Field—Correlation Effects on Rayleigh—Enhanced Nondegenerate Four—Wave Mixing

We study Rayleigh-enhanced nondegenerate four-wave mixing (NFWM) with time-delayed,correlated fluctuating fields.The importance of the field correlation is revealed in the Rayleigh-enhanced NFWM spectrum when the time delay is varied.The Rayleigh-enhanced NFWM is employed to study the ultrafast processes in the frequency domain.A relaxation time as short as 220 fs was deduced in the Rayleigh-enhanced NFWM experiments in carbon disulphide.     

萜烯低聚物与马来酸酐的加成反应及其制备环氧树脂的研究

松节油经阳离子聚合反应可生成聚萜烯。其中分子量较大 ,软化点在 80℃以上部分称为萜烯树脂 ,广泛用作热熔胶、压敏胶的增粘剂。而分子量较小 ,常温下为液体的部分称萜烯低聚物 ,由于其软化点低 ,一般不适合作增粘剂使用。迄今为止 ,萜烯低聚物作为一种工业副产品 ,国内外尚未见有效的利用。目前 ,我国萜烯树脂年生产能力近 2 0 0 0 0吨 ,其中每年副产萜烯低聚物 30 0 0多吨 ,均用作燃料使用。如能将这部分产品进行化学改性 ,制备出适合于工业用途的精细化学品 ,将会大大提高其价值。萜烯低聚物的成分比较复杂 ,主要是三萜和二萜聚合物 ,其…     

等差数列的两个性质

性质1若等差数列的项数为奇数,前n项和为Sn,中间项为M(n为奇数),则Sn= Mn．证明中间项为M,2M=a1 an, Sn=(a1 an)n/2=2Mn/2=Mn．推论若数列的项数为奇数,则奇数项和S奇=n奇M(n奇为奇数项项数),偶数项之和S偶=n偶M(n偶为偶数项项数)．     

Suppression and Enhancement in Parametric Two-Photon Resonant Nondegenerate Four-Wave Mixing via Quantum Interference

Quantum interference may lead to suppression and enhancement of the two-photon resonant nondegenerate fourwave mixing signal in a cascade four-level system.Such phenomena are demonstrated in Ba through inducing atomic coherence between the ground state 6s^2 and the doubly excited autoionizing Rydberg state 6trod.This method can be used as a new spectroscopic tool for measuring the transition dipole moment between two highly excited atomic states.     

A meshless algorithm with moving least square approximations for elliptic Signorini problems

Based on the moving least square(MLS) approximations and the boundary integral equations(BIEs), a meshless algorithm is presented in this paper for elliptic Signorini problems. In the algorithm, a projection operator is used to tackle the nonlinear boundary inequality conditions. The Signorini problem is then reformulated as BIEs and the unknown boundary variables are approximated by the MLS approximations. Accordingly, only a nodal data structure on the boundary of a domain is required. The convergence of the algorithm is proven. Numerical examples are given to show the high convergence rate and high computational efficiency of the presented algorithm.     

光氧化反应的研究VII. 赤霉酸甲酯的单线态氧反应

本文初次探讨赤霉酸甲酯的敏化光氧化反应规律及其在合成应用上的可能性。     

Au-Cu-Ni-MoS_2四组元自润滑复合镀层及其在人造地球卫星短波天线机构上的应用

根据我国宇航事业早期的有关任务要求,作者曾发展了一种在铝底材上电沉积Au—Cu—Ni—MoS_2四组元复合镀层的技术。该镀层在大气或超高真空条件下具有良好的耐磨性、防冷焊性和导电性;已多次成功地应用到人造地球卫星短波天线机构的滑动部位上。本文主要介绍该镀层的工艺条件,镀液组成、MoS_2预处理等因素对于镀层耐磨性的影响。     

叶子节点对于网络同步能力影响的研究

系统考察了叶子节点对于网络同步能力的影响,发现随着叶子节点比例的增加,网络的同步能力下降,同时给出了数值结果以及理论解释. 关键词： 复杂网络 叶子节点 同步能力     

光氧化反应的研究VII. 赤霉酸甲酯的单线态氧反应

本文初次探讨赤霉酸甲酯的敏化光氧化反应规律及其在合成应用上的可能性。     

光氧化反应的研究 Ⅶ.赤霉酸甲酯的单线态氧反应

赤霉素(gibberellins)是一类重要的植物生长激素,应用广泛,它们的合成反应研究颇受重视.Adam等较系统地探讨了其光化学反应,例如光催化芳构化、光致环加成以及Norrish Ⅰ型反应等.最近周维善应用Sharpless试剂改良氧化法于赤霉酸衍生物的合成.但是迄今仍无有关赤霉素类光氧化反应的报道.鉴于多种重要生物分子的光动态作用(photodynamic action)所引起的光氧化损害在理论和应用上的重要意义,故有必要考察赤