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1.
大学化学实验课程是培养材料、化学、化工等专业人才应用基本操作和理论解决实际问题的综合性实践训练环节。文章探讨了当前大学化学实验发展由于受到仪器设备大型化、专业化、成本大、更新快等因素限制出现瓶颈,设计了线上线下混合实验教学模式,进行相应的软硬件建设,并开展线上线下混合式实验教学模式的改革与探索。该教学模式具有良好的教学效果,并且可复制可推广,为创新人才的培养和实验教学的创新提供了有益的借鉴。  相似文献   
2.
田成诗  刘怡 《运筹与管理》2021,30(9):232-239
随着我国经济进入高质量发展阶段,经济发展与碳排放之间的关系日益受到关注。本文基于1997~2016年省级面板数据,运用非参数广义加性混合模型研究了中国碳排放与经济发展的关系。文中,不可观测的时间相关效应和残差自相关结构被作为独立变量加入模型,收入效应和时间相关效应对碳排放的影响可能存在异质性也予以考虑。实证结果显示,东部和中部地区的最适模型中收入效应具有异质性,西部地区的最适模型中包含异质性时间相关效应;中国碳排放与经济发展之间不存在倒U型关系;在未来的节能减排工作中,应充分考虑中国经济发展阶段性、区域差异性及碳排放驱动因素的异质性。  相似文献   
3.
考虑授权再制造企业融资金额无法满足资金短缺需求的情况,构建资金约束下再制造企业的决策模型,研究初始资金及融资策略对再制造企业生产决策的影响。研究表明:资金约束下初始资金成为影响再制造企业生产决策的关键,同时授权费的增加会增大资金压力,限制其利润的增长;不论融资金额是否能满足资金短缺需求,再制造企业融资策略的选择都受初始资金限制,当其融资偏好为风险厌恶型时,可选择混合融资策略;在一定条件下再制造企业选择股权融资可提升再制造产品的社会效益。  相似文献   
4.
In order to solve the problem that single median filtering and gaussian filtering algorithm is not effective in suppressing impulse noise and poisson noise simultaneously in low illumination image, and the edge detail protection is insufficient, an open and close mix-median-gaussian (OCMMG) filtering algorithm based on field programmable gate array (FPGA) was proposed. Firstly, the minimum four-direction difference was used to detect the anomaly degree of each pixel point, the weight was allocated according to the threshold of pulse noise discrimination, and the first step was filtering. Then, the four-direction edge detection algorithm was used to extract image edges, and the second step was filtered according to the set edge confidence characterization value. Finally, the images collected by electron bombarded active pixel sensor (EBAPS) under the condition of 1×10−3 lx illumination were processed by FPGA in real time. The experimental results show that the FPGA processing results are consistent with the software simulation processing results. Compared with the median filtering and gaussian filtering algorithm, the peak signal-to-noise ratio (PSNR) of the algorithm is improved by 3.23% and 16.34%, the structural similarity is improved by 14.66% and 33.86%, and the edge retention index is improved by 0.49% and 4.21%, respectively, which can effectively remove the mixed noise of EBAPS image and meet the real-time requirements. © 2022 Editorial office of Journal of Applied Optics. All rights reserved.  相似文献   
5.
利用1H NMR技术研究了离子/非离子表面活性剂形成的二元混合体系,结果显示表面活性剂的混合导致各组分的临界胶束浓度(CMC)均比各自纯溶液有所降低,用吸附平衡理论清楚地解释了这个现象.通过定量分析,发现不同的表面活性剂混合使得其组分CMC降低的程度各异,可以理解为它们吸附于界面单分子吸附层上的分子之间相互作用的不同(相吸或相斥)引起的.由此揭示了"协同效应"的实质,可以为选择适当的表面活性剂类型和混合比例以达到预期的性能提供有力的参考.  相似文献   
6.
A rosin-based ester tertiary amine salt (RETAS) cationic surfactant was obtained using natural rosin as raw material. GC-MS of RETAS was detailed analyzed. The pH-responsive mechanism of rosin-based ester tertiary amine (RETA) and RETAS was confirmed by applying theoretical calculations about electrostatic potential maps of RETA and RETAS cation using Gaussian software. Mixed system surfactants were obtained by blending RETAS cationic surfactant with sodium dodecyl benzene sulfonate (SDBS) anionic surfactant. The binary mixed surfactant systems of RETAS and SDBS had obvious synergistic effect. The γcmc and CMC were 39.40?mN/m and 0.56?mmol/L at the optimum molar fraction of RETAS (α)?=?0.6, respectively. The stability time of emulsion with the optimum mixed system as emulsifier increased to 309?s at α?=?0.6. The emulsifying capacity of RETAS was much better than that of RETA. RETAS had pH-responsive targeted release and the optimum mixed system showed a relatively sustained drug release by using doxorubicin (DOX) as a model drug. These results indicate that RETAS surfactant and mixed system surfactant are both promising for applications in drug delivery and emulsification.  相似文献   
7.
In this paper, we consider a class of split mixed vector quasivariational inequality problems in real Hilbert spaces and establish new gap functions by using the method of the nonlinear scalarization function. Further, we obtain some error bounds for the underlying split mixed vector quasivariational inequality problems in terms of regularized gap functions. Finally, we give some examples to illustrate our results. The results obtained in this paper are new.  相似文献   
8.
Fe–Sn–O mixed oxides were synthesized and used as catalysts for Baeyer–Villiger oxidation of cyclohexanone, which showed both high catalytic activity and selectivity. X‐ray powder diffraction and scanning electron microscopy suggested that the Fe–Sn–O catalysts had a tetragonal structure with a grain size of 29.3 nm. An ε‐caprolactone yield as high as 98.8% was obtained in a small‐scale experiment (5 mmol of cyclohexanone). In a scale‐up test (20 mmol of cyclohexanone), the cyclohexanone conversion and ε‐caprolactone yield were 96.7 and 96.5%, respectively. In addition, the catalysts can be reused five times without any major decline in catalytic activity. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   
9.
A highly efficient catalytic system composed of a bifunctional polyacrylonitrile fiber (PANF‐PA[BnBr]) and a metal chloride was employed to produce 5‐hydroxymethylfurfural (HMF) from sucrose in mixed‐aqueous systems. The promoter of PANF‐PA[BnBr] incorporates protonic acid groups that promote the hydrolysis of the glycosidic bond to convert sucrose into glucose and fructose, and then catalyzes fructose dehydration to HMF, while the ammonium moiety may promote synergetically with the metal chloride the isomerization of glucose to fructose and transfer HMF from the aqueous to the organic phase. The detailed characterization by elemental analysis, FTIR spectroscopy, and SEM confirmed the rangeability of the fiber promoter during the modification and utilization processes. Excellent results in terms of high yield (72.8 %) of HMF, superior recyclability (6 cycles) of the process, and effective scale‐up and simple separation procedures of the catalytic system were obtained. Moreover, the prominent features (high strength, good flexibility, etc.) of the fibers are very attractive for fix‐bed reactor.  相似文献   
10.
We construct the Green function for the mixed boundary value problem for the linear Stokes system in a two‐dimensional Lipschitz domain.  相似文献   
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