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排序方式: 共有3059条查询结果,搜索用时 15 毫秒
1.
Marcia Cristina Kaezer Fran a Rosane Aguiar da Silva San Gil Jean-Guillaume Eon 《Catalysis Today》2003,78(1-4):105-115
γ-Al2O3 supported vanadium oxides were modified by tungsten and molybdenum oxides in order to improve dispersion and selectivity towards olefins in propane oxidative dehydrogenation (ODH). Both vanadium–tungsten and vanadium–molybdenum catalysts were obtained by adsorption of mixed isopolyanions (VW5O195−, V2W4O194−, VMo5O195− and V2Mo4O194−) from aqueous solutions. The isopolyanion solutions were characterized by UV-Vis and 51V NMR spectroscopy. Vanadium, vanadium–tungsten and vanadium–molybdenum precursors and catalysts were also characterized by UV-Vis (diffuse reflectance) and solid state 51V NMR spectroscopy. An improved selectivity to propene in the presence of tungsten and molybdenum in VOx/γ-Al2O3 was observed and attributed to dilution of vanadium by tungsten or molybdenum oxides on the γ-Al2O3 surface. 相似文献
2.
From its foundation until 2004, ETRI has registered over 1,000 US patents. This letter analyzes the characteristics of these patents and addresses the explanatory factors affecting their citation counts. For explanatory variables, research team related variables, invention specific variables, and geographical domain related variables are suggested. Zero‐altered count data models are used to test the impact of independent variables. A key finding is that technological cumulativeness, the scale of invention, outputs in the electronic field, and the degree of dependence on the US technology domain positively affect the citation counts of ETRI‐invented US patents. The magnitude of international presence appears to negatively affect the citation counts of ETRI‐invented US patents. 相似文献
3.
Temperature and pH‐responsive interpenetrating polymer network (IPN) hydrogels, constructed with poly(methacrylic acid) (PMAA) and poly(vinyl alcohol) (PVA), by a sequential IPN method, were studied. The characterization of IPN hydrogels was investigated by Fourier‐transform infrared spectroscopy, differential scanning calorimetry (DSC) and swelling under various conditions. The IPN hydrogels exhibited relatively high swelling ratios, in the range 230–380 %, at 25 °C. The swelling ratios of the PMAA/PVA IPN hydrogels were pH and temperature dependent. DSC was used for the quantitative determination of the amounts of freezing and non‐freezing water. The amount of free water increased with increasing PMAA content in the IPN hydrogels. Copyright © 2004 Society of Chemical Industry 相似文献
4.
Massimiliano Corsini Elisa Drelie Gelasca Touradj Ebrahimi Mauro Barni 《Multimedia, IEEE Transactions on》2007,9(2):247-256
This paper addresses the problem of assessing distortions produced by watermarking 3D meshes. In particular, a new methodology for subjective evaluation of the quality of 3D objects is proposed and implemented. Two objective metrics derived from measures of surface roughness are then proposed and their efficiency to predict the perceptual impact of 3D watermarking is assessed and compared with the state of the art. Results obtained show good correlations between the proposed objective metrics and subjective assessments by human observers 相似文献
5.
6.
AJ Dorta M Ferra R Bu-Colfiu L García M Gil X Escobar G Martín NA Díaz OM Perez MT Interián 《Canadian Metallurgical Quarterly》1993,10(10):490-491
It is essential to know how the immune system acts in different neurological diseases, some of them non very well known or of unknown etiology at all. It was applied Reiber and Felgenhauer's formula in 56 patients with different diseases. IgA, IgM, IgG and albumin were quantified in sera and cerebrospinal fluid by simple immunodiffusion. It was observed more frequent IgG local synthesis and IgA in this sample. 相似文献
7.
Wrinkling is a well known phenomenon experimented by tension membranes in Civil Engineering applications. This paper will
present an efficient numerical technique for the computational simulation of such wrinkles in a prestressed membrane. In particular,
the relaxed energy approach (Pipkin in IMA J Appl Math 36:85–99, 1986) is particularized for prestressed membranes (Gil in
Textile composites and inflatable structures, CIMNE, 2003) undergoing moderate strains. Wrinkling conditions in terms of the
Euler-Lagrange finite deformation tensor along principal directions will be obtained. This will provide a framework to describe
properly the initial instant when wrinkles start to be encountered in a prestressed Saint Venant–Kirchhoff hyperelastic membrane.
