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排序方式: 共有187条查询结果,搜索用时 93 毫秒
61.
Ion Nistor 《International Journal of Non》2002,37(3):565-569
Two variational principles are derived for the mixed boundary value problem of Cosserat solid. These principles are a generalization of the stationary principle of potential energy and the stationary principle of complementary energy from non-linear theory of elasticity. 相似文献
62.
Dan Donescu Raluca Somoghi Catalin Ilie Spataru Doina Manaila-Maximean Denis Mihaela Panaitescu Eugeniu Vasile Cristina L. Nistor 《Colloid and polymer science》2013,291(10):2345-2358
The work describes a study for preparing polystyrene (PSt) and polymethyl methacrylate (PMMA) latex, containing magnetite (Fe3O4), covalently bounded to the polymeric chains. The magnetite was functionalized with various alkoxysilanes containing double bonds: vinyltriethoxysilane (VTES), methacryloyl propyl trimethoxysilane (MPTS) and vinyldimethylethoxysilane (VMe2TES). The ferrite-silane composite forms higher average size particles with MPTS than with VTES. Ferrite functionalized with VMe2TES forms stable latexes with both PSt and PMMA polymers. PSt forms also stable latexes with ferrite functionalized with VTES but unstable with ferrite functionalized with MPTS. 相似文献
63.
Silviu Jipa Radu Setnescu Tanta Setnescu Madalina Dumitru Ion Mihalcea Cornel Podina 《高分子科学杂志,A辑:纯化学与应用化学》2013,50(7):1103-1115
Abstract The protecting effect against radiation induced oxidation of poly-ethylene provided by several additives, namely pyrene, Irganox 1222 and Irganox 1010 has been investigated by mean of FTIR spectroscopy and chemiluminescence (CL) technique. Pyrene appears to be more effective and more stable to irradiation than phenolic antioxidants. Thus, about half of initial pyrene seems to remain unchanged after an exposure of the material to γ60Co rays at 240 kGy (dose rate 1 kGy/h) in presence of air. Under the same conditions, about 90% of initial Irganox 1010 seems to be consumed as indicate a comparison of induction oxidation times of initial and irradiated material. The stabilizing effect of the residues resulted by pyrolysis at 850°C in inert atmosphere of several polymers, such as polyacrylonitrile, polyvinylchloride and methyl cellulose is discussed as well. 相似文献
64.
Ioana Dorina Vlaicu Madalina Constand Rodica Olar Dana Marinescu Maria Nicoleta Grecu Veronica Lazar Mariana Carmen Chifiriuc Mihaela Badea 《Journal of Thermal Analysis and Calorimetry》2013,113(3):1369-1377
Three new coordinative compounds that contain mixed ligands (5,6-dimethylbenzimidazole and acrylato anion) were synthesized and characterized. The features of complexes have been assigned from microanalytical, IR, UV–Vis and EPR spectra as well as thermal analysis. IR data are in accordance with unidentate nature of 5,6-dimethylbenzimidazole while the acrilato ion acts as uni- or bidentate ligand. The electronic spectra display the characteristic pattern of square pyramidal or octahedral stereochemistry, which were confirmed by the EPR spectra. Antibacterial and antifungal activities of the complexes have been determined in vitro, against various Gram-negative and Gram-positive bacteria and fungi. The tested complexes exhibited different spectra of antimicrobial activity and inhibited the microbial ability to colonize the inert surfaces, acting as potential anti-adherence and biofilm-controlling agents. Thermal decomposition evidenced several well-defined steps as dehydration (complex 2), 5,6-dimethylbenzimidazole molecule release (all complexes) and the acrylate decomposition in carbonate (complex 3). The final residue is in all cases copper (II) oxide. 相似文献
65.
