三螺旋蛋白质中孤立子的温度效应

在作者已给出的描述三螺旋蛋白质分子的哈密顿函数基础上，得到了孤立子存在的临界温度和热容器，其结果与实验结果一致。     

Coupling Reaction of 4-Chloro-7-H-Pyrrolo[2,3-d]Pyrimidine with 2,3,5-Tri-O-Acetyl-β-D-Ribofuranosyl Chloride

Tubercidin (4-amino-7--D-riobofuranosyl-7-H-pyrrolo[2,3-d]pyrimidine) 1, an antibio-tic substance produced in the culture broth of Streptomyces tubericidus1, is an adenosine analog in which N-7 is replaced by a carbon atom. It has attracted much attention due to the biological activities for the growth inhibition of certain tumors, and many derivatives of tubercidin have been synthesized2-5.For the synthesis of tubercidin analogs, 4-chloro-7-H-pyrrolo[2,3-d]pyrimidine-2,3,5-tri-O-acetyl--D-r…     

Solvent effect on the conformational behaviour of amino acid and oligopeptide derivatives

The solvent effect on acetyl amino acid methyl esters and C- and N-protected di- and tripeptide derivatives has been studied in deuterium oxide (D₂O), 1.1.1.3.3.3-hexafluoroisopropanol (HFiP), dimethyl sulfoxide (DMSO) and methylene chloride (CH₂Cl₂). The interpretation is based on the amide I region. For the amino acid derivatives the relative shift of the amide I signal clearly indicates the strength of the interaction with the solvent molecules. However, in HFiP and DMSO solutions the occurrence of two overlapping signals for the amide I and the ester carbonyl signal, respectively, indicates the existence of two major conformers. Knowing the solvent effects on the small amino acid esters allows the assignment of the signals in di- and tripeptide derivatives. Although the identification of turn structures in these flexible molecules is not possible, the band positions and intensity of the deconvoluted amide I region clearly shows that certain conformers can be stabilised. It can be concluded that the band profile in the amide I region is determined by the number of amino acid residues linked in the molecule, the bulkiness of the side chains and their sequence and to a major extend by the solvent properties.     

X射线显微术

综述了Ｘ射线显微术的基本原理，成像模式和技术及其在生命科学，材料科学等方面应用的新进展，同时简述了Ｘ线射显微术应用过程中应注意的几个问题。     

硼氢化反应机理Ⅳ——甲基腈硼氢化反应的反应途径解析(英文)

利用量子化学从头计算法ＲＨＦ／４－３１Ｇ基组对ＣＨ３ＣＮ＋ＢＨ３反应进行了理论研究．ＩＲＣ分析表明：甲基腈与甲硼烷通过“类四中心”过渡态，直接加成生成产物．计算的活化能是３４６２６８ｋＪ／ｍｏｌ．计算发现在反应途径中，ＢＨ３分子片随着与ＣＨ３ＣＮ分子片的接近经历一个由电子受体到电子授体的变化，并用前线轨道理论作了解释．     

A novel approach to the determination of the crosslink density in rubber materials with the dipolar correlation effect in low magnetic fields

We present a novel NMR approach to the determination of crosslink densities in rubber materials. The method is based on the dipolar correlation effect (DCE) on the stimulated echo examined in a series of rubber samples and linear polyisoprene. The parameter evaluated from the echo attenuation curves is the mean‐squared dipolar fluctuation associated with anisotropic reorientations of macromolecular backbones. The contributions to the DCE of the constraints due to excluded volume effects and chemical crosslinks are estimated. A strong dependence of the mean‐squared dipolar fluctuation on the crosslink density of rubber combined with the simplicity of performing the measurements with inexpensive low‐field instruments suggests that the DCE is a useful tool for routine applications. The potential and problems of performing DCE measurements in low‐magnetic‐field conditions are discussed in detail. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 39: 2207–2216, 2001     

Can shadowing mimic the QCD phase transition?

The directed flow of protons is studied in the quark-gluon string model as a function of the impact parameter for S+S and Pb+Pb reactions at 160 AGeV/c. A significant reduction of the directed flow in midrapidity range, which can lead to the development of the antiflow, is found due to the absorption of early emitted particles by massive spectators (shadowing effect). This effect can mimic the formation of the quark-gluon plasma (QGP). However, in the absorption scenario the antiflow is stronger for the system of light colliding nuclei than for the heavy ones, while in the case of the plasma creation the effect should be opposite.     

Si doping effect on self-organized InAs/GaAs quantum dots

In situ ultra high vacuum scanning probe microscopy (SPM) and low-temperature photoluminescence (PL) studies have been performed on Si-doped self-organized InAs/GaAs quantum dots samples to investigate the Si doping effects. Remarkably, when Si is doped in the sample, according to the SPM images, more small dots are formed when compared with images from undoped samples. On the PL spectra, high-energy band tail which correspond to the small dots appear, with increasing doping concentration, the integral intensity of the high-energy band tail account for the whole peak increase too. We relate this phenomenon to a model that takes the Si atom as the nucleation center for QDs formation.     

Sources of Error in Sorption and Density Measurements

In sorption measurements, volumetric or gravimetric procedures are commonly used to determine the amount adsorbed. At low pressures, thermomolecular flow and pressure differences according to Knudsen's law disturb measurements. In volumetry, calibration of the dead space is required; in gravimetry, the influence of buoyancy has to be taken into account. In both cases, adsorption of the calibrating gas, usually helium, may disturb the measurements [1]. From the calibration measurements, the density of the sample can in principle be calculated. However, it has been observed in many experiments that its value depends on the calibrating gas. This revised version was published online in July 2006 with corrections to the Cover Date.     

不锈钢(00Cr18Ni9)动态累积损伤研究

用一级压缩气体炮加载技术和可变平板电容传感技术，对不锈钢（００Ｃｒ１８Ｎｉ９） 动态累积损伤进行了实验研究，给出了层裂累积损伤连续度量的经验关系式，并对损伤度与动载历史的相互关系进行分析、讨论。