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排序方式: 共有107条查询结果,搜索用时 0 毫秒
1.
2.
Stefan Spange Frank Simon Heidrun Schutz Andrea Schramm Heinz Winkelmann 《高分子科学杂志,A辑:纯化学与应用化学》2013,50(11):997-1006
Abstract The preparation of cationically active oligo-p-methoxystyrene-silica composites by cationic interfacial polymerization is described. In addition to the effective preparation of the interfacial initiator, p-methoxybenzylium-hydrogen sulfate-silica, and p-methoxybenzylium-trifluoroacetate-silica, a procedure to yield new kinds of composites is reported. The outstanding properties of the “living” oligo-p-methoxy-styryl-hydrogen sulfate-silica is demonstrated by means of zeta potential measurements, solid-state 13C-NMR spectroscopy, UV/Vis spectroscopy, and electron scanning microscopy. 相似文献
3.
Let X be a compact complex homogeneous manifold and let Aut(X) be the complex Lie group of holomorphic automorphisms of X. It is well-known that the dimension of Aut(X) is bounded by an integer that depends only on n=dim
X. Moreover, if X is K?hler then dimAut (X)≤n(n+2) with equality only when X is complex projective space. In this article examples of non-K?hler compact complex homogeneous manifolds X are given that demonstrate dimAut(X) can depend exponentially on n.
Let X be a connected compact complex manifold of dimension n. The group of holomorphic automorphisms of X, Aut(X), is a complex Lie group [3]. For a fixed n>1, the dimension of Aut(X) can be arbitrarily large compared to n. Simple examples are provided by the Hirzebruch surfaces F
m
, m∈N, for which dimAut(F
m
)=m+5, see, e.g. [2, Example 2.4.2].
If X is homogeneous, that is, any point of X can be mapped to any other point of X under a holomorphic automorphism, then the dimension of the automorphism group of X is bounded by an integer that depends only on n, see [1, 2, 6]. The estimate given in [2, Theorem 3.8.2] is roughly dimAut(X)≤(n+2)
n
. For many classes of manifolds, however, the dimension of the automorphism group never exceeds n(n+2). For example, it follows directly from the classification given by Borel and Remmert [4], that if X is a compact homogeneous K?hler manifold, then dimAut(X)≤n(n+2) with equality only when X is complex projective space P
n
. It is an old question raised by Remmert, see [2, p. 99], [6], whether this same bound applies to all compact complex homogeneous
manifolds.
In this note we show that this is not the case by constructing non-K?hler compact complex homogeneous manifolds whose automorphism
group has a dimension that depends exponentially on n. The simplest case among these examples has n=3m+1 and dimAut(X)=3m+3
m
, so the above conjectured bound is exceeded when n≥19. These manifolds have the structure of non-trivial fiber bundles over products of flag manifolds with parallelizable fibers
given as the quotient of a solvable group by a discrete subgroup. They are constructed using the original ideas of Otte [6,
7] and are surprisingly similar to examples found there. Generally, a product of manifolds does not result in an automorphism
group with a large dimension relative to n. Nevertheless, products are used in an essential way in the construction given here, and it is perhaps this feature that
caused such examples to be previously overlooked.
Oblatum 13-X-97 & 24-X-1997 相似文献
4.
J. Winkelmann 《Physica A》1976,83(2):276-300
A fluid mixture consisting of molecules with permanent electric dipole moment and scalar polarizability is described by means of correlation functions. To analyse the two-particle correlation functions we extend the graph-theoretical conception developed by Wertheim in the case of multicomponent systems by using graphs with colored points. In order to carry out a topological reduction of these sets of colored graphs the corresponding functions are found to be matrices or tensors. By the aid of a new connecting formalism the tensor notation preserves the structure of the equations in the analysis of correlation functions. These functions can be separated with respect to the range of interactions involved. Then, in applying the results to the case of a polar multicomponent mixture we can derive equations for the dielectric constant of systems consisting of both rigid and polarizable dipoles. These equations involve a correlation factor matrix which is the multicomponent equivalence of the Kirkwood factor. The dielectric expressions are used to obtain dipolar contributions to the Helmholtz free energy of mixing. 相似文献
5.
Jrg Winkelmann 《Mathematische Nachrichten》1997,186(1):285-302
We investigate under which conditions an algebraic group G defined over a locally compact field k admitr a subgroup Γ? G(k) which is dense in the Zariski topology, but discerte in the topology induced by the locally compact topology on k. For non—solvable groups we provide a complete answer. 相似文献
6.
Rebbi's multispin coding technique is improved and applied to the kinetic Ising model with size 600*600*600. We give the central part of our computer program (for a CDC Cyber 76), which will be helpful also in a simulation of smaller systems, and describe the other tricks necessary to go to large lattices. The magnetizationM atT=1.4*T
c is found to decay asymptotically as exp(-t/2.90) ift is measured in Monte Carlo steps per spin, and M(t = 0) = 1 initially. 相似文献
7.
Jörg Winkelmann 《Transformation Groups》2008,13(1):195-209
We study non-Kähler manifolds with trivial logarithmic tangent bundle. We show that each such manifold arises as a fibre bundle with a compact complex parallelizable manifold as basis and a compactficiation of a semi-torus as fibre. 相似文献
8.
9.
10.
M. Winkelmann G. Fischer B. Pilawa E. Dormann 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,26(2):199-209
Nuclear magnetic resonance (NMR) and relaxation of 63Cu and 65Cu in a powder sample of the heavy-fermion paramagnet CeCu6 is measured and analysed quantitatively. Five different Cu sites are accessible to a detailed analysis. We derive quadrupolar
splitting frequencies, Ce to Cu transferred hyperfine field coupling constants, and transversal as well as longitudinal relaxation
behaviour. Only small relaxation anomalies are observed at the orthorhombic to monoclinic structural phase transition of CeCu6. We point to the different importance of transferred hyperfine interaction and local conduction electron density for static
or dynamic part, respectively, of Cu hyperfine interaction. The different sign of the transferred hyperfine interaction from
Ce3+ to different Cu neighbours reveals the different competing interaction mechanisms, giving rise to the heavy-fermion paramagnetic
behavior of CeCu6.
Received 20 November 2001 相似文献