排序方式: 共有19条查询结果,搜索用时 15 毫秒
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A. Uhrig L. Banyai S. Gaponenko A. Wörner N. Neuroth C. Klingshirn 《Zeitschrift für Physik D Atoms, Molecules and Clusters》1991,20(1):345-348
In this contribution we present and discuss our measurements on CdS1?x Se x quantum dots in a glass matrix. In linear absorption measurements we find the typical blue shift of the transitions with decreasing crystallite radius due to quantization. The luminescence shows a significant Stokes shift with respect to absorption, which is interpreted in terms of strong exciton-phonon coupling and allows to deduce the Huang-Rhys factor S. Under high excitation we find an additional emission band on the high energy side, which can be attributed to the recombination of an excited two electron-hole pair state to a one electron-hole pair state in agreement with theory. Pump and probe beam experiments give a bleaching but no hole burning. Finally we discuss some open questions especially concerning the high energy structures in the absorption spectrum. 相似文献
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Trent D Lund Timothy W West Lilyan Y Tian Lihong H Bu Daniel L Simmons Kenneth DR Setchell Herman Adlercreutz Edwin D Lephart 《BMC neuroscience》2001,2(1):20-13
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In learning and memory tasks, requiring visual spatial memory (VSM), males exhibit superior performance to females (a difference attributed to the hormonal influence of estrogen). This study examined the influence of phytoestrogens (estrogen-like plant compounds) on VSM, utilizing radial arm-maze methods to examine varying aspects of memory. Additionally, brain phytoestrogen, calbindin (CALB), and cyclooxygenase-2 (COX-2) levels were determined. 相似文献4.
H. -E. Swoboda F. A. Majumder V. G. Lyssenko C. Klingshirn L. Banyai 《Zeitschrift für Physik B Condensed Matter》1988,70(3):341-348
We investigate and analyze the time-integrated nonlinear optical behaviour of an electronhole plasma in CdS as a function of the temperature and the exciting intensity. The competition between the temperature dependences of the absorption tail and of the manyparticle effects leads with increasing temperature around 160 K to a turn-over from a red- to a blue-shift of the absorption edge under excitation. The frequency dependence of the absorption for high plasma concentrations is in good agreement with theoretical calculations. 相似文献
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We present (1)H NMR chemical shift calculations of liquid water based on first principles molecular dynamics simulations under periodic boundary conditions. We focus on the impact of computational parameters on the structural and spectroscopic data, which is an important question for understanding how sensitive the computed (1)H NMR resonances are upon variation of the simulation setup. In particular, we discuss the influence of the exchange-correlation functional and the size of the basis set, the choice for the fictitious electronic mass and the use of pseudopotentials for the nuclear magnetic resonance (NMR) calculation on one hand and the underlying Car-Parrinello-type molecular dynamics simulations on the other hand. Our findings show that the direct effect of these parameters on (1)H shifts is not big, whereas the indirect dependence via the structural data is more important. The (1)H NMR chemical shifts clearly reflect the induced structural changes, illustrating once again the sensitivity of (1)H NMR observables on small changes in the local chemical structure of complex hydrogen-bonded liquids. 相似文献
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DR.G. Domairry A. Mohsenzadeh M. Famouri 《Communications in Nonlinear Science & Numerical Simulation》2009,14(1):85-95
In this paper Jeffery–Hamel flow has been studied and its nonlinear ordinary differential equation has been solved through homotopy analysis method (HAM). The obtained solution in comparison with the numerical ones represents a remarkable accuracy. The results also indicate that HAM can provide us with a convenient way to control and adjust the convergence region. 相似文献
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Crystal Blake Kimberly M Fabick Kenneth DR Setchell Trent D Lund Edwin D Lephart 《BMC neuroscience》2011,12(1):28
Background
Soy-derived isoflavones potentially protect against obesity and depression. In five different studies we examined the influence of soy-containing diets or equol injections on depression, serotonin levels, body weight gain (BW) and white adipose tissue (WAT) deposition in female Long-Evans rats at various stages of life [rats were intact, ovariectomized or experienced natural ovarian failure (NOF)]. 相似文献10.
We show that Bose condensation in real time occurs in a finite system not only as an accumulation of the bosons in the ground state below a critical temperature, but also as a rapid enhancement of an arbitrary small symmetry breaking, followed by a very slow decay of the symmetry breaking order parameter from the almost ideal value to the vanishing equilibrium value. We show this analytically on an exactly soluble model and numerically on a model of noninteracting bosons in an oscillator potential. 相似文献