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排序方式: 共有175条查询结果,搜索用时 31 毫秒
1.
Sigurd Assing 《Communications in Mathematical Physics》2002,225(3):611-632
We consider the stationarity of a Burgers equation with an external random force of gradient type in one space dimension.
The expected stationary measure is the white noise measure on the space of tempered distributions. As a consequence, the nonlinearity
of the formal equation u
t
+λu
u
x
=νu
xx
+η
x
is ill-defined. Introducing a pregenerator we can formulate a generalized martingale problem leading to a meaningful version
of the formal equation which was an open problem.
Received: 9 March 2001 / Accepted: 10 October 2001 相似文献
2.
Sigurd Hofmann 《Acta Physica Hungarica A》2004,19(1-2):31-38
The nuclear shell model predicts that the next doubly magic shellclosure beyond 208Pb is at a proton number between Z=114 and 126 and at a neutron number N=184. The outstanding aim of experimental investigations is the exploration of this region of spherical ‘Superheavy Elements’. This article describes the experiments that were performed recently at the GSI SHIP. They resulted in an unambiguous identification of elements 110 to 112. They were negative so far in searching for elements 113, 116, and 118. The measured decay data are compared with theoretical predictions. Some aspects concerning the reaction mechanism are also presented. 相似文献
3.
4.
Rosselli S Ramminger AD Wagner T Lieser G Höger S 《Chemistry (Weinheim an der Bergstrasse, Germany)》2003,9(15):3481-3491
Shape-persistent macrocycles based on the phenyl-ethynyl-butadienyl backbone containing two extraannular hydroxyl groups were prepared by the oxidative coupling of the appropriate phenylethynyl oligomers. Carbodiimide-directed coupling with independently synthesized polystyrene carboxylic acid oligomers led to ABA coil-ring-coil block copolymers in which the central macrocycle serves as rigid and the polystyrene oligomers as flexible elements. Depending on the size of the coil blocks, these structures aggregate in cyclohexane into supramolecular hollow cylindrical brushes in which the rigid core is surrounded by the flexible matrix. However, in the solid state it is not possible to identify a morphology in which isolated channels based on aggregated macrocycles are embedded in a matrix of polystyrene. Detailed X-ray and electron diffraction studies on samples prepared from a solution in cyclohexane under equilibrium conditions show that the material adopts a lamellar morphology in the solid state in which columns of macrocycles are aggregated into layers which are separated by polystyrene. 相似文献
5.
6.
The amphiphilic shape-persistent macrocycle 1 containing four phenol-OH groups as polar side groups and four hexyloxy groups as nonpolar side groups in an adaptable arrangement was recrystallized from solvents of different polarity. X-ray crystallography reveals that the conformation of the macrocycle is solvent dependent such that in the pyridine solvate only two of the nonpolar side groups point outward while in the THF solvate all four of them point outward. Moreover, in the latter case the three-dimensional packing leads to the formation of a supramolecular channel structure with a large pore size. 相似文献
7.
8.
Dr. Debangshu Chaudhuri Dr. Eva Sigmund Annemarie Meyer Lisa Röck Philippe Klemm Sebastian Lautenschlager Agnes Schmid Shane R. Yost Prof. Dr. Troy Van Voorhis Dr. Sebastian Bange Prof. Dr. Sigurd Höger Prof. Dr. John M. Lupton 《Angewandte Chemie (International ed. in English)》2013,52(50):13449-13452
9.
Walter MJ Lupton JM Becker K Feldmann J Gaefke G Höger S 《Physical review letters》2007,98(13):137401
Simultaneous surface enhanced Raman scattering (SERS) and fluorescence is demonstrated from single conjugated polymer chains. As resonance enhancement of SERS depends on the spectral overlap of the polymer's absorption and the incident laser, resonance Raman and fluorescence effectively probe the absorbing and emitting part of the polymer, respectively. The optical phonon energies change along the polymer chain, providing a window to spatially track excited state relaxation. Whereas a mean spatial redistribution of the excitation is witnessed by a change in vibronic fingerprint following interchromophoric energy transfer, intrachromophoric exciton self-trapping leaves the vibrations unchanged. 相似文献
10.
Sigurd Angenent 《数学学报(英文版)》2008,24(12):1949-1952
Given a symmetric Finsler metric on T^2 whose geodesic flow has zero topological entropy, we show that the lift in the universal covering R^2 →T^2 of any closed geodesic on T^2 must be an embedded curve in R^2. 相似文献