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排序方式: 共有247条查询结果,搜索用时 15 毫秒
71.
72.
V. Hepp O. Braun H.J. Grimm H. Ströbele C. Thöl T.J. Thouw F. Gandini C. Kiesling D.E. Plane W. Wittek 《Physics letters. [Part B]》1976,65(5):487-491
Differential cross sections for have been measured at K? momenta between 680 and 840 MeV/c in a bubble chamber experiment. For K?n → Σoπ? the Σo polarization was also determined. The measurements were combined with the available data on K?p → Σπ in an energy-dependent partial wave analysis in the center of mass energy range from 1520 to 1745 MeV. An acceptable fit was obtained with the well established resonances. 相似文献
73.
74.
Dr. Sybrin P. Schröder Wendy A. Offen Alexandra Males Dr. Yi Jin Dr. Casper de Boer Jacopo Enotarpi Laura Marino Prof. Dr. Gijsbert A. van der Marel Dr. Bogdan I. Florea Prof. Dr. Jeroen D. C. Codée Prof. Dr. Herman S. Overkleeft Prof. Dr. Gideon J. Davies 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(37):9519-9523
There is a vast genomic resource for enzymes active on carbohydrates. Lagging far behind, however, are functional chemical tools for the rapid characterization of carbohydrate-active enzymes. Activity-based probes (ABPs) offer one chemical solution to these issues with ABPs based upon cyclophellitol epoxide and aziridine covalent and irreversible inhibitors representing a potent and widespread approach. Such inhibitors for enzymes active on polysaccharides are potentially limited by the requirement for several glycosidic bonds, themselves substrates for the enzyme targets. Here, it is shown that non-hydrolysable trisaccharide can be synthesized and applied even to enzymes with challenging subsite requirements. It was found that incorporation of carbasugar moieties, which was accomplished by cuprate-assisted regioselective trans-diaxial epoxide opening of carba-mannal synthesised for this purpose, yields inactivators that act as powerful activity-based inhibitors for α-1,6 endo-mannanases. 3-D structures at 1.35–1.47 Å resolutions confirm the design rationale and binding to the enzymatic nucleophile. Carbasugar oligosaccharide cyclophellitols offer a powerful new approach for the design of robust endoglycosidase inhibitors, while the synthesis procedures presented here should allow adaptation towards activity-based endoglycosidase probes as well as configurational isosteres targeting other endoglycosidase families. 相似文献
75.
The dynamic surface tension (DST) and the surface viscoelastic modulus of sodium oleate aqueous solutions at different concentrations were measured using an image analysis tensiometer based on the oscillating bubble technique. The diffusion coefficient of oleate moieties was calculated from DST measurements and the surface viscoelastic modulus using the Langmuir-Szyszkowski and the diffusion-controlled adsorption models. The viscoelastic moduli obtained from model calculations were compared with the corresponding experimental values. The diffusion coefficient of C(12)(EO)(6) in water and the parameters of the Langmuir-Szyszkowski adsorption isotherm were taken from the literature and used to calculate the surface viscoelastic modulus of its aqueous solutions at different concentrations. The foaming properties of both C(12)(EO)(6) and sodium oleate solutions, viz., the foam conductance and the water volume fraction in the foam, were measured using a commercial Foamscan device. Foaming experiments with C(12)(EO)(6) and sodium oleate solutions were carried out either under static conditions; i.e., the foam conductance and the water volume fraction were measured as a function of time after the generation of a fixed volume of foam, or under dynamic conditions; i.e., the foam conductance and the water volume fraction were measured during foam formation. The variations in the foam permeability as a function of surfactant concentration were related to the viscoelastic properties of the air/water interface and to the presence of micelles in the foam films. With foams in which the water volume fraction was higher than 0.05, the foam electrical conduction could be described using a simple parallel resistor model and their conductance measurements were related to the foam water volume fraction. The results related to water drainage under static conditions were used to interpret water drainage under dynamic conditions. Preliminary conjectures on the influence of foam permeability and water volume fraction on the yield of the flotation deinking process were drawn from these results. 相似文献
76.
A. Killis J.F. Le Nest A. Gandini H. Cheradame J.P. Cohen-Addad 《Solid State Ionics》1984,14(3):231-237
Examination of the quantitative correlation between the ionic conductivity and the dynamic mechanical properties of cross-linked polyether networks filled with an inorganic salt supports the assumption that mobile ions and chains segments need the same free volume fraction for their diffusion. The spin-spin relaxation time of the different nuclei belonging either to the macromolecular chains or to the ionic species exhibits the same free volume dependence. From the study of the conductivity variations with respect to salt concentration it is concluded that its dissociation is probably complete even at relatively high concentration. 相似文献
77.
