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131.
The comparative study of the electronic absorption spectra (uv) of dithieno[c,e]dihydro azepins, oxepins and thiepins and of the corresponding bithiophens shows that “twist” forms are privileged for the cyclic compounds. This conclusion is confirmed by a theoretical analysis (CNDO/S) and by a study of sterically hindered compounds. 相似文献
132.
Dominique Foata 《Advances in Mathematics》1979,31(3):330-349
The cofactor expression (? 1)i+j for the (i, j)-entry in the inverse of a matrix (I ? B) is proved to be equal to the corresponding entry of the series Σm≥0Bm, by using purely combinatorial methods: circuit monoid techniques and monomial rearrangements. Moreover, the identity is shown to hold in a non-commutative formal power series algebra. 相似文献
133.
A simple theoretical model which assumes a linear increase with thorium concentration for the cerium 4? level with respect to the Fermi level can explain both the decrease of the superconducting temperature and the logarithmic slope of the Kondo resistivity in LaTh based alloys with cerium impurities. The model yields two different maxima for || and , the second one of which occurs when the resistivity minimum disappears, in very good agreement with experimental data. 相似文献
134.
D.-Q. Yang E. Sacher M. Meunier 《Applied Physics A: Materials Science & Processing》2005,80(3):575-579
Ex-situ contact-mode atomic force microscopy (C-AFM) was used to study the evolution of the topography of nanoscale Au clusters, deposited onto SiO2/Si surfaces, as a function of Ar+ beam irradiation. Various nanoscale Au surface patterns were created, at an ion beam energy of 2.5 keV, by controlling the ion beam conditions. These patterns include ordered or disordered spheres as well as a nanoporous metal layer. We found that the original ( 4 nm) clusters coalesced, under the ion beam, to form both larger clusters ( 9 nm) and a nanoporous interphase layer ( 6.5 nm). Under continued irradiation, both the original clusters and the nanoporous layer were absorbed into the larger clusters.PACS 39.29+k; 81.16.-c; 61.46.+w 相似文献
135.
The Ti-mediated reaction of Grignard reagents with nitriles was investigated with sub-stoichiometric amounts of titanium isopropoxide. Cyanoesters were converted to spirocyclopropanelactams in good yields using as low as 0.05 eq of Ti(O(i)Pr)4. Under similar conditions, cyanocarbonates led to spirocyclopropane oxazolidinones and/or aminocyclopropylcarbinols. A very short synthesis of the naturally occurring aminocyclopropanecarboxylic acid illustrates the usefulness of this methodology. 相似文献
136.
Armspach D Poorters L Matt D Benmerad B Balegroune F Toupet L 《Organic & biomolecular chemistry》2005,3(14):2588-2592
1,3-Bis[bis(4-tert-butylphenyl)chloromethyl]benzene and 1,3-bis[bis(4-anisyl)chloromethyl]benzene were employed as regioselective capping reagents for the preparation of C-6A,C-6B-bridged, permethylated alpha- and beta-CD derivatives; isolated yields up to 55% of proximally capped, methylated CDs were obtained, thus opening the way to the straightforward preparation of a wide range of A,B-functionalised CDs. As revealed by a single crystal X-ray diffraction study, the benzene-1,3-bis[bis(4-tert-butylphenyl)methyl] spacer is perfectly suited for A,B-capping of beta-cyclodextrin. 相似文献
137.
Maioli P Meunier T Gleyzes S Auffeves A Nogues G Brune M Raimond JM Haroche S 《Physical review letters》2005,94(11):113601
We present an efficient, state-selective, nondemolition atom-counting procedure based on the dispersive interaction of a sample of circular Rydberg atoms with a mesoscopic field contained in a high-quality superconducting cavity. The state-dependent atomic index of refraction, proportional to the atom number, shifts the classical field phase. A homodyne procedure translates the information from the phase to the intensity. The final field intensity is readout by a mesoscopic atomic sample. This method opens promising routes for quantum information processing and nonclassical state generation with Rydberg atoms. 相似文献
138.
139.
Guyonvarch J Certon D Ratsimandresy L Patat F Lethiecq M 《The Journal of the Acoustical Society of America》2005,117(1):200-209
The theoretical response of a 1-3 piezocomposite plate submitted to localized electrical excitation was studied with the theory of guided waves. The theoretical modeling was based on the global matrix method, and the piezocomposite material was considered as a homogeneous medium. To validate the theoretical results, experimental displacement measurements were performed with an interferometric probe on two piezocomposite plates, one with a single element and one with an array of electrodes. The measured response on the single-element plate was mainly supported by the S0 and S3 modes of the plate. Homogenization limits of the composite in terms of frequency and wave number are defined on the basis of data from this sample. Within these limits, the piezocomposite material operates as a homogeneous medium, and comparison between theoretical and experimental results allows the equivalent electroacoustic parameters to be evaluated. A second sample was measured to study the effects of the electrode array on the electroacoustic response of the plate. Two kinds of electrical excitation were studied. 相似文献
140.
Boullet J Sabourdy D Desfarges-Berthelemot A Kermène V Pagnoux D Roy P Dussardier B Blanc W 《Optics letters》2005,30(15):1962-1964
Coherent combining is demonstrated in a clad-pumped Yb-doped double-core fiber laser. A slope efficiency of more than 70% is achieved with 96% of the total output power in the fundamental mode of one of the two cores. This high combining efficiency is obtained when both cores are coupled via a biconical fused taper in a Michelson interferometer configuration. 相似文献