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31.
Dipl.‐Chem. Fabian Schax Dr. Eckhard Bill Dr. Christian Herwig Prof. Dr. Christian Limberg 《Angewandte Chemie (International ed. in English)》2014,53(47):12741-12745
The reaction of a tripodal trisilanol with n‐butyllithium and CrCl2 results in a dinuclear CrII complex ( 1 ), which is capable of cleaving O2 to yield in a unique complex ( 2 ) with an asymmetric diamond core composed of two CrIV?O units. Magnetic susceptibility data reveal significant exchange coupling of CrII (S=2) in 1 and large zero‐field splitting for CrIV (S=1) in 2 owing to strong spin–orbit coupling of the ground state. The CrIV?O compound can also be generated using PhIO, and evidence was gathered that although it is the stable product isolated after excessive O2 treatment, it further activates O2 to yield an intermediate species that oxidizes THF or Me‐THF. By extensive 18O labeling studies we were able to show, that in the course of this process 18O2 exchanges its label with siloxide O atoms of the ligand via terminal oxido ligands. 相似文献
32.
33.
Eckhard Steffen 《Discrete Mathematics》2004,280(1-3):191-214
Cubic bridgeless graphs with chromatic index four are called uncolorable. We introduce parameters measuring the uncolorability of those graphs and relate them to each other. For k=2,3, let ck be the maximum size of a k-colorable subgraph of a cubic graph G=(V,E). We consider r3=|E|−c3 and
. We show that on one side r3 and r2 bound each other, but on the other side that the difference between them can be arbitrarily large. We also compare them to the oddness ω of G, the smallest possible number of odd circuits in a 2-factor of G. We construct cyclically 5-edge connected cubic graphs where r3 and ω are arbitrarily far apart, and show that for each 1c<2 there is a cubic graph such that ωcr3. For k=2,3, let ζk denote the largest fraction of edges that can be k-colored. We give best possible bounds for these parameters, and relate them to each other. 相似文献
34.
Eckhard M. S. Hitzer 《Advances in Applied Clifford Algebras》2003,13(1):11-45
This paper introduces the new interactive Java sketching software KamiWaAi, recently developed at the University of Fukui.
Its graphical user interface enables the user without any knowledge of both mathematics or computer science, to do full three
dimensional “drawings” on the screen. The resulting constructions can be reshaped interactively by dragging its points over
the screen. The programming approach is new. KamiWaAi implements geometric objects like points, lines, circles, spheres, etc.
directly as software objects (Java classes) of the same name. These software objects are geometric entities mathematically
defined and manipulated in a conformal geometric algebra, combining the five dimensions of origin, three space and infinity.
Simple geometric products in this algebra represent geometric unions, intersections, arbitrary rotations and translations,
projections, distance, etc. To ease the coordinate free and matrix free implementation of this fundamental geometric product,
a new algebraic three level approach is presented. Finally details about the Java classes of the new GeometricAlgebra software
package and their associated methods are given. KamiWaAi is available for free internet download. 相似文献
35.
Kathrin Krammer Nadja Ratzka Eckhard Klieme Frank Lipowsky Christine Pauli Kurt Reusser 《ZDM》2006,38(5):422-432
Within the framework of a yearlong teacher education program we examined the conditions and effectiveness of learning with classroom videos. In online phases and face-to-face sessions (blended learning), 20 teachers from two different countries. (Germany and Switzerland) analyzed videos of their own mathlessons and math-lessons of other teachers. Using different instruments, the training program was evaluated from a scientific perspective. The evaluation aimed to obtain information about processes within the training, about the acceptance of the training by the teachers and the patterns of perception of teaching processes of the teachers. 相似文献
36.
S. Eckhard 《Fresenius' Journal of Analytical Chemistry》1961,184(4):298
Ohne Zusammenfassung 相似文献
37.
38.
Ohne ZusammenfassungVortrag, gehalten auf der Tagung der Gesellschaft Deutscher Chemiker — Fachgruppe Analytische Chemie — am 25. Oktober 1958 in Marburg/Lahn.Dissertation, Chemisches Institut der Universität Köln. 相似文献
39.
S. Eckhard Margot Zimmermann Ursula Baumann und Klaus Brodersen 《Fresenius' Journal of Analytical Chemistry》1960,175(6):451-454
Ohne Zusammenfassung 相似文献
40.