首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 109 毫秒
1.
系统梳理了电离、离子反应专题的已有研究,分析了电离、离子反应内容对学生认识发展的作用,进而确立了化学1模块电离、离子反应专题的教学论问题并进行了阐述分析。在上述研究的基础上,设计了化学1模块电离、离子反应专题的单元整体教学,并进行了教学实践,取得了较好的教学效果。  相似文献   

2.
基于工程教育专业认证标准的要求,结合专业课程的特点,对我校制药工程专业的分析化学实验教学大纲进行了标准化改造。标准化的教学大纲更加突出了专业适用性,关联了教学要求与教学内容和考核评定,增加了考核量化指标与课程持续改进的方式,进一步规范了分析化学实验课程的教学。标准教学大纲的构建为实验教学活动提供了更加明确的指导,有利于缩小不同教师教学的差异性,保证了实验教学的质量,为建立可持续完善的工程类实验教学标准体系提供了具体参考。  相似文献   

3.
储氢合金电极的表面修饰研究   总被引:1,自引:0,他引:1  
杨凯  吴锋  李丽  王敬 《物理化学学报》2003,19(12):1167-1170
利用等离子体技术对AA型MH/Ni电池的储氢合金电极进行了镀覆导电膜层的表面修饰,用XRD及SEM对电极结构进行了表征.极片经过表面修饰的电池,其内阻降低了24%,放电容量有了明显提高,5C (7.5 A) 放电容量提高了200 mA•h,放电平台电压提高了约0.14 V,导电膜层还起到了电极保护层的作用,抑制了合金的粉化,提高了电池的循环稳定性.同时,电池内压显著降低,电池性能有了较大改善.  相似文献   

4.
前言     
自20世纪初期,德国化学家EmilFischer首先合成了甘氨酸二肽片段,并第一次提出“peptide”(多肽)这一名词,多肽化学的研究已经历了100多年的发展.1953年,Vigneand小组首次完成了生物活性肽催产素的合成,并因此于1955年获得了诺贝尔化学奖.1963年,Merrifield提出了多肽固相合成法,并发明了第一台多肽自动合成仪,大大简化了多肽合成的流程、提高了合成的效率,从而促使多肽化学实现了飞跃式发展,Merrifield也因此获得了1984年诺贝尔化学奖.1965年,我国科学家完成了牛结晶胰岛素的合成,  相似文献   

5.
对单组分非理想气体,推导了它的逸度因子的微分方程式。对多组分非理想气体,推导了各组分逸度因子满足的微分方程式,定义了一个总逸度因子,并找到了总逸度因子和各组分逸度因子之间的关系。同样,对非理想溶液,推导了各组分活度系数满足的微分方程式,定义了非理想溶液的总活度系数,并找到了两者满足的关系。最后分析了逸度因子和活度系数之间的异同点。  相似文献   

6.
杜鹃花科植物有毒成分的电子结构及构效关系   总被引:10,自引:0,他引:10  
本文应用INDO方法, 对由杜鹃花科植物中提取分离的九个化合物进行了量子化学计算, 得到了分子轨道波函数等多种电子结构信息, 并计算了这些化合物活性部位的分子静电势, 得到了静电势图。用分子图形技术与药理性质相同的其它生物碱类毒素进行了空间结构比较。研究了它们的电子结构特征和活性部位, 讨论了作用机理及电子结构与毒性之间的关系。  相似文献   

7.
左旋薄荷醇的合成现状及进展   总被引:1,自引:0,他引:1  
陈旭敏  黄山  陆涛  赵小龙  姜标 《有机化学》2009,29(6):884-890
阐述了左旋薄荷醇的理化性质及其应用现状和全球生产状况. 介绍了薄荷醇的合成思路、已经工业化的合成路线和一些有较高工业应用价值的路线, 并介绍了关于这些路线的最新研究进展. 最后对所介绍的路线进行了总结, 展望了其发展前景.  相似文献   

8.
药用基础实验化学教学改革   总被引:2,自引:0,他引:2  
对药用基础实验化学教学进行了改革探索,加强了教学管理,强化了基础实验和基本技能训练,增强了与专业课相适应的应用性实验和研究性实验。  相似文献   

9.
阎存仙  刘洪霖 《化学学报》1985,43(4):322-326
本文应用X射线光电子能谱技术测得了气态肼的内层电子能谱、Auger电子能谱和价带电子能谱,对其电子结构进行了系统研究。又采用了不同能量的X射线为激发源,对比了Mg Ka 和 Zr M:价带能谱,定性地获得了肼的分子轨道的组成。本文对肼电子能谱进行了量子化学研究,用从头计算法给出了分子轨道波函数的成分,并指认了能谱,实验结果和计算值之间的一致性很好。  相似文献   

10.
铁酸镁超微粒子的制备及结构特征   总被引:2,自引:0,他引:2  
采用两种方法制得了尖晶石结构纯相MgFe2O4样品.Moessbauer分析发现,一种样品表现出了完全的超顺磁性,另一种表现出了部分超顺磁性.这揭示出了样品具有很小的粒子尺度.首次在实验上发现了MgFe2O4IR-V2谱带的劈裂现象,报导了拉曼光谱,通过ESR分析,进一步揭示了两样品的结构特征,并讨论了性质之间的相关性。  相似文献   

