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41.
Abstract
C18 formate ester (5) [2-(6-methyl-8-(2,6,6-trimethyl-1-cyclohexen-1-yl)-3E,5E,7E-octatrienyl formate], a highly reactive analog of retinal, was synthesized and its interaction with bacterioopsin studied. The formate ester, in the absence of purple or bleached membrane, undergoes very rapid reaction (tl/2 = 0.9 min) in neutral buffer but with membrane present it diffuses more rapidly into the membrane where it reacts slowly. Incorporation of 5 in the membrane results in a 38 nm (3900 cm-1 ) red shift which remains after reconstitution with retinal. Similar experiments with the corresponding C18 alcohol (4) results in a red shift, but this absorption blue shifts upon reconstitution with retinal. Washing the formate ester-treated membrane with bovine serum albumin or the corresponding lyophilized preparation with hexane, treatments that remove retinal oxime, fails to remove the UV-visible absorption, suggesting that a covalent bond between the C18 moiety and a nucleophilic group of the protein has probably formed. 相似文献
C
42.
Thermal cyclization of β-haloalkylidenebisbenzylcarbamates (III) and subsequent hydro-genolysis of the intermediate 4-carbobenzoxyamino-2-oxazolidinones (IV) afford 4-amino-2-oxazolidinones (V). Some of the chemical properties of the aminooxazolidinones are also described. 相似文献
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In the framework of dynamic programming we provide two results:
This research was supported by the fund for the promotion of research in the technion. 相似文献
| An example where uniform convergence of theT-stage value does not imply equality of the limit and the lower infinite value. |
| Generalized Tauberian theorems, that relate uniform convergence of theT-stage value to uniform convergence of values associated with a general distribution on stages. |
46.
Adamová D Agakichiev G Antończyk D Appelshäuser H Belaga V Bielcíková J Braun-Munzinger P Busch O Cherlin A Damjanovic S Dietel T Dietrich L Drees A Esumi SI Filimonov K Fomenko K Fraenkel Z Garabatos C Glässel P Hering G Holeczek J Krobath G Kushpil V Ludolphs W Maas A Marín A Milosević J Miśkowiec D Ortega R Panebrattsev Y Petchenova O Petrácek V Radomski S Rak J Ravinovich I Rehak P Sako H Schmitz W Schukraft J Sedykh S Shimansky S Stachel J Sumbera M Tilsner H Tserruya I Tsiledakis G 《Physical review letters》2006,96(15):152301
We report on results of a measurement of meson production in central Pb-Au collisions at E(lab) = 158A GeV. For the first time in the history of high energy heavy-ion collisions, phi mesons were reconstructed both in the K+K- and the dilepton decay channels in the same experiment. This measurement yields rapidity densities near midrapidity, from the two decay channels, of 2.05 +/- 0.14(stat) +/- 0.25(syst) and 2.04 +/- 0.49(stat) +/- 0.32(syst), respectively. The shape of the measured transverse momentum spectrum is also in close agreement in both decay channels. The data rule out a possible enhancement of the phi yield in the leptonic over the hadronic decay channel of a factor 1.6 or larger at the 95% C.L. This rules out the discrepancy reported in the literature between measurements of the hadronic and dimuon decay channels by two different experiments. 相似文献
47.
Processes of collimation of electrically charged particles near a rotating black hole are discussed. It is assumed that the black hole is immersed in a weak magnetic field aligned with rotation axis. This situation is relevant for understanding pre-collimation of astrophysical jets. The magnetic field affects the motion of material and restricts the validity of various scenarios which use the test-particle (cold plasma) approximation. A simplified criterion to estimate the relevance of this approximation is discussed in connection with the mechanism of the dissipative collimation, as proposed by de Felice and Curir. 相似文献
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Dov M. Gabbay 《Logica Universalis》2011,5(2):255-318
In this paper we show that some versions of Dung’s abstract argumentation frames are equivalent to classical propositional
logic. In fact, Dung’s attack relation is none other than the generalised Peirce–Quine dagger connective of classical logic
which can generate the other connectives ?, ù, ú, ?{\neg, \wedge, \vee, \to} of classical logic. After establishing the above correspondence we offer variations of the Dung argumentation frames in parallel
to variations of classical logic, such as resource logics, predicate logic, etc., etc., and create resource argumentation
frames, predicate argumentation frames, etc., etc. We also offer the notion of logic proof as a geometrical walk along the
nodes of a Dung network and thus we are able to offer a geometrical abstraction of the notion of inference based argumentation.
Thus our paper is also a contribution to the question: 相似文献
50.
Dynamic cleavage fracture experiments of brittle single crystal silicon revealed several length scales of surface and path instabilities: macroscale path selection, mesoscale crack deflection, and nanoscale surface ridges. These phenomena cannot be predicted or explained by any of the continuum mechanics based equations of motion of dynamic cracks, as presumably critical energy dissipation mechanisms are not fully accounted for in the theories. Experimentally measured maximum crack speed, always lower than the theoretical limit, is another phenomenon that is as yet not well understood.We suggest that these phenomena depend on velocity dependent and anisotropic material property that resists crack propagation. The basic approach is that the bond breaking mechanisms during dynamic crack propagation vibrate the atoms at the crack front to generate thermal phonon emission, or heat, which provides additional energy dissipation mechanisms. This energy dissipation mechanism is a material property that resists crack propagation. To evaluate this property, we combined the continuum based elastodynamic Freund equation of motion with molecular dynamics atomistic computer “experiments”.We analyzed the above experimental dynamic fracture instabilities in silicon with the obtained velocity dependent and anisotropic material property and show its importance in cleavage of brittle crystals. 相似文献