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如何提高学生分组实验的效果 总被引:1,自引:0,他引:1
物理实验在物理教学中的重要作用已日益引起广大物理教师的重视.借助物理实验不仅能使学生生动地感知物理现象,加深对物理概念的认识,更重要的是能使学生理解和掌握运用实验手段,处理物理问题的基本程序和技能,培养严谨细致的科学态度和实事求是、坚 相似文献
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Zhanwen Zhang Shaoyu Liu Xiaolan Tang Dahong Nie Ganghua Tang Aixia Sun Ying Xiong Hui Ma Fuhua Wen Ping Hu 《Journal of Radioanalytical and Nuclear Chemistry》2018,316(1):153-159
The aim of this study was to synthesize the optically pure [18F]FPA, and to investigate the diagnostic value of different isomers. Semi-automated radiosynthesis of R-[18F]FPA or S-[18F]FPA was respectively from the chiral precursor (S)- or (R)-ethyl 2-(((trifluoromethyl)sulfonyl)oxy)propanoate via a two-step reaction and performed on the commercial FDG synthesizer. The improved radiochemical yields of R-[18F]FPA and S-[18F]FPA were 30–40% (decay-uncorrected, n = 10) in 35 min. There was no significant difference on the biodistribution of two enantiomers in normal mice (P > 0.05), but positron emission tomography imaging demonstrated that R-[18F]FPA was more suitable for PC3 tumor imaging than S-[18F]FPA and [18F]FDG. 相似文献
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We report on the synthesis of Fe3O4@SiO2 nanoparticles incorporated poly(divinylbenzene) monolithic column via in situ polymerization. The monolith had larger specific surface area and relatively uniform porous structure and was characterized by scanning electron microscopy, nitrogen adsorption–desorption, and Fourier transform infrared spectroscopy. The monolith was then applied for the evaluation of gas chromatography separation properties. Here, an electromagnetic induction heating technique was employed to control the column temperature with the thermal effect of eddy current in ferromagnetic materials Fe3O4. The monolith offered good separation efficiency for benzene and toluene and a higher column efficiency was obtained up to 4481 and 9216 plates per meter, respectively. In addition, the injection volume and column capacity of the proposed system are as much as 5 µL and 100 ng. This makes it possible to use a UV detector. The fabricated Fe3O4@SiO2 nanoparticles incorporated poly(divinylbenzene) monolithic column has been shown to be very promising for gas chromatography separation. 相似文献
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The application of multilayer perceptron artificial neural networks (MLP ANN) based on genetic input selection for quantification of the unresolved peaks in micellar electrokinetic capillary chromatography (MECC) is reported. An optimization strategy for genetic input selection was also proposed. When the corresponding CE peaks cannot be resolved completely only by separation techniques, MLP ANN based on genetic input selection can be a suitable tool to resolve the problem. Both the spectra and the electrophoretograms of the unseparated analytes were used as the multivariate input data. The two kinds of the data were suitable for quantification of overlapped CE peaks by MLP ANN based on genetic input selection. The study also shows that the applying of genetic input selection in MLP ANN can improve the precision of quantification in both completely and partially overlapped CE peaks to some extent. 相似文献
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