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11.
V. G. Pleshakov V. M. Akimov E. Huipe Nava S. V. Lindeman Yu. T. Struchkov K. D. Ambacheu A. G. Dudareva M. A. Ryashentseva V. P. Zvolinsky N. S. Prostakov 《Russian Chemical Bulletin》1995,44(4):682-688
Based on thermogravimetric characteristics first obtained for the model 6H-indeno [1,2-b]quinoline, the scheme of thermal conversions of this compound in the temperature range 20–700 °C has been proposed, and the limit of its thermal stability (300 °C) has been determined. This temperature is recommended as the optimum for synthesizing fused benzoaza(diaza)fluorenes. Based on the results of X-ray structural analysis, the molecules of the studied indenoquinoline form centrosymmetric pairs, which are arranged in (110) layers. The molecules are orientationally disordered. The observed self-association of these molecules is similar to the - association of fused heterocyclic systems with-excessive and
****- deficient fragments. It has been suggested that interferon-inducing and antitumor compounds with an annelated indenyl fragment have a common mechanism of action according to the intercalation model of stacking structures.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 703–709, April, 1995. 相似文献
12.
L. Montrucchio 《Journal of Optimization Theory and Applications》1994,80(3):385-406
We study the relationship between the dynamical complexity of optimal paths and the discount factor in general infinite-horizon discrete-time concave problems. Given a dynamic systemx
t+1=h(x
t
), defined on the state space, we find two discount factors 0 < * ** < 1 having the following properties. For any fixed discount factor 0 < < *, the dynamic system is the solution to some concave problem. For any discount factor ** < < 1, the dynamic system is not the solution to any strongly concave problem. We prove that the upper bound ** is a decreasing function of the topological entropy of the dynamic system. Different upper bounds are also discussed.This research was partially supported by MURST, National Group on Nonlinear dynamics in Economics and Social Sciences. The author would like to thank two anonymous referees for helpful comments and suggestions. 相似文献
13.
A. Bershadskii 《Journal of statistical physics》1994,77(3-4):909-914
Corrections of Batchelor's spectral law –1 of passive scalar-fluctuations are obtained by taking into account the topological instabilities of small-scale vortex sheets: –4/3 for supercritical and –5/4 for subcritical regimes. The corresponding fractal dimensions of the scalar interface areD
=8/3 for supercritical andD
=11/4 for subcritical regimes. Good agreement with experimental data is established. 相似文献
14.
H. D. Junghenn 《Transactions of the American Mathematical Society》1996,348(3):1051-1073
A weakly continuous, equicontinuous representation of a semitopological semigroup on a locally convex topological vector space gives rise to a family of operator semigroup compactifications of , one for each invariant subspace of . We consider those invariant subspaces which are maximal with respect to the associated compactification possessing a given property of semigroup compactifications and show that under suitable hypotheses this maximality is preserved under the formation of projective limits, strict inductive limits and tensor products.
15.
K. A. Lyssenko D. V. Lyubetsky M. Yu. Antipin I. L. Odinets 《Russian Chemical Bulletin》2005,54(11):2484-2491
The nature of the intramolecular O—H...O bond was studied and its energy was estimated by X-ray diffraction analysis and quantum-chemical
calculations (B3LYP/6-311G**) of (diphenylphosphoryl)acylacetonitriles. The influence of the nature of the substituents at
the double bond in the H-bonded ring and the crystal packing effects on the hydrogen bond were investigated.
Dedicated to Corresponding Member of the Russian Academy of Sciences T. A. Mastryukova.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2406–2413, November, 2005. 相似文献
16.
