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41.
CHEN Bao-Zhen HUANG Zu-Qia 《理论物理通讯》2004,42(9)
The theoretical signal-pressure curves are calculated from approximate analytical solutions of the coupledequations describing the third order parametric wave mixing in a gas-filled capillary of femto-second laser pulses. Thecomparison with the corresponding experimental curves suggests that the following three factors exert important influ-ences on the degree of fitting between the theoretical and experimental results: the walk-off, the phase modulation, andthe third order harmonic of idler pulse. 相似文献
42.
Enrique Casanovas 《Mathematical Logic Quarterly》2003,49(5):475-478
We prove a property of generic homogeneity of tuples starting an infinite indiscernible sequence in a simple theory and we use it to give a shorter proof of the Independence Theorem for Lascar strong types. We also characterize the relation of starting an infinite indiscernible sequence in terms of coheirs. 相似文献
43.
44.
Uncertainty about the nature and significance of nonlinearities and the manner in which dynamics affect future realizations makes model specification the most difficult aspect of modeling dynamic systems. By interpreting several popular fishery models as subcases of a nesting dynamic Taylor series approximation, we isolate the specification differences between these models in a way that accounts for commonalities. On the argument that the differences due to alternative nonlinear forms are likely to be small compared to more mundane considerations such as delay difference and general dynamic lag specification, we propose an alternative model that uses the terms from the first order approximation common to all models combined with a data-based determination of the appropriate lags using the methods of state space time series analysis. Finally, the success of the alternative models is judged in an application to Pacific halibut data. 相似文献
45.
46.
John A. Mikroyannidis Larysa Fenenko Masayuki Yahiro Chihaya Adachi 《Journal of polymer science. Part A, Polymer chemistry》2007,45(20):4661-4670
Three new copolymers, namely poly(fluorenevinylene‐alt‐naphthalenevinylene) ( N ), poly(fluorenevinylene‐alt‐anthracenevinylene) ( A ) and poly(fluorenevinylene‐alt‐pyrenevinylene) ( P ), were synthesized by Heck coupling of 9,9‐dihexyl‐2, 7‐divinylfluorene with a polynuclear aromatic dibromide. The 9,10‐disubstituted anthracene was obtained exclusively for A while N and P were obtained as a mixture of two isomers with predominant the 1,4‐disubstituted naphthalene and 1,8‐disubstituted pyrene, respectively. The polymers were soluble in common organic solvents and decomposed above 370 °C. Their glass transition temperature increased from 58 to 110 °C by increasing the number of the phenyl rings of the polynuclear aromatic moiety. Rather high‐efficiency blue and blue‐greenish photoluminescence (PL) of these copolymers in solution was largely decreased in their films, indicating the presence of concentration quenching in the solid state. The OLED using these polymers demonstrated green EL in the case of copolymers N and A , and red EL in the P derivative with ηEL = 0.26–0.31%. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 4661–4670, 2007 相似文献
47.
ZHU Hai-Xia YAN Shi-Lei 《理论物理通讯》2004,42(11)
We study the ferromagnetic properties of spin-1 system, which is considered in the frame of the bond dilution and random positive or negative anisotropy Blume-Capel model in the effective field theory and a cutting approximation. The investigation of phase diagrams displays some rich properties of the trajectory of tricritical point, reentrant henomena at low temperatures. Under certain both bond concentrations and random negative anisotropy, there are new transition lines of double tricritical points. So special emphasis is placed on the influence of the bond dilution and random anisotropy on phase diagrams. The magnetizations of the system are also discussed. Some results have not been evealed in previous reports. 相似文献
48.
半导体激光器到单模光纤耦合技术的现状及发展趋势 总被引:1,自引:0,他引:1
简要阐述了半导体激光器到单模光纤的耦合损耗来源,详细介绍和分析了耦合技术的发展和现状,并探讨了耦合技术的发展趋势。 相似文献
49.
报道两种带宽极窄的采用单指换能器制作的声表面波滤波器。一种是利用单指换能器声同步频率与反射频率之间的相位叠加与相消来制作的体积极小(芯片面积只有采用双指换能器的三分之一不到)的高频极窄带声表面波滤波器,其3dB带宽的相位变化只120°;另一种是采用合理布局的单指无内反射换能器制作的高频极布带声表面波滤波器,其幅频特性同采用双指换能器制作的同类型的声表面波滤波器一样。最后给出了这两种声表面波滤波器的较详细的理论分析和实验结果。关键词 相似文献
50.
报道声表面波可程序抽头延迟线的研制情况。对该器件的总体结构,电路原理框图、声表面波可程序抽头延迟线结构作了一个扼要的概念。同时分别报道了我所研制的各类声表面波可程序抽头延迟线器件性能指标及相应的图片说明,最后对该器件仍存在的一些问题作了探讨。 相似文献