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91.
92.
Christian Bär 《Communications in Mathematical Physics》1997,188(3):709-721
We prove that the nodal set (zero set) of a solution of a generalized Dirac equation on a Riemannian manifold has codimension
2 at least. If the underlying manifold is a surface, then the nodal set is discrete. We obtain a quick proof of the fact that
the nodal set of an eigenfunction for the Laplace-Beltrami operator on a Riemannian manifold consists of a smooth hypersurface
and a singular set of lower dimension. We also see that the nodal set of a Δ-harmonic differential form on a closed manifold
has codimension 2 at least; a fact which is not true if the manifold is not closed. Examples show that all bounds are optimal.
Received: 28 October 1996 / Accepted: 3 March 1997 相似文献
93.
The separation of the toxicologically important aldehyde acrolein from other carbonyl compounds by high performance liquid chromatography after derivatization to 2,4-dinitrophenylhydrazones is critically discussed on the basis of a selection of published methods. A method is proposed whereby the compounds acrolein, acetone, and propanal may be reproducibly separated to baseline by a reversed phase HPLC procedure employing a ternary mixture of methanol, water, and acetonitrile as mobile phase. 相似文献
94.
Michael Demuth Peter Stollmann Günter Stolz Jan van Casteren 《Integral Equations and Operator Theory》1995,23(2):145-153
We give trace norm estimates for products of integral operators and for diffusion semigroups. These are applied to differences of heat semigroups. A natural example of an integral operator with finite trace which is not trace class is given. 相似文献
95.
Christian Hill 《Journal of Molecular Spectroscopy》2007,241(1):15-17
Recently-formulated centrifugal distortion corrections to the spin-spin Hamiltonian have been used to analyse the first excited triplet state (ã3A2) of deuterated selenoformaldehyde. By including six spin-spin centrifugal distortion parameters, it is possible to account for the energy levels of this state using a single set of three rotational constants, A, B, and C, where previously nine spin-dependent parameters were required. 相似文献
96.
In this paper we deal with nonlinear second-order boundary value problems with impulses. The impulsive functions depend implicitly on the different considered variables and the boundary value conditions are nonlinear. In both cases functional dependence on the solution is allowed. The existence results follow from the existence of a pair of well-ordered lower and upper solutions. 相似文献
97.
98.
Jan J. Dijkstra 《Topology and its Applications》2006,153(15):2948-2951
In 1988 A. Gutek proved that there exist one-point connectifications of hereditarily disconnected spaces that do not have the fixed point property. We improve on this result by constructing a one-point connectification of a totally disconnected space without the fixed point property. 相似文献
99.
Christian Wolf 《Journal of statistical physics》2006,122(6):1111-1138
In this paper we introduce the notion of generalized physical and SRB measures. These measures naturally generalize classical
physical and SRB measures to measures which are supported on invariant sets that are not necessarily attractors. We then perform
a detailed case study of these measures for hyperbolic Hènon maps. For this class of systems we are able to develop a complete
theory about the existence, uniqueness, finiteness, and properties of these natural measures. Moreover, we derive a classification
for the existence of a measure of full dimension. We also consider general hyperbolic surface diffeomorphisms and discuss
possible extensions of, as well as the differences to, the results for Hènon maps. Finally, we study the regular dependence
of the dimension of the generalized physical/SRB measure on the diffeomorphism. For the proofs we apply various techniques
from smooth ergodic theory including the thermodynamic formalism.
2000
Mathematics Subject Classification. Primary: 37C45, 37D20, 37D35, Secondary: 37A35, 37E30 相似文献
100.
Peptidosulfonamides are an emerging group of peptidomimetics with a variety of applications in medicinal chemistry. We present a novel approach to the synthesis of peptidosulfonamides, and apply it to a series of new potential inhibitors of the bacterial peptidoglycan biosynthesis enzymes MurD and MurE. The synthesis was conducted via N-phthalimido β-aminoethanesulfonyl chlorides, which are new building blocks for the synthesis of peptidosulfonamides. In the most crucial step, sulfonic acids or their sodium salts were converted into the corresponding sulfonyl chlorides using an excess of either SOCl2 or SOCl2/DMF, and then coupled to the C-protected amino acid. None of the compounds significantly inhibited MurD, however, some inhibited MurE; one had an IC50 below 200 μM, which constitutes a promising starting point for further development. Molecular modelling simulations were performed on two analogues to investigate the absence of inhibitory activity of the sulfonamide compounds on MurD. 相似文献