994 resultados para 604


Relevância:

10.00% 10.00%

Publicador:

Resumo:

As a kind of novel green solvent, Room Temperature Ionic Liquids (RTILs) have been paid ever-increasing attentions in RTIL-based extraction for metal separation, since they have many unique proper-ties, such as non-volatile and non-flammable. The progress of that is mainly composed of the partition properties, mechanisms, defects, overcome methods and forecasts of the processes on the environmental analytical chemistry, has been reviewed.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Five zinc (II) complexes (1-5) with 4 '-phenyl-2,2 ':6 ',2 ''-terpyridine (ptpy) derivatives as ligands have been synthesized and fully characterized. The para-position of phenyl in ptpy is substituted by the group (R), i.e. tert-butyl (t-Bu), hexyloxy (OHex), carbazole-9-yl (Cz), naphthalen-1-yl-phenyl-amine-N-yl (NPA) and diphenyl amine-N-yl (DPA), with different electron-donating ability. With increasing donor ability of the R, the emission color of the complexes in film was modulated from violet (392 nm) to reddish orange (604 nm). The photoexcited luminescence exhibits significant solvatochromism because the emission of the complexes involves the intra-ligand charge transfer (ILCT) excited state. The electrochemical investigations show that the complexes with stronger electro-donating substituent have lower oxidation potential and then higher HOMO level. The electroluminescence (EL) properties of these zinc (II) complexes were studied with the device structure of ITO/PEDOT/Zn (II) complex: PBD:PMMA/BCP/AlQ/ LiF/Al. Complexes 3, 4 and 5 exhibit EL wavelength at 552, 600 and 609 nm with maximum current efficiency of 5.28, 2.83 and 2.00 cd/A, respectively.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Circular dichoism and UV-vis measurements were used to study the interaction between porphyrin and monoclonal antibodies ( McAbs). McAbs-porphyrin complex formation is usually accompanied by significant bathochromic shift and hyperchromicity changes of the absorption maxima in the porphyrin soret band region. Induced CD spectra in the same region (350 similar to 450 nm) were detected upon complex formation. They follow Lamb-Beer's law and exhibit isosbestic behavior. Both the UV-Vis and induced CD spectra of the antibody: porphyrin complex remain unchanged over a broad pH range ( pH 6 similar to 11), indicating remarkable stability of the complex and reflecting the dominant role of hydrophobic interaction between the hapten benzophenone and the antibody combining site.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

圆二色谱 (CD)和紫外可见光谱 (UV VIS)可用来研究单克隆抗体 (McAb) 卟啉之间的相互作用。卟啉形成McAb 卟啉复合物 ,在Soret带区域最大吸收峰有显著红移和增色现象。在 3 5 0~ 45 0nm区域 ,形成复合物时能检测诱导的CD光谱。CD光谱遵守朗伯 比尔定律 ,显示等吸收行为。McAb 卟啉复合物的紫外可见吸收及诱导的CD光谱在pH 6~ 1 1的范围内保持不变 ,说明复合物异常稳定 ,也说明McAb 卟啉结合位点之间疏水相互作用是主要因素。

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Crystal structure of a novel aryl ether ketone polymer poly(aryl ether ketone ether ketone ketone containing meta-phenyl linkage)(PEKEKmK) was determined by means of WAXD and ED. An orthorhombic unit cell is proposed containing two chains with a=0.772 nm, b=0.604 nm and c=2.572 nm. According to the orthorhombic system, the 10 reflections of this polymer were indexed.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

The X-ray diffraction patterns of the crystalline aromatic ketone polymer PEKEKmK (aryl ether ketone ether ketone ketone polymer containing meta-phenyl links) have been investigated (for the chemical structure, see Formula). An orthorhombic unit cell is proposed to contain two chains with a = 0.772 nm, b = 0.604 nm and c = 2.572 nm. According to the orthorhombic system, the 11 reflections of this polymer were indexed. Meanwhile, variation in unit cell parameters with crystallization temperatures of PEKEKmK was also investigated. [GRAPHICS]

Relevância:

10.00% 10.00%

Publicador:

Resumo:

目的 探讨几种新型可生物降解聚酯类合物的结构及生物环境对降解规律的影响 ,为临床选择应用该类材料提供实验依据 .方法 将自行合成的聚己内酯 (PCL)、聚丙交酯(PL A)、以及它们不同摩尔比的共聚物 (PCL A2 / 1,PCL A1/2 )分别置于胆汁、胰组织悬液和血浆中 1~ 7d,植入兔肌肉内2 4wk,观察材料质量损失、超微形态变化和分子量变化 .结果  PCL 在 2 4wk内各种性质变化最慢 :质量损失不明显 ,分子质量在胰腺悬液中下降 19.8% ,形态无明显变化 ;PCL A2 / 1在 2 4wk时质量损失 0 .5 % ,分子质量下降 6 1.7% ,材料断面出现蚀刻形态 ;PCL A1/ 2在 2 4wk质量损失 40 .4% ,分子质量下降 6 .6 % ,形态出现空洞、碎裂 ;PL A在 2 4wk质量损失 79.2 % ,分子质量下降 15 .1% ,形态完全降解 .结论 不同结构的材料在不同环境中体现不同的降解性质 .

