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101.
Ch. -Ed. Pfister 《Communications in Mathematical Physics》1975,41(2):109-117
It is shown for the Heisenberg model that the correlation functions are analytic inh andT if Re(h)≠0 andT is positive. 相似文献
102.
A novel synthetic approach to 2-oxo-Δ3-A-nor-steroids is described. The photochemical ring contraction of epoxyketones, cf. 4 → 5 , serves as the key step of this procedure, which gives notably higher yields than the previously published syntheses (e.g., overall yield 6 → 10 40%). 相似文献
103.
Helmut Pfister 《Archiv der Mathematik》1976,27(1):86-92
Ohne Zusammenfassung 相似文献
104.
Femtosecond infrared pump-probe spectroscopy of the N-H mode of a stable alpha-helix reveals two excited-state absorption bands, which disappear upon unfolding of the helix. A quantitative comparison with polaron theory shows that these two bands reflect two types of two-vibron bound states connected to the trapping of two vibrons at the same site and at nearest neighbor sites, respectively. The latter states originate from an acoustic phonon in the helix, which correlates adjacent sites. 相似文献
105.
We report the first measurement of the quantum phase-difference noise of an ultrastable nondegenerate optical parametric oscillator that emits twin beams classically phase locked at exact frequency degeneracy. The measurement illustrates the property of a lossless balanced beam splitter to convert number-difference squeezing into phase-difference squeezing, and thus provides indirect evidence for Heisenberg-limited interferometry using twin beams. This experiment is a generalization of the Hong-Ou-Mandel interference effect for continuous variables and constitutes a milestone towards continuous-variable entanglement of bright, ultrastable nondegenerate beams. 相似文献
106.
Stepped chutes are a standard element in hydraulic engineering. Among others, two basic problems have not yet been addressed so far. These include the direct spray reduction on stepped chutes for relatively small discharges by an improved step edge geometry, and the cavitation damage up to the point of self-aeration for relatively large discharges. This research adds to these two items by systematic observations on a stepped chute of definite slope and step size. The test data were analyzed resulting in preliminary recommendations for an improved performance of stepped chutes. It was concluded that the present knowledge applies also for stepped chutes extended with an aerator as proposed herein. The latter may be easily added to existing designs, of which the design discharge is increased. 相似文献
107.
We report on structural characterization of vorticity bands formed in a wormlike micellar solution by Rheo--small-angle neutron scattering and video imaging experiments. Below a critical shear stress tau{c} in Newtonian and shear-thinning regime, only a minor flow alignment of the micelles is observed. Above tau{c}, in the shear-thickening regime, alternating transparent and turbid bands are formed. Triggered small-angle neutron scattering shows different anisotropic patterns in both bands indicating strongly aligned structures. By high-speed video imaging, we show that such an alignment of micelles does not correspond to a phase of lower viscosity. 相似文献
108.
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110.
二氧化硅悬浮体和水解聚丙烯酰胺体系的流变性 总被引:6,自引:0,他引:6
研究了二氧化硅悬浮体的流变性。在固体含量较少的情况下, 体系呈Newton型;固体含量达到一定程度以后, 产生三维结构, 为假塑性体系。三维结构的固体含量与pH值有关。实验证实, 在等电点(i,e, p)附近三维结构最为疏松。还研究了水解聚丙烯酰胺(HPAM)对悬浮体流变性能的影响。HPAM破坏了二氧化硅粒子聚集体结构, 呈絮凝体结构, 并出现触变性。当高聚物在固体表面覆盖一半时, 具有最大触变性和动剪切力。HPAM的水解度达到一定程度, 由于对固体粒子由“强”吸附转变为“弱”吸附, 固体粒子“屏蔽”了高分子间的相互作用, 出现了负触变性现象。在流动时粒子会脱附, 静止以后又产生吸附, 这种吸附与脱附是产生负触变性的主要原因。HPAM水解过度或用量过多, 均会减弱负触变性现象。 相似文献