11.
研究了硬段侧链含有氟化双季铵盐的系列聚氨酯(FQPUs)的表面性能和抗菌性能. 水接触角测试和表面自由能测试结果表明, 加入少量氟化双季铵盐扩链剂, 可以使聚氨酯表面富集氟碳链, 氟化双季铵盐聚氨酯表面自由能很低, 具有很好的抗黏附性能. 迁移到表面的两条氟碳链在常温下不会发生链反转, 使材料的抗黏附性能得以保持. 同时, 使材料表面形成一层疏水层, 减小材料的吸水率. XPS研究结果表明, 氟碳链的-CF3位于材料的最外层, 材料的次表面是具有良好杀菌性能的双季铵盐, 这样形成了具有多重抗菌性能的表面. 另外, XPS研究结果表明, 材料表面化学结构与材料本体的微相分离结构相关. 抗菌性能测试结果表明, 氟化双季铵盐聚氨酯抗金黄色葡萄球菌的能力很强, 对于大肠杆菌的抗菌效果有所下降, 但相对于单季铵盐聚氨酯的抗菌效果有一定提高.  相似文献   

12.
傅强 《高分子科学》2004,(6):559-566
INTRODUCTIONPolyurethanes (PU) have been widely used for manufacturing medical devices because of their excellentmechanical properties and moderate biocompatibility[1]. Although polyurethanes used in applications requiringall of the above properties have been successful for short-term use, the problems of long-term thromboresistanceand biostability in a biological environment still remain unsolved[2,3]. A legitimate approach to improving theproperties of polyurethanes is introduction of f…  相似文献   

13.
水性含氟聚氨酯的研究进展   总被引:9,自引:0,他引:9  
水性含氟聚氨酯具有低的VOC排放,同时由于氟元素的引入,解决了传统水性聚氨酯耐水、耐油性差的缺点,大大拓展了其在涂料、皮革、油墨等领域的应用范围,因此受到广泛关注.本文综述了近年来国内外水性含氟聚氨酯的主要研究进展,综合比较了两种合成水性含氟聚氨酯主要方法,即核壳乳液聚合法和缩聚共聚法的各自特点,并对由两种不同方法制备的水性含氟聚氨的性能进行了讨论.  相似文献   

14.
A novel fluorinated polyurethane (FPU) with fluorine-containing pendent groups was prepared by using fluorinated polyether glycol (PTMG-g-HFP) as a soft segment, 1,6-hexamethylene diisocyanate (HDI) or toluene diisocyanate (TD1) as a hard segment and 1,4-butanodiol (BDO) as a chain extender. FTIR, ^1H NMR, ^13C NMR and GPC were used to characterize the structure of the fluorinated polyurethane. Thermal stabilities of the fluorinated polyurethane and the corresponding hydrogenated polyurethane were studied by TGA. XPS analysis at two different sampling depths for the fluorinated polyurethane was used to investigate the surface compositions of FPU. The results showed the fluorine enrichment on the surface of FPU.  相似文献   

15.
The effects of soft segment length on the variations in morphology, surface composition, and hydrophilicity have been studied in fluorinated polyurethanes (FPUs) and correlated with their preliminary blood compatibility as evidenced by in vitro platelet adhesion experiments. The fluorinated polyurethanes were obtained using hexamethylene diisocyanate (HDI) and chain extender of 2,2,3,3-tetrafluoro-1,4-butanediol (TF) as the hard segment as well as various soft segments—polytetramethyl oxides (PTMO) with molecular weights of 650, 1000, 1400, and 2000. The increased phase separation in hard-segment domains with lengthening soft segment was observed by FT-IR, which is believed to result in enhanced strength of hydrogen bonds and good hard-segment order arrangement. Thin-film XRD results indicate at least three lateral distances existing between adjacent hard segments in the crystallized hard segment. Their distribution depends strongly on the length of soft segment. Lengthening soft segment promotes the formation of dense arrangement of crystallized hard segments. Compared with the effect of phase separation, surface composition was found to exert a major influence on the preliminary blood compatibility of fluorinated polyurethanes. Increasing fluorine content by decreasing soft segment length promotes reduction in platelet adhesion and activation on polyurethane surfaces.  相似文献   

16.
A novel fluorinated polyurethane (FPU) was prepared by fluorinated polyether glycol (PTMG-g-HFP) as a soft segment, 1,6-hexamethylene diisocyanate (HDI) or toluene diisocyanate (TDI) as a hard segment and 1,4-butanodiol (BDO) as a chain extender. Fourier transform infrared spectroscopy (FTIR), 1H NMR, 13C NMR and gel permeation chromatography (GPC) were used to characterize the structure of the fluorinated polyurethane. The thermal stabilities of the fluorinated polyurethane and the corresponding hydrogenated polyurethane were studied by thermogravimetric analysis (TGA). X-ray photoelectron spectroscopy (XPS) analysis at two different sampling depths for the fluorinated polyurethane was used to investigate the surface compositions of FPU. And the mechanical properties of the fluorinated polyurethane and the corresponding hydrogenated polyurethane were also measured. Chemical resistance of polyurethane films was estimated through spot tests with different solvents. The results showed that FPU had high thermal stability, strain-hardening property and good chemical resistance. The XPS measurements showed the fluorine enrichment on the surface of FPU.  相似文献   