Subsequently, a modified Helmholtz’s free energy functional will be introduced with the purpose of describing the modified
constitutive behaviour of the continuum after the onset of wrinkling. Consistent derivations of the stress tensor as well
as the constitutive tensor will de depicted. The results will be particularized for membranes and cables in a Finite Element
discretization basis. Some numerical examples will prove the accuracy and robustness of the described algorithm. 相似文献
8.
Thompson Robert J.; Gil Karen M.; Keith Barbara R.; Gustafson Kathryn E.; George Linda K.; Kinney Thomas R. 《Canadian Metallurgical Quarterly》1994,62(4):856
Rates of poor psychological adjustment of children with sickle cell disease remained relatively constant over initial and follow-up assessment points. 50 children (aged 7–12 yrs) and their mothers completed the initial protocol. 30 children completed the follow-up plus 5 additional children and their mothers. These Ss were aged 7–24 yrs at follow-up. With initial levels of adjustment controlled, children's strategies for coping with pain accounted for a significant increment in child-reported symptoms and mother-reported internalizing behavior problems at follow-up beyond the contribution of illness and demographic parameters and follow-up interval. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
9.
V Blanc P Gil N Bamas-Jacques S Lorenzon M Zagorec J Schleuniger D Bisch F Blanche L Debussche J Crouzet D Thibaut 《Canadian Metallurgical Quarterly》1997,23(2):191-202
Dextran has been used as a carrier molecule for the synthesis of monofunctional peptide-dextran conjugates. The immunodetection of such carrier immobilized peptides on ELISA plates was compared to that of peptides adsorbed directly to immunoplates. The main features observed with peptide-dextran conjugates were as follows: only small amounts of peptide (1-2 mg) were necessary for coupling via alpha- or epsilon-amino groups to NaIO4-activated dextran (4 mg); the coupling yield was up to 68%; an amino acid analysis of the conjugate enabled the amount of carrier immobilized peptide to be calculated; an estimated 15-17 peptides were bound per dextran molecule (MW 73,500); using a carbohydrate as carrier reduces the possibility of non-specific interactions because no hydrophobic or ionic sites and no protein-like epitopes exist on the carrier apart from the peptide ligand. It can be assumed that some peptide ligands provide the forces for an interaction with the plate surface whereas other remain free for the interaction with the antibody. Thus, the detection with monoclonal anti-peptide antibodies allowed peptide-dextran conjugates to be used at coating concentrations of 1-3 nM peptide, corresponding to 0.6-2.6 ng peptide-dextran per well. In contrast, concentrations of 150-500 nM were required for coating with peptides. The applicability of monofunctional peptide-dextran conjugates was demonstrated by investigating the titer and specificity of a polyclonal anti-peptide serum developed against human gastrointestinal glutathione peroxidase. The introduction of biotin as a second ligand of the dextran conjugate permitted its capture on streptavidin coated plates. This synthesis of bifunctional peptide-biotin-dextran conjugates opens up additional possibilities for applications. 相似文献
10.
Preparation and characterisation of vanadium catalysts supported over alumina-pillared clays 总被引:1,自引:0,他引:1
M. A. Vicente C. Belver R. Trujillano M. A. Baares-Muoz V. Rives S. A. Korili A. Gil L. M. Gandía J. -F. Lambert 《Catalysis Today》2003,78(1-4):181-190
Supported vanadium-containing catalysts were prepared by impregnation of Al-pillared clays with NaVO3 precursor aqueous solutions. A montmorillonite and a saponite, both natural as well as previously pillared with Al13-Keggin polycations, were used as supports, being impregnated with solutions of the precursor by means of the incipient wetness technique. The layered structure of the supports is maintained after impregnation, and even after calcination of the impregnated solids at 500 °C, although with a significant worsening of the textural properties of the solids, in particular, a loss of specific surface area. Three crystalline vanadium-containing phases were identified in the impregnated solids, namely, NaV3O8, AlVO4 and V2O5 (shcherbinaite). The reduction of these phases to V3+ species was observed as wide processes in the 450–750 °C range, all of them centred at ca. 600 °C. 相似文献