Proton NMR characterization of chain structure in butylene terephthalate-ϵ-caprolactone copolyesters

A series of butylene terephthalate-ϵ-caprolactone copolyesters (BCL) with different hard-segment content were synthesized and their chain structures were carefully investigated by high resolution ¹H-NMR spectroscopy. The analysis from ¹H-NMR spectra of samples reveals that BCL chain chemical and sequence structure is specific and complicated because of the unavoidable transesterification between BT and CL segments during synthesis process and so BCL copolyesters are segmented copolyesters with certain random property as confirmed by DSC measurements. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 3770–3777, 1999     

软X光能谱仪的一种新的解谱方法

提出软X光能谱仪的一种新的解谱方法即最大熵法,运用新的平滑方法即样条拟合方法处理滤片的边带结构,并对最大熵法的收敛性和稳定性进行了分析.结果表明,该方法的谱回推精度高,收敛速度快且对噪声不很敏感.该方法适用于根据软X光能谱仪的测量结果回推靶等离子体的软X光谱.     

Light-scattering by optically soft randomly oriented spheroids

In the framework of the Rayleigh–Gans–Debye approximation and anomalous diffraction approaches, the light scattering characteristics of randomly oriented spheroids have been investigated. It has been proved that the system of randomly oriented spheroids is equivalent to the system of polydisperse spherical particles that have the same values of volume and surface area as nonspherical particles. The power law size distribution meeting these requirements has been obtained.     

软土的各向异性损伤对剪切带形成的影响

在软土各向异性弹塑性损伤模型的基础上,把小应变模型扩展到有限应变模型,推导出不排水平面应变条件下的剪切带形成条件,分析K0固结状态下各向异性损伤对剪切带形成的影响.以上海软土为例,分析临界状态参数β=0.9时,损伤变量D1,D2的不同组合的剪切角和简单剪切模量与有效平均主应力比(g/p')的关系曲线.计算结果表明,损伤变量越大,越接近不稳定状态,垂直方向损伤对剪切带的影响比水平方向的强烈. 特别指出无论土为横观各向同性损伤的情况,还是各向异性损伤的情况,在本文研究的条件下,不稳定状态(g/p'为最小值)相应两个剪切角约在50°和130°,这对研究弹塑性损伤对剪切带形成与变化有指导意义.     

利用慢度曲面研究立方晶系晶体的铁弹相变

讨论了慢度曲面与声学模软化之间的关系.立方晶系晶体声学模的软化即对应其在某一方向上的最大慢度,软模的本征矢的方向即为与最大慢度相对应的声学模的偏振化方向.通过求解Christoffel方程可找到某些方向上的最大慢度和与它们对应的声学模的偏振化方向.从而晶体在本征铁弹相变前后结构对称性的变化可以通过分析Christoffel方程的解及利用居里原理来确定.     

FT-Raman spectra of cis–bis(thiourea)selenium(II) chloride and bromide

The FT-Raman spectra of Se(tu)₂Cl₂ and Se(tu)₂Br₂ complexes are reported for the first time. The important modifications observed in the Raman active modes of thiourea molecules demonstrate a very strong interaction between the Se(II) ion and the sulfur atom of the ligand. As a result of this coordination, and through a “resonance-assisted” mechanism, an intense hydrogen-bonded network is present in the crystal structure of the complexes with notable vibrational effects.     

金属萃取平衡与软-硬酸碱规则

软硬酸碱规则从宏观角度描述化合物的形成及性质,在配合物稳定性的判断方面有广泛应用.前文^[1]报道了萃取速率常数与金属离子的软硬酸碱强度的关系,本文研究了萃取平衡常数与金属离子的软硬酸碱强度的关系.     

β-丙内酯的反应性分析

利用原子键电负性均衡方法研究了β丙内酯与不同亲核试剂的反应性.研究表明,Fukui函数不是决定反应选择性的唯一因素,而局域意义的软硬酸碱原理可用来理解此类反应性.     

正负电子对撞多粒子末态的动力学起伏

运用Jetset产生器分别在实验室系和冲度轴坐标系中对e⁺e^—对撞多粒子末态中阶乘矩的标度性质进行了研究.在这两种情况下,用各向同性的相空间分割得到的三维InF₂～InM都近似于直线,表明e⁺e^－对撞末态相空间中的动力学起伏近似各向同性.在实验室系中由p_x,p_y,p_z的F²～M拟合Ochs公式得到的三个γ值近似相等;在冲度轴系中,在φ方向上适当选取起始拟合点,三个γ值也比较相近,进一步肯定了这一论断.这一结果表明,软、硬过程动力学起伏的本质特征──各向异性或(近似)各向同性,可以通过碰撞过程中阶乘矩标度性质的研究而揭示出来.因此,深入研究各种碰撞过程中阶乘矩的标度性质,对于了解碰撞动力学的本质有重要意义.     

Some problems associated with the disturbed matrix Lyapunov equation for linear time-invariant discrete systems

Both the Lyapunov stability and popov’s hyperstability ofdiscrete linear time-invariant system in case of system para-meter disturbance are discussed in this paper.The allowabledisturbance ranges are given so that the maintenance of theLyapunov stability and the popov’s hyperstability of a dis-crete linear system is guaranteed.The results find theirsignificance in the MRAC.