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61.
62.
A. M. Yakunin A. Yu. Silov P. M. Koenraad W. Van Roy J. De Boeck J. H. Wolter 《Superlattices and Microstructures》2003,34(3-6):539
An individual Mn acceptor in GaAs is mapped by cross-sectional scanning tunneling microscopy (X-STM) at room temperature and a strongly anisotropic shape of the acceptor state is observed. An acceptor state manifests itself as a cross-like feature which we attribute to a valence hole weakly bound to the Mn ion forming the (Mn2+3d5+hole) complex. We propose that the observed anisotropy of the Mn acceptor wavefunction is due to the d-wave present in the acceptor ground state. 相似文献
63.
The synthesis of several analogues of (±)-semivioxanthin including five thiophene analogues, using directed metalation are reported. The strategy consisted of the synthesis of functionalized naphthalene or benzo[b]thiophene as building blocks followed by annelation of the pyrone. 相似文献
64.
Minimal, rigid foliations by curves on ℂℙ
n 总被引:1,自引:0,他引:1
We prove the existence of minimal and rigid singular holomorphic foliations by curves on the projective space ℂℙ
n
for every dimension n≥2 and every degree d≥2. Precisely, we construct a foliation ℱ which is induced by a homogeneous vector field of degree d, has a finite singular set and all the regular leaves are dense in the whole of ℂℙ
n
. Moreover, ℱ satisfies many additional properties expected from chaotic dynamics and is rigid in the following sense: if
ℱ is conjugate to another holomorphic foliation by a homeomorphism sufficiently close to the identity, then these foliations
are also conjugate by a projective transformation. Finally, all these properties are persistent for small perturbations of
ℱ.?This is done by considering pseudo-groups generated on the unit ball 𝔹
n
⊆ℂ
n
by small perturbations of elements in Diff(ℂ
n
,0). Under open conditions on the generators, we prove the existence of many pseudo-flows in their closure (for the C
0-topology) acting transitively on the ball. Dynamical features as minimality, ergodicity, positive entropy and rigidity may
easily be derived from this approach. Finally, some of these pseudo-groups are realized in the transverse dynamics of polynomial
vector fields in ℂℙ
n
.
Received March 7, 2002 / final version received November 26, 2002?Published online February 7, 2003
Most of this work has been carried out during a visit of the first author to IMPA/RJ and a visit of the second author to the
University of Lille 1. We would like to thank these institutes for hospitality and express our gratitude to CNPq-Brazil and
CNRS-France for the financial support which made these visits possible. We are also indebted to Paulo Sad, Marcel Nicolau
and the referee whose comments helped us to improve on the preliminary version. Finally, the second author has partially conducted
this research for the Clay Mathematics Institute. 相似文献
65.
Nieves Gonzlez Carlos Elvira Julio San Romn 《Journal of polymer science. Part A, Polymer chemistry》2003,41(3):395-407
This article deals with the synthesis of hydrophilic methacrylic monomers derived from ethyl pyrrolidone [2‐ethyl‐(2‐pyrrolidone) methacrylate (EPM)] and ethyl pyrrolidine [2‐ethyl‐(2‐pyrrolidine) methacrylate (EPyM)] and their respective homopolymers. For the determination of their reactivity in radical copolymerization reactions, both monomers were copolymerized with methyl methacrylate (MMA), the reactivity ratios being calculated by the application of linear and nonlinear mathematical methods. EPM and MMA had ratios of rEPM = 1.11 and rMMA = 0.76, and this indicated that EPM with MMA had a higher reactivity in radical copolymerization processes than vinyl pyrrolidone (VP; rVP = 0.005 and rMMA = 4.7). EPyM and MMA had reactivity ratios of rEPyM = 1.31 and rMMA = 0.92, and this implied, as for the EPM–MMA copolymers, a tendency to form random or Bernoullian copolymers. The glass‐transition temperatures of the prepared copolymers were determined by differential scanning calorimetry (DSC) and were found to adjust to the Fox equation. Total‐conversion copolymers were prepared, and their behavior in aqueous media was found to be dependent on the copolymer composition. The swelling kinetics of the copolymers followed water transport mechanism case II, which is the most desirable kinetic behavior for a swelling controlled‐release material. Finally, the different states of water in the hydrogels—nonfreezing water, freezing bound water, and unbound freezing water—were determined by DSC and found to be dependent on the hydrophilic and hydrophobic units of the copolymers. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 395–407, 2003 相似文献
66.
Deák L. Bottyán L. Major M. Nagy D. L. Spiering H. Szilágyi E. Tanczikó F. 《Hyperfine Interactions》2002,144(1-4):45-52
Hyperfine Interactions - Synchrotron Mössbauer Reflectometry (SMR), the grazing incidence nuclear resonant scattering of synchrotron radiation, can be applied to perform depth-selective phase... 相似文献
67.
复Finsler流形上的Koppelman-Leray-Norguet公式 总被引:1,自引:1,他引:0
利用不变积分核(Berndtsson核),复Finsler度量和联系于Chern-Finsler联络的非线性联络,研究复Finsler流形上具有逐块光滑C~((1))边界的有界域上(p,q)型微分形式的积分表示,得到了(p,q)型微分形式的Koppelman-Leray-Norguet公式和■-方程的解.作为应用,利用复Finsler度量和联系于Chern-Finsler联络的非线性联络,给出了Stein流形上具有逐块光滑C~((1))边界的有界域上(p,q)型微分形式的Koppelman- Leray-Norguet公式以及■-方程的解,并且得到了Stein流形上实非退化强拟凸多面体上(p,q)型微分形式的积分表示式和■-方程的解. 相似文献
68.
P. Schuurmans J. Wouters P. De Moor N. Severijns W. Vanderpoorten J. Vanhaverbeke L. Vanneste 《Hyperfine Interactions》1992,75(1-4):423-430
Anisotropic α-emission from nuclei in the decay chain from223Ra to207Tl has been observed using low temperature nuclear orientation in combination with high resolution α-detection at 4.2 K. Information
on partial wave amplitudes as well as hyperfine interactions has been extracted. 相似文献
69.
70.
After carefull analysis in a turbulent zero-pressure gradient flow, various simple algebraic turbulence models were applied to the almost separated flow on the upperside of an airfoil at incidence. The Johnson-King and Horton non-equilibrium (or rate equation) models give clearly improved results. 相似文献