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161.
介绍三代微光和超二代微光夜视技术的发展概况:阐明了它们各自的原理、技术特点和关键课题;着重指出了两者间的异同和相互联系。  相似文献   
162.
163.
In this paper, we established an analytical formula for the second virial coefficient (SVC) with Morse potential without using any numerical methods, and the obtained formula is applied to the calculation of the speed of sound of some matter at high temperature. This approach is based on the series expansion formula and special functions, which allows the exact evaluations of any thermodynamic properties of matter using the SVC. As an application, the obtained analytical formula is used for evaluation of the SVC with Morse potential for high‐temperature gas and the plasma region of the intermolecular interactions of neutral atom gases of B, Si, Zn, H2, N2, O2, NO, CO, He, Ne, Ar, Kr , and Xe . Based on the obtained formula of SVC, the speed of sound for gases of N2, Ar , and Zn are also determined analytically. A specific maximum temperature is chosen for every gas to ensure that there are still neutral atoms in the gas, and low temperatures are avoided due to quantum effects. The results are compared with numerical data and another analytical data from the literature. The new analytical solution is shown to be in good agreement with the compared data and is verified to supply proper thermodynamic data.  相似文献   
164.
This paper is concerned with a one-dimensional nonisentropic compressible planar magnetohydrodynamic flow with general initial data, whose behaviors at far fields x→± are different. The low Mach limit for the system is rigorously justified. The limit relies on the uniform estimates including weighted time derivatives and an extended convergence lemma.  相似文献   
165.
为探讨IDose 4迭代重建技术在低剂量CT肾动脉血管造影中的应用价值,选取205例拟行肾动脉CT血管造影患者,随机将其分为4组,A组(51例)采用管电压100 kV、管电流100 mA,碘海醇370 mg I/mL及IDose 4迭代重建技术,B组(51例)采用管电压100 kV、管电流150 mA,碘海醇270 mg I/mL及IDose 4迭代重建技术,C组(51例)采用管电压80 kV、管电流180 mA,碘海醇270 mg I/mL及IDose 4迭代重建技术,D组(52例)管电压120 kV、管电流120 mA,碘海醇370 mg I/mL及滤波反投影(FBP)重建技术。分析各组图像肾主动脉干CT值、噪声(SD)、信噪比(SNR)和噪声比(CNR),受检者接受CT有效剂量(ED)、容积CT剂量指数(CTDI vol)、剂量长度乘积(DLP)、碘摄入量以及重建图像评分差异和诊断效能。结果显示,A、B、C组重建图像评分优于D组,肾动脉主干CT值、SD、SNR、CNR均高于D组,B、C组肾动脉主干CT值、SD略低于A组。A、B、C组CTDI vol、DLP、ED均低于D组,B组CTDI vol、DLP、ED高于A组。A、B、C、D组诊断肾主动脉狭窄准确率分别为92.68%、86.49%、84.62%、82.86%。证实IDose 4迭代重建技术能降低受试者受辐射和造影剂剂量,提高成像质量,在低剂量CT肾动脉血管造影中具有较高可行性和实用性。  相似文献   
166.
We show that the Cauchy problem for a class of dispersive perturbations of Burgers' equations containing the low dispersion Benjamin–Ono equation
?tu?Dxα?xu=?x(u2),0<α1,
is locally well-posed in Hs(R) when s>sα:=32?5α4. As a consequence, we obtain global well-posedness in the energy space Hα2(R) as soon as α2>sα, i.e. α>67.  相似文献   
167.
Starting from a field theory action that describes a Dirac fermion, we propose and analyze a model based on a low‐relativistic Pauli equation coupled to a torsion‐like term to study Spin Hall Effect (SHE). We point out a very particular connection between the modified Pauli equation and the (SHE), where what we refer to torsion as field playing an important role in the spin‐orbit (SO) coupling process. In this scenario, we present a proposal of a spin‐type current, considering the tiny contributions of torsion in connection with intrinsic anisotropy of the crystal electric field.  相似文献   
168.
范德瓦耳斯气液状态方程纵横谈   总被引:4,自引:1,他引:4  
胡颉  佘守宪 《大学物理》2005,24(10):15-20
首先强调了范氏方程是气液系统的状态方程,范氏方程可以很好地说明物质气态和液态的相互转变.分析了焦-汤效应,简述了气体的液化与低温的获得.  相似文献   
169.
In the context, some lanthanide (Eu3+, Tb3+ and Sm3+) complexes with conjugated carboxylic acids (pyridine-carboxylic acids derivatives) have been synthesized and characterized. The low temperature fluorescent spectra for these complexes have been measured at nitrogen atmosphere (77 K), indicating that the central Ln3+ ions locate in an equivalent coordination environment with low symmetry for most of these lanthanide complexes belonging to dimeric or polymeric structure. Therefore, the electronic dipole transition (supersensitive transition) (5D07F2 for Eu3+, 5D47F6 for Tb3+, 4G5/26H9/2 for Sm3+) and magnetic dipole transition (5D07F1 for Eu3+, 5D47F5 for Tb3+, 4G5/26H5/2 for Sm3+) show the regular change in the corresponding split number of fluorescent spectra, which can be realized to predict the fine structure of lanthanide complexes.  相似文献   
170.
Crystallization Behavior of Sol-Gel Derived Films by Self-Seeding Process   总被引:2,自引:0,他引:2  
We propose the novel preparation method, Self-seeding Process, based on the following concept for low temperature crystallization of oxide films. Introduction of desirable inhomogeneity should give lowering of a crystallization temperature through heterogeneous nucleation accompanied with reduced activation energy. We carried out inspection of the above concept through use of PZT films. PZT gel films with the desirable inhomogeneity of microstructure were prepared, and their crystallization behaviors was examined. The PZT film was successfully crystallized at 500°C by the self-seeding process. The single phase (001) oriented PZT film with 0.55 m in thickness was obtained at 550°C for 5 min. The self-seeding process by microstructure control is efficient for the low temperature process of the oxide thin film.  相似文献   
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