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81.
Hideki Miyatake-Ondozabal 《Tetrahedron》2010,66(33):6331-5750
On heating, a hydroxy-keto-dioxinone underwent retro-Diels-Alder fragmentation and the resultant α,γ-diketo-ketene was efficiently trapped intramolecularly by a secondary alcohol to provide a macrocyclic triketo-lactone. Following ketal hydrolysis, transannular aromatization gave the resorcylate natural product, (S)-(−)-zearalenone. 相似文献
82.
An analytical strategy micelle to trapping solution stacking (MSS) was developed in acidic buffer in micellar electrokinetic chromatography (MEKC). The stacking mechanism is based on the transport, release, capturing of molecules bound to micelle carriers that are made to collapse into trapping solution (TS) to serve as the medium to contain and stacking the analytes. Tetrandrine and fangchinoline were selected as model mixture using sodium dodecyl sulfate (SDS) micelles as carrier to demonstrate this stacking method. The experiments by MSS-MEKC were carried out and further compared with those by normal MEKC. The results reveal that 113–123-fold improvements in the detection sensitivity was obtained for the analytes, and separation and determination of tetrandrine and fangchinoline in Stephaniae tetrandrae S. Moore and Fengtongan capsules were finished under optimum conditions using the sample matrix containing 8.0 mM SDS and TS containing 50 mM H3PO4–55% (v/v) ethanol. 相似文献
83.
84.
In this paper, we investigate an Al2O3/HfSiO stack as the blocking layer of a metal-oxide-nitride-oxide-silicon-type (MONOS) memory capacitor. Compared with a memory capacitor with a single HfSiO layer as the blocking layer or an Al2O3/HfO2 stack as the blocking layer, the sample with the Al2O3/HfSiO stack as the blocking layer shows high program/erase (P/E) speed and good data retention characteristics. These improved performances can be explained by energy band engineering. The experimental results demonstrate that the memory device with an Al2O3/HfSiO stack as the blocking layer has great potential for further high-performance nonvolatile memory applications. 相似文献
85.
86.
87.
In the present paper, self‐focusing of laser beams in relativistic plasmas is studied by the moment theory approach. The equilibrium beam radius of the self‐trapped laser beams is also derived. Results are compared with the paraxial ray theory. It is observed from the analysis that at higher intensities, the equilibrium beam radius increases in case of the paraxial ray theory, whereas it becomes independent of the beam intensity in case of the moment theory. Analysis also confirms the role of relativistic electrons travelling with the light pulse in (3D PIC) simulation studies (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
88.
Ying Wang Yousong GuShou Peng Wanyu Ding Hualin Wang Weiping Chai 《Applied Surface Science》2011,257(18):8044-8047
Transparent conducting Al-doped ZnO (ZnO:Al, AZO) thin films with good optical and electrical characteristics were prepared by direct current pulse magnetron sputtering. Textured surfaces of AZO films were obtained by etching with NaOH solution successfully and the effect of substrate temperature on the surface texture was investigated. The surface is covered with craters after etching with 5% NaOH solution, and the crater diameter decreases gradually as substrate temperature increases. For AZO film deposited at 270, the crater diameters is 0.5-1 μm, which is an effective surface texture for light trapping. 相似文献
89.
90.
We consider a four-level model for alkali metal atoms with optical pumping by nonresonant light under conditions when magnetic
dipole transitions are induced between energy sublevels of the hyperfine structure in the ground state. We present the dependences
of the observed signal as a function of the frequency detuning of the applied rf fields relative to the resonant value, calculated
in the density matrix formalism. We note the absence of a light shift in the radiofrequency-optical resonance signal, independent
of the amplitude of the rf field and the optical and thermal relaxation rates. We show that when using a modulation technique
for phase detection of the signal, its maximum discrimination ability is observed under conditions for simultaneous modulation
of the pump light intensity and the frequency of the rf field, which in principle does not occur in the classical two-level
model for optically oriented atoms in magnetic resonance.
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Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 73, No. 3, pp. 326–329, May–June, 2006. 相似文献