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排序方式: 共有347条查询结果,搜索用时 15 毫秒
1.
2.
X-ray diffraction patterns of nanocrystalline Fe-Cu-Nb-Si-B (FINEMET) alloys reveal that bcc α-Fe/α-FeSi crystallites with
the average grain size of 20(5) nm are dispersed in amorphous matrix. Enhanced electron—electron interaction (EEI) and quantum
interference (QI) effects as well as electron-magnon (and/or electron-spin fluctuation) scattering turn out to be the main
mechanisms that govern the temperature dependence of resistivity. Of all the inelastic scattering processes, inelastic electron-phonon
scattering is the most effective mechanism to destroy phase coherence of electron wave functions. The diffusion constant,
density of states at the Fermi level and the inelastic scattering time have been estimated, for the first time, for the alloys
in question
Article presented at the International Symposium on Advances in Superconductivity and Magnetism: Materials, Mechanisms and
Devices, ASMM2D-2001, 25–28 September 2001, Mangalore, India. 相似文献
3.
A short and efficient enantioselective synthesis of sulfobacin A has been achieved using the Sharpless asymmetric dihydroxylation and the regiospecific nucleophilic opening of a cyclic sulfate as the key steps. 相似文献
4.
5.
A photometric method for the determination of malathion is described. Malathion dissolved in carbon tetrachloride is hydrolysed at room temperature with sodium ethoxide to dimethyl dithiophosphate (DMDTP) and fumarate. The DMDTP is converted into a molybdenum-DMDTP complex and determined spectrometrically. 相似文献
6.
Comparison of adsorbents for on-line solid-phase extraction of polycyclic aromatic hydrocarbons before liquid chromatography with UV detection 总被引:1,自引:0,他引:1
Summary On-line solid-phase extraction (SPE) coupled with reversed-phase liquid chromatography and UV detection at 254 nm has been
used for the determination of trace-level polycyclic aromatic hydrocarbons (PAH) in soil extracts. Five commercially available
adsorbents (C8, C18, PLRP-S, PRP-1, and Bond-Elut Env) were evaluated. Results showed that recovery of the PAH decreased with increasing molecular
weight, because of their poorer solubility. Recovery of high-molecular-weight PAH was significantly improved by addition of
10% (v/v) acetonitrile to the sample before loading of the SPE adsorbent. PAH recovery ranged from 64.0 to 108% when a 50
mL sample spiked with 1 μg L−1 was applied to these adsorbents. Determination of PAH was possible with detection limits below 0.05 μg L−1, which corresponds to 0.2 μg kg−1 soil. The method was successfully used to determine PAH in soil extracts. 相似文献
7.
A simple spectrophotometric method for determination of isoxsuprine hydrochloride in pharmaceuticals
A spectrophotometric method has been developed for the determination of isoxsuprine hydrochloride and its dosage forms, based on its coupling reaction with diazotized sulphanilic acid. The yellow chromophore has an absorption maximum at 440 nm. Beer's law holds over the range 0.8-8 mu/ml in the final solution. 相似文献
8.
A simple but rapid and accurate method for the estimation of allyl in aqueous solution has been developed, based on its oxidation with chloramine-T at room temperature, in 0.5-1.0M hydrochloric acid medium. The reaction involves a two-electron change. The effect of such variables such as pH of the medium, presence of foreign ions and perchloric or sulphuric acid on the rate of oxidation is discussed. 相似文献
9.
J. P. Agrawal N. M. Bhide S. R. Naidu 《Journal of Thermal Analysis and Calorimetry》1993,39(3):351-358
The optimization of proportions of novolac epoxy resin, Dobeckot E4 and polyamide hardener, EH411 has been established by DSC and the data indicates that resin-polyamide, 100∶40 and 100∶50, appear to be optimum where ‘extent of cure’ is maximum. The kinetic parameters for these formulations have been evaluated using isothermal and dynamic modes by employing DSC. The rate constants have been evaluated for curing process of these formulations using isothermal DSC mode in the temperature range of 70°–90°C. These have also been predicted at 20°±1°C (room temperature) by extrapolating the data obtained at elevated temperatures. A comparison of the predicted values with the experimental values shows that there is a good agreement between them. 相似文献
10.
T. Gangaiah P. Ramadevi G. R. K. Naidu K. Venugopal Chetty 《Journal of Radioanalytical and Nuclear Chemistry》1991,150(1):177-182
Isotopic exchange behaviour of bis(diethyldithio carbamate) nickel(II) complex with nickel(II) in chloroform and methanol medium was studied. The studies were carried out at different temperatures varying the concentration of both metal ion and the complex. The results show that the complex is labile in the kinetic sense. Increase in temperature increases the isotopic exchange rate. The increase in concentration also results in enhancement of the rate of reaction. 相似文献