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81.
Paul Baret Eliezer Barreiro Andrew E. Greene Jean-Louis Luch Marco-Antonio Teixeira Pierre Crabbe 《Tetrahedron》1979,35(24):2931-2938
New allenic prostanoids 5c, d, 7,9c, and 15b have been prepared by total synthesis. In each case a cuprate-propargylic acetate reaction was used as the key step. 相似文献
82.
L.J. Azevedo W.G. Clark G. Deutscher R.L. Greene G.B. Street L.J. Suter 《Solid State Communications》1976,19(3):197-201
A measurement of the temperature and angular dependence of the upper critical magnetic field Hc2 in crystals of polymeric (SN)x is reported. A large anisotropy is observed at all temperatures with Hc26 = 8.1 ± 0.4 kOe parallel to, and Hc2⊥ = 870 ± 80 Oe perpendicular to, the polymer axis at 0°K. The results are explained in terms of the polymeric crystal structure and fibrous morphology of (SN)x. 相似文献
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We report measurements of the temperature dependence of the thermoelectric power and electrical conductivity for polyacetylene heavily doped (more than 10%) with arsenic pentafluoride. The thermopower is small, positive and linear with temperature. The conductivity is very large for a polymeric system, about 1000 (Ω cm)-1 at room temperature, and as temperature is decreased drops in value by less than a factor of two, becoming essentially temperature independent below 4 K. The samples exhibited ohmic behavior at the current densities used and did not show any frequency dependence up to 1000 Hz. No evidence for superconductivity was found down to 30 mK. The results are interpreted as the first conclusive evidence for the existence of a metallic state at all temperatures in this material. 相似文献
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A new, vectorial approach to fast correlation attacks on binary memoryless combiners is proposed. Instead of individual input sequences or their linear combinations, the new attack is targeting subsets of input sequences as a whole thus exploiting the full correlation between the chosen subset and the output sequence. In particular, the set of all the input sequences can be chosen as the target. The attack is based on a novel iterative probabilistic algorithm which is also applicable to general memoryless combiners over finite fields or finite rings. To illustrate the effectiveness of the introduced approach, experimental results obtained for random balanced combining functions are presentedMost of this work was done while he was with Rome CryptoDesign Center, Gemplus, Italy 相似文献
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The motion of a holonomic scleronomic non-conservative mechanicalsystem with minimal dissipation is considered. As applicationsof the theory several problems are studied in detail. 相似文献