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排序方式: 共有129条查询结果,搜索用时 46 毫秒
81.
JPC – Journal of Planar Chromatography – Modern TLC - 相似文献
82.
Radoslaw Iwankiewicz 《PAMM》2009,9(1):559-562
Stochastic point processes are the mathematical tools relevant to all problems where the phenomena have the nature of a random train of events. Applications may be found in structural dynamics where some stochastic excitations may be adequately idealized as random trains of impulses or general pulses. An example of application in mechanics of materials is the stochastic model of the grain growth processes in polycrystalline nanomaterials. Based on the stochastic differential equations formulation, analysis methods such as the moment equations method or the method of equation for the response probability density are dealt with. (© 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
83.
W. Czaja G. Harbeke L. Krausbauer E. Meier B.J. Curtis H. Brunner E. Tosatti 《Solid State Communications》1973,13(9):1445-1449
The bielectron model proposed by Gross et al. to interpret the observed absorption and emission spectra in BiI3 is critically examined and found to be untenable. A defect-associated donor-acceptor-pair model is proposed instead which successfully explains the relevant experimental data. 相似文献
84.
Denis Blackmore Alexander A. Balinsky Radoslaw Kycia Anatolij K. Prykarpatski 《Entropy (Basel, Switzerland)》2021,23(11)
We review some analytic, measure-theoretic and topological techniques for studying ergodicity and entropy of discrete dynamical systems, with a focus on Boole-type transformations and their generalizations. In particular, we present a new proof of the ergodicity of the 1-dimensional Boole map and prove that a certain 2-dimensional generalization is also ergodic. Moreover, we compute and demonstrate the equivalence of metric and topological entropies of the 1-dimensional Boole map employing “compactified”representations and well-known formulas. Several examples are included to illustrate the results. We also introduce new multidimensional Boole-type transformations invariant with respect to higher dimensional Lebesgue measures and investigate their ergodicity and metric and topological entropies. 相似文献
85.
Slurry polymerizations of ethylene over vanadium catalysts (based on VCl4 and VOCl3) and their MgCl2(THF)2-supported equivalents were studied. Unsupported vanadium catalysts were found to be unstable while the vanadium active sites deposited on the MgCl2(THF)2 complex are stable. A sharply outlined correlation was found between the concentration of vanadium(III) and catalyst productivity. The high activity and stability of the vanadium catalyst when supported on the magnesium complex is attributed to the increase of resistance to reduction of active vanadium(III) to inactive vanadium(II) by an organoaluminium co-catalyst. 相似文献
86.
Tsuge M Berski S Stachowski R Räsänen M Latajka Z Khriachtchev L 《The journal of physical chemistry. A》2012,116(18):4510-4517
We investigate the conditions when noble-gas hydrides can be found in real environments and report on the preparation and identification of the HXeBr···CO(2) complex in a xenon matrix and HXeBr in a carbon dioxide matrix. The H-Xe stretching mode of the HXeBr···CO(2) complex in a xenon matrix is observed at 1557 cm(-1), showing a spectral shift of +53 cm(-1) from the HXeBr monomer. The calculations at the CCSD(T)/aug-cc-pVTZ-PP(Xe,Br) level of theory give two stable structures for the HXeBr···CO(2) complex with frequency shifts of +55 and +103 cm(-1), respectively. On the basis of the calculations, the experimentally observed band is assigned to the more stable structure with a "parallel" geometry. The HXeBr molecule was prepared in a carbon dioxide matrix and has the H-Xe stretching frequency of 1646 cm(-1), meaning a strong matrix shift and stabilization of the H-Xe bond. The deuterated species DXeBr in a carbon dioxide matrix absorbs at 1200 cm(-1). This is the first case where a noble-gas hydride is prepared in a molecular solid. The thermal stabilities of HXeBr and HXeBr···CO(2) complex in a xenon matrix and HXeBr in a carbon dioxide matrix were examined. We have found a high thermal stability of HXeBr in carbon dioxide ice (at least up to 100 K), i.e., under conditions that may occur in nature. 相似文献
87.
