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1.
在3.0-5.0 GPa,1150-1750 ℃,1-480 min条件范围内,合成了钠铝辉石,通过XRD、SEM及IR分析对比研究了人工翡翠和天然翡翠的微观精细结构;通过DAT分析测定了人工翡翠与天然翡翠的熔点,淬火实验检验了人工翡翠的熔点,通过退火及老化实验研究了翡翠的热稳定性。同时还就人工翡翠和天然翡翠的硬度、密度及折射率等其它物化性质进行了比较研究。根据上述研究总结了合成优质钠铝辉石翡翠的最佳实验条件为压力>4.0 GPa,温度>1450 ℃,晶化时间>45 min。  相似文献   

2.
培养研究型的中学化学教师   总被引:1,自引:0,他引:1  
沈理明 《化学教育》2003,24(7):15-16
中国基础教育的改革,需要研究型的中学化学教师。本文阐述了从研究素质结构入手,构建课程体系及教学模式,培养师范生的教学技能及教学研究能力。  相似文献   

3.
应用循环伏安法,现场紫外可见光谱电化学方法及现场FT-IR光谱电化学方法研究了标题配合物不同氧化状态的电位及光谱特征,指认了各步电极反应发生的点位,研究了硝基对不同氧化态金属卟啉电学性质,光谱性质的影响。  相似文献   

4.
全无机富勒类及骨架掺杂富勒烯的研究,是当前富勒烯研究中的热点课题之一,由于全无机富勒烯及骨架掺杂富勒烯在分子结构,电子结构及电、磁学性质上都有独到之处,对它们的研究,不仅在理论上有重大意义,而且在应用上也有望获得新型功能材料,本文对全机无富勒烯及骨架掺杂富勒烯的研究进行了评述与分析。  相似文献   

5.
魏春英  杨频 《化学进展》2002,14(4):246-250
本文主要对国内稀土离子跨膜运输研究的进展作了评述,着重介绍了用荧光法及膜片钳法研究的结果,并对该领域的研究前景作了展望。  相似文献   

6.
金属抗癌剂研究进展与两极互补理论   总被引:8,自引:0,他引:8  
介绍了铂,钛,钌,锡及金属茂配合抗癌活性及作用机理研究的最新进展和90年代金属抗癌剂研究的新动向。并简要介绍了两极互补理论,该理论概括了金属抗癌剂的分子结构,作用方式。立体选择性的特点,对金属抗癌剂的分子设计具有指导意义。  相似文献   

7.
单壁碳纳米管的结构修饰   总被引:7,自引:0,他引:7  
朱为宏  朱世琴  田禾 《有机化学》2002,22(12):964-973
由于单壁碳纳米管具有独特的结构、电学及机械等性能,可望在许多新领域得 到应用,已引起广泛的关注。但由于单壁碳纳米管不溶于水和常见的有机溶剂,极 大地制约了其应用性能的研究。随着单壁碳纳米管制备技术的不断完善,其研究方 向已开始转向结构修饰及应用性能的研究。主要介绍近年来单壁碳纳米管结构修饰 方面的最新发展状况,重点讨论化学功能化及物理吸附。  相似文献   

8.
成都市大气颗粒物的特性研究   总被引:11,自引:1,他引:11  
以成都市东区为研究区域,研究了该区总悬浮颗粒物(哪)含量及其中重金属的含量随季节变化的特征,通过粉煤灰与哪中重金属含量的关系、富集因子分析来判断颗粒物中重金属的来源。研究表明,TSP及其中重金属的含量随季节变化明显且特征相似;哪的含量严重超标;由监测结果大致推断出了该区域哪及其中重金属的主要来源。  相似文献   

9.
新型微量元素制剂——复合蛋白锌的基础研究与临床应用   总被引:4,自引:0,他引:4  
报道了复合蛋白锌基础研究与临床应用,进行了理化性质的研究,试验结果证明本品系锌与氨基酸、蛋白质形成的复合物,属有机锌。药理学研究表明,对小鼠精神神经系统、心血管系统及呼吸系统等均无明显影响,进行了毒理研究、急性毒性试验,相当于临床用量的125倍,动物健康生存,无毒性反应;长期毒性试验,连续6个月服用复合蛋白锌,剂理相当于用量的25.5倍及51倍,未观察到的动物死亡及毒性反应;经检查血常规、血液生化  相似文献   

