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871.
A cyclopentadienyl radical annelated with two homoadamantene frameworks 1 was synthesized and isolated in stable, crystalline form by the single-electron oxidation of the corresponding cyclopentadienyl anion. The X-ray structure clearly demonstrated distinct bond alternation in the cyclopentadienyl ring, suggesting that radical 1 has the characteristics of a spin-localized 2,4-cyclopentadien-1-yl radical. The two homoadamantene frameworks are nonequivalent in crystals at 100 K, while ESR spectra indicated that they are equivalent in toluene at room temperature due to rapid changes in conformation. 相似文献
872.
Toshikazu Ito 《Topology》2005,44(1):73-84
We prove that if a holomorphic one-form Ω in a neighborhood of a closed euclidian ball , in the n-dimensional complex affine space, defines a distribution transverse to the boundary sphere , then n is even and Ω admits a sole singularity q∈B2n. Moreover, this singularity is simple. 相似文献
873.
Calculations of equilibrium properties of dense matter predict that at subnuclear densities nuclei can be rodlike or slablike. To investigate whether transitions between phases with nonspherical nuclei can occur during the collapse of a star, we perform quantum molecular dynamic simulations of the compression of dense matter. We have succeeded in simulating the transitions between rodlike and slablike nuclei and between slablike nuclei and cylindrical bubbles. Our results strongly suggest that nonspherical nuclei can be formed in the inner cores of collapsing stars. 相似文献
874.
Sodium disulfide and monosulfide were selectively formed via the direct reaction of sulfur and an equimolar amount of sodium in 1,2-dimethoxyethane at 70 degrees C in the presence of a catalytic amount of aromatic hydrocarbons and ketone. 相似文献
875.
Thermal decomposition of 4-alkylidenepyrazolines 14 bearing a methoxycarbonyl group at C-3, prepared by 1,3-dipolar cycloaddition between allenecarboxylates 12 and diazoalkanes 13, was carried out. Unlike normal 4-alkylidenepyrazolines, which decompose in stepwise mechanisms at high temperatures, 14 decomposed concertedly at moderately low temperatures (45-110 degrees C), resulting in selective formation of the two isomeric alkylidenecyclopropanes 7 arising from the bond formation between the exo-methylene carbon and the 5-carbon. The selective formation and the configurations of the products are rationalized in terms of the concerted process via the folded conformation of the pyrazolines. Introduction of an electron-withdrawing group at the 3-position of the 4-alkylidenepyrazoline system causes the polarization of the C(3)-N(2) bond inducing the properties of intramolecular diazonium salt 8, in which the pi-electrons on the methylene carbon become more nucleophilic and participate in the cleavage of the C(5)-N(1) bond. The X-ray crystal structure of the typical normal alkylidenepyrazoline 14a with only small steric interactions between the substituents was determined to be a nearly planar ring structure. 相似文献
876.
We introduce an efficient and numerically stable method for calculating linear response functions chi(q,omega) of quantum systems at finite temperatures. The method is a combination of numerical solution of the time-dependent Schr?dinger equation, random vector representation of trace, and Chebyshev polynomial expansion of Boltzmann operator. This method should be very useful for a wide range of strongly correlated quantum systems at finite temperatures. We present an application to the ESR spectrum of s=1 / 2 antiferromagnet Cu benzoate. 相似文献
877.
S. Baba K. Hata S. Ichikawa T. Sekine Y. Nagame A. Yokoyama M. Shoji T. Saito N. Takahashi H. Baba I. Fujiwara 《Zeitschrift für Physik A Hadrons and Nuclei》1988,331(1):53-62
Evaporation-residue excitation functions for16O and12C+197Au reactions were measured by means of the activation technique. The competition between evaporation and fission of the compound nuclei was studied by comparing the observed evaporation-residue data with the published fission excitation functions. A newly devised analysis was applied in order to deduce a fission barrier height at a specified angular momentum and determine the relevant fissioning nucleus as well. We found the fission barriers to be 8.2 MeV for the211Fr nucleus at 16? and 8.2 MeV for the207At nucleus at 27?. 相似文献
878.
Kenichi Ozawa Nobuo Sugimoto Nobuhiko Koga Yasuhiro Kubota Yasunori Saito Akio Nomura Atsushi Minato Tetsuo Aoki Toshikazu Itabe Hiroo Kunimori 《Optical Review》1997,4(4):450-452
Optical characteristics of the retroreflector in space (RIS) on the Advanced Earth Observing Satellite (ADEOS) in orbit were tested using a second harmonics Nd:YAG laser. The intensity of reflection from the RIS was analyzed with an intensified charge coupled device camera by comparing the image with those of stars. It was confirmed that the RIS in orbit is working properly as a retroreflector. 相似文献
879.
880.