Shalibo Y Rofe Y Barth I Friedland L Bialczack R Martinis JM Katz N 《Physical review letters》2012,108(3):037701
We measure the state dynamics of a tunable anharmonic quantum system, the Josephson phase circuit, under the excitation of a frequency-chirped drive. At small anharmonicity, the state evolves like a wave packet-a characteristic response in classical oscillators; in this regime, we report exponentially enhanced lifetimes of highly excited states, held by the drive. At large anharmonicity, we observe sharp steps, corresponding to the excitation of discrete energy levels. The continuous transition between the two regimes is mapped by measuring the threshold of these two effects. 相似文献
88.
Radoslaw Czaja Messoud Efendiev 《Journal of Mathematical Analysis and Applications》2011,381(2):766-765
The existence of a pullback exponential attractor being a family of compact and positively invariant sets with a uniform bound on their fractal dimension which at a uniform exponential rate pullback attract bounded subsets of the phase space under the evolution process is proved for the nonautonomous logistic equation and a system of reaction-diffusion equations with time-dependent external forces including the case of the FitzHugh-Nagumo system. 相似文献
89.
Aeration of municipal landfills contributes to the acceleration of organic matter degradation and to the decrease of pollutant
emission into air, water, and soil. Biodegradation of organic matter present in municipal waste, deposited in a landfill,
by microorganisms under anaerobic conditions is a slow process. The aim of the study was to carry out simulations of an aerobic
landfill in lysimeters, to determine the influence of aeration rate on the degradation of organic matter present in landfills,
and to formulate a mathematical model defining the changes of carbon content in leachate and in gas produced. In this work,
simulation of aerobic landfill leachate degradation was carried out in laboratory scale lysimeters with the working volume
of 15 L. The changes of BOD5, COD, and ammonium nitrogen concentration during aeration were similar for all aeration rates.
During aeration, the BOD5 index decreased by 99.9 %, COD decreased by 95.1 %, and ammonium nitrogen concentration by 93 %.
The proposed kinetic model defines the processes of organic carbon content changes in simulated leachate and the quantity
of carbon dioxide for aerobic landfill simulation quite well. 相似文献
90.
Ethylene/POSS copolymerization behavior of postmetallocene catalysts and copolymer characteristics
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Paweł Groch Katarzyna Dziubek Krystyna Czaja Marzena Białek Katarzyna Adamczyk‐Tomiak Stanisław Rabiej Beata Dudziec 《Journal of polymer science. Part A, Polymer chemistry》2017,55(23):3918-3934
Copolymerization of ethylene with iso‐butyl substituted monoalkenyl(siloxy)‐ or monoalkenylsilsesquioxane (POSS) comonomers over bis(phenoxy‐imine) and salen‐type titanium and zirconium catalysts was studied. It was found that the polyreaction performance was significantly depended by the kind of the catalyst and by the structure and concentration of POSS in the feed. The POSS comonomer was efficiently incorporated into the polymer chain at up to 0.2 mol %. The differences in the copolymer compositions as the functions of the catalyst kind and the POSS comonomer were observed, including the varied number‐average sequence length of ethylene and unsaturated end groups, as determined by 1H NMR and FT‐IR. The presence of POSS comonomers affected also the melting and crystallization behavior of the copolymers, as evidenced by DSC, because of influence on the polymer chain arrangement. The POSS units could act as the nucleating agents. Moreover, the crystal and structural parameters of ethylene/POSS copolymers were evaluated on the basis of X‐ray results, and the limited self‐aggregation of POSS incorporated into the polymer chain, the small number and size of POSS aggregates, and the increased crystallinity degree of copolymers were demonstrated. The ethylene/POSS copolymers produced by postmetallocenes offered also high thermal stability and interesting morphological properties. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 3918–3934 相似文献