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201.
Bhattacharjee A Chavarot-Kerlidou M Andreiadis ES Fontecave M Field MJ Artero V 《Inorganic chemistry》2012,51(13):7087-7093
A combined theoretical and experimental approach has been employed to characterize the hydrido-cobaloxime [HCo(dmgH)(2)(PnBu(3))] compound. This complex was originally investigated by Schrauzer et al. [Schrauzer et al., J. Am. Chem. Soc. 1971, 93,1505] and has since been referred to as a key, stable analogue of the hydride intermediate involved in hydrogen evolution catalyzed by cobaloxime compounds [Artero, V. et al. Angew. Chem., Int. Ed. 2011, 50, 7238-7266]. We employed quantum chemical calculations, using density functional theory and correlated RI-SCS-MP2 methods, to characterize the structural and electronic properties of the compound and observed important differences between the calculated (1)H NMR spectrum and that reported in the original study by Schrauzer and Holland. To calibrate the theoretical model, the stable hydrido tetraamine cobalt(III) complex [HCo(tmen)(2)(OH(2))](2+) (tmen = 2,3-dimethyl-butane-2,3-diamine) [Rahman, A. F. M. M. et al. Chem. Commun. 2003, 2748-2749] was subjected to a similar analysis, and, in this case, the calculated results agreed well with those obtained experimentally. As a follow-up to the computational work, the title hydrido-cobaloxime compound was synthesized and recharacterized experimentally, together with the Co(I) derivative, giving results that were in agreement with the theoretical predictions. 相似文献
202.
We use techniques from homotopy theory, in particular the connection between configuration spaces and iterated loop spaces,
to give geometric explanations of stability results for the cohomology of the varieties of regular semisimple elements in
the simple complex Lie algebras of classical type A, B or C, as well as in the group . We show that the cohomology spaces of stable versions of these varieties have an algebraic stucture, which identifies them
as “free Poisson algebras” with suitable degree shifts. Using this, we are able to give explicit formulae for the corresponding
Poincaré series, which lead to power series identities by comparison with earlier work. The cases of type B and C involve ideas from equivariant homotopy theory. Our results may be interpreted in terms of the actions of a Weyl group on
its coinvariant algebra (i.e. the coordinate ring of the affine space on which it acts, modulo the invariants of positive
degree; this space coincides with the cohomology ring of the flag variety of the associated Lie group) and on the cohomology
of its associated complex discriminant variety.
Received August 31, 1998; in final form August 1, 1999 / Published online October 30, 2000 相似文献
203.
Ion Grosu Loïc Toupet Gerard Plé Sorin Mager Eugen Mesaros Andreea Varga Elena Bogdan 《Monatshefte für Chemie / Chemical Monthly》2000,131(3):277-286
Summary. The synthesis and stereochemistry of new dibrominated spiro-1,3-dioxane derivatives are reported. Investigations by means
of NMR methods and single crystal X-ray diffraction for two compounds revealed the high regio- and diastereoselectivity of
the bromination reaction of some new spiro-1,3-dioxanes and the asymmetric induction of the chiral carbon atom located in
the spiro skeleton.
Received July 13, 1999. Accepted October 21, 1999 相似文献
204.
Hydrogen gas is burned in air to raise and maintain the stagnation temperature of a supersonic combustion test facility to
a desired setpoint. In order to reach the desired operating conditions for stagnation temperature, there are three phases
to the hydrogen control; H2 ignition at facility start-up, H2 ramp-up while the facility is ramped-up, and H2 iteration to achieve the desired temperature setpoint. Each phase incorporates a different type of control. Fuzzy logic is
used to design a computer based supervisory controller that recognizes the different phases of operation and chooses the appropriate
control method.
Received: 28 November 1999/Accepted: 2 November 2000 相似文献
205.
Eugen Dieterich D. B. Dott J. Biel H. Beckurts A. Schraut Th. Schlosser O. Schlickum B. Fischer F. A. Flückiger E. R. Squibb Charles M. Stillwell Adrian Gallois L. D. Godshall E. Luttgen S. J. Hinsdale Holdermann G. Loff und O. Schreiber 《Fresenius' Journal of Analytical Chemistry》1890,29(1):484-492
Ohne Zusammenfassung 相似文献
206.
207.
We show the power of posets in computational geometry by solving several problems posed on a set S of n points in the plane: (1) find the n − k − 1 rectilinear farthest neighbors (or, equivalently, k nearest neighbors) to every point of S (extendable to higher dimensions), (2) enumerate the k largest (smallest) rectilinear distances in decreasing (increasing) order among the points of S, (3) given a distance δ > 0, report all the pairs of points that belong to S and are of rectilinear distance δ or more (less), covering k ≥ n/2 points of S by rectilinear (4) and circular (5) concentric rings, and (6) given a number k ≥ n/2 decide whether a query rectangle contains k points or less. 相似文献
208.
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210.