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41.
42.
We investigate intersubband Rabi flopping in modulation-doped semiconductor quantum wells with and without the propagation effects, respectively. It is shown that propagation effects have a larger impact on Rabi flopping than the nonlinearities rooted from electron-electron interactions in multiple quantum wells. By using ultrashort π pulses, an almost complete population inversion exists if the propagation effects are not considered; while no complete population inversion occurs in the presence of propagation effects. Furthermore, the magnitude of the impact of propagation effects may be controlled by varying the carrier density. 相似文献
43.
用自行组装的直流辉光放电原子发射光谱(dc G D A E S)仪器对分析铜合金的某些基本特性进行了研究 探讨了光源放电室结构、放电气体压力、放电电压等操作参数以及试样尺寸大小对放电性能及元素谱线强度的影响,并进行了优化 考察了在不同放电气压条件下样品的溅射率和优化条件下辉光放电的稳定性最后,分析了铜合金标准样品中的 Al和 Mn,结果较满意 相似文献
44.
W. Rohde B. Schiemenz H. Leberling P. Hammann H. M. Zu Selhausen 《Mathematical Methods of Operations Research》1980,24(2):B67-B72
Ohne Zusammenfassung 相似文献
45.
An oscillatory characteristic of diffraction is observed as a result of strong beam coupling in a weakly oxidized LiNbO3:Ce:Cu crystal during the recording step in the production of nonvolatile photorefractive holograms. On this basis the optimal switching time from the recording step to the fixing step for high diffraction of a fixed hologram is studied. It is shown that switching after the first diffraction maximum leads theoretically to fixed diffraction of as much as 100% with a suitable switching time. Both an experimental demonstration and a theoretical simulation are presented. 相似文献
46.
Polymethyl methacrylate modified carbon nanotubes were prepared using γ radiation, and the modified carbon nanotubes exhibited
strong luminescence (∼
∼568 nm) at room temperature and an absorption peak at ∼
∼247 nm can be observed in the polymer modified samples. 相似文献
47.
Naturally occurring saponins are attractive candidates or lead compounds for new drug design and development and thus have become important synthetic targets. This short account reviews the recent progress in the chemical synthesis and structure-activity relationship (SAR) studies of naturally occurring saponins and their derivatives. 相似文献
48.
1 INTRODUCTIONItwaswellknown thatelementsofthesecondary and higherrow are in generaldifficulty to form multiplebondsin which apπ hybridized stateisinvolved〔1〕.Thus,simple compounds containing multiple phosphorus carbon bonds,such as methyl dynephosphine( HC≡P) 〔2 - 3〕 and methylenephosphine( H2 C=PH〔4〕,are notstableat room temperature.Three methods to stabilize compounds containing double ormultiple bond involving phosphorusatom in the pπ hybridized state are often used.The f… 相似文献
49.
Kwang Ik KIM Zu Han LIU 《数学学报(英文版)》2008,24(1):75-86
We study the minimizers of the Ginzburg-Landau model for variable thickness, superconducting, thin films with high k, placed in an applied magnetic field hex, when hex is of the order of the "first critical field", i.e. of the order of |lnε|. We obtain the asymptotic estimates of minimal energy and describe the possible locations of the vortices. 相似文献
50.
Determination of Fatty Acid Methyl Esters in Biodiesel Produced from Yellow Horn Oil by LC 总被引:2,自引:0,他引:2
Yu-Jie Fu Yuan-Gang Zu Li-Li Wang Nai-Jing Zhang Wei Liu Shuang-Ming Li Su Zhang 《Chromatographia》2008,67(1-2):9-14
A simple and accurate HPLC method with refractive index detection was developed to determine the main fatty acid methyl esters
in biodiesel produced from yellow horn oil. Methyl linoleate, methyl linolenate, methyl arachidate, methyl stearate, methyl
palmitate and methyl oleate were separated on a HIQ SIL C18W column using methanol as mobile phase. The method has good repeatability
and precision, the intraday and interday RSD for both retention time and peak area was less than 3.2%. The LOD (S/N = 3) and
LOQ (S/N = 9) were less than 0.004 and 0.015 mg mL−1, respectively. 相似文献