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231.
While nuclear magnetic resonance diffusion experiments are widely used to resolve structures confining the diffusion process, it has been elusive whether they can exactly reveal these structures. This question is closely related to x-ray scattering and to Kac's "hear the drum" problem. Although the shape of the drum is not "hearable," we show that the confining boundary of closed pores can indeed be detected using modified Stejskal-Tanner magnetic field gradients that preserve the phase information and enable imaging of the average pore in a porous medium with a largely increased signal-to-noise ratio. 相似文献
232.
Abstract A series of unsymmetrical dimeric mesogens was prepared, members of which were composed of a 4′-pentyloxybiphenyl-4-carboxyl core and a 4′-substituted-benzylidene-4-oxyaniline core joined via an alklyene spacer. The structural variants were cyano, nitro and trifluoromethyl. Comparison of mesophase behaviour of the unsymmetrical dimers with that of corresponding monomeric ‘halves’ and also with that of corresponding symmetrical dimers indicated a tendency for the unsymmetrical dimers to form smectic phases although not as highly ordered as those of some of the monomers corresponding to a relevant core group. 相似文献
233.
Let E be a Denjoy–Carleman class of ultradifferentiable functions of Beurling type on the real line that strictly contains another class F of Roumieu type. We show that the set S of functions in E that are nowhere in the class F is large in the topological sense (it is residual), in the measure theoretic sense (it is prevalent), and that S∪{0} contains an infinite dimensional linear subspace (it is lineable). Consequences for the Gevrey classes are given. Similar results are also obtained for classes of ultradifferentiable functions defined imposing conditions on the Fourier–Laplace transform of the function. 相似文献
234.
P. Achenbach C. Ayerbe Gayoso J. C. Bernauer S. Bianchin R. B?hm O. Borodina D. Bosnar M. B?sz V. Bozkurt P. Byd?ovsky L. Debenjak M. O. Distler A. Esser I. Fri??i? M. Gómez Rodríguez B. G?küzüm K. Grie?inger P. Jennewein E. Kim M. Makek H. Merkel S. Minami U. Müller D. Nakajima L. Nungesser B. ?zel-Tashenov J. Pochodzalla Ch. Rappold T. R. Saito S. Sánchez Majos B. S. Schlimme S. ?irca M. Weinriefer C. J. Yoon 《The European Physical Journal A - Hadrons and Nuclei》2012,48(2):1-8
Cross-section measurements of the exclusive p(e, e??K +)??, ?? 0electroproduction reactions have been performed at the Mainz Microtron MAMI in the A1 spectrometer facility using for the first time the KAOS spectrometer for kaon detection. These processes were studied in a kinematical region not covered by any previous experiment. The nucleon was probed in its third-resonance region with virtual photons of low four-momenta, Q 2 = 0.030?C0.055 (GeV/c)2. The MAMI data indicate a smooth transition in Q2 from photoproduction to electroproduction cross-sections. Comparison with predictions of effective Lagrangian models based on the isobar approach reveal that strong longitudinal couplings of the virtual photon to the N* resonances can be excluded from these models. Modern isobar and Regge-plus-resonance models are in agreement with the data. 相似文献
235.
Dr. Alexander Kiefer Chantal D. Bader Dr. Jana Held Anna Esser Priv.-Doz. Dr. Dr. Jan Rybniker Dr. Martin Empting Prof. Dr. Rolf Müller Prof. Dr. Uli Kazmaier 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(37):8894-8902
Cyclomarins are highly potent antimycobacterial and antiplasmodial cyclopeptides isolated from a marine bacterium (Streptomyces sp.). Previous studies have identified the target proteins and elucidated a novel mode of action, however there are currently only a few studies examining the structure–activity relationship (SAR) for both pathogens. Herein, we report the synthesis and biological evaluation of 17 novel desoxycyclomarin-inspired analogues. Optimization via side chain modifications of the non-canonical amino acids led to potent lead structures for each pathogen. 相似文献
236.
237.
Spectroscopic Identification of a Bidentate Binding Motif in the Anionic Magnesium–CO2 Complex ([ClMgCO2]−) 下载免费PDF全文
Glenn B. S. Miller Tim K. Esser Harald Knorke Sandy Gewinner Dr. Wieland Schöllkopf Dr. Nadja Heine Prof. Dr. Knut R. Asmis Prof. Dr. Einar Uggerud 《Angewandte Chemie (International ed. in English)》2014,53(52):14407-14410
A magnesium complex incorporating a novel metal–CO2 binding motif is spectroscopically identified. Here we show with the help of infrared photodissociation spectroscopy that the complex exists solely in the [ClMg(η2‐O2C)]? form. This bidentate double oxygen metal–CO2 coordination has previously not been observed in neutral nor in charged unimetallic complexes. The antisymmetric CO2 stretching mode in [ClMg(η2‐O2C)]? is found at 1128 cm?1, which is considerably redshifted from the corresponding mode in bare CO2 at 2349 cm?1, suggesting that the CO2 moiety has a considerable negative charge (~1.8 e?). We also employed electronic structure calculations and kinetic analysis to support the interpretation of the experimental results. 相似文献
238.