排序方式: 共有15条查询结果,搜索用时 15 毫秒
1.
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. 相似文献
2.
研究等待时间分布为截断幂律分布的连续时间随机行走(CTRW)模型,分析比较截断幂律分布的可能随机抽样方法,并提出一套可以对其进行精确抽样的乘分布舍选算法.数值结果表明:当幂律指数α > 0.2时,该算法的抽样效率在80%以上.利用该算法可以成功得出CTRW模型描述的三种反常输运过程的标度关系. 相似文献
3.
Suppression and Enhancement in Parametric Two-Photon Resonant Nondegenerate Four-Wave Mixing via Quantum Interference 总被引:1,自引:0,他引:1 下载免费PDF全文
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. 相似文献
4.
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 总被引:3,自引:0,他引:3
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… 相似文献
5.
6.
7.
A meshless algorithm with moving least square approximations for elliptic Signorini problems 下载免费PDF全文
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. 相似文献
8.
9.
10.
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 相似文献