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91.
The effect of various types of substituents (X=OH, CH3, CN, SiH3) in benzene radical cations and anions have been investigated using INDO-SCF computations with and without π conjugation admitted between the substituent and the adjacent substrate. The inductive effect of the substituent has been found to play a minor role in determining the more stable configuration, the latter being determined in all cases investigated by the π conjugative interactions. A OEMO analysis of such interactions provides a better understanding of the key factors controlling the configuration preferentially stabilized in the various cases. 相似文献
92.
Lodovico Lunazzi Claudio Magagnoli Maurizio Guerra Dante Macciantelli 《Tetrahedron letters》1979,20(32):3031-3032
Low temperatures C-13 NMR spectra allowed the determination of the rotational barrier of N-methyl aniline in solution. The shifts of the anisochronous ortho and meta carbons were assigned by calculations. 相似文献
93.
D.R. Botterill D.W. Braben R. Kikuchi P.R. Norton A. Del Guerra A. Giazotto M.A. Giorgi A. Steffanini 《Physics letters. [Part B]》1973,45(4):405-408
The total cross section for the reaction ep → enπ+ at momentum transfers |k2| between 0.08 and 0.32 ()2 and for centre of mass energies between threshold, at W = 1.078 GeV, and W = 1.106 GeV has been measured by detecting the electron and neutron in coincidence. Comparisons are made with both current algebra and dispersion relation theoretical models. 相似文献
94.
95.
The electro-polymerization of trans-anethole in 1,2-dichloroethane solution with tetraethyland tetrabutylammonium perchlorates as supporting electrolytes was studied: the dependences of polymerization rates and molecular weight on some experimental parameters were determined.To investigate the electrolytic formation of initiating species, the anolyte from the electrolysis of the supporting salt in the absence of monomer was examined; the presence of electrolytically produced perchloric acid was ascertained unequivocally. However, owing to the polarographic behaviour of anethole, which shows an oxidation wave at lower anodic potential than the solvent—salt couple, it was not possible to postulate any reaction mechanism based on a single initiation reaction.The fact that the polymerizations were carried out without control of the anodic potential and some of the kinetic results indicate that two parallel initiation reactions (direct monomer oxidation and protonation by electrolytically formed perchloric acid) can occur. 相似文献
96.
Costa D. P. T. S. Beatrice L. C. S. Guerra L. S. C. Ribeiro M. A. Zanin F. A. A. Queiroga A. S. Limeira Júnior F. A. Gerbi M. E. M. M. 《Laser Physics》2010,20(4):876-880
Laser Physics - The aim of the present study was to compare marginal infiltration in Class V cavities prepared on extracted human premolars with either high-speed rotation or a Er:YAG laser. Class... 相似文献
97.
We measure polarization-resolved instantaneous patterns in a large-aspect ratio quasi-isotropic Nd:YAG laser. High correlation between the instantaneous orthogonal polarization patterns recorded at the earlier stages of the laser pulse has been found due to the strong cross saturation between both polarization modes. 相似文献
98.
99.
Given a collection of test functions, one defines the associated Schur–Agler class as the intersection of the contractive multipliers over the collection of all positive kernels for which each test function is a contractive multiplier. We indicate extensions of this framework to the case where the test functions, kernel functions, and Schur–Agler-class functions are allowed to be matrix- or operator-valued. We illustrate the general theory with two examples: (1) the matrix-valued Schur class over a finitely-connected planar domain and (2) the matrix-valued version of the constrained Hardy algebra (bounded analytic functions on the unit disk with derivative at the origin constrained to have zero value). Emphasis is on examples where the matrix-valued version is not obtained as a simple tensoring with ${{\mathbb C}^{N}}$ of the scalar-valued version. 相似文献
100.