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排序方式: 共有785条查询结果,搜索用时 31 毫秒
741.
Saleta Vazquez‐Rodriguez Miranda Wright Catherine M. Rogers Adam P. Cribbs Srikannathasan Velupillai Martin Philpott Henry Lee James E. Dunford Kilian V. M. Huber Matthew B. Robers James D. Vasta Marie‐Laetitia Thezenas Sarah Bonham Benedikt Kessler James Bennett Oleg Fedorov Florence Raynaud Adam Donovan Julian Blagg Vassilios Bavetsias Udo Oppermann Chas Bountra Akane Kawamura Paul E. Brennan 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(2):525-529
742.
Soraru Gian Domenico Babonneau Florence Gervais Christel Dallabona Nicola 《Journal of Sol-Gel Science and Technology》2000,18(1):11-19
A new sol-gel route, without any external water addition, for the preparation of hybrid RSiO1.5/B2O3 gels (R = Me, Et, Vi) is reported. The gels are easily synthesized by reacting B(OH)3 with the liquid silicon alkoxide. The gels have been characterized mainly by FT-IR and 11B MAS NMR spectroscopy. The results show that this new sol-gel process allows the formation of a homogeneous borosilicate gel in which trigonal BO3 units are incorporated into the siloxane network via B—O—Si bonds. 相似文献
743.
Léger C Lederer F Guigliarelli B Bertrand P 《Journal of the American Chemical Society》2006,128(1):180-187
In protein film voltammetry, a redox enzyme is directly connected to an electrode; in the presence of substrate and when the driving force provided by the electrode is appropriate, a current flow reveals the steady-state turnover. We show that, in the case of a multicenter enzyme, this signal reports on the energetics and kinetics of electron transfer (ET) along the redox chain that wires the active site to the electrode, and this provides a new strategy for studying intramolecular ET. We propose a model which takes into account all the enzyme's redox microstates, and we prove it useful to interpret data for various enzymes. Several general ideas emerge from this analysis. Considering the reversibility of ET is a requirement: the usual picture, where ET is depicted as a series of irreversible steps, is oversimplified and lacks the important features that we emphasize. We give justification to the concept of apparent reduction potential on the time scale of turnover and we explain how the value of this potential relates to the thermodynamic and kinetic properties of the system. When intramolecular ET does not limit turnover, the redox chain merely mediates the driving force provided by the electrode or the soluble redox partner, whereas when intramolecular ET is slow, the enzyme behaves as if its active active site had apparent redox properties which depend on the reduction potentials of the relays. This suggests an alternative to the idea that redox chains are optimized in terms of speed: evolutionary pressure may have resulted in slowing down intramolecular ET in order to tune the enzyme's "operating potential". 相似文献
744.
745.
Stability of [Ru(II)(tpy)(bpy)(OH(2))](2+)-modified graphite electrodes during indirect electrolyses
The stability of a graphite felt electrode modified by covalent attachment of [Ru(II)(tpy)(bpy)(OH(2))](2+) is investigated during the indirect electrolyses of alcohols in a flow cell. The continuous increase of the local potential of the electrode during the electrolyses attests to its degradation. Cyclic voltammetry analyses of the modified electrode after electrolyses show a total decrease of 80-90% of the wave corresponding to the Ru(III/II) couple. The concentration of remaining alcohol measured at the outlet of the cell is almost constant during all the electrolyses but increase when the potential exceeds 0.95 V(SCE). At low potentials, the electrode can be regenerated by reaction with Ru(II)Cl(2)(DMSO)(tpy) and then CF(3)SO(3)H, followed by hydrolysis, showing that the bipyridine ligand remains covalently attached to the electrode. At high potentials, the graphite is oxidized and the catalyst is partly lost in the reaction medium. XPS analyses of Ru core levels reveal that the ruthenium disappeared after electrolysis, showing that the degradation of the modified electrode is due to the demetalation of the oxidized complex. 相似文献
746.
We present a straightforward and high yielding method to synthesize constrained helical peptides via thioether ligation; this method represents an attractive alternative to the formation of lactam bridge constraints to induce helicity in peptides. 相似文献
747.
748.
New amphiphilic cyclodextrins fully substituted with sugar residues on the primary face have been synthesised and enzymatically modified. 相似文献
749.
Dickie AJ Quist F Whitehead MA Kakkar AK 《Langmuir : the ACS journal of surfaces and colloids》2004,20(11):4315-4317
A serial templating methodology using linked aminosilane/stannane units and simple beaker chemistry yields thin film nanoassemblies on semiconductor surfaces that provide nucleating sites for crystallization of octadecanol, the morphologies of which could be tailored using subtle variations in the backbone structure of bridged aminosilane/stannanes. 相似文献
750.
Vanholsbeeck F Coen S Emplit P Martinelli C Leplingard F Sylvestre T 《Optics letters》2004,29(23):2719-2721
We present a new numerical model of cascaded Raman fiber lasers that takes into account the chromatic dispersion of the fiber and includes the full spectrum of the intracavity field. This model explains and describes remarkably well a new operating regime found experimentally and reveals that chromatic dispersion is truly a new degree of freedom in the design of cascaded Raman lasers. 相似文献