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 78 毫秒
1.
环氧乙烷和环氧丙烷开环聚合   总被引:6,自引:0,他引:6  
张治国  尹红 《化学进展》2007,19(1):145-152
环氧乙烷和环氧丙烷的开环聚合产物在表面活性剂工业和聚氨酯工业得到了极为广泛的应用.本文综述了近几年来发展的用于环氧乙烷和环氧丙烷开环聚合的各类催化剂体系,分别讨论了各类催化剂体系对环氧乙烷和环氧丙烷的不同作用机制,考察了反应物结构对反应活性和选择性的影响,重点介绍了配位络合催化剂体系在环氧乙烷和环氧丙烷开环聚合反应中的应用,并指出了今后研究的方向.  相似文献   

2.
花粉蛋白和多糖的研究   总被引:1,自引:0,他引:1  
金声  许家喜  缪平 《有机化学》1993,13(2):202-205
从葡萄和罂粟花粉中分别纯化得RP3I和PSPP1-4肽, 测定了它们的生理活性,并合成了PSPP1以外的肽, 从Typha Angustifilia和codonopsis pilosula花粉获得了TA-C和CPA-E多糖, 并研究了它们的部份特征和结构。  相似文献   

3.
王梅祥 《化学进展》2018,30(5):463-475
本文介绍了杂杯芳烃和冠芳烃的研究起源,总结了杂杯芳烃和冠芳烃的设计与合成、构象和大环空腔结构特征,展示了杂杯芳烃和冠芳烃的分子识别和组装性质,概述了杂杯芳烃和冠芳烃在功能材料的制备中的应用,展望了大环超分子化学未来的发展方向。  相似文献   

4.
围绕新世纪应用化学创新人才培养模式和具体措施,确定了以理为主、理工融合为特点的培养方案,提出了课内教学和课外教学相结合的教学模式和累加式考核方法,明确了教学、科研同步发展的教学思想,并就师资队伍建设、专业教材更新和创新人才培养等方面展开了深入研究和实践。  相似文献   

5.
“先天不足”和“后天失调”的全球性“元素病”,引起了各国政府的关注。中国政府出台了一系列法律文件,成立了国家级的相应机构进行调研和治理。与此同时,加大了元素科学和生命科学的教育和宣传力度,取得可喜的成绩,控制了“碘缺乏病”和“硒缺乏病”,儿童锌缺乏率和儿童铅超标率下降。为了减少各种慢性病的发病率,  相似文献   

6.
苯并三唑和8-羟基喹啉对铜的缓蚀协同作用   总被引:12,自引:0,他引:12  
通过电化学极化曲线和电化学阻抗谱研究了苯并三唑(BTA)和8 羟基喹啉(HQ)对铜的缓蚀协同作用, BTA和HQ复配使用后提高了电极的膜电阻,降低了电极的膜电容,增强了对铜腐蚀的抑制作用.通过MM2分子力学程序和PPP SCF量子化学方法优化计算了BTA和HQ的分子结构参数,分析讨论了它们之间的缓蚀协同效应.  相似文献   

7.
钙钛矿型高温质子导体研究进展   总被引:7,自引:0,他引:7  
介绍了钙钛矿型和复合钙钛矿型化合物的结构、常用的制备方法和传导性质,详细分析了其传导机理,评述了其研究进展和在气体传感器、固体燃料电池、有机物加氢和脱氢以及常压电化学合成氨等方面的应用,展望了应用前景和发展趋向.  相似文献   

8.
《分析化学》2008,36(5):641
该书重点介绍了气相色谱的分析方法、常用技术和应用。内容涉及了气相色谱的基本原理、仪器的结构和操作方法及气相色谱的新发展和新技术。该书是《色谱技术丛书》之分册,在第一版基础上作了修改和充实,力求实用性、新颖性和典型性。例如,第四章集中介绍了气相色谱的各种进样技术,第五章介绍了毛细管一气相色谱的应用实例;  相似文献   

9.
均分散氧化钛粒子的制备研究   总被引:22,自引:0,他引:22  
用升温水解法制备了组成为TiO2的球形和椭球形均分散粒子。系统地研究了制备条件对粒子大小和形状的影响,用电子显微镜和红外光谱对粒子的形态和组成进行了分析。跟踪测定了均分散粒子形成过程中体系电导率的变化,探讨了均分散粒子的形成机制。  相似文献   

10.
多氯萘的来源及环境污染特征研究   总被引:2,自引:0,他引:2  
多氯萘(PCNs)具有和二口恶英类(PCDD/Fs)相似的结构和毒性,在全球的环境和生物样品中都能被检测到.本文介绍了环境中PCNs的主要来源和环境归宿,重点介绍了焚烧和金属冶炼等过程中PCNs的排放特征,归纳了当前全球环境介质和生物体中PCNs的污染水平和分布特征,对我国多种环境介质和生物体中PCNs污染水平和分布特征的相关研究进行了归纳和讨论.最后提出了PCNs相关研究领域研究进展与面临的挑战.  相似文献   

11.
Poly(hexafluoropropylene oxide), poly(HFPO), networks were prepared from functional polymers by end linking via urethane groups. The prepolymers were characterized by NMR spectroscopy and GPC. The networks were characterized by determination of the number of network chains from the shear modulus, and were snown to contain both trifunctional crosslinks and difunctional links. The properties of the networks were investigated by a range of techniques. Compared with fully-fluorinated networks formed via triazine cross-links, investigated previously, the urethane-linked networks were more readily prepared but were poorer elastomers, were less thermally stable, and were less resistant to swelling by common polar solvents. © 1995 John Wiley & Sons, Inc.  相似文献   

