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排序方式: 共有173条查询结果,搜索用时 46 毫秒
91.
J. F. Liang D. Shapira C. J. Gross R. L. Varner H. Amro J. R. Beene J. D. Bierman A. L. Caraley A. Galindo-Uribarri J. Gomez del Campo P. A. Hausladen K. L. Jones J. J. Kolata Y. Larochelle W. Loveland P. E. Mueller D. Peterson D. C. Radford D. W. Stracener 《The European physical journal. Special topics》2007,150(1):35-36
Evaporation residue and fission cross sections of radioactive
132Sn on 64Ni were measured. Statistical model calculations
using parameters simultaneously fitting stable Sn+64Ni data
reproduce the 132Sn induced reaction very well. A large
sub-barrier fusion
enhancement was observed. The enhancement can be accounted for by
coupled-channels calculations including inelastic excitation of the
projectile and target, and neutron transfer. 相似文献
92.
Y. Eisenberg B. Haber U. Karshon J. Mikenberg S. Pitluck E.E. Ronat A. Shapira G. Yekutieli 《Physics letters. [Part B]》1974,48(4):354-358
In a high statistics experiment a large dσ/dt′ slope of (23.7 ± 3.2) GeV?2 is obtained in the forward direction. The natural parity exchange cross-section shows a dip at t′ ≈ 0.2 GeV2 and peak at ≈ 0.6 GeV2. The ?o is separated from the S-wave background and we obtain ?00F ≈ 0.94, at t′ = 0. 相似文献
93.
Shapira B Lupulescu A Shrot Y Frydman L 《Journal of magnetic resonance (San Diego, Calif. : 1997)》2004,166(2):152-163
We have recently proposed and demonstrated an approach that enables the acquisition of 2D nuclear magnetic resonance (NMR) spectra within a single scan. The approach is based on spatially encoding the spins' evolution along the indirect domain with the aid of a magnetic field gradient, and subsequently decoding this information numerous times over the course of the signal acquisition while spins are subject to a train of gradient echoes. The present paper discusses further considerations pertaining the 2D line shapes arising from this new way of collecting NMR data. Specific issues that are hereby addressed include (i) the effects introduced by fast relaxation onto the spatial encoding process, particularly the line widths and line shapes that will then arise in the frequency domain; (ii) approaches capable of correcting for the mixed-phase kernels resulting in these fast-relaxation cases, corresponding in essence to spatially encoded analogs of the TPPI and hypercomplex time-domain acquisition procedures; (iii) the enveloping characteristics imposed by the use of discrete excitation pulses on the attainable spectral widths along the indirect domain; and (iv) an analysis of the signal-to-noise characteristics of the methodology, with experimental corroborations of theoretical predictions and an illustration of the method's capabilities to analyze protein solutions in the mM-range concentration. 相似文献
94.
Yaish Y Prus O Buchstab E Shapira S Yoseph GB Sivan U Stern A 《Physical review letters》2000,84(21):4954-4957
The "metallic" characteristics of high density holes in GaAs/AlGaAs heterostructures are attributed to inelastic scattering between the two split heavy hole bands. Landau fan diagrams and weak field magnetoresistance are employed to measure the interband scattering rate. The inelastic rate is found to depend on temperature with an activation energy similar to that characterizing the longitudinal resistance. It is argued that acoustic plasmon mediated Coulomb scattering might be responsible for the Arrhenius dependence on temperature. The absence of standard Coulomb scattering characterized by a power-law dependence upon temperature is pointed out. 相似文献
95.
We propose a novel method for the detection and sorting of recorded neural spikes using wavelet packets. We employ the best basis via the Shannon's information cost function and local discriminant basis using mutual information. We demonstrate the efficiency of the method on data recorded in vitro from 2D neural networks. We show that our method is superior both in separation from noise and in identifying superimposed spikes. 相似文献
96.
97.
2D NMR relies on monitoring systematic changes in the phases incurred by spin coherences as a function of an encoding time t(1), whose value changes over the course of independent experiments. The intrinsic multiscan nature of such protocols implies that resistive and/or hybrid magnets, capable of delivering the highest magnetic field strengths but possessing poor temporal stabilities, become unsuitable for 2D NMR acquisitions. It is here shown with a series of homo- and hetero-nuclear examples that such limitations can be bypassed using recently proposed 2D "ultrafast" acquisition schemes, which correlate interactions along all spectral dimensions within a single scan. 相似文献
98.
99.
We study the behavior of depth and Stanley depth along short exact sequences of multigraded modules and under reduction modulo an element. 相似文献
100.
A method is proposed for nonlinear beam shaping, employing a non‐collinear quasi phase‐matched interaction in a crystal whose nonlinear coefficient is encoded by a computer generated hologram pattern. In this method the same axis is used for both satisfying the phase‐matching requirements and encoding the holographic information, the result is a single shaped beam in the generated frequency. This allows to shape beams in one‐dimension using a very simple method to fabricate patterned nonlinear crystals and to shape beams in two‐dimensions with high conversion efficiency. The one‐dimensional case is experimentally demonstrated by converting a fundamental Gaussian beam into Hermite‐Gaussian beams at the second harmonic in a KTiOPO4 crystal. The two‐dimensional case is demonstrated by generating Hermite‐Gaussian and Laguerre‐Gaussian beams in a stoichiometric lithium tantalate crystal. The suggested scheme enables broad wavelength tuning by simply tilting the crystal. 相似文献