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排序方式: 共有699条查询结果,搜索用时 15 毫秒
1.
In this paper we use real analysis techniques to establish a new real Paley-Wiener theorems for the Fourier-Bessel transform associated with the Weinstein operator. More precisely we characterize the C ∞-functions whose image under the Fourier-Bessel transform are functions with compact support through an L p growth condition, p ∈ [1, +∞] and we give another version of the real Paley-Wiener theorem for L 2-functions. 相似文献
2.
J. -Ph. Jay J. Ben Youssef H. Le Gall 《Journal of magnetism and magnetic materials》2002,240(1-3):287-290
The dynamic response of trilayer magnetoresistive permalloy/Cu/Co films was studied by high-frequency permeability spectra measurements. The resonance frequency is shown to depend on the interlayer copper thickness. This dependence is related to exchange coupling between permalloy and cobalt and the interaction field is estimated using the Landau–Lifschitz–Gilbert model. 相似文献
3.
Youssef Randjiou 《Journal of Theoretical Probability》2006,19(3):701-720
Let μ+(t) and μ−(t) be the locations of the maximum and minimum, respectively, of a standard Brownian motion in the interval [0,t]. We establish a joint integral test for the lower functions of μ+(t) and μ−(t), in the sense of Paul Lévy. In particular, it yields the law of the iterated logarithm for max(μ+(t),μ−(t)) as a straightforward consequence. Our result is in agreement with well-known theorems of Chung and Erdős [(1952) Trans. Amer. Math. Soc. 72, 179–186.], and Csáki, F?ldes and Révész [(1987) Prob. Theory Relat. Fields
76, 477–497].
相似文献
4.
5.
A. M. Ghander A. Z. El-Sonbati M. A. Diab 《Journal of polymer science. Part A, Polymer chemistry》1989,27(2):447-452
Poly(bis-p-phenylenediaminosulphoxide) was prepared by Michael addition of p-bis-N-sulphinylphenylenediamine with p-phenylenediamine at 150°C. Thermal and electrical behaviors of the polymer have been studied. The polymer is found to have increased conductivity possibly due to the participation of lone pairs of electrons on nitrogen and sulphur atoms with σ bond of the macrochain. Thermogravimetric analysis indicates that the polymer is fairly stable than other conducting polymers up to 200°C. The activation energy of the polymer was measured and found to be 13 kcal mol?1. 相似文献
6.
Zusammenfassung Es werden die Veresterungsgeschwindigkeiten der Monoaminobenzoesäuren und der 1- und 2-Pyridinkarbonsäuren bei 25° mit Chlorwasserstoff als Katalysator sowohl in wasserfreiem als auch in wasserhaltigem Glykol und in wasserfreiem Glyzerin gemessen, die derm- und derp-Aminobenzoesäure und der 2-Pyridinkarbonsäure (Nikotinsäure) auch in wasserhaltigem Glyzerin. Die Abhängigkeit der monomolekularen Geschwindigkeitskonstanten vom Wassergehalt (w) des Mediums und dem Überschuß der Konzentration der Salzsäure über die der organischen Säure, bzw. ihres Esters (C) wird für die drei zuletzt genannten Säuren durch Formeln dargestellt. Diese Geschwindigkeitskonstanten nehmen durchwegs sowohl in wasserfreiem als auch in wasserhaltigem Glykol und Glyzerin nicht nur rascher als die Konzentration der gesamten Salzsäure, sondern auch als die des obigen Überschusses, d. h. der freien Salzsäure, zu.FürC=1/3 sind beiw=0.03 die Geschwindigkeitskonstanten derm- und derp-Aminobenzoesäure und der Nikotinsäure in Äthylalkohol um 20–30 %, die der Anthranilsäure um 70%, die der Pikolinsäure um 130% größer als in Glykol, beiw=0.7 dagegen die der drei ersteren Säuren um 35–50% kleiner.In Glykol sind die Konstanten bei der Anthranilsäure und den Pyridinkarbonsäuren kleiner als in Glyzerin, bei den übrigen wie bei den früher untersuchten Säuren aber größer.Die sterische Wirkung der Aminogruppe in Orthostellung ist in Glykol größer, in Glyzerin kleiner als in Äthylalkohol.Unter gleichen Bedingungen Bind die Konstanten der Veresterungsgeschwindigkeit der Nikotinsäure in Glykol und Glyzerin etwa viermal, in Äthylalkohol nur etwa zweimal größer als die der Pikolinsäure. 相似文献
7.
