forshortwave-1ength…     

Transfer Volumes of Small Peptides from Water to Aqueous Xylitol Solutions at 298.15 K

Densities have been measured by an oscillating-tube densimeter for aqueous solutions of glycylglycine and glycylglycylglycine in aqueous xylitol solutions with xylitol mass fractions ranging from 0 to 0.15 at 298.15 K. Apparent molar volumes and limiting partial molar volumes have been used to calculate the corresponding transfer volumes from water to different concentrations of xylitol + water mixtures. The results are interpreted in terms of the cosphere overlap model.     

丙三醇对水溶液中血红蛋白构象的影响——荧光猝灭和动态光散射研究

利用荧光猝灭法和动态光散射法测定丙三醇-水混合溶剂中血红蛋白(Hb)与联苯胺的结合距离和Hb的流体动力学半径, 并通过分析Hb荧光光谱和吸收光谱的变化, 探讨丙三醇与蛋白质分子在水溶液中相互作用的机理及其对蛋白质构象的影响. 结果表明, 丙三醇-水混合溶剂中Hb通过优先水化作用形成更紧密的构象, 溶剂体系的氢键形成能力下降对稳定蛋白质的构象有重要的影响, 丙三醇浓度较高的混合溶剂中氢键网络发生崩塌, 导致蛋白质构象产生进一步的折叠. 实验显示, 尽管Hb在丙三醇-水混合溶剂中保持较完整的血红素疏水空穴结构, 但是血红素疏水空穴以外肽段的构象发生显著变化, 并对血红蛋白的聚集状态造成一定的影响.