Enrico Marchetti Roland Brast Bernard Delabre Rob Donaldson Enrico Fedrigo Christoph Frank Norbert Hubin Johann Kolb Miska Le Louarn Jean-Louis Lizon Sylvain Oberti Fernando Quirs-Pacheco Roland Reiss Joana Santos Sebastien Tordo Elise Vernet Roberto Ragazzoni Carmelo Arcidiacono Paolo Bagnara Andrea Baruffolo Emiliano Diolaiti Jacopo Farinato Matteo Lombini 《Comptes Rendus Physique》2005,6(10):1118-1128
The European Southern Observatory (ESO) together with external research institutes have built a Multi-Conjugate Adaptive Optics (MCAO) Demonstrator (MAD) to perform wide field-of-view adaptive optics correction (2′ in K band). The aim of MAD is to demonstrate the on-sky feasibility of the MCAO technique and to evaluate its critical aspects in the framework of both the 2nd generation instrumentation for the Very Large Telescope (VLT) and the Overwhelmingly Large Telescope (OWL). The MAD module will be installed on the VLT to perform on-sky observations. MAD comprises two deformable mirrors and two different multi-reference wavefront sensors with natural guide stars. In this article we present the MAD design, some aspects of the MAD calibration and the first closed-loop results in the laboratory in Single Conjugated Adaptive Optics (SCAO) and Ground Layer Adaptive Optics (GLAO) configurations. To cite this article: E. Marchetti et al., C. R. Physique 6 (2005). 相似文献
78.
Dr. Francesco Fasano Dr. Jacopo Dosso Dr. C. Grazia Bezzu Dr. Mariolino Carta François Kerff Dr. Nicola Demitri Prof. Dr. Bao-Lian Su Prof. Dr. Davide Bonifazi 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(12):4124-4133
Building on the MOF approach to prepare porous materials, herein we report the engineering of porous BN-doped materials using tricarboxylic hexaarylborazine ligands, which are laterally decorated with functional groups at the full-carbon ‘inner shell’. Whilst an open porous 3D entangled structure could be obtained from the double interpenetration of two identical metal frameworks derived from the methyl substituted borazine, the chlorine-functionalised linker undergoes formation of a porous layered 2D honeycomb structure, as shown by single-crystal X-ray diffraction analysis. In this architecture, the borazine cores are rotated by 60° in alternating layers, thus generating large rhombohedral channels running perpendicular to the planes of the networks. An analogous unsubstituted full-carbon metal framework was synthesised for comparison. The resulting MOF revealed a crystalline 3D entangled porous structure, composed by three mutually interpenetrating networks, hence denser than those obtained from the borazine linkers. Their microporosity and CO2 uptake were investigated, with the porous 3D BN-MOF entangled structure exhibiting a large apparent BET specific surface area (1091 m2 g−1) and significant CO2 reversible adsorption (3.31 mmol g−1) at 1 bar and 273 K. 相似文献
79.
An improved iterative solution to solve the electrostatic problem in the polarizable continuum model
Christian Silvio Pomelli Jacopo Tomasi Vincenzo Barone 《Theoretical chemistry accounts》2001,105(6):446-451
We present a discrete iterative interpolation scheme (DIIS) to improve the convergence rate of electrostatic calculations
in the polarizable continuum model (PCM) to describe solvent effects on molecular solutes. The electrostatic calculations
may easily become the bottleneck of the calculation when the solute size is large. For large molecules iterative procedures
turn out to be computationally more convenient than matrix inversion or closure methods. The DIIS scheme is compared here
to another iterative procedure (DAMP) and to the biconjugate gradient (BCG) method. The comparisons show that DIIS leads to
a sizeable saving of computational time for the C-PCM and IEF-PCM methods (average 40%) compared to DAMP, and more than 50%
with respect to the BCG method.
Received: 5 October 2000 / Accepted: 13 November 2000 / Published online: 19 January 2001 相似文献
80.
Sgrignani Jacopo Novati Beatrice Colombo Giorgio Grazioso Giovanni 《Journal of computer-aided molecular design》2015,29(5):441-450
Journal of Computer-Aided Molecular Design - AmpC β-lactamase is a hydrolytic enzyme conferring resistance to β-lactam antibiotics in multiple Gram-negative bacteria. Therefore,... 相似文献