The kinetics of the crystallization of barium chromate in presence of polyphosphate and phosphonates
M. N. Ramsis M. S. Antonious E. N. Rizkalla A. O. Youssef 《Monatshefte für Chemie / Chemical Monthly》1996,127(11):1099-1108
Summary The inhibiting effect of polyphosphate and phosphonates on the crystallization of barium chromate for both seeded and unseeded systems has been investigated using the changes in ionic conductivity of the lattice ions in supersaturated solutions containing stoichiometric concentrations of barium and chromate at 298 K. The inhibitors studied are sodium tripolyphosphate (STP), ethylenediaminetetramethylenephosphonic acid (ENTMP), and 1-hydroxyethylidene-1,1-diphosphonic acid (HEDP). The effect of these inhibitors on the growth of crystals has been studied at several inhibitor concentrations. The influence of these additives on barium chromate crystallization could be interpreted in terms of aLangmuir type adsorption isotherm. The crystallization retarding effect due to inhibitors is in the orderHEDP>STP>ENTMP. The inhibitors studied can be used as effective compounds for scale formation control.Deceased 相似文献
8.
Micromethods are described for the determination of organic sulfoxides and disulfides based on reduction with titanium (III) sulfate solution, the excess of which is titrated with standard ferric alum as usual. The procedures developed depended on the nature of the compound whether aromatic or aliphatic. Quantitative reduction of sulfoxides was achieved in presence of ammonium thiocyanate and sodium acetate but whereas aryl sulfoxides required heating at 70 °C for 30 minutes, the alkyl members demanded heating at 90 °C for one hour. Complete reduction of disulfides was possible in presence of acetate buffer and heating at 50 °C for 15 minutes for aromatic disulfides and at 80 °C for 30 minutes in case of the aliphatic ones. a Calculated by dividing the total titer in a ratio of 2:12. b Calculated using the total titer consumed. Sulfonyl halides, thiocyanates, and isothiocyanates do not react with the titanium(III) solution. The effect of the various sulfur functions on the determination of the nitro group with titanium(III) was also studied and various nitro-substituted sulfur compounds were successfully analyzed. 相似文献
9.
Tarek M. El-Gogary Mostafa A. Diab Shreen F. El-Tantawy 《Monatshefte für Chemie / Chemical Monthly》2006,137(8):1027-1042
Summary. Equilibrium constants and molar extinction coefficients for 1:1 charge-transfer complexes between 2-hydroxyaniline (HA), 5-chloro-2-hydroxyaniline (CHA), and 4-bromo-2,6-dimethylaniline (BMA) as donors and iodine, as a typical σ-acceptor were determined spectrophotometrically in chloroform, dichloromethane, and
carbontetrachloride solutions. Spectral characteristics and formation constants are discussed in terms of donor molecular
structure and solvent polarity. The stoichiometry of the complexes was established to be 1:1. For this purpose, optical data
were subjected to the form of the Rose-Drago equation for 1:1 equilibria. Electronic absorption spectra of the studied anilines were measured in different solvents. Spectral
data were reported and band maxima were assigned to the appropriate molecular orbital transitions (π–π* and n–π* electronic transition). Solvent effects on the electronic transitions were discussed. Optimized geometry of the studied anilines
was obtained at B3LYP/6-31 + G(d). The effect of the electronic factors of the substituents on the geometrical parameters
of the ring has been explored. Geometrical values of the ring deviate from the regular hexagonal ring. Intramolecular H-bonds
in HA and CHA have been computed at B3LYP/6-31 + G(d) and MP2/6-31 + G(d) levels. The H-bonding distance was calculated to be 2.105 ? in
HA and 2.127 ? in CHA.
Abstracted from her M.Sc. thesis 相似文献
10.
Farah Diab Hawraa Zbeeb Francesca Baldini Piero Portincasa Mohamad Khalil Laura Vergani 《Molecules (Basel, Switzerland)》2022,27(15)
Numerous plants, plant extracts, and plant-derived compounds are being explored for their beneficial effects against overweight and liver diseases. Obesity is associated with the increased prevalence of non-alcoholic fatty liver disease (NAFLD), becoming the most common liver disease in Western countries. Obesity and NAFLD are closely associated with many other metabolic alternations such as insulin resistance, diabetes mellitus, and cardiovascular diseases. Many herbs of the Lamiaceae family are widely employed as food and spices in the Mediterranean area, but also in folk medicine, and their use for the management of metabolic disorders is well documented. Hereby, we summarized the scientific results of the medicinal and nutraceutical potential of plants from the Lamiaceae family for prevention and mitigation of overweight and fatty liver. The evidence indicates that Lamiaceae plants may be a cost-effective source of nutraceuticals and/or phytochemicals to be used in the management of metabolic-related conditions such as obesity and NAFLD. PubMed, Google Scholar, Scopus, and SciFinder were accessed to collect data on traditional medicinal plants, compounds derived from plants, their reported anti-obesity mechanisms, and therapeutic targets. 相似文献