12.
Arachin and its molecular species (arachin I and arachin II) were separated and isolated. The number and kind of subunits of arachin, arachin I and arachin II were determined. Studies were carried out under different experimental conditions using slab gel electrophoresis, size-exclusion chromatography and reversed-phase high-performance liquid chromatography. Gel electrophoresis was done under varying concentrations of resolving gel. Tube gel as well as slab gel electrophoresis were used and continuous as well as discontinuous buffer systems were used for both types of electrophoresis. In addition, the subunits were separated by reversed-phase HPLC using a gradient program. Arachin and arachin II were found to have 12 subunits each while arachin I showed six subunits. The subunits of arachin I were allowed to reconstitute by removing SDS. Eight combinations were tried for studying the reconstitution pattern. Molecular weight and weight ratio in each case were also determined.  相似文献   

13.
对烘烤前后南瓜籽中的化学成分进行分析并对比。采用同时蒸馏萃取装置萃取南瓜籽中的挥发性成分,采取超临界CO2萃取技术萃取南瓜籽油脂,并将其分为酸、碱、中性三个部分,用气相色谱-质谱联用方法分析其中化学成分并进行对比。结果表明,南瓜籽挥发性成分中含有多种醛类和酯类化合物,烘烤后产生了大量的烷基吡嗪,其在碱性部分中的相对含量比烘烤前提高14倍多,不饱和醛类化合物含量也有明显提高。南瓜籽油脂中的主要化学成分是油酸、亚油酸及其酯类。还含有生物活性功能成分如植物甾醇、角鲨烯和维生素E等。烘烤后除角鲨烯含量有所降低,维生素E、植物甾醇、亚麻酸等均有提高。  相似文献   

14.
A series of binary and ternary rare earth complexes with para-substitued benzoic acids and 1,10-phenanthroline were synthesized. The phosphorescence spectra were measured and the lowest triplet state energies of ligands were determined, the phosphorescence lifetimes were obtained and intramolecular energy transfer mechanism between ligands was studied. The luminescence properties were also measured and were in agreement with the prediction. The energy match and intramolecular energy transfer process in these binary and ternary complexes were discussed in detail.  相似文献   

15.
A new styryl dye were prepared, 2-[2-(4-dipropylamino-phenyl)-vinyl]-1,3,3-trimethyl-3H-indolium chloride (DPPTVI) chloride. Its infrared and Raman were measured. Quantum chemical calculations were computed for both the isolated and the solute cation. Optimized geometry, atomic net charges were calculated. The calculated vibrational frequencies were scaled to the experimental ones. Only 12 scale factors were used for the scaling of 174 vibrational modes. Based on these results, normal coordinate analysis were carried out for both the isolated and the solute cations. Infrared and Raman spectra were simulated. The results for the isolated and the solute cations were compared.  相似文献   

16.
Several benzimidazole derivatives having electron-withdrawing or -donating substituent(s) at the benzene moiety were used as models of the imidazole moiety of purine bases and their nitration with nitrogen dioxide and ozone (so-called Kyodai nitration) were examined. Products were extracted from the reaction mixture with AcOEt and their structures were analyzed. 1-Nitrobenzimidazole derivatives and unexpected 1-nitrobenzotriazole derivatives were identified. Although the yields of 1-nitrobenzimidazole derivatives were quite low, these were all new compounds that could be obtained only by Kyodai nitration. It was speculated that benzotriazoles were formed via 1-nitrobenzimidazoles and subsequent nitration toward benzotriazoles resulted in the formation of 1-nitrobenzotriazoles.  相似文献   

17.
利用密度泛函理论方法研究了IClO2异构化反应机理. 优化得到了七种异构体, 其中OIClO和IClOO还未见报道, 对各异构体的热力学稳定性进行了比较. 找到了异构化过程的过渡态, 并通过内禀反应坐标(IRC)计算确认了各个异构体之间的相互转化关系. 从量子拓扑学的角度, 对典型异构化反应通道IRC途径上的各点进行了电子密度拓扑分析, 讨论了反应过程中化学键的断裂、生成以及化学键的变化规律, 找到了反应途径上的能量过渡态(ETS)和结构过渡态(STS).  相似文献   

18.
Bacterial proteomes were analyzed by use of electrophoretically mediated microanalysis (EMMA) and field-enhanced stacking. A water-soluble protein fraction was injected onto a capillary. Next, a fluorogenic reagent was injected and allowed to react with the protein mixture, producing fluorescent products that were separated by submicellar capillary electrophoresis and detected by laser-induced fluorescence. By use of a low-ionic strength sample buffer and a brief electrophoretic step, slow moving anionic proteins were stacked at the reagent-sample interface and were preferentially labeled. By reversing the order of sample injection and labeling reagent, fast moving cationic proteins were preferentially labeled. By adjustment of the sample buffer pH, proteins with different isoelectric points were selectively labeled. Electrophoresis fingerprints were generated for the water-soluble protein fraction from six Staphylococcus species. The protein patterns produced were species-specific and were used to construct a phylogenetic tree.  相似文献   

19.
《Colloids and Surfaces》1989,23(3):231-240
Densities and surface tensions of 2-propanol+dichloromethane and n-pentane+methylacetate mixtures were determined over the whole composition range at 298.15 K, by the maximum bubble pressure method. Positive excess surface tensions were observed in the first mixture and negative excess surface tensions were observed in the second mixture. Different equations existing in the literature were applied and calculated values were compared with the experimental ones. Hoar and Melford's equations were the best.  相似文献   

20.
以过氧化二苯甲酰为引发剂,使丙烯睛在涤沦(PET)纤维上接枝共聚。接枝纤维在含铜化合物,含硫还原剂溶液中反应,制备PET导电纤维。讨论了影响接枝共聚的各种因素,选择出最佳聚合条件。对该纤维的导电成份和结构以及性能进行了研究。  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