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排序方式: 共有249条查询结果,搜索用时 46 毫秒
51.
Asmaa Abdella Ashraf F. El-Baz Ibrahim A. Ibrahim Emad Eldin Mahrous Shang-Tian Yang 《Natural product research》2018,32(20):2382-2391
β-glucosidase enzyme produced from Aspergillus niger NRRL 3122 has been partially purified and characterised. Its molecular weight was 180 KDa. The optimal pH and temperature were 3.98 and 55 °C, respectively. It promoted the hydrolysis of soy flour isoflavone glycosides to their aglycone. Two-level Plackett–Burman design was applied and effective variables for genistein production were determined. Reaction time had a significant positive effect, and pH had a significant negative effect. They were further evaluated using Box–Behnken model. Accordingly, the optimal combination of the major reaction affecting factors was reaction time, 5 h and pH, 4. The concentration of genistein increased by 11.73 folds using this optimal combination. The antioxidant activity of the non-biotransformed and biotransformed soy flour extracts was determined by DPPH method. It was found that biotransformation increased the antioxidant activity by four folds. 相似文献
52.
Weldon F Hammarström L Mukhtar E Hage R Gunneweg E Haasnoot JG Reedijk J Browne WR Guckian AL Vos JG 《Inorganic chemistry》2004,43(14):4471-4481
A series of homo- and heteronuclear ruthenium and osmium polypyridyl complexes with the bridging ligands 1,3-bis(5-(2-pyridyl)-1H-1,2,4-triazol-3-yl)benzene (H(2)mL) and 1,4-bis(5-(2-pyridyl)-1H-1,2,4-triazol-3-yl)benzene (H(2)pL) are reported. The photophysical properties of these compounds are investigated, and particular attention is paid to the heteronuclear (RuOs) compounds, which exhibit dual emission. This is in contrast to phenyl-bridged polypyridine Ru-Os complexes with a similar metal-metal distance, in which the Ru emission is strongly quenched because the nature of the bridging ligand allows for an efficient through-bond coupling. The results obtained for the compounds reported here suggest that energy transfer is predominantly taking place via a dipole-dipole, F?rster type, mechanism, that may dominate when through-bond coupling is weak. This is in stark contrast to ground state interaction, which is found to be critically dependent on the nature of the bridging unit employed. 相似文献
53.
The inexpensive natural phosphate, both alone and doped with potassium fluoride, is a new basic catalyst for the synthesis of α,β-unsaturated arylsulfones. Activation by water and benzyltriethylammonium chloride has also been investigated. When using an ammonium salt, natural phosphate doped with potassium fluoride is an excellent solid support for the synthesis of α,β-unsaturated arylsulfones, leading to excellent yields in a few minutes. 相似文献
54.
A modified front‐tracking method was proposed for the simulation of fluid‐flexible body interactions with large deformations. A large deformable body was modeled by restructuring the body using a grid adaptation. Discontinuities in the viscosity at the fluid‐structure interface were incorporated by distributing the viscosity across the interface using an indicator function. A viscosity gradient field was created near the interface, and a smooth transition occurred between the structure and the fluid. The fluid motion was defined on the Eulerian domain and was solved using the fractional step method on a staggered Cartesian grid system. The solid motion was described by Lagrangian variables and was solved by the finite element method on an unstructured triangular mesh. The fluid motion and the structure motion were independently solved, and their interaction force was calculated using a feedback law. The interaction force was the restoring force of a stiff spring with damping, and spread from the Lagrangian coordinates to the Eulerian grid by a smoothed approximation of the Dirac delta function. In the numerical simulations, we validated the effect of the grid adaptation on the solid solver using a vibrating circular ring. The effects of the viscosity gradient field were verified by solving the deformation of a circular disk in a linear shear flow, including an elastic ring moving through a channel with constriction, deformation of a suspended catenary, and a swimming jellyfish. A comparison of the numerical results with the theoretical solutions was presented. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
55.
Nonlinear Dynamics - The nonlinear dynamics of the six-pole rotor active magnetic bearings system is studied in this article for the first time. Two control configurations based on a... 相似文献
56.
Dr. Edlira Suljoti Raul Garcia‐Diez Dr. Sergey I. Bokarev Dr. Kathrin M. Lange Roland Schoch Brian Dierker Marcus Dantz Kenji Yamamoto Nicholas Engel Dr. Kaan Atak Prof. Dr. Oliver Kühn Prof. Dr. Matthias Bauer Prof. Dr. Jan‐Erik Rubensson Prof. Dr. Emad F. Aziz 《Angewandte Chemie (International ed. in English)》2013,52(37):9841-9844
57.
Research on Chemical Intermediates - The electrochemical reduction of S-phenyl benzenethiosulfonate (1) was investigated by cyclic voltammetry at different scan rates (0.1–60 V/s)... 相似文献
58.
Niklas Ottosson Emad F. Aziz Ioana L. Bradeanu Sbastien Legendre Gunnar
hrwall Svante Svensson Olle Bjrneholm Wolfgang Eberhardt 《Chemical physics letters》2008,460(4-6):540-542
Formaldehyde in aqueous solution is hydrolysed and forms methanediol. Using X-ray absorption spectroscopy we show that the hydrolysation product can be identified by a distinct electronic signature in the spectra. This is manifested by the disappearance of the oxygen 1s → π* absorption line. The X-ray absorption spectrum of aqueous formaldehyde is compared with those of the structurally similar formamide and urea, which are in contrast not hydrolysed in aqueous solution. We thereby demonstrate the exceptional sensitivity and simplicity of the technique to monitor this fundamental process in the aqueous phase. 相似文献
59.
Abu Elella Mahmoud H. Abdallah Heba M. Gamal Heba Moustafa Essam B. Goda Emad S. 《Cellulose (London, England)》2022,29(13):7317-7330
Cellulose - Antimicrobial hydrogels have enticed a major concern for repairing soft tissues, particularly prohibiting bacterial infections that are frequently accompanied by impaired wound healing.... 相似文献
60.
Much progress has been made in the research of synchronization for chaotic real or complex nonlinear systems. In this paper we introduce a new type of synchronization which can be studied only for chaotic complex nonlinear systems. This type of synchronization may be called complex lag synchronization (CLS). A definition of CLS is introduced and investigated for two identical chaotic complex nonlinear systems. Based on Lyapunov function a scheme is designed to achieve CLS of chaotic attractors of these systems. The effectiveness of the obtained results is illustrated by a simulation example. Numerical results are plotted to show state variables, modulus errors and phase errors of these chaotic attractors after synchronization to prove that CLS is achieved. 相似文献