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211.
高等教育要适应世界潮流和时代变化,本科教育须进一步提高实践教学的比重,加强理论教学与实践教学相结合,完善协同育人机制。结合学科发展和企业发展需求,中山大学化学学院与金发科技股份有限公司(简称金发科技)共同建设大学生实践教学基地。本文以中山大学-金发科技本科实践教学基地为例,探讨大学生校外实践基地建设过程中遇到的问题以及实践基地的建设内容与成果体会。 相似文献
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213.
《Physics and Chemistry of Liquids》2012,50(2):153-165
Densities and viscosities for the system, water (W)?+?sulfolane (SFL), have been determined for the entire range of composition at temperatures ranging from 303.15 to 323.15?K. Density, excess molar volume, viscosity, excess viscosity and thermodynamic activation parameters for viscous flow have been calculated and plotted against the mole fraction of SFL. The measured properties and some of the derived properties have been fitted to appropriate polynomial equations. These have been explained in terms of such factors, as, dipole–dipole interaction, partial accommodation of water molecules into the structural network of SFL and H-bonding between SFL and H2O. 相似文献
214.
《Analytical letters》2012,45(12):1305-1313
Abstract The solid monoxime of 2, 3-butanedione is a more convenient material than liquid dione for the homogenous generation of DMG. 2, 3-butanedione dioxime. Determinations of Ni in steels and in pure Ni(II) solutions have shown the optimum pH and order of adding reagents. Gravimetric and/or an EDTA titrimetric finish are possible for a method of reliability within ± 0.2 mg of Ni in 50–150 mg Ni. The solid has the same character and filterability as that from the 1960 dione method of Salesin and Gordon1. 相似文献
215.
利用“每课一题”这个教学环节从已有知识中提取基本原理,并应用于新知识的学习;提取学生的问题编制习题,让学生暴露产生问题的根源并从根本上解决。探讨了每课一题的必要性及其基本类型。 相似文献
216.
《Analytical letters》2012,45(8):1531-1543
ABSTRACT Three simple and sensitive spectrophotometric methods for the determination of ipratropium bromide (IPB) in liquid for nebulization are described. Method A, is based on the formation of a charge transfer complex with iodine. The reaction product is measured spectrophotometrically at 278 nm. Method B, is based oh the formation of an ion – association complex between the drug and an acidic dye, Bromocresol green (BCG), which is extractable into chloroform and has an absorption maximum at 418 nm. Method C, uses derivative spectrophotometry for the determination of IPB by measuring the D2-value at 232 nm. Beer's law is obeyed over the concentration range 1-10, 2-16 and 5-30 μg ml? for method A, B and C, respectively. The optimum conditions for the formation of the charge transfer or ion-association complexes were optimized. The proposed methods were applied for the determination of IPB in liquid for nebulization. Evaporation to dryness and extraction of the residue with isopropanol, were performed before application of methods A & B. Mean percentage recoveries were found to be 99.67 ± 0.79, 99.26 ± 1.06 and 100.21 ± 0.85 for method A, B, and C, respectively. 相似文献
217.
局部方差在图像质量评价中的应用 总被引:4,自引:0,他引:4
将灰度图像的局部方差分布(QLS)作为表征图像结构信息的一个重要特征,对局部方差分布矩阵进行奇异值分解,计算得到相应的奇异值特征向量;通过计算降质图像与原参考图像局部方差矩阵奇异值特征向量的夹角大小度量两图像的结构相似度,实现了对降质图像的质量评价。实验结果表明:局部方差分布更能突出图像的结构特征,评价结果优于传统的均方误差(MSE)、峰值信噪比(PSNR)、结构相似度(SSIM)以及直接评价图像像素分布的奇异值分析(SVD)等方法,与人眼视觉感知效果的一致性较好。 相似文献
218.
Bharathi Avula Babu L. Tekwani Narayan D. Chaurasiya NP Dhammika Nanayakkara Yan‐Hong Wang Shabana I. Khan Vijender R. Adelli Rajnish Sahu Mahmoud A. Elsohly James D. McChesney Ikhlas A. Khan Larry A. Walker 《Journal of mass spectrometry : JMS》2013,48(2):276-285
Therapeutic efficiency and hemolytic toxicity of primaquine (PQ), the only drug available for radical cure of relapsing vivax malaria are believed to be mediated by its metabolites. However, identification of these metabolites has remained a major challenge apparently due to low quantities and their reactive nature. Drug candidates labeled with stable isotopes afford convenient tools for tracking drug‐derived metabolites in complex matrices by liquid chromatography‐tandem mass spectrometry (LC‐MS‐MS) and filtering for masses with twin peaks attributable to the label. This study was undertaken to identify metabolites of PQ from an in vitro incubation of a 1:1 w/w mixture of 13C6‐PQ/PQ with primary human hepatocytes. Acquity ultra‐performance LC (UHPLC) was integrated with QTOF‐MS to combine the efficiency of separation with high sensitivity, selectivity of detection and accurate mass determination. UHPLC retention time, twin mass peaks with difference of 6 (originating from 13C6‐PQ/PQ), and MS‐MS fragmentation pattern were used for phenotyping. Besides carboxy‐PQ (cPQ), formed by oxidative deamination of PQ to an aldehyde and subsequent oxidation, several other metabolites were identified: including PQ alcohol, predictably generated by oxidative deamination of PQ to an aldehyde and subsequent reduction, its acetate and the alcohol's glucuronide conjugate. Trace amounts of quinone‐imine metabolites of PQ and cPQ were also detected which may be generated by hydroxylation of the PQ/cPQ quinoline ring at the 5‐position and subsequent oxidation. These findings shed additional light on the human hepatic metabolism of PQ, and the method can be applied for identification of reactive PQ metabolites generated in vivo in preclinical and clinical studies. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
219.
Preparation and Characterization of Cyclohexyl Moiety Toughened POSS-Reinforced Epoxy Nanocomposites
Polyhedral oligomeric silsesquioxane (POSS)-reinforced epoxy nanocomposites were prepared by reacting commercially available diglycidyl ether of bisphenol-A (DGEBA) and tetraglycidyl diamino diphenyl methane (TGDDM) epoxy resins with 1,1-bis(3-methyl-4-glycidyloxyphenyl)cyclohexane (Cy-Ep) separately and reinforced with POSS nanocluster. POSS (OAPS)-reinforced hybrid Cy-Ep-epoxy resin castings were characterized for their mechanical and morphological properties. The data obtained from mechanical studies indicated that the incorporation of nano OAPS into Cy-Ep modified hybrid systems results in improved stability. Among the epoxy systems studied, the TGDDM-based hybrid epoxy system exhibited higher values of tensile and flexural properties than that of the DGEBA hybrid epoxy system, whereas the impact strength of the DGEBA system was higher than that of the TGDDM system. The dispersion of POSS was confirmed by scanning electron microscopy and visual observation studies. 相似文献
220.