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本科生毕业论文质量关系着高等学校的教育质量、人才培养和学生科研创新能力的培养.论述了本科生毕业论文存在的重视程度不够、工作时间不足等问题,结合指导本科生毕业论文的工作实践经验,探讨了有效提高本科生毕业论文质量的关键. 相似文献
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对本科生毕业论文成绩评定方法的改进张国刘凤岐马荣堂(吉林大学材料科学系)(吉林大学化学系长春130023)本科生毕业论文工作是本科生教学中一个十分重要的环节。在完成毕业论文过程中,学生在导师的指导下把过去学到的理论知识用于解决某一具体科研课题,在文献... 相似文献
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化工类本科毕业设计存在的问题及其应对策略的探索与实践 总被引:1,自引:0,他引:1
毕业论文(设计)是化工类本科生培养计划中的一个重要环节。根据当前化工类本科学生毕业论文(设计)教学中存在的主要问题进行剖析,从选题、开题、指导、管理等几个方面进行了探讨和分析。 相似文献
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国家战略性新兴产业涉及到非常多的高分子材料产品和技术,属于高分子材料与工程专业的教学内容。同时,社会对复合型、应用型毕业生的需求量大。本文总结归纳了加强应用型的高分子材料与工程专业建设的教学实践经验,大力增强与产业发展联系紧密的教学内容,一批专业对口的大中型企业参与指导学生的创新实践活动,校企联合布置一批有创新性、产业急需的毕业论文课题,共同指导与评价学生的毕业论文。以学生能力为导向的校企协同育人,可强化应用型人才的创新能力与素质,提供与产业需求匹配度高的人才资源。 相似文献
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针对本科生参加科技实践活动对综合能力是否有影响的问题,通过跟踪调查及分析吉林大学化学学院2011级化学专业127名本科生,发现参与科技实践活动的52名学生的有机化学、物理化学、计算机应用基础等课程的平均成绩优于全体学生的平均成绩;在获得各项奖励的学生中,参与科技实践活动的学生占69.2%;在获得毕业论文优秀成绩的学生中,参与科技实践活动的学生占56.5%;在被"推免"攻读研究生(保研)的学生中,参与科技实践活动的学生占84.4%;在出国留学学生中,参与科技实践活动的学生占64.3%。可见,参与科技实践活动不仅不影响本科生的课程学习,而且会提升他们的综合能力。 相似文献
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为深入开展创新创业教育与实践,培养学生创新创业能力,提高本科生人才培养质量,进一步推动创新创业教育改革,南开大学开展了“国家级大学生创新创业训练计划”项目。化学学院结合学科自身特点,践行科教融合、理论联系实际的培养方法,不仅能够引导本科生积极参加科研训练,还能将本科生的创新结果应用于实际生产中。实现“科研反哺教学”与“教学支撑科研”这样一个相互补充、相互促进的统一体。本文介绍了一组比较典型的本科生参与“国创”项目的例子,从项目准备入手介绍了该“国创”项目的具体实施过程、同学们所遇困难及收获心得等,希望将我们积累的一些经验与化学相关专业的同学分享,助力他们更好地完成创新项目。 相似文献
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Charles H. Langley Diwakar M. Pawar Eric A. Noe 《Journal of Molecular Structure》2005,732(1-3):99-111
The optimized geometries, relative free energies and related thermodynamic properties, harmonic frequencies, and dipole moments have been calculated at the HF and MP2 levels for ethynyl formate (1a), ethynyl acetate (1b), cyano formate, HCO2CN (1c), cyano acetate (1d), S-ethynyl thioformate (2a), S-ethynyl thioacetate (2b), S-cyano thioformate (2c), S-cyano thioacetate (2d), N-ethynylformamide (3a), N-ethynylacetamide (3b), N-cyanoformamide (3c), and N-cyanoacetamide (3d) with the gaussian 98 program. For ethynyl formate, the calculation for 25 °C at the MP2/6-311++G(df,pd) level predicts that the Z isomer is more stable by 1.23 kcal/mol. For S-ethynyl thioformate, calculations at the MP2/6-311++G(2d,2p) level predict that the E isomer is favored by 0.71 kcal/mol at 25 °C. The E isomers of N-ethynylformamide and N-ethynylacetamide were found at all levels to be more stable than the Z isomers at 25 °C. For cyano formate and cyano acetate, calculations at the MP2/6-311++G(df,pd) level predict that the Z isomers are more stable at 25 °C by 1.50 and 2.72 kcal/mol, respectively. At this level and temperature, the Z isomers of 2c, 2d, 3c, and 3d are predicted to have free energies of 0.46, −0.07, 1.22, and 2.28 kcal/mol, respectively, relative to the E conformations. Z to E free-energy barriers at 25 °C of 8.63, 10.64, 17.63, 7.39, and 14.03 kcal/mol were calculated for 1a, 2a, 3a, 1c, and 3c at the HF/6-311G(d,p) level, and at the HF/6-311+G(d,p) level, the free-energy barrier for 2c was 7.08 kcal/mol. 相似文献
