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排序方式: 共有406条查询结果,搜索用时 296 毫秒
81.
Gennady Mokrousov Elena Knyazeva Liubov Maliy 《Journal of Solid State Electrochemistry》2012,16(7):2429-2433
We propose a new method for the voltammetric detection of metals and metal compounds on surfaces of sold materials. The method is based on the reduction of oxidized metal compounds using an alkali amalgam droplet, the dissolution of the metals in the amalgam droplet, finally followed by recording the voltammetric anodic dissolution of the metal. The sample collection and all the following steps, including the voltammetric measurement, are performed at the same site of the sample and without any temporal interruption as one and the same electrode system is used for all steps. The proposed method is as an easy to handle, non-destructive express analysis for a wide range of samples. 相似文献
82.
83.
Rasmussen CJ Gor GY Neimark AV 《Langmuir : the ACS journal of surfaces and colloids》2012,28(10):4702-4711
We investigate the onset of cavitation in a metastable fluid confined to nanoscale pores with nonwetting defects present. Using grand canonical and gauge cell mesocanonical Monte Carlo simulations, we study the degree of metastability (relative vapor pressure), at which the critical bubble forms in a spherical pore with a circular nonwetting defect. It is shown that an increase of the defect size leads to a transition from homogeneous to heterogeneous nucleation of critical bubbles formed at the defect site. In this case, the desorption process may be initiated at larger relative vapor pressures than those predicted by the theories of homogeneous cavitation. 相似文献
84.
Alexander O. Terent’ev Igor B. Krylov Vera A. Vil’ Zhanna Yu. Pastukhova Sergey A. Fastov Gennady I. Nikishin 《Central European Journal of Chemistry》2012,10(2):360-367
It was found that oximes undergo deoximation in the presence of the H2O2aq-HBraq system to form ketones and bromo ketones. This reaction provided the basis for the synthesis of dibromo ketones in yields
varying from 40% to 94%. This method is environmentally friendly, sustainable, and easy to perform. The results of this investigation
extend the potential of the use of oximes for the protection of carbonyl group, thus offering the ability to perform not only
conventional deoximation but also the subsequent bromination of ketones. The reaction is easily scaled up and dibromo ketones
can be prepared in gram amounts.
相似文献
85.
Gennady S. Mishuris Alexander B. Movchan Leonid I. Slepyan 《Journal of the mechanics and physics of solids》2009,57(12):1958-1979
We consider a Mode III lattice with an interface layer where the dynamic crack growth is caused by a localised sinusoidal wave. In the wave–fracture scenario, the ‘feeding wave’ (here also called the knife wave) delivers energy to the moving crack front, while the dissipative waves carry a part of this energy away from the front. The questions addressed here are:
- • What are the conditions of existence of the localised knife wave?
- • What is the lower bound of the amplitude of the feeding wave, which supports the crack propagation, for a given deformational fracture criterion?
- • How does the crack speed depend on the amplitude of the feeding wave?
- • What are the dissipative waves? How much energy is irradiated by these waves and what is the total dissipation?
- • What are the conditions of existence of the steady-state regime for the propagating crack?
Keywords: A. Dynamic fracture; A. Vibrations; B. Inhomogeneous material; B. Supersonic crack; C. Integral transforms 相似文献
86.
An Asymptotic Model of Seismic Reflection from a Permeable Layer 总被引:1,自引:0,他引:1
Analysis of compression wave propagation in a poroelastic medium predicts a peak of reflection from a high-permeability layer
in the low-frequency end of the spectrum. An explicit formula expresses the resonant frequency through the elastic moduli
of the solid skeleton, the permeability of the reservoir rock, the fluid viscosity and compressibility, and the reservoir
thickness. This result is obtained through a low-frequency asymptotic analysis of Biot’s model of poroelasticity. A review
of the derivation of the main equations from the Hooke’s law, momentum and mass balance equations, and Darcy’s law suggests
an alternative new physical interpretation of some coefficients of the classical poroelasticity. The velocity of wave propagation,
the attenuation factor, and the wave number are expressed in the form of power series with respect to a small dimensionless
parameter. The absolute value of this parameter is equal to the product of the kinematic reservoir fluid mobility and the
wave frequency. Retaining only the leading terms of the series leads to explicit and relatively simple expressions for the
reflection and transmission coefficients for a planar wave crossing an interface between two permeable media, as well as wave
reflection from a thin highly permeable layer (a lens). Practical applications of the obtained asymptotic formulae are seismic
modeling, inversion, and attribute analysis. 相似文献
87.
Orlando Avila-Pozos Gennady Mishuris Alexander Movchan 《Continuum Mechanics and Thermodynamics》2010,22(6-8):545-553
A bi-material waveguide is assumed to have an array of sufficiently long cracks parallel to the boundaries. The Bloch–Floquet waves propagating along such a waveguide are dispersive, and the band gaps are clearly identified. Slow waves are supported by a system of long cracks, and such modes are represented by the flat dispersion surfaces. Asymptotic analysis combines a lower-dimensional approximation together with the boundary layers occurring near the crack tips. Stress intensity factors are evaluated via the boundary layer analysis, which is matched with the outer fields corresponding to the lower-dimensional model. Evolution of such an elastic system is discussed as the cracks grow as a consequence of the stress concentration, which occurs for some slow waves leading to the crack opening. The asymptotic analysis is supplied with numerical simulations and physical examples. 相似文献
88.
89.
Skiba Ekaterina A. Gladysheva Evgenia K. Budaeva Vera V. Aleshina Lyudmila A. Sakovich Gennady V. 《Cellulose (London, England)》2022,29(3):1543-1555
Cellulose - The global abundance and availability of oat hulls make them a promising feedstock to produce a unique type of cellulose, the bacterial one. This is the first study examining how a... 相似文献
90.
Burilov V. A. Bogdanov I. M. Garipova R. I. Volodina A. A. Mironova D. A. Evtugyn V. G. Solovieva S. E. Antipin I. S. 《Russian Chemical Bulletin》2022,71(1):131-138
Russian Chemical Bulletin - New bifunctional amphiphilic oxyethylimidazolium derivatives of calix[4]arene with terminal alkynyl or azide fragments in the polar moiety of the molecule were... 相似文献