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31.
Simon Graßl Clémence Hamze Thaddäus J. Koller Prof. Dr. Paul Knochel 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(15):3752-3755
(Hetero)aryl, benzylic, and alkyl zinc halides were thiolated with N-thiophthalimides at 25 °C within 1 h in the presence of 5–10 % Cu(OAc)2 ⋅ H2O to furnish the corresponding polyfunctionalized thioethers in good yields. This electrophilic thiolation was extended to the introduction of trifluoromethylthio (SCF3), thiocyanate (SCN), and selenophenyl (SePh) groups. The utility of this method was shown in a seven-step synthesis of a potent cathepsin D inhibitor in 34 % overall yield. 相似文献
32.
33.
34.
Th. Wercide heißen 《Zeitschrift für Physik A Hadrons and Nuclei》1927,42(5-6):480-480
35.
Isotope shifts have been measured in Sm II from which the shifts between pure configurations 4f 6 s and 4f 65d can be determined. The specific mass shift for such a “transition” was estimated to be (?1±2)mK for a change of two neutrons. The values derived for the change in the nuclear charge distribution,δ〈r 2〉, are in good agreement with the results obtained from isotope shift measurements in Sm I (H. Brand et al.: J. Phys. B11, L99, 1978). The weighted mean values representing the best information onδ〈r 2〉 presently available are in fm2: [144, 148] 0.488(23); [148, 150] 0.285(14); [150, 152] 0.400(19); [152, 154] 0.217(11). 相似文献
36.
Interplay of charge, spin, orbital and lattice correlations in colossal magnetoresistance manganites
A. Weiße H. Fehske 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,30(4):487-494
We derive a realistic microscopic model for doped colossal magnetoresistance manganites, which includes the dynamics of charge,
spin, orbital and lattice degrees of freedom on a quantum mechanical level. The model respects the SU(2) spin symmetry and the full multiplet structure of the manganese ions within the cubic lattice. Concentrating on the hole
doped domain ( 0≤x≤0.5) we study the influence of the electron-lattice interaction on spin and orbital correlations by means of exact diagonalisation
techniques. We find that the lattice can cause a considerable suppression of the coupling between spin and orbital degrees
of freedom and show how changes in the magnetic correlations are reflected in dynamic phonon correlations. In addition, our
calculation gives detailed insights into orbital correlations and demonstrates the possibility of complex orbital states.
Received 4 September 2002 / Received in final form 8 November 2002 Published online 31 December 2002 相似文献
37.
We study the minimization of a quadratic functional where the Tichonov regularization term is an H s -norm with a fractional s > 0. Moreover, pointwise bounds for the unknown solution are given. A multilevel approach as an equivalent norm concept is introduced. We show higher regularity of the solution of the variational inequality. This regularity is used to show the existence of regular Lagrange multipliers in function space. The theory is illustrated by two applications: a Dirichlet boundary control problem and a parameter identification problem. 相似文献
38.
The C. Neumann system describes a particle on the sphere S
n
under the influence of a potential that is a quadratic form. We study the case that the quadratic form has ℓ +1 distinct eigenvalues with multiplicity. Each group of m
σ
equal eigenvalues gives rise to an O(m
σ
)-symmetry in configuration space. The combined symmetry group G is a direct product of ℓ + 1 such factors, and its cotangent lift has an Ad*-equivariant momentum mapping. Regular reduction leads to the Rosochatius
system on S
ℓ
, which has the same form as the Neumann system albeit for an additional effective potential. 相似文献
39.
E. García-Matres N. Stüßer M. Hofmann M. Reehuis 《The European Physical Journal B - Condensed Matter and Complex Systems》2003,32(1):35-42
The magnetic structures of Mn1-xFexWO4 with x
= 0.0, 0.16, 0.21, 0.225, 0.232, 0.24, 0.27, 0.29, and 1.0 were refined from neutron powder diffraction data. The magnetic phase
diagram could be completed in the coexistence range of different magnetic structures up to x
= 0.29. For the magnetic state at 1.5 K a commensurate antiferromagnetic structure with a propagation vector
= (±1/4, 1/2, 1/2) was found for x
⩽ 0.22 while the magnetic spins order with
= (1/2, 0, 0) for x
≥ 0.22. In the latter phase, additionally, weak magnetic reflections indexed to an incommensurate ordering with
= (- 0.214, 1/2, 0.457) occur in the diffraction pattern up to x
= 0.29 indicating the occurence of a reentrant phase. For 0.12 ⩽
x
⩽ 0.29 the low temperature phases are separated from a magnetic high temperature phase showing only magnetic reflections indexed
to a spin arrangement with
= (1/2, 0, 0). The magnetic phase diagram is discussed qualitatively considering random superexchange between the statistically distributed
Mn2+- and Fe2+-ions in the coexistence range 0.12 ⩽
x
⩽ 0.29 of different magnetic structures related to those of pure MnWO4 and FeWO4.
Received 9 October 2002 Published online 14 March 2003 相似文献
40.