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101.
This study proposes an interpretation of the UV photoelectron spectrum of propynal mainly with semi-empirical calculations. The electronic structure of 16 other conjugated ynals and ynones has been studied by the same techniques, and the variations of the first ionization potential, associated with the exceptionally deep oxygen lone pair, may be interpreted in terms of polar effect and intramolecular interactions. The discussion about the set π-, π≡ that cannot be separated yields only some qualitative results. 相似文献
102.
Coordination of two dithiafulvenyldiphenylphosphines on a Mo(CO)(4) fragment allows a carbon-carbon bond formation upon oxidation, leading to a novel type of metallacycle substituted by a redox active vinylogous tetrathiafulvalene. 相似文献
103.
M. Bachiri P. Perros B. Verneuil G. Mouvier P. Carlier 《Journal of mass spectrometry : JMS》1980,15(2):84-91
This study is based on results obtained by new techniques for observing metastable ions which make it possible to determine the fragmentation paths of conjugated ynals and ynones. For the ynals, the most interesting fragment is the [M–28]+˙ ion. For the ynones, when a McLafferty rearrangement is feasible, the ion arising therefrom is more abundant than the [M? CO]+. ion. However, this elimination of a neutral CO molecule is quite important for the true acetylene ketones. 相似文献
104.
Carlier D Croguennec L Ceder G Ménétrier M Shao-Horn Y Delmas C 《Inorganic chemistry》2004,43(3):914-922
The metastable O2-LiCoO(2) phase undergoes several reversible phase transitions upon lithium deintercalation. The first transition leads to an unusual oxygen stacking in such layered compounds. This stacking is found to be stable for 0.52 < x < or = 0.72 in Li(x)()CoO(2) and is called T(#)2. We studied this phase from a structural viewpoint using X-ray and neutron diffraction (ab initio method). The new stacking derives from the O2 one by gliding every second CoO(2) slab by (1/3, 1/6, 0). The lithium ions are found to occupy very distorted tetrahedral sites in this structure. We also discuss the possibility of this T(#)2 phase to exhibit stacking faults, whose amount depends on the method used to prepare this deintercalated phase. 相似文献
105.
The microwave spectrum of silyl acetylene in the 3ν10 state has been investigated from 9 to 117 GHz. After an assignment by graphical methods, the analysis has been carried out by a diagonalization of the energy matrix. Many anomalies appear in that spectrum; in particular, the |l| = 1 and |l| = 3 states cannot be fitted with a unique set of parameters. 相似文献
106.
In HMPA-THF solution, lithiated 1-naphthylacetonitrile undergoes highly syn-selective addition to aromatic aldehydes, providing the first access to such syn-aldols. Syn-selectivity is also observed with two other arylacetonitriles. Aldolate equilibration and crossover experiments demonstrate that HMPA promotes retro-aldol reaction and that aldol diastereoselectivity under these conditions is thermodynamically controlled. 相似文献
107.
Stability and optimization of dispersion-managed soliton control 总被引:1,自引:0,他引:1
Dispersion-managed solitons with in-line all-optical regeneration are shown to be subject to amplitude and timing-jitter instabilities. We identify and discuss the different natures of these instabilities by means of a linear stability analysis, which is in good agreement with the full numerical solutions of the governing equations. Stable pulse propagation can be achieved through appropriate choices of dispersion map and pulse energy. 相似文献
108.
The analytical solution developed by Dagan and Indelman (Water Resources Res. 35 (12) (1999) 3639–3647) for modelling the transport of a tracer in an infinite heterogeneous porous media in a dipole flow is extended by accounting for the presence of no flow finite boundaries. The results obtained are compared to those corresponding to the infinite domain, emphasizing the important influence of the boundaries on the elution at the pumping well and the effect of the medium's heterogeneity. The analytical results are then compared to experimental data and provide good matching. To cite this article: J.-P. Carlier, P. Ackerer, C. R. Mecanique 331 (2003). 相似文献
109.
Enrique Fernández-Cara Dany Nina-Huamán Miguel R. Nuñez-Chávez Franciane B. Vieira 《Journal of Optimization Theory and Applications》2017,175(3):652-682
This paper deals with the analysis of the internal and boundary control of a one-dimensional parabolic partial differential equation with nonlinear diffusion. First, we prove a local null controllability result with distributed controls, locally supported in space. The proof relies on local inversion (more precisely, we use Liusternik’s Inverse Function Theorem), together with some appropriate specific estimates. We also establish a similar result with controls on one side of the boundary. Then, we consider an iterative algorithm for the computation of null controls, we prove the convergence of the iterates, and we perform some numerical experiments. 相似文献
110.
[structure: see text]. Magnesium-bromine exchange on enantiopure cyclopropyl bromonitrile 5 at -100 degrees C for 1 min followed by a D2O quench gives the deuterionitrile in 81% ee (retention); additional trapping experiments establish t(1/2)(rac) = 11.4 h at -100 degrees C. These experiments provide the first glimpse into the stereochemical aspects of Mg-Br exchange. The intermediate formed is the first metalated nitrile demonstrated to possess macroscopic configurational stability. 相似文献