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排序方式: 共有683条查询结果,搜索用时 15 毫秒
1.
2.
Alexandre N. Carvalho German Lozada-Cruz 《Journal of Mathematical Analysis and Applications》2007,325(2):1216-1239
We obtain existence of asymptotically stable nonconstant equilibrium solutions for semilinear parabolic equations with nonlinear boundary conditions on small domains connected by thin channels. We prove the convergence of eigenvalues and eigenfunctions of the Laplace operator in such domains. This information is used to show that the asymptotic dynamics of the heat equation in this domain is equivalent to the asymptotic dynamics of a system of two ordinary differential equations diffusively (weakly) coupled. The main tools employed are the invariant manifold theory and a uniform trace theorem. 相似文献
3.
Z. B. Alfassi F. Groppi M. L. Bonardi O. Presler U. German 《Journal of Radioanalytical and Nuclear Chemistry》2006,268(3):639-640
Summary The paper deals with the common mistake of interpolating calculation of the efficiency of gamma-detectors by the inverse square
law of the distance of the source from the detector cap and suggests the use of the distance from the virtual point detector
instead. 相似文献
4.
O. N. German 《Mathematical Notes》2004,75(1-2):51-65
Some results about asymptotic directions for best approximations of linear forms similar to known results on best simultaneous approximations are obtained. 相似文献
5.
Isabel Brandariz José L. Barriada Teresa Vilari?o Manuel E. Sastre de Vicente 《Monatshefte für Chemie / Chemical Monthly》2004,343(6):1475-1488
Several reported procedures for calibrating glass electrodes in proton concentration are compared. Some recommendations for non-experts are also given. The examined procedures can be classified into two broad categories, namely: those based on direct potential difference measurements of solutions of known proton concentration and those that use one or several pH standards to calibrate the electrode and subsequently measure the pH of solutions containing known proton concentrations. With a single buffer, the two types of procedures lead to equivalent results. However, if two pH buffers are used, the slope of the calibration graph in proton concentration will differ from the real electrode slope to an extent proportional to the difference between the liquid junction potentials of the two buffers. Therefore, any other method is preferable under these circumstances. 相似文献
6.
In the present work we obtained the experimental pKs of the amino acid alpha-alanine in NaCl at 25 degrees and different ionic strengths. The equilibrium constants have been potentiometrically determined with a commercial glass electrode and the results analysed through three models: two directly based on the Pitzer and Scatchard approaches to the ion specific interaction theory and the other based on a simpler modification of the Debye-Hückel equation. The three models fit the data reasonably well and the extrapolated pK values obtained show a good agreement. The goodness of the ridge regression method cannot be probed in this case. 相似文献
7.
N. G. Zharova É. D. German A. M. Kuznetsov I. O. Shapiro 《Russian Chemical Bulletin》1989,38(2):270-276
1. | The influence of the components of the effect of the structural reorganization of the anionic fragments of monalkylbenzenes and nitroalkanes on the kinetics of their ionization was determined. |
2. | A model of the mechanism of the elementary act in the ionization of monoalkylbenzenes and nitroalkanes in a polar medium, which takes into account the effects of the reorganization of the solvent, the geometric structure of the reactants, and the redistribution of the electron density in them, has been proposed. |
8.
F. Catalina C. Peinado E. L. Madruga R. Sastre J. L. Mateo N. S. Allen 《Journal of polymer science. Part A, Polymer chemistry》1990,28(5):967-972
A novel monomer, 2-acryloyl thioxanthone (TXA), was prepared by reaction of 2-hydroxy thioxanthone with acryloyl chloride. Copolymerization of TXA with methyl methacrylate (MMA) in DMF at 80°C was studied in order to evaluate relative reactivities of these monomers. Values of 1.36 and 0.5 were found for the respective reactivity ratios of MMA and TXA, respectively. The resonance stabilization and polar properties were determined and discussed in terms of spectroscopic data. 相似文献
9.
V. F. Cherstkov É. A. Avetisyan B. L. Tumanskii S. R. Sterlin N. N. Bubnov L. S. German 《Russian Chemical Bulletin》1990,39(10):2223-2223
Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 10, pp. 2450–2451, October, 1990. 相似文献
10.