Relevância:

10.00% 10.00%

Publicador:

Resumo:

A compact non-stoichiometric molybdenum (VI, V) oxide of blue film was grown on carbon fiber (CF) microelectrode surface be cycling the potential between + 0.2V and - 0.70V in a freshly prepared Na2MoO4 solution containing 5 x 10(-3) mol/L H2SO4. The quantity-of the oxide is controlled by the charge passing the electrode. The electrochemical pretreatment of CF microelectrode not only mises the deposition velocity of molybdenum oxide on CF surface, but also improves greatly the cyclic voltammetric behavior of the molybdenum oxide film prior to the electrodeposition. The cathodic processes are believed to yield the hydrogen molybdenum oxide bronzes HxMoO3(0 < x < 2), or substoichiometric lower molybdenum oxides with the formula MoO3-y(0 < y < 1). The anodic response results from the reversible oxidation of molybdenum bronze/Mo(V) centers [or perhaps Mo(IV) in more reduced coatings], to Mo(VI). Further information was gained about the chemical composition and valent state of Mo from XPS and SEM.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

在新鲜配制的Na_2MoO_4的弱酸性水溶液中,通过循环电位扫描在碳纤维微电极表面可沉积一层均匀的蓝色氧化钼(VI,V)薄膜,膜的厚度通过电量进行控制.在电沉积之前,电极的阳极化处理不仅可以加快氧化钼的电沉积,而且可以改善膜的伏安行为.溶液的pH值对膜的电沉积和伏安行为有极大的影响.膜的阴极过程被认为是产生青钼铜:H_xMoO_3(0

Relevância:

10.00% 10.00%

Publicador:

Resumo:

本文介绍了自制的毛细管电泳-安培检测装置.此装置不用任何接头隔离高压电场,用碳纤维微盘电极作为工作电极,在 25μm毛细管上实现了儿茶酚,多巴胺的分离及亚硝酸极的检测.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Clinopyroxene NaAlSi2O6 was synthesized under varying pressures of 3.0-5.0GPa and at the temperature range of 1150.1750 degrees C, for periods of 1.480min. The glass material was completely transformed into homogeneous penetrating fibrous texture of clino

Relevância:

10.00% 10.00%

Publicador:

Resumo:

在3.0-5.0GPa,1150-1750℃,1-480min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>4.0GPa,温度>1450℃,晶化时间>45min。

Relevância:

10.00% 10.00%

Publicador:

Resumo:

The radiation-induced chain-scission and racemization of isotactic poly(methylmethacrylate)(iso-PMMA) in amorphous and semi-crystalline state as well as in solution have been studied with nuclear magnetic resonance and molar mass deter-mination. It is shown that the chain-scission is dominant for iso-PMMA in dilute solution while the racemization reaction is not favorable in this case. On the contrary, the racemization is favorable when iso-PMMA was irradiated in its crystalline state while chain-scission is not. Such experimental results could be well explained by the mobility of molecules and "cage effect". The hypothesis, we proposed previously that the chain-scission, racemization and recombination are in competition and the final result depends on the state of molecular motion at which iso-PMMA was irradiated, has been verified verified once again.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

以全同立构聚甲基丙烯酸甲酯(iso-PMMA)为对象,用核磁共振谱和分子量测定等手段,研究了不同物理状态,即无定型固态,结晶态和稀溶液状态下的辐射裂解和辐射消旋反应.结果表明,在稀溶液状态下辐照,其裂解反应最强,而消旋反应最弱;结晶状态下辐照,则裂解反应最弱而消旋反应最强.这充分说明了分子的活动性对反应的影响,进一步验证了前已提出的高分子链断裂-重合-消旋的平衡反应机理.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

关于氯化聚乙烯(CPE)或聚氯乙烯(PVC)与乙烯—醋酸乙烯酯共聚物(EVA)共混体系相容性的研究,已有不少报道,其中Coleman等人运用FTIR方法研究了含VA45%的EVA与CPE、PVC的共混体系,测定了该体系的低临界共溶温度(LCST)。一般认为,如果VA含量更低,由于EVA本身的结晶,共混体系将变得难以