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41.
The metal-catalyzed stereoselective 1,3-dipolar cycloaddition of azomethine ylides and acrylates using recyclable meso-hydrobenzoin-derived chiral auxiliaries is described. Cleavage of the auxiliary leads to highly substituted pyrrolidines in up to 87% enantiomeric excess. 相似文献
42.
Alexandru Mihai Bica 《Numerical Algorithms》2011,58(3):351-377
A new numerical method for Fredholm functional integral equations is proposed. The method combines the fixed point technique
with numerical integration and cubic spline interpolation. The convergence and the numerical stability of the method are proved
and tested on some numerical examples. 相似文献
43.
Magnetorheological (MR) elastomer was prepared using silicone rubber and soft magnetic carbonyl iron microspheres, and then examined as dielectric materials for manufacturing electric capacitors. As a specific element, capacity of the capacitors located in a magnetic field was found to be sensitive to both the MR suspension proportion to the silicone rubber and the intensity of the applied magnetic field. Viscoelastic characteristics of the MR elastomer, represented by storage modulus and creep behavior, were also studied. 相似文献
44.
Bica K Gärtner P Gritsch PJ Ressmann AK Schröder C Zirbs R 《Chemical communications (Cambridge, England)》2012,48(41):5013-5015
We present the application of ionic liquid-aqueous micellar solutions as reaction media for Diels-Alder reaction and found that reaction rates could be significantly increased compared to the reaction in water. 相似文献
45.
Viorel Cîrcu Ana S. Mocanu Constantin Roşu Doina Manaila-Maximean Florea Dumitraşcu 《Journal of Thermal Analysis and Calorimetry》2012,107(3):877-886
A series of ortho-metallated palladium(II) complexes with two dimeric liquid crystals Schiff base (methoxy and decyloxy as terminal groups)
as cyclometallated ligands and N-aryl-N′-benzoyl thiourea derivatives as co-ligands were prepared and investigated for their liquid crystalline properties. Their
structures were assigned based on elemental analysis, FT-IR and 1H NMR spectroscopy while the thermal behaviour was investigated by differential scanning calorimetry and polarising optical
microscopy. The complexes with Schiff base ligand bearing methoxy group as terminal group show extensive decomposition during
melting while the complexes with Schiff base having decyloxy group as terminal group show monotropic nematic phases, with
the mesophase stability strongly related to the type of N-aryl-N′-benzoyl thiourea derivative used. Their liquid crystalline properties are compared with their analogues having N,N-dialkyl-N′-benzoyl thiourea as co-ligands which were reported previously. One of the latter complexes was also investigated by thermally
stimulated depolarisation currents method while the optical transmission was recorded simultaneously. The thermally stimulated
depolarisation currents and optical transmission spectra confirmed the previous observation regarding the phase transition
temperatures. The current intensity–applied voltage dependencies of this complex were investigated by specific electrical
measurements. 相似文献
46.
Four (P,N)-ligands (1-4) with different steric and electronic properties were synthesized. They were used to prepare the monocationic palladium complexes [Pd(P,N)(CH3)(NCCH3)](PF6) (9-12). The structures of the newly prepared ligand 3 and the neutral palladium complex [Pd(P,N)(CH3)Cl] (10) were analysed by X-ray. The catalytic activity of the palladium complexes toward the copolymerization of styrene and ethylene with CO was low or non-existent. The nickel complexes [Ni(P,N)(1-naphthyl)Cl] (13-16), modified with the ligands 1-4, were prepared and their catalytic activity toward ethylene oligomerization was studied. They showed high activity at ambient temperature and low ethylene pressure (1-12 bar) in the presence of MAO. 相似文献
47.
The surface photoelectric effect and the surface plasmon resonances appear when a p/transverse magnetic polarized laser hits a gas-solid interface. We model this effect in the long wave length (LWL) domain (λvac > 10 nm, ?ω < 124 eV) by combining the Ampère-Maxwell equation, written in classical approximation, with the material equation for the susceptibility. The resulting model, called the vector potential from the electron density (VPED), calculates the susceptibility as a product of the bulk susceptibility and the electron density of the actual system. The bulk susceptibility is a sum of the bound electron scalar susceptibility taken from the experiment and of the conduction electron non-local isotropic susceptibility tensor in a jellium metal (Lindhard, 1954 [1]). The electron density is the square of the wave function solution of the Schrödinger equation. The analysis of observables, the reflectance R and the photoelectron yield Y as well as the induced charge density permits to identify and characterize the multipole surface plasmon resonance of Al(111) appearing at ωm ∼ 0.8ωp or 11-12 eV. 相似文献
48.
On the magnetic structure of magnetite/oleic acid/benzene ferrofluids by small-angle neutron scattering 总被引:1,自引:0,他引:1
M. V. Avdeev M. Balasoiu V. L. Aksenov V. M. Garamus J. Kohlbrecher D. Bica L. Vekas 《Journal of magnetism and magnetic materials》2004,270(3):371-379
Magnetic small-angle scattering of non-polarized and polarized neutrons from ferrofluds (magnetite covered by oleic acid in benzene) is analyzed. A complex correlation in the magnetic structure is observed. It takes place at the length of more than the particle size, and has a core-shell-like organization. Along with it no spatial interparticle correlation in the nuclear structure is detected. 相似文献
49.
Doina Humelnicu Catalin Blegescu Dumitru Ganju 《Journal of Radioanalytical and Nuclear Chemistry》2014,299(3):1183-1190
Adsorption behavior of uranyl and thorium ions from synthetic radioactive solutions onto functionalized silica as sorbent has been investigated. The effect of contact time, initial concentration of radioactive solutions, sorbent mass, pH value and temperature on the adsorption capacity of the sorbent was investigated. Negative values of Gibbs free energy of adsorption suggested the spontaneity of the adsorption process on both functionalized silica with –NH2 groups and with –SH groups. Positive values obtained for ΔH° indicates that the adsorption is an endothermic process. The adsorption isotherms were better fitted by Freundlich model and the adsorption kinetic was well described by the pseudo-second order equation. Desorption studies indicated that the most favorable desorptive reagents for UO2 2+ is HNO3 1 M and for Th4+ is EDTA 1 M solutions. 相似文献
50.
In this paper a class of solutions of KP is discussed. Theory of these solutions, referred to here as breathers, is developed and it is shown that a subclass of these solutions can be used to construct more general solutions of KP similarly to how the functions ei(λx+νy) are used to perform the same task in the theory of Fourier transform. Nonlinear superposition formula for general solutions of KP similar to the Fourier expansion formula is considered. 相似文献