R. Bruce King 《Theoretical chemistry accounts》1980,56(4):269-296
The following procedure is described for investigating the qualitative dynamics of simple chemical systems: 1) A so-called influence diagram is generated representing the relationships between the reference reactants (phase-determining intermediates); 2) This influence diagram is used to generate a truth table indicating possible transitions between state vectors representing the signs of the time derivatives of of the reference reactant concentrations; 3) The truth table is used to determine a state transition diagram representing the flow topology around unstable equilibrium points; 4) The characteristic equation of the adjacency matrix of the influence diagram is solved in order to determine the presence of such unstable equilibrium points. The two types of qualitative dynamics possible for chemical systems containing two reference reactants and one feedback circuit are bifurcation between two attracting regions (bistability) and limit cycle oscillation. However, in two reference reactant systems oscillation requires an additional self-activating loop to generate the unstable equilibrium point required for its realization. Bistability and limit cycle oscillation are also two of the possible types of qualitative dynamics for chemical systems containing three reference reactants. However, chemical systems with three reference reactants and two or more feedback circuits can also contain interlocking limit cycles, which can lead to toroidal oscillations or chaos. The influence diagrams are given for the systems exhibiting these various types of dynamic behavior along with a summary of the important properties of all 729 possible influences for simple chemical systems containing three reference reactants. 相似文献
17.
The article reviews in brief, thede novo group additivity approach and, at length, the different topological approaches to obtain predictive and internally consistent
correlations between various properties and structural features of molecules. The stress has mainly been on the molecular
connectivity method. A new rational scheme for nomenclature of connectivity indices of different orders and types is introduced.
The concept of the perturbation connectivity parameter developed by us recently has been applied to obtain correlations for
molar refraction, boiling point, molar volume, heat of atomisation, heat of combustion, heat of vaporisation, magnetic susceptibility
and critical constants of alkanes, alcohols and alkylbenzenes. A comparative study of various approaches reveals that the
present perturbation topological approach has an edge over other similar methods. 相似文献
18.
配位化学的创始与现代化 总被引:2,自引:0,他引:2
本文扼要介绍了韦尔纳配位理论的第一篇文章的内容,讨论了配位化学的发展和现代化。配合物稳定性决定于多种作用力与组分间的互补性和拓扑约束性。 相似文献
19.
分子拓扑指数在晶格能中的应用凌天才(重庆师范学院化学系重庆630047)关键词拓扑指数,晶格能分子拓扑指数实际上是分子图的不变量。自wiener ̄[1]于1947年首次提出wiener指数并用以关联烃类的沸点等数据以来,分子拓扑指数广泛用于关联与预测... 相似文献
20.
《Chemistry (Weinheim an der Bergstrasse, Germany)》2003,9(13):3112-3121
The thiourea S,S‐dioxide molecule is recognized as a zwitterion with a high dipole moment and an unusually long C? S bond. The molecule has a most interesting set of intermolecular interactions in the crystalline state—a relatively strong O???H? N hydrogen bond and very weak intermolecular C???S and N???O interactions. The molecule has Cs symmetry, and each oxygen atom is hydrogen‐bonded to two hydrogen atoms with O???H? N distances of 2.837 and 2.826 Å and angles of 176.61 and 158.38°. The electron density distribution is obtained both from Xray diffraction data at 110 K and from a periodic density functional theory (DFT) calculation. Bond characterization is made in terms of the analysis of topological properties. The covalent characters of the C? N, N? H, C? S, and S? O bonds are apparent, and the agreement on the topological properties between experiment and theory is adequate. The features of the Laplacian distributions, bond paths, and atomic domains are comparable. In a systematic approach, DFT calculations are performed based on a monomer, a dimer, a heptamer, and a crystal to see the effect on the electron density distribution due to the intermolecular interactions. The dipole moment of the molecule is enhanced in the solid state. The typical values of ρb and Hb of the hydrogen bonds and weak intermolecular C???S and N???O interactions are given. All the interactions are verified by the location of the bond critical point and its associated topological properties. The isovalue surface of Laplacian charge density and the detailed atomic graph around each atomic site reveal the shape of the valence‐shell charge concentration and provide a reasonable interpretation of the bonding of each atom. 相似文献