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181.
Georg Halfter 《Fresenius' Journal of Analytical Chemistry》1948,128(2-3):266-269
Ohne Zusammenfassung 相似文献
182.
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184.
Markus Clemens Moritz HeliasThorsten Steinmetz Georg Wimmer 《Journal of Computational and Applied Mathematics》2008
The simulation of slowly varying transient electric high-voltage fields and magnetic fields requires the repeated and successive solution of high-dimensional linear algebraic systems of equations with identical or near-identical system matrices and different right-hand side vectors. For these solution processes which are required within implicit time integration schemes and nonlinear (quasi-)Newton–Raphson methods an iterative multiple right-hand side (mrhs) scheme is used which recycles vector subspaces resulting from previous preconditioned conjugate gradient iteration runs. The combination of this scheme with a subspace projection extrapolation start value generation scheme is discussed. Numerical results for three-dimensional electric and magnetic field simulations are presented and the efficiency of the new schemes re-using eigenvector information from previous iteration processes with different tolerance criteria are compared to those of standard conjugate gradient iterations. 相似文献
185.
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B. Ittermann M. Füllgrabe M. Heemeier F. Kroll F. Mai K. Marbach P. Meier D. Peters G. Welker W. Geithner S. Kappertz S. Wilbert R. Neugart P. Lievens U. Georg M. Keim 《Hyperfine Interactions》2000,129(1-4):423-441
β-active probe nuclei are implanted in nominally undoped ZnSe crystals. β-radiation detected nuclear magnetic resonance (β-NMR)
studies are described for two different probe nuclei, 8Li and 12B. This way, the implantation behavior of two “opposite”dopants, one acceptor (Li) and one donor (B) can be characterized
by the same microscopic technique. Such characterizations are attempted in terms of the structure of intermediate or final
lattice sites, defect charge states, or the kinetics of defect reactions and site changes.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
188.
Georg Gregor 《Monatshefte für Chemie / Chemical Monthly》1894,15(1):437-445
Ohne Zusammenfassung 相似文献
189.
Andreas J. Steiner Georg Schitter Arnold E. Stütz Tanja M. Wrodnigg Chris A. Tarling Stephen G. Withers Don J. Mahuran Michael B. Tropak 《Tetrahedron: Asymmetry》2009,20(6-8):832-835
Cyclisation by double reductive amination of 2-acetamino-2-deoxy-d-xylo-hexos-5-ulose with N-2 protected l-lysine derivatives provided 2-acetamino-1,2-dideoxynojirimycin derivatives without any observable epimer formation at C-5. Modifications on the lysine moiety gave access to lipophilic derivatives that exhibited improved hexosaminidase inhibitory activities. 相似文献
190.
Qing‐Jiang Pan Dr. Grigory A. Shamov Dr. Georg Schreckenbach Prof. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(7):2282-2290
On the basis of uranyl complexes reacting with a polypyrrolic ligand (H4L), we explored structures and reaction energies of a series of new binuclear uranium(VI) complexes using relativistic density functional theory. Full geometry optimizations on [(UO2)2(L)], in which two uranyl groups were initially placed into the pacman ligand cavity, led to two minimum‐energy structures. These complexes with cation–cation interactions (CCI) exhibit unusual coordination modes of uranyls: one is a T‐shaped ( T ) skeleton formed by two linear uranyls {Oexo?U2?Oendo→U1(?Oexo)2}, and another is a butterfly‐like ( B ) unit with one linear uranyl coordinating side‐by‐side to a second cis‐uranyl. The CCI in T was confirmed by the calculated longest distance and lowest stretching vibrational frequency of U2?Oendo among the four U?O bonds. Isomer B is more stable than T , for which experimental tetrameric analogues are known. The formation of B and T complexes from the mononuclear [(UO2)(H2L)(thf)] ( M ) was found to be endothermic. The further protonation and dehydration of B and T are thermodynamically favorable. As a possible product, we have found a trianglelike binuclear uranium(VI) complex having a O?U?O?U?O unit. 相似文献