排序方式: 共有34条查询结果,搜索用时 46 毫秒
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Conway GD Borba DN Alper B Bartlett DV Gormezano C von Hellermann MG Maas AC Parail VV Smeulders P Zastrow KD 《Physical review letters》2000,84(7):1463-1466
Correlation of density turbulence suppression and reduced plasma transport is observed in the internal transport barrier (ITB) region of JET tokamak discharges with optimized magnetic shear. The suppression occurs in two stages. First, low frequency turbulence and ion transport are reduced across the plasma core by a toroidal velocity shear generated by intense auxiliary heating. Then with the ITB formation, high frequency turbulence and electron transport are reduced locally within the steep pressure gradient region of the ITB. 相似文献
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Direct numerical simulation (DNS) has shown that Rayleigh–Bénard convection in a fluid-saturated porous medium self-organizes into narrowly spaced plumes at (ostensibly) asymptotically high values of the Rayleigh number Ra. In this Letter a combination of DNS and upper bound theory is used to investigate the dependence of the Nusselt number Nu on the domain aspect ratio L at large Ra . A novel algorithm is introduced to solve the optimization problems arising from the upper bound analysis, allowing for the best available bounds to be extended up to Ra≈2.65×104. The dependence of the bounds on L(Ra) is explored and a “minimal flow unit” is identified. 相似文献
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Secondo Martinengo Alessandro Fumagalli Paolo Chini 《Journal of organometallic chemistry》1985,284(2):275-279
The anion [Rh6(CO)14]4? has been isolated from the reaction of [Rh6(CO)16] with alkali hydroxides in aqueous solution. It shows high reactivity towards electrophiles and in redox condensations with other rhodium clusters; and is rapidly decomposed by carbon monoxide. 相似文献
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Luigi Garlaschelli Secondo Martinengo Paolo Chini Franco Canziani Robert Bau 《Journal of organometallic chemistry》1981,213(1):379-388
1 The anions [Ir4(CO)11(COOR)- (R Me, Et) have been prepared by reacting Ir4(CO)12 with alkali alkoxides in dry alcohol and under an atmosphere of carbon monoxide. The reaction of [Ir4(CO)11(COOMe)]- with primary and secondary alcohols (EtOH, PriOH) gives rise to specific alcoholysis. The anions [Ir4(CO)11(COOR)- react with acids in THF solution to give quantitatively Ir4(CO)12. The chemical, spectroscopic and crystallographic characterization of the tetranuclear anions are reported. 相似文献
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Marian N. Aziz Arzoo Patel Amany Iskander Avisankar Chini Delphine Gout Subhrangsu S. Mandal Carl J. Lovely 《Molecules (Basel, Switzerland)》2022,27(3)
An efficient surface-mediated synthetic method to facilitate access to a novel class of thiazolidines is described. The rationale behind the design of the targeted thiazolidines was to prepare stable thiazolidine analogues and evaluate their anti-proliferative activity against a breast cancer cell line (MCF7). Most of the synthesized analogues exhibited increased potency ranging from 2–15-fold higher compared to the standard reference, cisplatin. The most active thiazolidines contain a halogenated or electron withdrawing group attached to the N-phenyl ring of exocyclic 2-imino group. However, combination of the two substituents did not enhance the activity. The anti-proliferative activity was measured in terms of IC50 values using an MTT assay. 相似文献
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Helane?MS?Costa Augusto?CV?Freitas Júnior Ian?PG?Amaral Izaura?Y?Hirata Patrícia?MG?Paiva Luiz?B?CarvalhoJr Vitor?Oliveira Ranilson?S?BezerraEmail author 《Chemistry Central journal》2013,7(1):166
Background
Over the past decades, the economic development and world population growth has led to increased for food demand. Increasing the fish production is considered one of the alternatives to meet the increased food demand, but the processing of fish leads to by-products such as skin, bones and viscera, a source of environmental contamination. Fish viscera have been reported as an important source of digestive proteases with interesting characteristics for biotechnological processes. Thus, the aim of this study was to purify and to characterize a trypsin from the processing by-products of crevalle jack (Caranx hippos) fish.Results
A 27.5 kDa trypsin with N-terminal amino acid sequence IVGGFECTPHVFAYQ was easily purified from the pyloric caeca of the crevalle jack. Its physicochemical and kinetic properties were evaluated using N-α-benzoyl-DL-arginine-p-nitroanilide (BApNA) as substrate. In addition, the effects of various metal ions and specific protease inhibitors on trypsin activity were determined. Optimum pH and temperature were 8.0 and 50°C, respectively. After incubation at 50°C for 30 min the enzyme lost only 20% of its activity. K m , kcat, and k cat /K m values using BApNA as substrate were 0.689 mM, 6.9 s-1, and 10 s-1 mM-1, respectively. High inhibition of trypsin activity was observed after incubation with Cd2+, Al3+, Zn2+, Cu2+, Pb2+, and Hg2+ at 1 mM, revealing high sensitivity of the enzyme to metal ions.Conclusions
Extraction of a thermostable trypsin from by-products of the fishery industry confirms the potential of these materials as an alternative source of these biomolecules. Furthermore, the results suggest that this trypsin-like enzyme presents interesting biotechnological properties for industrial applications.29.
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P. Chini G. Ciani L. Garlaschelli M. Manassero S. Martinengo A. Sironi F. Canziani 《Journal of organometallic chemistry》1978,152(2):C35-C38
[Ir4(CO)11X]? anions are obtained by reaction of halide and pseudo-halide ions with Ir4(CO)12. X-ray determination of the structure of [Ir4(CO)11Br]? shows that the carbonyl arrangement differs from that of the parent Ir4(CO)12, and is similar to that known for Co4(CO)12; one terminal CO group in the basal M3(CO)9 moiety is replaced by the bromide ligand, and two of the bridging CO groups become markedly asymmetric. 相似文献