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Several kinds of tea, camomile and herbal tea were analysed to determine natural and artificial radioactivity. The radionuclides were determined by alpha (210Po) and gamma (228Ac, 214Pb, 214Bi, 210Pb, 40K and 137Cs) spectrometry. 228Ac ranged between 0.6 and 9.0 Bq kg−1dry; 210Po between 1.90 and 36.1 Bq kg−1dry; 214Pb and 214Bi between 0.7 and 4.9 Bq kg−1dry; 210Pb between < 10.0 and 58.9 Bq kg−1dry; 40K between 463 and 936 Bq kg−1dry; 137Cs between < 0.3 and 2.6 Bq kg−1dry. The percentage of 210Po extraction in infusion was also determined; the arithmetical mean value of percentage of 210Po extraction resulted 20.7 ± 7.50. 相似文献
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黎志明 《广东微量元素科学》2010,17(7):49-70
从心脑血管疾病的流行率、心脑血管疾病的元素病因、心脑血管疾病的元素诊断和心脑血管疾病的元素治疗等4个方面讨论了元素医学防治心脑血管疾病的临床意义。 相似文献
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阐述了SHAB规则,分类,酸碱软硬度的定量标度和理论解释。根据SHAB规则把体内微量元素分为Lewis硬酸,软酸与交界酸和硬碱,软碱与交界碱,体内不同体液和器官含有丰富的软硬配体,与各类软硬酸(金属离子)结合成不同稳定性的配合物,发挥其生物活性作用。 相似文献
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Gas chromatography-mass spectrometry (GC-MS) and liquid chromatography with fluorescence detection (LC-FL) methods have been proposed for the determination of low level nitrite and nitrate in biological, food and environmental samples. The methods include derivatization of aqueous nitrite with 2,3-diaminonaphthalene (DAN), enzymatic reduction of nitrate to nitrite, extraction with toluene and chromatographic analyses of highly fluorescent 2,3-naphthotriazole (NAT) derivative of nitrite by using GC-MS in selected-ion-monitoring (SIM) mode and LC-FL. Nitrite and nitrate ions in solid samples were extracted with 0.5 M aqueous NaOH by sonication. The recoveries of nitrite and nitrate ions based on GC-MS and LC-FL results were 98.40% and 98.10% and the precision of these methods, as indicated by the relative standard deviations (RSDs) were 1.00% for nitrite and 1.20% for nitrate, respectively. The limits of detection of the GC-MS in SIM mode and LC-FL methods based on S/N = 3 were 0.02 and 0.29 pg/ml for nitrite and 0.03 and 0.30 pg/ml for nitrate, respectively. 相似文献
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M. Gaber S. S. Al-Shihry A. A. El-Bindary 《Journal of Thermal Analysis and Calorimetry》2005,82(1):63-68
Summary Proton-ligand dissociation constant of 2-mercapto-5-(2-hydroxynaphthylideamino)-1,3,4-thiadiazole (MHT) and the stepwise stability
constants of its metal complexes were determined potentiometrically in 40 mass/mass% ethanol-water mixture containing 0.1
M KCl. The stabilities of the complexes follow the order: Cu2+>Ni2+>Co2+>Mn2+. The dissociation constant (pKH) of MHT and the stability constants (logK) of its metal complexes were determined at different temperatures and the corresponding thermodynamic parameters were calculated
and discussed. The proton dissociation process is non-spontaneous, endothermic and entropically unfavoured. The formation
of the metal complexes was found to be spontaneous, endothermic and entropically favoured. 相似文献
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Iwona A. Rutkowska Anna Wadas Ewelina Szaniawska Anna Chmielnicka Agnieszka Zlotorowicz Pawel J. Kulesza 《Current Opinion in Electrochemistry》2020
