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221.
Sovichea Lay Hai-ning Yu Bao-xiang Hu Sheng-rong Shen 《Journal of Zhejiang University. Science. B》2016,17(6):465-475
A pre-treatment methodology for clenbuterol hydrochloride (CLEN) isolation and enrichment in a complex matrix environment was developed through exploiting molecularly imprinted polymers (MIPs). CLEN-imprinted polymers were synthesized by the combined use of ally-β-cyclodextrin (ally-β-CD) and methacrylic acid (MAA), allyl-β-CD and acrylonitrile (AN), and allyl-β-CD and methyl methacrylate (MMA) as the binary functional monomers. MAA-linked allyl-β-CD MIPs (M-MAA) were characterized by Fourier transform-infrared (FT-IR) spectroscopy and a scanning electron microscope (SEM). Based upon the results, M-MAA polymers generally proved to be an excellent selective extraction compared to its references: AN-linked allyl-β-CD MIPs (M-AN) and MMA-linked allyl-β-CD MIPs (M-MMA). M-MAA polymers were eventually chosen to run through a molecularly imprinted solid-phase extraction (MISPE) micro-column to enrich CLEN residues spiked in pig livers. A high recovery was achieved, ranging from 91.03% to 96.76% with relative standard deviation (RSD) ≤4.45%. 相似文献
222.
Hui-ping Lin Jun Lin Juan Li Jing-hong Xu Christian Mehl 《Journal of Zhejiang University. Science. B》2016,17(11):864-873
Resin-dentin bond degradation is a major cause of restoration failures. The major aim of the current study was to evaluate the impact of a remineralization medium on collagen matrices of hybrid layers of three different adhesive resins using nanotechnology methods. Coronal dentin surfaces were prepared from freshly extracted premolars and bonded to composite resin using three adhesive resins (FluoroBond II, Xeno-III-Bond, and iBond). From each tooth, two central slabs were selected for the study. The slabs used as controls were immersed in a simulated body fluid (SBF). The experimental slabs were immersed in a Portland cement-based remineralization medium that contained two biomimetic analogs (biomineralization medium (BRM)). Eight slabs per group were retrieved after 1, 2, 3, and 4 months, respectively and immersed in Rhodamine B for 24 h. Confocal laser scanning microscopy was used to evaluate the permeability of hybrid layers to Rhodamine B. Data were analyzed by analysis of variance (ANOVA) and Tukey’s honest significant difference (HSD) tests. After four months, all BRM specimens exhibited a significantly smaller fluorescent area than SBF specimens, indicating a remineralization of the hybrid layer (P≤0.05). A clinically applicable biomimetic remineralization delivery system could potentially slow down bond degradation. 相似文献
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An excellent airfoil with a high lift-to-drag ratio may decrease oil consumption and enhance the voyage. Based on NACA 0012, an improved airfoil is explored in this paper. The class/shape function transformation has been proved to be a good method for airfoil parameterization, and in this paper it is modified to improve imitation accuracy. The computational fluid dynamics method is applied to obtain numerically the aerodynamic parameters of the parameterized airfoil, and the result is proved credible by comparison with available experimental data in the open literature. A polynomial-based response surface model and the uniform Latin hypercube sampling method are employed to decrease computational cost. Finally, the nonlinear programming by quadratic Lagrangian method is utilized to modify the multi-island genetic algorithm, which has an improved optimization effect than the method used on its own. The obtained result shows that the modified class/shape function transformation method produces a better imitation of an airfoil in the nose and tail regions than the original method, and that it will satisfy the tolerance zone of the model in a wind tunnel. The response surface model based on the uniform Latin hypercube sampling method gives an accurate prediction of the lift-to-drag ratio with changes in the design variables. The numerical result of the flow around the airfoil shows reasonable agreement with the experimental data graphically and quantitatively. Ultimately, an airfoil with better capacity than the original one is acquired using the multi-island genetic algorithm based nonlinear programming by quadratic Lagrangian optimization method. The pressure contours and lift-to-drag ratio along with the attack angle have been compared with those of the original airfoil, and the results demonstrate the strength of the optimized airfoil. The process for exploring an improved airfoil through parameterization to optimization is worth referencing in future work. 相似文献
225.
Shujie Liu Xianxuan Xu James H. Stronge 《Educational Assessment, Evaluation and Accountability》2016,28(2):161-177
Teacher performance evaluation currently is receiving unprecedented attention from policy makers, scholars, and practitioners worldwide. This study is one of the few studies of teacher perceptions regarding teacher performance measures that focus on China. We employed a quantitative dominant mixed research design to investigate Chinese teachers’ preferences for teacher performance measures and the possible reasons for their preferences. Considering the quantitative results, the surveyed Chinese teachers identified fulfillment of additional roles, collaboration with faculty and staff, and students’ test scores as the most important measures for performance evaluation. Qualitatively, the most important measures that the surveyed teachers reported were the teacher’s morality, workload, and students’ test scores. 相似文献
226.
技能训练要心智技能和操作技能相结合 总被引:1,自引:2,他引:1
讲练一体化教学是实现心智技能和操作技能相结合的有效途径.指导与示范是促进技能形成的关键。符合学生技能训练心理行为特征的要求是:目的明确,方法正确,由易到难,速度适当,方式多样,及时反馈。要运用学习迁移的原理,提高技能训练效果。 相似文献
227.
Christian Rullang Eike Emrich Christian Pierdzioch Freya Gassmann 《Sportwissenschaft》2016,46(4):275-286
Sports clubs depend on the pooling of resources by their members. The supportive distribution of the resources within a club is facilitated in particular by the effectiveness of incremental standards. A basic prerequisite for a fair distribution of resources is a minimum of community spirit among the members. Based on a nationwide survey of football clubs and an ordinal logistic regression model, factors were determined that reflect the extent of the community spirit within a club. The opening up of the club by payment to players and perceived problems with acquiring and binding of volunteers are associated with a reduction of community spirit. In contrast, the perception that the club activities can be continued in the long term shows a positive correlation to a highly developed community spirit. 相似文献
228.
三十多年来,广西的出版史料搜集、整理、出版和研究取得了显著成就。以《广西出版史志资料》为代表的史料编辑成果,收集了从雕版印刷时期到20世纪90年代末广西的出版史料,时间跨度大、史料翔实,展现了广西出版的历史与成就,为综合性的大型区域出版史的编写与当今的出版实践提供了重要的资源。 相似文献
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