17.
Novel fluorinated polyurethane hybrid latexes in the size range of 40–50 nm, fluoroalkyl acrylate as fluorinated monomers, with various fluorine content (F% = 9∼26 wt%) were successfully prepared via emulsion polymerization process without traditional emulsifier. The waterborne polyurethane, which was synthesized by using isophronediisocyanate, dimethylol propionic acid, polyethylene glycols, etc., served not only as copolymerizable macromonomer but also as polymeric high molecular weight emulsifier. The structures of polyurethane macromonomer and fluorinated polyurethane were characterized by Fourier transform infrared and H1-NMR. Particle size, zeta potential, micromorphology of the latex par.ticles, and surface properties were investigated by dynamic light scattering, potential particle size analyzer, transmission electron microscopy, and contact angle measurement, respectively. Results illustrated that the advantage of this process is that the size of fluorinated polyurethane hybrid particle is less sensitive to the composition. Furthermore, it was showed that fluorinated polyurethane latex particles had core-shell structures, especially when the content of fluorine was 26.08 wt%. Moreover, there was an obvious migration of fluorinated groups to the surface during the formation of fluorinated polymer films, although fluorinated groups were covered by polyurethane in latex particles.  相似文献   

18.
Li  Ning  Zeng  Fang-Lei  Wang  Yu  Qu  De-Zhi  Zhang  Chun  Li  Juan  Huo  Jin-Zhao  Bai  Yong-Ping 《高分子科学》2018,36(1):85-97
In this study, two fluorinated polyurethanes(FPU) containing carborane groups in the main chains were firstly designed and synthesized via the reaction of hexamethylene diisocyanate trimer(HDI trimer) with fluorinated polyesters(CFPETs) having hydroxyl-terminated carborane groups at room temperature. The structures of carborane fluorinated polyesters(CFPETs) and polyurethanes(CFPUs) were characterized by gel permeation chromatography(GPC), Fourier transform infrared(FTIR) spectroscopy and nuclear magnetic resonance(NMR) measurements. The thermal stability, mechanical properties, Shore A hardness, solvent resistance and acid-alkali resistance of the carborane fluorinated polyurethane films were also studied. Thermogravimetric analysis(TGA) tests manifested that the introduction of carborane groups into the main chain of fluorinated polyurethane endowed the obtained fluorinated polyurethane with excellent thermal stability. The thermal decomposition temperature of carborane fluorinated polyurethane(CFPU) increased by 190 °C compared with that of the carborane-free fluorinated polyurethane(FPU). Even at 800 °C, CFPU showed the char yield of 66.5%, which was higher than that of FPU(34.3%). The carborane-containing fluorinated polyurethanes also showed excellent chemical resistance and prominent mechanical property even after the cured films being immersed into Jet aircraft oil or 37% HCl for 168 h or at high temperature(700 °C). It is found that the structural characteristics of carborane group and the compacted structure of CFPU effectively improve the thermal stability, mechanical property, solvent resistance and acid-alkali resistance of the carborane-free fluorinated polyurethane. These excellent properties make CFPU as the useful raw materials to prepare the high temperature resistant coatings or adhesives for automotive engines, engine or fuel tank of aircraft and other equipment working in high-temperature or high concentrations of acid-alkali environments.  相似文献   

19.
The surface phase separated structure of polyurethanes is always desired due to the advantage of better biocompatibility, compared with the homogeneous one. The key issue is how to control and characterize the surface morphology. In this work, we report the uppermost surface morphology of fluorinated poly(carbonate urethane)s with fluorinated side chains attached to hard segments as studied by AFM, XPS and contact angle measurement. A self-assembled micro-domain with the fluorinated side chain standing up on the uppermost surface has been proposed for polyurethane with higher fluorinated content, based on the result obtained  相似文献   

20.
For the first time, through macromonomer radical copolymerization, a novel fluorinated polyurethane (FPU) was synthesized based on partly acrylate-endcapped polyurethane macromonomers with hexafluorobutyl acrylate (HFBA). Partly acrylate-endcapped polyurethane (PU) macromonomers were synthesized using isophronediisocyanate (IPDI), dimethylol propionic acid (DMPA), polyethylene adipate glycols (PEA) etc. The novel fluorinated polymer, which bore PU side chains and fluorinated side chains, was confirmed by F19 NMR spectroscopy, X-ray photoelectron spectroscopy (XPS), elemental analysis, scanning electron spectroscopy (SEM) etc. Copolymerization of polyurethane macromonomers with hexafluorobutyl acrylate (HFBA) was briefly investigated. The surface tension of FPU solution was measured and showed sharply decrease compared to that of pure polyurethane. Results from SEM showed a uniform size distribution of phase micro-domains on the fracture surface of FPU.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号