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31.
32.
Coating Carbon Nanotubes with Europium Oxide 总被引:4,自引:0,他引:4
HuiQunCAO GuangYanHONG JingHuiYAN JiLinZHANG GuiXiaLIU 《中国化学快报》2003,14(12):1293-1295
Carbon nanotubes (CNTS) coating with europium oxide by a simple method is reported in this letter for the first time. The CNTS were refluxed in a solution of nitric acid containing europium nitrate, and the pH value was subsequently ajusted with ammonia solution. At last, the mixture was filtered and annealed. The TEM micrograph showed that the CNTS were covered with a uniform thin layer with thickness of about 15 nm. The XRD results revealed that the CNTS were coated with europium oxide. 相似文献
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A method of tracking ensembles of particle images 总被引:8,自引:4,他引:4
A method for tracking ensembles of particle images of a digital PIV record by making use of the minimum quadratic difference (MQD) technique is described. The similarity of this method with correlation schemes used for the evaluation of PIV is discussed. The method is exemplified with two applications that are also evaluated by auto- and cross-correlation, respectively.Receipt of a fellowship from Deutscher Akademischer Austauschdienst (DAAD) for L. C. Gui is gratefully acknowledged. 相似文献
36.
On the way of the "1990 International Trans-Antarctic Expedition", the first author of this paper, the Chinese member of the expedition, collected 104 snow samples in 25-cm surface snow along a 5986-km route on Antarctic ice sheet from west to east. The geographical distribution of δD across the Antarctica by the longest route is obtained from stable isotope analysis for the first time. After discussing regional differences of physical geographic conditions, maritime-continental influence, altitudes and latitudes at sampling sites, the distribution of δD is considered to have a close relation to latitudes, but the topographic effect is prominent in some particular regions. The mean annual temperature at sampling site and its relationship with δD in surface snow covering Antarctica from west to east are discussed also. The δD-temperature gradient from the south end of Antarctic Peninsula to Vostok obtained in this paper is very close to that in Terre Adelie Land obtained by predecessors. The snow-dri 相似文献
37.
The electrochemical and in-situ surface-enhanced Raman spectroscopy (SERS) techniques were used to investigate the electrooxidation behavior of methanol in acidic, neutral and alkaline media at a Pt-Ru nanoparticle modified glassy carbon (Pt-Ru/GC) electrode. The results showed that methanol could be dissociated spontaneously at the Pt-Ru/GC electrode to produce a strongly adsorbed intermediate, CO. It was found that CO could be oxidized more easily in the alkaline medium than in the acidic and neutral media. The peak potential of methanol oxidation was shifted from 0.663 and 0.708 V in the acidic and neutral media to -0.030 V in the alkaline medium, which is due to that the adsorption strength of CO on the Pt surface in the alkaline medium is weaker than that in the acidic and neutral media. The final product of the methanol oxidation is CO2. However, in the alkaline medium, CO2 produced would form CO3^2- and HCO3^- resulting in the decrease in the alkaline concentration and then in the decrease in the performance of DMFC. Therefore, the performance of the alkaline DMFC is not Stable. 相似文献
38.
3He/4He ratios in samples of sea water obtained at depths from surface to 300 m in the upper layer of the Western Pacific Ocean were measured by a mass spectrometer VG5400. The lateral and vertical distribution of He isotopes in the studied area was discussed in detail on the basis of 3He/4He ratios. Excess and depleted 3He. in relation to δ3He value of surface water in equilibrium with air has been discussed in the area, which may be mainly attributed to the incorporation of the North Pacific Intermediate Water with the Equatorial Upwelling and the exchange of water masses between the South China Sea and the Western Pacific, respectively. The present work in Western Pacific has also indicated that He isotopes may be used as a tracer for mixing processes of water masses and oceanic circulation. 相似文献
39.
A New Reaction-controlled Phase-transfer Catalyst System 总被引:1,自引:0,他引:1
MingQiangLI XiGaoJIAN GuiMeiWANG YanYU 《中国化学快报》2004,15(3):350-352
A new reaction-controlled phase-transfer catalyst system was designed and synthesized.In this system, heteropolytungstate [C7H7N(CH3)3]9PW9O34 was used for catalytic epoxidation of cyclohexene with H2O2 as the oxidant. The conversion of H2O2 was 100% and the yield of cyclohexene oxide was 87.1% based on cyclohexene. Infrared spectra showed that both fresh catalyst and the recovered catalyst do have completely same absorption peak, indicating the structure of catalyst is very stability and can be recycled. 相似文献
40.
合成了一系列以不同长度柔韧链相连的p/p型单核锌双卟啉配合物。选用Tripos力场,利用分子动力学模拟退火和分子力学构象搜索相结合的方法对该系列双卟啉进行了能量优化和构象分析。理论计算结果表明:该类双卟啉稳定存在的最低能量构象为叠合式,最高能量构象为伸展式,并存在一系列的中间能量构象;双卟啉分子内π-π作用和能量转移与双卟啉存在的两种主要构象密切相关;分析了分子内π-π作用的本质。运用不同光谱测试手段验证了理论计算结果: 利用可见和相应二阶导数吸收光谱研究了双卟啉主要存在的叠合式和伸展式构象,通过红外光谱观察了对双卟啉构象和卟啉环间π-π作用较为敏感的吸收谱带;利用荧光光谱计算了双卟啉的分子内能量转移效率。 相似文献