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61.
Stereoselective synthesis of tetrahydrofuro- and tetrahydropyrano[3,2-c]benzothiopyrans was achieved by intramolecular [4+2]cycloaddition of o-thiobenzoquinone methides that were generated in situ from bis(2-formylphenyl) disulfide and alkenols in the presence of iodine under mild reaction conditions. 相似文献
62.
Ag(core)–AgCl(shell) microcrystal composites (Ag@AgCl) have been formed on an α-Fe2O3 film-coated SnO2 electrode by a 2 step method consisting of the electrochemical reduction of Ag+ ions and the subsequent electrochemical oxidation. The synergy of α-Fe2O3 and Ag@AgCl gave rise to a high visible light-induced reactivity (λex > 420 nm) for the oxidation of 2-naphthol (2-NAP) used as a model water pollutant in the presence and absence of oxygen. These findings were attributable to the function of Ag@AgCl composites as an excellent charge-separation promoter and built-in acceptor. 相似文献
63.
64.
Yosuke Morishige Kichinosuke Hirokawa Kazo Yasuda 《Fresenius' Journal of Analytical Chemistry》1994,350(6):410-412
The role of metallic matrix modifiers in AAS is considered; for elements reduced, together with modifier elements, during ashing and the beginning of the atomization process, the thermodynamic activity and melting points of the alloys formed are important. For Mg2+, prevention of the effects of halide ions is considered, as is also the behaviour of buffer and/or carrier in emission spectrometric analysis of the other alkali and alkaline earths. 相似文献
65.
The fluorescent products formed from methylguanidine or phenylguanidine and benzoin in the presence of dimethylformamide are shown to be the corresponding 2-substituted amino-4, 5-diphenylimidazoles. They fluoresce most intensely at pH 9–10 and the fluorescence is stabilized by β-mercaptoethanol. 相似文献
66.
Yosuke Ohkura Kenji Ohtsubo Kiyoshi Zaitsu Kazuya Kohashi 《Analytica chimica acta》1978,99(2):317-324
A sensitive fluorimetric method for the determination of aromatic aldehydes is based on their reaction in dilute sulfuric acid with a new reagent, 2,2'-dithiobis(l-amino-naphthalene) in the presence of tri-n-butylphosphine, sodium sulfite and sodium phosphite at ambient temperature. The fluorescences produced are fairly characteristic of individual aldehydes. The method is extremely selective for aromatic aldehydes and very sensitive, especially for p-hydroxybenzaldehyde, o-methoxybenzaldehyde, p-methoxybenzaldehyde and p-tolualdehyde which can be determined at concentrations of as little as 3–5 ng ml-1. 相似文献
67.
Ijima Y Matoishi K Terao Y Doi N Yanagawa H Ohta H 《Chemical communications (Cambridge, England)》2005,(7):877-879
The introduction of two mutations (G74C/C188S) based on the estimated reaction mechanism resulted in the inversion of enantioselectivity of arylmalonate decarboxylase, which catalyses the asymmetric decarboxylation of arylmethylmalonate to give optically active arylpropionate. 相似文献
68.
69.
We calculate the exact Landau-Zener transition probabilities for a qubit with an arbitrary linear coupling to a bath at zero temperature. The final quantum state exhibits a peculiar entanglement between the qubit and the bath. In the special case of diagonal coupling, the bath does not influence the transition probability, whatever the speed of the Landau-Zener sweep. It is proposed to use Landau-Zener transitions to determine both the reorganization energy and the integrated spectral density of the bath. Possible applications include circuit QED and molecular nanomagnets. 相似文献
70.
A tellurite glass fiber with a high Brillouin gain was employed for distributed strain measurement with Brillouin optical correlation-domain reflectometry (BOCDR). First, the spatial resolution of BOCDR was evaluated using the tellurite fiber. With the high Brillouin gain of the fiber, it was confirmed clearly in the experiment that the spatial resolution is limited by the Rayleigh scattering-induced noise. Then, the dependence of the Brillouin frequency shift (BFS) on strain in the tellurite fiber was investigated, showing a negative dependence with a coefficient of −0.023 MHz/με. Using this tellurite fiber, the distribution of the BFS around a 1-cm strain-applied section was successfully measured with BOCDR of a nominal spatial resolution of 6 mm. 相似文献