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181.
This paper constructs a class of Harish-Chandra modules with multiplicity ≤1 of the two parameter deformation of Virasoro algebra and proves a classification theorem. 相似文献
182.
溴酸钾-亚甲蓝催化光度法测定硝酸盐和亚硝酸盐 总被引:15,自引:1,他引:15
用镉柱将NO-3 还原为NO-2 ,利用在磷酸介质中NO-2 对溴酸钾氧化亚甲蓝这一褪色反应具有强烈的催化作用而建立了同时测定痕量硝酸盐和亚硝酸盐的新方法。本方法简便、快速、灵敏 ,对亚硝酸盐和硝酸盐测定的线性范围分别为 0~ 2 0 0 μg·L-1和 0 0 0 3~ 310 μg·L-1,用于测定各种水样中痕量NO-2 和NO-3 的含量均获得满意结果 相似文献
183.
FU JingLi CHEN LiQun & CHEN BenYong Institute of Mathematical Physics Zhejiang Sci-Tech University Hangzhou China 《中国科学:物理学 力学 天文学(英文版)》2010,(3)
We investigate Noether symmetries and conservation laws of the discrete nonconserved systems with nonregular lattices. The operators of discrete transformation and discrete differentiation to the right and left are introduced for the systems. Based on the invariance of discrete Hamilton action on nonregular lattices of the systems with the nonconserved forces under the infinitesimal transformations with respect to the time and generalized coordinates, we give the discrete analog of generalized variational f... 相似文献
184.
An analysis of seismic attenuation in random porous media 总被引:1,自引:0,他引:1
LIU Jiong BA Jing MA JianWei & YANG HuiZhu Institute of Seismic Exploration School of Aerospace Tsinghua University Beijing China Research Institute of Petroleum Exploration & Development PetroChina Beijing 《中国科学:物理学 力学 天文学(英文版)》2010,(4)
The attenuation of seismic wave in rocks has been one of the interesting research topics, but till now no poroelasticity models can thoroughly explain the strong attenuation of wave in rocks. In this paper, a random porous medium model is designed to study the law of wave propagation in complex rocks based on the theory of Biot poroelasticity and the general theory of stochastic process. This model sets the density of grain, porosity, permeability and modulus of frame as random parameters in space, and only one fluid infiltrates in rocks for the sake of better simulation effect in line with real rocks in earth strata. Numerical simulations are implemented. Two different inverse quality factors of fast P-wave are obtained by different methods to assess attenuation through records of virtual detectors in wave field (One is amplitude decay method in time domain and the other is spectral ratio method in frequency domain). Comparing the attenuation results of random porous medium with those of homogeneous porous medium, we conclude that the attenuation of seismic wave of homogeneous porous medium is far weaker than that of random porous medium. In random porous media, the higher heterogeneous level is, the stronger the attenuation becomes, and when heterogeneity σ = 0.15 in simulation, the attenuation result is consistent with that by actual observation. Since the central frequency (50 Hz) of source in numerical simulation is in earthquake band, the numerical results prove that heterogeneous porous structure is one of the important factors causing strong attenuation in real stratum at intermediate and low frequency. 相似文献
185.
何忠蛟 《中国光学快报(英文版)》2010,(3):259-261
<正>A novel band-rejection filter based on a Bragg fiber with a defect layer is proposed.A defect layer is introduced in the periodic high/low index layers in the cladding of the Bragg fiber,which results in large confinement loss for some resonant wavelengths inside the band gap range of the Bragg fiber.A segment of the Bragg fiber with a defect layer can be used as a band-rejection filter,whose characteristics are mainly determined by the structure of the Bragg fiber.The simulation results show that the bandwidth of such a band-rejection filter is dependent on the number of the periodic high/low index layers in both sides of the defect layer in the cladding of the Bragg fiber. 相似文献
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在超高真空系统中,超薄层 Pt淀积膜原位蒸发在原子清洁的 Si(111)表面上形成 Pt/Si界面.利用光电子谱技术(XPS和UPS)研究了Pt/Si 界面的化学性质.测量了Si2p和Pt 4f芯能级和价带电子态,并着重研究这些芯能级及电子态在低覆盖度时的变化.由 Si(2p)峰的强度随 Pt 覆盖度的变化可以清楚证明:在 300 K下淀积亚单原子层至数个单原子层 Pt的 Pt/Si(111)界面发生强烈混合作用,其原子组伤是缓变的.由于Si原子周围的 Pt原子数不断增加,所以 Pt 4f芯能级化学位移随 Pt原子覆盖度的增加而逐步减小,而Si 2p芯能级化学位移则逐步增大.同时,Pt 4f峰的线形也产生明显变化,对称性增加;Si 2p峰的线形则对称性降低.淀积亚单原子层至数单原子层Pt的UPS谱,主要显示两个峰:-4.2eV(A峰),-6.0eV(B峰).A峰随着覆盖度的增加移向费米能边,而B峰则保持不变.这说明Ptd-Sip键合不受周围Pt原子增加的影响.利用Pt/Si界面Pt原子向Si原子的间隙扩散模型讨论了所观察到的结果. 相似文献