F-调和映照的不存在性定理

本文主要讨论一类F-调和映照的不存在性问题,从而得到相应的Liouville型定理．     

Toward self-assembling dendritic macromolecules from conventional monomers by a combination of living radical polymerization and irreversible terminator multifunctional initiator

TERMINI stands for irreversible terminator multifunctional initiator and represents a new concept elaborated in our laboratory for the design of novel macromolecules with complex architecture from a diversity of commercial monomers. TERMINI is a masked multifunctional initiator that quantitatively interrupts a living polymerization. After demasking, the TERMINI-derived repeat unit provides access to a quantitative reinitiation of the same living polymerization in more than one direction, thus becoming a branching point. In this article, with a combination of self-regulated metal-catalyzed living radical polymerization and TERMINI, we demonstrate a new method for the divergent synthesis of dendritic poly(methyl methacrylate) containing a bifunctional core at its focal point. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 505–513, 2004     

中心为氨基、末端为硝基的苯乙炔树枝状分子的合成

将固定相合成与“收敛/发散”方法相结合,合成了第一、二代苯乙炔树枝状分子.通过Heck-Cassar-Sonogashira-Hagihara偶联反应,将其中心和末端分别修饰上供电子的氨基和拉电子的硝基,得到第一、二代中心为氨基、末端为硝基的苯乙炔树枝状分子NH₂-G1-(NO₂)₂和NH₂-G2-(NO₂)₄.用傅里叶变换红外光谱跟踪了整个固定相合成过程.苯乙炔树枝状分子的紫外-可见吸收光谱呈现出规律性变化.     

Short and Divergent Total Synthesis of (+)‐Machaeriol B, (+)‐Machaeriol D, (+)‐Δ8‐THC,and Analogues

Short and highly efficient stereoselective syntheses provide machaeriols and cannabinoids in a divergent approach starting from a common precursor, commercially available (S)‐perillic acid. Key features of the novel strategy are a stereospecific palladium‐catalyzed decarboxylative arylation and a one‐pot sequence comprising a stereoselective hydroboration followed by oxidation or reduction of the corresponding intermediary boranes. The divergent approach is convincingly demonstrated by the five‐step syntheses of (+)‐machaeriol B, (+)‐machaeriol D, and related analogues, and the four‐step synthesis of (+)‐Δ⁸‐THC and an analogue.     

无机化学教学中“原子结构”内容怎样突破重点和难点*

基于对“原子结构”内容的科学界定,认为章节定名为“原子与原子结构”较为合理,讲授内容应包含原子的结构和性质、原子结构模型的建立和演变、核外电子的排布、原子核结构模型简介和原子结构与元素周期律的关系等5大模块。提出在系统性中突出“玻尔原子模型、核外电子运动状态的描述、4个量子数、核外电子的排布和原子结构与元素周期律的关系”的教学重点;通过提前举办“量子力学基本概念”专题讲座,有利于“量子化的原子结构模型”这一教学难点的突破,并针对每一难点提出了具体的方法措施。提议讲授采用发散思维为主、收敛思维为辅以及有所为有所不为、张弛有度的哲学方法;目的在于通过本章学习后, 使学生在获得基础知识的同时,能学到些许科学的思想方法、学习方法和研究方法。     

Extended Mild-Slope Equation

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A Generalized Face Number for Regular Hyperbolic Honeycombs

A generalized face number, typically taking negative rational values for a regular hyperbolic honeycomb, is constructed in three different ways – via differential geometry, combinatorics, and divergent series.     

On the interaction of cubically nonlinear transverse plane waves in an elastic material

The paper presents theoretical results on the interaction of cubically nonlinear harmonic elastic plane waves in a nonlinear material described by the Murnaghan potential. The interaction of two harmonic transverse waves is studied using the method of slowly varying amplitude. Reduced and evolution equations and the Manley-Rowe relations are derived. An analysis is made of the mechanism of energy transfer from the strong pumping wave, which has frequency ω, to the weak signal wave, which has frequency 3ω because of this interaction. A switching mechanism for hypersonic waves in a nonlinear elastic material is described, which is similar to the switching mechanism observed in transistors __________ Translated from Prikladnaya Mekhanika, Vol. 42, No. 6, pp. 61–70, June 2006.     

COMPLETE CONVERGENCE FOR A CLASS OF MIXING SEQUENCES

Under some conditions on probability, the author obtains some results on the complete convergence for partial sums of not necessary identically distributed ρ-mixing sequences, and the complete convergence for partial sums of B-valued martingale differences is also studied. As application the author gives the corresponding results on the complete convergence for randomly indexed partial sums.     

On the Extrapolation of Perturbation Series

We discuss certain special cases of algebraic approximants that are given as zeroes of so-called effective characteristic polynomials and their generalization to a multiseries setting. These approximants are useful for the convergence acceleration or summation of quantum mechanical perturbation series. Examples are given and some properties discussed.