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141.
An efficient synthesis of o-nitrobenzylcarbonyl compounds is demonstrated through the Swern-type oxidation of readily accessible phenethanol analogues. Reductive cyclization of o-nitrobenzylcarbonyl 3 using catalytic Raney nickel gives 1H-indol-2-yl-1H-quinoline 2 in 95% yield. Hydrolysis of 2 affords the KDR kinase inhibitor 1 in quantitative yield. The examination of the reductive cyclization reaction and optimization of conditions is described. 相似文献
142.
Halliwell CM Davies JA Gallop JC Josephs-Franks PW 《Bioelectrochemistry (Amsterdam, Netherlands)》2004,63(1-2):225-228
A mutant (K27C) of the blue copper protein azurin [Eur. J. Biochem. 194 (1990) 109; J. Mol. Biol. 221 (1991) 765] for orientated immobilisation on gold surfaces was analysed by scanning tunnelling microscopy (STM) both in a resting state and following the application of a short potential pulse between the tip and sample. 相似文献
143.
Barkan A Tittel FK Mittleman DM Dengler R Siegel PH Scalari G Ajili L Faist J Beere HE Linfield EH Davies AG Ritchie DA 《Optics letters》2004,29(6):575-577
We have measured the spectral linewidths of three continuous-wave quantum cascade lasers operating at terahertz frequencies by heterodyning the free-running quantum cascade laser with two far-infrared gas lasers. Beat notes are detected with a GaAs diode mixer and a microwave spectrum analyzer, permitting very precise frequency measurements and giving instantaneous linewidths of less than -30 kHz. Characteristics are also reported for frequency tuning as the injection current is varied. 相似文献
144.
R.?J.?Davies N.?E.?ZafeiropoulosEmail author K.?Schneider S.?V.?Roth M.?Burghammer C.?Riekel J.?C.?Kotek M.?Stamm 《Colloid and polymer science》2004,282(8):854-866
The mechanical behaviour of semi-crystalline polymers is greatly influenced by the properties of the crystalline and the amorphous phases. As a result this topic has been the subject of extensive research. However, to date, a comprehensive relationship between the structure and mechanical properties for semi-crystalline polymers has yet to be established. This present study concerns the commissioning of a novel method for in situ data collection during the deformation of polymers. This involves the combination of three different techniques into a single experiment, namely tensile testing, synchrotron radiation wide angle X-ray scattering, and optical microscopy. For this current investigation, three isotactic polypropylene samples have been studied, produced using different thermal treatments. This enables the influence of thermal treatment on the mechanical properties and crystallographic structure to be assessed. The results indicate that tensile properties are influenced by thermal treatment via the relative fraction of -phase material in the sample. As the temperature increases at which thermal treatment takes place, iPP ductility decreases due to the greater rigidity of the increasing -phase content. Differences in crystal strain between the different iPP crystal phases are also observed although the reasons for such differences remain unclear. 相似文献
145.
Banks CE Moore RR Davies TJ Compton RG 《Chemical communications (Cambridge, England)》2004,(16):1804-1805
The basis of the electrocatalytic nature of multi-wall carbon nanotubes is suggested to reside in electron transfer from the ends of nanotubes, which structurally resemble the behaviour of edge plane (as opposed to basal plane) graphite, and is demonstrated via the comparison of the electrochemical oxidation of epinephrine and the electrochemical reduction of ferricyanide at nanotube-modified electrodes using different types of graphite electrodes and with C(60)-modified electrodes. 相似文献
146.
Köhler R Tredicucci A Beltram F Beere HE Linfield EH Davies AG Ritchie DA 《Optics letters》2003,28(10):810-812
Chirped-superlattice quantum-cascade lasers are reported that emit at lambda approximately 85 microm (3.6 THz), which is to the authors' knowledge the longest wavelength demonstrated so far with this technology. Collected peak output powers of 1.5 mW per facet were measured at liquid-helium temperature, and a maximum operating temperature of 45 K was reached. Record low-threshold-current densities of 95 and 115 A cm(-2) were observed in pulsed and continuous-wave operation, respectively. For the latter, output powers of a few hundred microwatts are estimated at low temperatures. 相似文献
147.
148.
A general method for the formation of N-hydroxyindoles is demonstrated through a lead-promoted intramolecular reductive cyclization of o-nitrobenzyl ketones and aldehydes under transfer hydrogenation conditions. The N-hydroxyindoles are isolated in high purity and excellent yield (>90%) in an operationally simple procedure. This new method is exemplified by a two-step synthesis of the naturally occurring 1-methoxyindole-3-carboxaldehyde, which is pivotal in many alkaloid total syntheses. 相似文献
149.
Palladium catalysed cyclisation-carbonylation of enynes to give cyclic gamma,delta-unsaturated acids
In the presence of acetic acid, trifurylphosphine and CO (2 atm), palladium catalyses the conversion of a range of enynes to cyclic delta,gamma-unsaturated carboxylic acids in good yield. 相似文献
150.
Myeloperoxidase released from activated phagocytes reacts with H(2)O(2) in the presence of chloride ions to give hypochlorous acid. This oxidant has been implicated in the fragmentation of glycosaminoglycans, such as hyaluronan and chondroitin sulfates. In this study it is shown that reaction of HOCl with glycosaminoglycans and model compounds yields chloramides derived from the N-acetyl function of the glycosamine rings. The results of EPR spin trapping and product studies are consistent with the formation of amidyl radicals from these chloramides via both metal ion-dependent and -independent processes. In the case of glycosaminoglycan-derived amidyl radicals, evidence has been obtained in studies with model glycosides that these radicals undergo rapid intramolecular abstraction reactions to give carbon-centered radicals at C-2 on the N-acetyl glycosamine rings (via a 1,2-hydrogen atom shift) and at C-4 on the neighboring uronic acid residues (via 1,5-hydrogen atom shifts). The C-4 carbon-centered radicals, and analogous species derived from model glycosides, undergo pH-independent beta-scission reactions that result in glycosidic bond cleavage. With N-acetyl glucosamine C-1 alkyl glycosides, product formation via this mechanism is near quantitative with respect to chloramide loss. Analogous reactions with the glycosaminoglycans result in selective fragmentation at disaccharide intervals, as evidenced by the formation of "ladders" on gels; this selectivity is less marked under atmospheric oxygen concentrations than under anoxic conditions, due to competing peroxyl radical reactions. As the extracellular matrix plays a key role in mediating cell adhesion, growth, activation, and signaling, such HOCl-mediated glycosaminoglycan fragmentation may play a key role in disease progression and resolution, with the resulting fragments modulating the magnitude and quality of the immune response in inflammatory conditions. 相似文献