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141.
We consider the 3-D axisymmetric incompressible Euler equations without swirls with vortex-sheets initial data. It is proved that the approximate solutions, generated by smoothing the initial data, converge strongly in provided that they have strong convergence in the region away from the symmetry axis. This implies that if there would appear singularity or energy lost in the process of limit for the approximate solutions, it then must happen in the region away from the symmetry axis. There is no restriction on the signs of initial vorticity here. In order to exclude the possible concentrations on the symmetry axis, we use the special structure of the equations for axisymmetric flows and careful choice of test functions. 相似文献
142.
《The Journal of chemical thermodynamics》2002,34(8):1329-1339
The water activities and osmotic coefficients of aqueous solutions of {(NH4 )2SO 4 + Li 2SO 4} and {(NH4 )2SO 4 + Na 2SO 4} have been determined at a temperature of 298.15 K with a hygrometric method, at molalities in the region 0.2 mol · kg − 1 to saturation of the solutes for different fractional ionic-strengthsy = 0.2, 0.5, and 0.8 of (NH 4)2SO 4. The experimental results are compared with the predictions obtained from our extended compared additivity model, as well as the models reported by Zdanovskii, Stokes and Robinson, Pitzer, and Lietzke-Stoughton. From these measurements, parameters of Pitzers model have been determined. These were used to predict solute activity coefficients in the mixture and calculate the excess Gibbs function at total molalities for different y for these systems. 相似文献
143.
Transmission behavior of light through a grating consisting of n-doped semiconductor with subwavelength slits under the application of external static magnetic fields is investigated. As dielectric constant of n-doped semiconductor can be substantially altered by applied magnetic field, in the Voigt configuration and for TM-polarized illumination, two transmission resonance peaks associated with localized waveguide modes of slits are significantly shifted toward the lower frequency regime with the increase of the applied magnetic field. These characteristics can be assigned to a reduction of effective plasma frequency of n-doped semiconductor under the applied magnetic field. Our findings may provide possibility for achieving tunable transmission resonance spectrum. 相似文献
144.
Polycrystalline samples with nominal composition of La0.7Ca0.3Mn1−xVxO3 (0?x?0.2) sintered in air were investigated by ac susceptibility, dc magnetization, magnetoresistance (MR), X-ray diffraction (XRD), scanning electron microscopy (SEM), and differential thermal analysis (DTA) measurements. It is found that V could not substitute for Mn to form La0.7Ca0.3Mn1−xVxO3 phase when the samples are sintered in air. The obtained samples contain several phases such as (La, Ca)Mn1−δO3, LaCa3V3O12, Mn3O4 phases, etc. and constitute multi-phase composites. The Curie temperature TC and spontaneous magnetization of the composites decrease, and the resistance of the composites increases as the V content increases. The addition of V may effectively improve the low-field MR response at low temperatures due to the variation in the microstructure of the composites. 相似文献
145.
We generalize the Schmidt-correlated states to multipartite systems. The related equivalence under SLOCC, the separability, entanglement witness, entanglement measures of negativity, concurrence and relative entropy are investigated in detail for the generalized Schmidt-correlated states. 相似文献
146.
Based upon Cartan's geometric formulation of differential equations, Harrison and Estabrook proposed a geometric approach for the symmetries of differential equations. In this Letter, we extend Harrison and Estabrook's approach to analyze the symmetries of differential-difference equations. The discrete exterior differential technique is applied in our approach. The Lie symmetry of (2+1)-dimensional Toda equation is investigated by means of our approach. 相似文献
147.
碘化物升华分离-电感耦合等离子体光谱法测定土壤和沉积物中砷、锑、铋、镉、锡 总被引:3,自引:0,他引:3
将土壤或水系沉积物样品与固体NH4I按1:0·25的比例在双球玻璃管中混匀后在苯灯喷焰上加热,使样品中的As,Sb,Bi,Cd和Sn转变为碘化物升华逸出而与基体分离,挥发物用盐酸溶解后用电感耦合等离子体光谱法(ICP-AES)测定。实验探讨了NH4I的用量、挥发和溶解条件,光谱测定条件,内标选择,测定谱线选择及背景和谱线干扰校正。用土壤和水系沉积物国家一级标准物质验证了方法的准确性和精密度,测定结果与标准值吻合。方法快速简便,结果可靠,检出限为0·01~0·35μg·g-1,适用于地球化学勘探大批量土壤和沉积物样品中As,Sb,Bi,Cd和Sn的测定。 相似文献
148.
Liang-Cheng ZHAO Jing-Gong WANG Xing LI Shuo ZHANG Zhao-Fa ZHANG Ming-Yue HU Feng LU Yi-Dan WANG Yan-Qiao HU Xiu-Ping GUO Qing-Xue LIU Hua-Jie LIU 《分析化学》2018,46(2):e1801-e1809
Inductively coupled plasma-atomic emission spectrometry/mass spectrometry (ICP-AES/MS) is a potentially powerful tool in chemical phase analysis of gold in batch mode, especially applicable to the low-grade gold ores with gold content of far below detection limit of the other methods, but it has not been used in gold phase analysis of gold ores. In this work, three types of typical gold deposits (altered rock type, quartz vein type, and microscopic disseminated type) and national standard reference materials of gold ores were used to establish and validate a method for gold phase analysis of gold ores using ICP-AES/MS. The optimum conditions of phase analysis were determined, including the sample granularity and preparation procedures, separation absorbent, pretreatment procedures of various phases of gold and optimized instrument parameters. Evaluation of the optimized method showed that this method had acceptable precision (RSD: 1.1%–10.6%) and accuracy (relative error, RE: 0.5%–6.3%), and the detection results of gold in ores were comparable with those obtained using the hydroquinone volumetric method-extraction flame atomic absorption spectrometry (VOL-AAS) and graphite furnace atomic absorption spectrometry (GFAAS) methods. The sum content of gold of the 4 phases (free gold, FAu; linked gold, LAu; sulphide-bearing gold, SAu; and other mineral-bearing gold, AAu) conformed to the total gold content and was consistent with the results of rock-mineral identification. The proposed method had a low detection limit (0.30 ng g–1) and wide linear range (5.0 ng mL–1–20.00 μg mL–1). It is a simple, rapid, and efficient method for gold phase analysis in batch form. 相似文献
149.
Hongye Zhang Tianhao Ji Linglong Li Xingyi Qi Yifan Liu Jianwang Cai Haiyan Du Jiayue Sun 《Acta Physico》2008,24(4):607-611
Ni-doped anatase TiO2 nanobelts (NBs) with different Ni2+ contents were simply prepared by combining ion-exchange with hydrothermal treatment. They were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FTIR), and magnetic measurement techniques. The results showed that Ni2+ cations doped into the TiO2 lattice and no metallic nickel clusters or nanoparticles could be found. The magnetic results demonstrated that the prepared Ni-doped TiO2 samples had complex magnetic mechanism including room-temperature ferromagnetic and paramagnetic behaviors, and with the increase of Ni2+ content, the magnetization also increased under the same applied field owing to uniform distribution of Ni2+ ions in TiO2 nanobelts. 相似文献
150.
A series of partially fluorinated naphthalene, anthracene, and chrysene derivatives have been synthesized by a convenient one-pot reaction of multi-fluorinated aromatics and 1,4-dilithio-1,2,3,4-tetraaryl-1,3-butadiene that was generated in situ from the reduction of diphenylacetylene derivatives with lithium naphthalenide. 相似文献