10.
对二氧环己酮—乙交酯共聚物的合成及性能研究   总被引:3,自引:0,他引:3  
本文研究了对二氧环己酮与乙交酯无规共聚物的化学结构,热性能。体外降解性能及共聚反应动力学。研究结果表明,随着单体配比中乙交酯含量的增加,共聚物中乙交酯含量增加,共聚物结晶能力下降,玻璃化转变温度升高,降解速率加快。随着聚合反应时间的延长,单体转化率及聚合物分子量不断增加。聚合时间超过96小时后,转化率及分子量变化趋于平缓。  相似文献   

11.
Macroporous hydrogels are characterized by large pore sizes, high pore volumes, and high specific surface area. Besides these characteristics, macroporous hydrogels based on thermally reversible polymers respond to temperature changes much faster than hydrogels prepared by a conventional method. Crosslinked poly(N-isopropylacrylamide) (polyNIPAAm) forms a thermally reversible hydrogel which shows a lower critical solution temperature (LCST) ca. 33°C in aqueous solutions. We have synthesized thermally reversible polyNIPAAm hydrogels having macroporous structures by a new method. These macroporous hydrogels have large pore volumes, large average pore sizes, and faster macromolecule permeation rates in comparison to conventional polyNIPAAm hydrogels synthesized by a conventional method. Compared with conventional polyNIPAAm hydrogels, the macroporous polyNIPAAm hydrogels have higher swelling ratios at temperatures below the LCST and exhibit faster deswelling and reswelling rates. The deswelling rates are especially rapid. These thermally reversible macroporous hydrogels may be very useful in controlled active agent delivery and toxin removal, as well as dewatering of solutions. Peptides or proteins may behave as if they were in bulk solution within the large aqueous pores, and this may reduce their inactivation when such gels are used for their storage and later release. The gels may also be useful in microrobotic devices due to their fast response to temperature. © 1992 John Wiley & Sons, Inc.  相似文献   

12.
Suwa  K.  Yamamoto  K.  Akashi  M.  Takano  K.  Tanaka  N.  Kunugi  S. 《Colloid and polymer science》1998,276(6):529-533
 We examined the effects of salt on the lower critical solution temperature (LCST) and lower critical solution pressure (LCSP) of aqueous solutions of poly (N-vinylisobutyramide), polyNVIBA, and compared them with those on poly(N-isopropylacrylamide), polyNIPAAm. We found that the addition of salt (such as Na2SO4, NaCl, or KCl) decreased the LCST of aqueous polyNVIBA from 45 °C to below 20 °C, almost linearly with the salt concentrations and dependent on the type of salt. We observed a similar concentration-dependent decrease in LCST for polyNIPAAm. When KI or NaSCN was added to each aqueous polymer solution, some smaller increases in LCST were observed at relatively low salt concentrations; higher concentrations of salt gave an almost linear decrease in LCST. As for LCSP, the addition of most types of salt lowered the transition pressure, but the effects were much more dependent on the type and the valence of the salt (especially of anion) in both polymers. Salt with divalent anion showed a larger decrease in LCSP, but those with mono valent anion showed a relatively small decrease, even showed a slight increase at lower salt concentrations in the case of polyNVIBA. Salt with I- or SCN- showed evident increases in LCSP up to 1 M and was maintained higher than the control even at 2 M. We discuss the interactions of the amide group in the side chains of polymers and water and their perturbation by ions. Received: 13 November 1997 Accepted: 22 January 1998  相似文献   

13.
Thermosensitive microspheres with 0.4–1.2 μm diameter consisting of a polystyrene core and poly(N-isopropylacrylamide) (polyNIPAAm) branches on their surfaces were prepared by the free radical polymerization of a polyNIPAAm macromonomer and styrene in ethanol. Electron spectroscopy for chemical analysis (ESCA) of the microsphere surface suggested that polyNIPAAm chains were favorably located on the surface of the microspheres. The morphology of the microspheres was observed by transmission electron micrograph (TEM) and the particle size of was estimated by submicron particle analyzer. The molecular weight of the polyNIPAAm macromonomer, the ratio of the macromonomer and styrene, and the polymerization temperature affected the particle size. Thermosensitive properties of polyNIPAAm-coated polystyrene microspheres were evaluated by the turbidity of their dispersion solutions and the hydrodynamic size of the miocrospheres. The transmittance in dispersion solutions changed clearly, similar to oligoNIPAAm and polyNIPAAm macromonomers. In addition, the particle size of microspheres decreased with rising temperature. These results were explained by the thermosensitivity of polyNIPAAm branches on the microsphere surface. © 1996 John Wiley & Sons, Inc.  相似文献   

