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991.
M. Regitz U. Annen E. P. O. Fuchs 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1-4)
Abstract 1,3-Butadienes 1 and 6-Methyl-2H-pyran-2-ones 6 react with two equivalents of phosphaalkynes 2 in a domino-reaction to the diphosphiranes 5 and 9 respectively. Diels-Alder-reaction of 1 with 2 leads to 3 which cannot be isolated. An Ene-reaction of the phosphacyclohexa-1,4-diene 3 with additional 2 gives 4 followed by an intramolecular Diels-Alder-reaction yielding the stable diphosphatricyclooctenes 5. 相似文献
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N. U. Aldiyarov E. A. Gridneva N. N. Koborov V. A. Kurnaev A. G. Mit’ L. M. Nazarenko E. M. Yakushev 《Technical Physics》2011,56(10):1439-1446
Physical foundations of a new method for mass-spectrometric determination of tritium concentration in hydrogen-containing
media, which is based on the effect of dissociation of molecular ions of hydrogen isotopes passing through thin carbon films,
are formulated. The effects accompanying the interaction of particles with a solid (angular scattering, change in the charge
state, energy losses in protons, deuterons, and tritons) are analyzed. The corresponding theoretical and experimental data
indicate that the proposed technology can be implemented in practice for a comparatively low particle energy of ∼10 keV/nucleus. 相似文献
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This paper presents the optimized K-means (OKM) algorithm that can homogenously segment an image into regions of interest with the capability of avoiding the dead centre and trapped centre at local minima phenomena. Despite the fact that the previous improvements of the conventional K-means (KM) algorithm could significantly reduce or avoid the former problem, the latter problem could only be avoided by those algorithms, if an appropriate initial value is assigned to all clusters. In this study the modification on the hard membership concept as employed by the conventional KM algorithm is considered. As the process of a pixel is assigned to its associate cluster, if the pixel has equal distance to two or more adjacent cluster centres, the pixel will be assigned to the cluster with null (e. g., no members) or to the cluster with a lower fitness value. The qualitative and quantitative analyses have been performed to investigate the robustness of the proposed algorithm. It is concluded that from the experimental results, the new approach is effective to avoid dead centre and trapped centre at local minima which leads to producing better and more homogenous segmented images. 相似文献
998.
We study the hard-core model on the Cayley tree. We show that this model admits only periodic Gibbs measures with the period two. We find sufficient conditions for all weakly periodic Gibbs measures to be translation invariant. 相似文献
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