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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.
B. Sanjeeva Rao M. Ramakrishna Murthy 《Journal of Polymer Science.Polymer Physics》1989,27(6):1187-1194
Electron spin resonance (ESR) spectra of poly(acrylic acid) (PAA) γ-irradiated in air at room temperature and recorded at room temperature and at liquid-nitrogen temperature have been studied to identify the radiation products. The ESR spectra are composed of eight lines with hyperfine splittings of 23 ± 1 G and 11 ± 1 G. The method of least-squares total curve fitting, employing the Lorentzian line shape function, to the observed spectra enabled the assignment of the spectra. Computed spectra obtained by the superposition of a singlet and the spectra due to chain radicals are considered to give the best fits to the observed ESR spectra. The singlet is assigned to the radicals COOH, and the component 10-line spectra are assigned to the chain radicals CH3? CH? CH2 ~ and/or ~ CH2? CH? CH2 ~. The observed change in line shape with temperature of the ESR spectra is attributed to the hindered oscillations of the methyl groups about the Cα? Cβ bond axis of the chain radicals. The existence of the methyl groups is confirmed by the measurement of infrared absorption. 相似文献
4.
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
5.
The K-shell X-ray fluorescence cross sections are determined experimentally for 10 elements such as Pb, Hg, Ir, W, Lu, Tm,
Dy, Tb, Gd and Nd at excitation energy of 661.6 keV associated with γ-rays of 137Cs radioisotope. The technique employed involves the measurement of total intensity of fluorescent K X-rays that follow the
photoeffect absorption of a known flux of γ-rays using a well type Nal(Tl) detector. The obtained results are compared with the available theoretical values and other
measured values. 相似文献
6.
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
7.
A total synthesis of d-(+)-biotin is described starting from d-(+)-glucosamine using acyliminium chemistry. 相似文献
8.
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
9.
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
10.
Studies on chemical modification of demineralized bone matrix (DBM) have opened new arenas in the field of clinical orthopedics owing to its potential osteoinductivity with desired chemical functionality. To widen its usage to biomolecular delivery, graft polymerization of glycidylmethacrylate onto DBM was carried out by a free-radical initiating process using ceric ammonium nitrate as an initiator. The evidence of the grafting reaction was examined by chemical analysis using Fourier transform IR spectroscopy. The grafting condition was standardized by regulating the reaction parameters such as the concentrations of the backbone, the monomer and the initiator, the polymerization temperature and time. The optimum polymerization temperature and time to have the maximum grafting yield were 40 °C and 3 h, respectively. The percentage of grafting and the percentage of grafting efficiency were determined as a function of the reaction parameters, and both were found to increasing initially and thereafter decrease in most of the cases. The grafting results are discussed in a detailed fashion and a reaction mechanism is proposed. 相似文献