14.
Monodisperse hydrogel beads composed of calcium alginate and crosslinked polyNIPAAm (N-isopropylacrylamide) were synthesized based on a simultaneous interpenetrating network process. With increasing the temperature above the phase transition temperature of polyNIPAAm, a core-shell type of hydrogel beads was developed; polyNIPAAm-enriched core region and Ca-alginate-enriched outer shell layer were observed. The thermally reversible formation of the core-shell double structure in the IPN hydrogel beads was applied for the temperature modulated drug release using indomethacin as a model drug.  相似文献   

15.
Free radical polymerization of N‐isopropylacrylamide (NIPAAm) and crosslinker solutions, which were fulfilled in silica particles with an interpenetrated and nanometer‐sized porous structure (a diameter of 3 mm and mean pore sizes of 15, 30, and 50 nm), fabricated hybrids of organic hydrogels and inorganic silica. Differential scanning calorimetric analyses of the hybrids revealed that silica components affected the thermoresponsive properties of polyNIPAAm hydrogels. Porous polyNIPAAm hydrogels were prepared by the subsequent acid treatment of the hybrids to remove silica. Transmission Fourier transformed infrared spectra indicated the selective extraction of silica. Scanning electron microscopic observation of the hydrogels confirmed the porous structure. The deswelling rate of porous hydrogels was 7 times larger than that of conventional hydrogels and increased with increasing the pore size of silica used. However, the swelling was not affected by the pore formation. The thermoresponsiveness of porous polyNIPAAm hydrogels could be regulated by the pore size. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 3542–3547, 2002  相似文献   

16.
氟碳端基聚合物合成及其表面吸附性能   总被引:5,自引:0,他引:5  
综述了近十年来氟端基聚合物的合成,表征及其在表面吸附行为的研究成果。通过含有氟烷基的引发剂或终止剂在活性阴离子聚合反应或自由基聚合反应中使聚合物接上氟端基。已经成功地利用活性阴离子聚合反应合成了氟端基聚苯乙烯,通过含氟自由基引发烯类单体(如丙烯酸,乙烯硅等)可在相应聚合物链上引入氟端基,另外,聚合物的化学改性方法也可将氟基团接在聚合物链端(如氟基聚氧乙烯,氟端基聚合物具有的表面活性,当水溶液中或聚  相似文献   

17.
Soluble Hf-containing polymers are significant processable precursors for the fabrication of ultra-high temperature ceramics. In this work, cyclic Hf-Schiff base polymers were synthesized via direct polymerization of hafnium alkoxide and bis-salen monomers. The defined structure and molecular weight of the polymers were characterized by NMR spectroscopy, gel permeation chromatography and MALDI-TOF mass spectroscopy. The feed ratio of monomers regulated the molecular weight and solubility of the polymers. This synthetic strategy features simple operation under ambient conditions, efficient reaction with high yield and cyclic polymers as the main products. The Hf-Schiff base polymers were converted to HfC/C materials after pyrolysis under argon at 1600 °C, which was identified by XRD measurements, elemental analyses and Raman spectroscopy. This work will inspire more precise and efficient synthesis and applications of metallopolymers.  相似文献   

18.
光致变色分子经掺杂或键合作用嵌在液晶聚合物中可形成光致变色液晶聚合物,在线性偏振光或非偏振光的照射下,此物质中光致变色分子的构型变化会引起整个液晶分子的二维或三维光致再取向的形成,本文综述了光致变色液晶聚合物的光致再取向的近期研究进展.  相似文献   

19.
采用低温溶液聚合方法,以N-(2,5-二羟基苯)亚甲基-4-取代苯胺和不同结构的二酰氯为单体,合成了两类新的高分子.聚合物的液晶行为用DSC、偏光显微镜和X射线衍射进行了表征,发现其中一类为向列型热致液晶高分子,另一类则无液晶性.随单体结构的改变,聚合物的特性粘数、熔点(Tm)和液晶态的清亮点(Ti)均呈现规律性变化。  相似文献   

20.
新的含T-型二维液晶基元的液晶高分子的合成   总被引:4,自引:0,他引:4  
采用低温溶液聚合方法,以N-(2,5-二羟基苯)亚甲基-4-取代苯胺和不同结构的二酰氯为单体,合成了两类新的高分子。聚合物的液晶行为用DSC、偏光显微镜和X射线衍射进行了表征,发现其中一类为向列型热致液晶高分子,另一类则无液晶性。随单体结构的改变,聚合物的特性粘数、熔点(Tm)和液晶态的清亮点(Ti)均呈现规律性变化。  相似文献   

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