Copper- and copper oxide–based materials are, in principle, promising components (supports, reactive sites, and visible light–absorbing semiconductors) of electrocatalysts and photocathodes for reduction of carbon dioxide. Electrochemical and photoelectrochemical approaches are generally suitable for the low-temperature CO2-conversion to carbon-based simple organic fuels or utility chemicals.Different concepts of utilization, including nanostructuring, doping, admixing, preconditioning, modification, or functionalization of various copper- and copper oxide–based systems for catalytic electroreduction and photoelectrochemical reduction of CO2 are elucidated, as well as important strategies to enhance the systems' overall activity and stability are discussed. 相似文献
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The high-resolution (1)H, (13)C, (1)H-(1)H COSY and (1)H-(13)C COSY NMR spectra have been recorded in CDCl(3) for arylacetonitriles 1-12 and analyzed. The arylacetonitriles 3-7 exist in two isomeric forms E (methyl group is anti to cyano group) and Z (the methyl group is syn to cyano group) in solution. Normal chair conformation with equatorial orientations of phenyl rings at C-2 and C-6 for monocyclic nitriles 1 and 2, epimeric chair structure EC (axial configuration of methyl group at C-3) for both the E and Z isomers of arylacetonitrile derivatives (3-7) and a distorted boat form, B(3), for the N-acylacetonitrile derivatives (8-10) have been proposed based on NMR data. The bicyclic nitriles 11 and 12 exist in twin chair conformations in solution. DFT calculations and chemical shifts also support these conformations. Geometry optimizations for 1-12 were carried out according to density functional theory using B3LYP/6-31G(d,p) basis set and for 1 and 8 the theoretical geometrical parameters have been compared with those of single crystal measurements. 相似文献
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M. G. Voronkov O. M. Trofimova Yu. I. Bolgova L. V. Klyba L. I. Larina A. I. Albanov V. A. Pestunovich N. F. Chernov K. B. Petrushenko 《Chemistry of Heterocyclic Compounds》2003,39(12):1639-1644
We have synthesized 1- and 2-(trimethylsilylmethyl)- and 1- and 2-(trimethoxysilylmethyl)benzotriazoles by reaction of 1,2,3-benzotriazolylsodium with trimethyl- or trimethoxy(chloromethyl)silane. We obtained 1- and 2-(silatranylmethyl)benzotriazoles by transesterification of the latter with triethanolamine. 相似文献
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C. K. Kim M. Aguilar-vega D. R. Paul 《Journal of Polymer Science.Polymer Physics》1992,30(10):1131-1142
Dynamic mechanical and gas transport properties for homogeneous homopolymer blends and random copolymers of bisphenol-A and tetramethyl bisphenol-A polycarbonates (PC-TMPC) were determined. The gas transport measurements were performed at 35°C for the gases He, H2, O2, Ar, N2, CH4, and CO2. The results show that the copolymers have lower permeability, apparent diffusion, and solubility coefficients than the blends. Permeability coefficients for blends follow a semilogarithmic ideal mixing rule while copolymers exhibit negative deviations from this. Specific volume measurements show that the free volume available for gas transport is slightly larger in copolymers than in blends of the same composition. These apparently contradictory results may relate to the differences in local mode chain motions observed for the copolymer and blend series. The γ relaxation processes in PC and TMPC seem to operate independently in the blends (no intermolecular coupling) while there is clear evidence for intramolecular coupling in the copolymers. © 1992 John Wiley & Sons, Inc. 相似文献