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911.
912.
913.
S. Yu. Kudryashov Yu. I. Arutyunov L. A. Onuchak 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2007,81(1):102-107
New methods for calculating the mean volumetric flow rate of the carrier gas and the retention time of the unretained substance in the column under conditions of gas chromatography were proposed. The methods are based on preliminary isothermal calibrations of the flow rate and holdup time for a packed column. A theoretical substantiation of the methods was given. Procedures of plotting calibration dependences for determining the indicated quantities at a desired temperature were described. The calculation results were compared to experimental data obtained by traditional methods. It was demonstrated that the use of calculation methods substantially simplifies the determination of the specific retention volume over a wide temperature range. 相似文献
914.
We establish constructive existence conditions and construct a generalized Green operator for the construction of solutions
of a Noetherian linear boundary-value problem for a system of ordinary differential equations with switchings and pulse action
in critical and noncritical cases.
__________
Translated from Neliniini Kolyvannya, Vol. 10, No. 1, pp. 51–65, January–March, 2007. 相似文献
915.
We consider the Dirichlet problem for a class of anisotropic degenerate elliptic equations. New a priori estimates for solutions and for the gradient of solutions are established. Based on these estimates sufficient conditions guaranteeing the solvability of the problem are formulated. The results are new even in the semilinear case when the principal part is the Laplace operator. 相似文献
916.
Estimates of the convergence rate in a transfer theorem for random sums centered by constants are presented. The estimates are obtained as a consequence of the estimates of the stability of the distributions of the sums represented in the form of special mixtures to small variations in the mixing and miscible distributions. 相似文献
917.
In this paper we prove existence results for semilinear neutral functional differential inclusions with finite or infinite
delay in Banach spaces. Our theory makes use of analytic semigroups and fractional powers of closed operators, integrated
semigroups and cosine families.
相似文献
918.
In cricket, a rain-affected pitch can make batting more difficult than normal. Several other conditions such as poor light or an initially lively pitch, may also result in difficulties for the batsmen. In this note, we refer to all of them as ‘sticky wickets’. On sticky wickets, lower order batsmen are often sent into ‘hold the fort’ until conditions improve. In this paper, a stochastic dynamic programming model is used to examine the appropriateness of this policy. The model suggests that the tactic is often optimal when the sticky wicket persists until the end of the day's play, but not often when the sticky wicket is transitory. In some circumstances, it is worthwhile, on a normal wicket near the end of the day, to send in a lower order batsman to hold the fort (a night watchman): when the wicket is sticky, this tactic is even more worthwhile. 相似文献
919.
The kinetics of a model reaction of hydroxypivalaldehyde oxidation with molecular oxygen in alkaline aqueous solution in the presence of 4% Pd/Al2O3 was studied with the aim of searching for promising heterogeneous catalysts for D-glucose oxidation. 相似文献
920.
S. Heinze P. Kurz D. Wortmann G. Bihlmayer S. Blügel 《Applied Physics A: Materials Science & Processing》2002,75(1):25-36
In this paper we present a density functional theory investigation of complex magnetic structures in ultra-thin films. The
focus is on magnetically frustrated antiferromagnetic Cr and Mn monolayers deposited on a triangular lattice provided by a
Ag (111) substrate. This involves non-collinear magnetic structures, which we treat by first-principles calculations on the
basis of the vector spin-density formulation of the density functional theory. We find for Cr/Ag (111) a coplanar non-collinear
periodic 120° Néel structure, for Mn/Ag (111) a row-wise antiferromagnetic structure, and for Fe/Ag (111) a ferromagnetic
structure as magnetic ground states. The spin-polarized scanning tunneling microscope (SP–STM) operated in the constant-current
mode is proposed as a powerful tool to investigate complex atomic-scale magnetic structures of otherwise chemically equivalent
atoms. We discuss a recent application of this operation mode of the SP–STM on Mn/W (110), which led to the first observation
of a two-dimensional antiferromagnet on a non-magnetic metal. The future potential of this approach is demonstrated by calculating
SP–STM images for different magnetic structures of Cr/Ag (111). The results show that the predicted non-collinear magnetic
ground state structure can clearly be discriminated from competing magnetic structures. A general discussion of the application
of different operation modes of the SP–STM is presented on the basis of the model of Tersoff and Hamann.
Received: 07 May 2001 / Accepted: 23 July 2001 / Published online: 3 April 2002 相似文献