In the present study, a novel mixture consisting of N,N′‐bis(salicylidene)‐1,2‐phenylenediamino cobalt (CoSalophen, CoSal) complex and (n‐butyl)4SiW12O40 (SiW12), have been used to chemically modify a carbon paste electrode (CPE) for sensitive determination of cysteine (CySH). The electrocatalytic effect of the newly developed modified CPE towards oxidation of CySH was evaluated by comparing cyclic and differential pulse voltammograms in the presence of cysteine at bare, CoSal, SiW12 and CoSal/SiW12 modified CPE. The differential pulse voltammetry method was applied as a sensitive method for quantitative detection of CySH trace amounts, the experimental conditions being optimized in order to evaluate the best analytical parameters of the sensor. Reproducibility and stability studies were also performed and the sensor was applied for the determination of CySH in a pharmaceutical sample and in human blood serum and urine samples. 相似文献
66.
Jeremy P Wilburn Madalina Ciobanu Nicholas I Buss Daniel A Lowy 《Analytica chimica acta》2004,511(1):83-89
Stable reference electrodes have previously been obtained by immersion of a stainless steel internal reference element (SSIRE) in a solution of steady pH, e.g., a stainless steel wire maintained in 2 mol/l HCl. Here, we report the miniaturization of this regular size reference half-cell by embedding thermally activated SSIREs in a copolymer matrix of a fixed and constant pH value. The resulting electrode is based on a polymer volume of 1-5 μl, while its contact area at the polymer/analyte solution interface is 0.4 mm2. Photopolymerized acrylic type hydrogel is used as the copolymer which contains a quaternary ammonium salt as the supporting electrolyte. These miniaturized reference electrodes show potential stability over the pH range of 1-13, maintain a constant potential value over the time, and are suitable for potentiometric and voltammetric measurements in both aqueous and organic media. Furthermore, they do not exhibit leakage problems. Hence, they do not contaminate the analytical sample, even when the reference electrodes (REs) are used in very small volumes and over extended period. 相似文献
67.
We extend Connes's computation of the cyclic cohomology groups of smooth algebras arising from foliations with separated graphs. We find that the characteristic classes of foliations factor through these groups. Our results also explain some results of Atiyah and Segal on orbifold Euler characteristic in the setting of cyclic homology.Partially supported by NSF grants DMS 92-03517 and DMS 89-03248.Partially supported by NSF grant DMS 92-05548. 相似文献
68.
E. Cojocaru N. Comaniciu L. N. Mihailescu L. Nanu L. C. Nistor V. Teodorescu 《Applied Physics A: Materials Science & Processing》1981,26(4):243-246
An analytical treatment of the thermal phenomena during free-running ruby laser annealing of boron implanted silicon is presented. The heat equation was solved for a simplified shape of the pulse train consisting of a uniform succession of triangular spikes, identical in energy. During one spike the optical and thermal parameters of the sample were taken constant, but for each new spike, new values of these parameters were calculated taking into account their temperature dependence. Such a model predicts the melting of the top surface before the laser pulse has ended, for energy densities higher than 9×104 J/m2. RHEED confirms the presence of recristallization at about the same value of the laser-pulse energy densities. 相似文献
69.
We have developed a multiwalled carbon nanotube/dihydropyran (MWCNT/DHP) composite sensor for the electrochemical detection of insulin in a microfluidic device. This sensor has been employed for physiological measurements of secreted insulin from pancreatic islets in a Cytosensor® previously modified to be a multianalyte microphysiometer (MAMP). When compared with other established electrochemical insulin sensors, the MWCNT/DHP composite film sensor presented improved resistance to fluidic shear forces, while achieving enhanced electrode kinetics. In addition, the preparation of the composite film is straightforward and facile with a self-polymerizing monomer, DHP, used to add mechanical stability to the film. The sensor film was able to detect insulin concentrations as low as 1 μM in the MAMP during calibration experiments. The MWCNT/DHP composite sensor has been successfully used for the direct detection of insulin secreted by islets in the microphysiometer. 相似文献
70.
Hosu Oana Barsan Madalina M. Cristea Cecilia Săndulescu Robert Brett Christopher M. A. 《Mikrochimica acta》2017,184(10):3919-3927
Microchimica Acta - The redox polymer poly(methylene blue) was synthesized by electropolymerization in ethaline deep eutectic solvent (PMBDES), and employed in a new nanostructured composite... 相似文献