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71.
The kinetic study of the efficient regioselective oxidation of the C? C double bond of 4‐methylcoumarins with isolated dimethyldioxirane was investigated using UV–vis spectroscopy methods. In the excess of dimethyldioxirane, the pyrone ring of a coumarin skeleton is selectively epoxidated and hydroxylated in neutral media, in high yields. Kinetic analyses demonstrate two independent reaction pathways, epoxidation and hydroxylation, respectively, which was also confirmed using kinetic isotope effect methods. Both reaction products were isolated, and their structures were determined by NMR and mass spectra. The position of methyl groups attached at the aromatic part of coumarin molecule shows significant influence on kinetic rate constants and activation parameters. © 2009 Wiley Periodicals, Inc. Int J Chem Kinet 41: 414–420, 2009 相似文献
72.
E. Marušic-Paloka 《Applied Mathematics and Optimization》2000,41(3):365-375
We prove the existence of the very weak solution of the Dirichlet problem for the Navier—Stokes system with L
2
boundary data. Under the small data assumption we also prove the uniqueness. We use the penalization method to study the linearized problem and then apply Banach's fixed
point theorem for the nonlinear problem with small boundary data. We extend our result to the case with no small data assumption by splitting the data on a large regular and small irregular part.
Accepted 15 March 1999 相似文献
73.
Sanja Frka Zlatica Kozarac 《International journal of environmental analytical chemistry》2013,93(5):325-335
The objective of this work was to develop electrochemical impedance spectroscopy (EIS) to characterise the physical properties of the sea surface microlayer ( ssm ). Samples from Lake Rogoznica in Croatia were extracted by n-hexane and dichloromethane (dcm) respectively and transferred to mercury electrodes. The EIS results were compared with those of a model phospholipid, dioleoyl phosphatidylcholine (DOPC) which forms near defect-free monolayers on a mercury surface. The ssm extracts formed inhomogeneous monolayers on the mercury surface and the dcm ssm extract monolayer showed greater surface roughness than the hexane ssm extract. The hexane ssm extract introduced defects and a greater surface roughness into mixed DOPC- ssm extract monolayers than the dcm ssm extract due to the lower compatibility of the non-polar hexane extract with the DOPC than that of the polar ssm extract. In addition, the dcm ssm component in the mixed DOPC- ssm monolayer showed an association with pyrene added to the solution. 相似文献
74.
Pajić Mila N. Krstajić Stevanović Sanja I. Radmilović Vuk V. Rogan Jelena R. Radmilović Velimir R. Gojković Snežana Lj. Jovanović Vladislava M. 《Journal of Solid State Electrochemistry》2016,20(12):3405-3414
Journal of Solid State Electrochemistry - Pt nanoparticles supported on Vulcan XC-72R were synthesized by water-in-oil microemulsion method. By incorporating different amounts of HCl as a capping... 相似文献
75.
Alain Bourgeat Olivier Gipouloux Eduard Marušić-Paloka 《Comptes Rendus Mecanique》2002,330(5):371-376
We consider a mathematical model describing the behavior of an underground waste repository, once the containers start to leak. Due to the high contrast of the characteristic lengths, numerical simulations on a such model are unrealistic. After renormalization, a small parameter ε appears and the global model is obtained when ε tends to zero, by means of homogenization and boundary layers methods. The asymptotic model obtained could be used as a global repository model for large field numerical simulations. To cite this article: A. Bourgeat et al., C. R. Mecanique 330 (2002) 371–376. 相似文献
76.
We propose a fiber-optic non-mechanical scanning laser Doppler velocimeter (LDV) with directional discrimination of the velocity component using a single transmission path. The LDV uses a polarization maintaining fiber (PMF) as the transmission path between the main body and probe. Two beams with different frequencies induced by acousto-optic modulators (AOMs) are transmitted to the probe as two orthogonal polarization modes of the PMF. The measurement position is axially scanned using gratings in the probe and the change in wavelength. The functions of the scan and directional discrimination are demonstrated experimentally. 相似文献
77.
78.
Djordjevic Jasmina Konjik Sanja Mitrović Darko Novak Andrej 《Journal of Optimization Theory and Applications》2021,190(1):316-338
Journal of Optimization Theory and Applications - We consider exact and averaged control problem for a system of quasilinear ODEs and SDEs with a nonnegative definite symmetric matrix of the... 相似文献
79.
Bo?idar Ivankovi? Josip Pe?ari? Sanja Varo?anec 《Mediterranean Journal of Mathematics》2011,8(4):543-551
In this paper we obtain properties of several mappings which are arisen from the Minkowski inequality. We investigate superadditivity
(subadditivity) and monotonicity of those functions, and give some refinements of the Minkowski inequality and the H?lder
inequality. 相似文献
80.
Jacobian smoothing Brown’s method for nonlinear complementarity problems (NCP) is studied in this paper. This method is a generalization of classical Brown’s method. It belongs to the class of Jacobian smoothing methods for solving semismooth equations. Local convergence of the proposed method is proved in the case of a strictly complementary solution of NCP. Furthermore, a locally convergent hybrid method for general NCP is introduced. Some numerical experiments are also presented. 相似文献