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731.
IntroductionTheincreasingnecessity0fpharmacologicalresearchforchiraldrugshasrenderedchiralseparationanactiveareaincaPillaryelectroph0resis(CE)today.Variousmodes0fCE,includingcaPillaryzoneelectroph0resis(CZE),micellarelectrokineticchromatography(MEKC),caPillarygelelectrophoresis(CGE)andcapillaryisotachophoresis(CITP),havebeenappliedforthispurp0se',amongwhichCZEisthemostpopularoneforitshighefficiency,lowexpenseandeaseofoperation.Forsuccessfulchiralseparati0ninCZE,theselectortypeisofcr… 相似文献
732.
Zilan L Xiaodong H Ke C Ruijuan N Xuhui L Xiaoping Z Tongjun Y Bei Z Song C Zhijian Y Zhizhong C Guoyi Z 《Micron (Oxford, England : 1993)》2005,36(3):281-284
Laser lift-off (LLO) technology is successfully used to prepare GaN-based TEM cross-sectional specimens. Detailed procedures of the method to prepare the specimens are demonstrated. Large thin areas suitable for TEM analysis were obtained. TEM images of the resulting GaN interface are studied, and the changes in structural quality are confined to approximately the first 250 nm of the epilayer. Clear TEM images of the whole epilayer and the InGaN quantum wells and the HRTEM images of the superlattice layer are demonstrated, showing that LLO is a quick and ideal method to study the crystal structure of the epilayer, especially if only the upper layers are of interest. 相似文献
733.
Y.?Xue G.?Wang H.-F.?Zhang J.-Y.?GaoEmail author 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2005,33(1):123-127
We propose a novel scheme for light amplification and gain equalization by
quantum interference. We find that the laser amplification can be observed at
three specific probe frequencies in a four-level system. Furthermore, we
show that three gain peaks can be combined into one to obtain
gain equalization. 相似文献
734.
Chunfeng?WuEmail author Kang?Xue 《International Journal of Theoretical Physics》2004,43(12):2395-2403
We investigate the realizations of Yangian algebra for a Dirac oscillator. Applying the representation theory of Y(sl(2)) to Dirac oscillator, shift operaors for different energy levelsfor this system are obtained. 相似文献
735.
In this study, we report a novel and simple solution-phase route for one-dimensional metal nanocrystals. BiIn nanocrystals were prepared by directly dispersing melting BiIn alloy at an appropriate solvent. The as-obtained BiIn nanocrystals with a dendritic shape possess a good crystalline phase. The morphology of the nanocrystals can be greatly modified by changing the reaction parameters. This strong UV emission might arise from the quantum-confined In2O3 particles. 相似文献
736.
ZENG Zhaoquan WANG Yong DU Xiaolong MEI Zengxia KONG Xianghe JIA Jinfeng XUE Qikun & ZHANG Ze . State Key Laboratory for Surface Physics Institute of Physics Chinese Academy of Sciences Beijing China . Laboratory of Electron Microscopy Institute of Physics Chinese Academy of Sciences Beijing China . College of Physics Engineering Qufu Normal University Qufu China . Beijing University of Technology Beijing China 《中国科学G辑(英文版)》2004,47(5):612-620
ZnO is a wide direct bandgap (Eg=3.37 eV at room temperature) II-VI compound semiconductor of wurtzite structure (a = 3.249 ? c = 5.207 ?. Compared to GaN and ZnS, ZnO has a larger exciton binding energy, ~60 meV (cf. ~25 meV for GaN and ~40 meV for ZnS), which is advantageous to realizing low-threshold excitonic lasers. Since optically pumped UV lasing of ZnO at room temperature was reported in 1997[1], much attention has been paid to the crystal quality improvement and p-type conduc… 相似文献
737.
738.
The universal variation pattern of the total energy of various fullerenes including single-walled carbon nanotubes with respect to their extra charge is revealed by the density-functional-theory calculations. The parabolic energy-charge curve with its lowest energy value corresponding to a negatively charged fullerene indicates that these carbon materials have positive electron affinity and are not in the most stable state. The positive electron affinity seems to originate from the pi-electrons and is found to be related to the aggregation property of fullerenes. 相似文献
739.
Building Pb nanomesas with atomic-layer precision 总被引:1,自引:0,他引:1
Jiang CS Li SC Yu HB Eom D Wang XD Ebert P Jia JF Xue QK Shih CK 《Physical review letters》2004,92(10):106104
We demonstrate a novel scheme for manipulating metallic nanostructures involving a macroscopic number of atoms, yet with precise control in their local structures. The scheme entails a two-step process: (a) a triggering step using a scanning tunneling microscope, followed by (b) self-driven and self-limiting mass-transfer process. By using this scheme, we construct Pb nanomesas on Si(111) substrates whose thickness can be controlled with atomic-layer precision. The kinetic barrier for the mass transfer and the underlying mechanism behind this novel manipulation are determined. 相似文献
740.
Zhang D Wu LZ Zhou L Han X Yang QZ Zhang LP Tung CH 《Journal of the American Chemical Society》2004,126(11):3440-3441
1,4-Dihydropyridines have been photocatalytically oxidized to pyridines by platinum(II) terpyridyl complexes with the generation of hydrogen in homogeneous solution. The hydrogen production proceeds in quantitative yield and with great catalytic turnover. 相似文献