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1.
旷亚非  王玲 《电化学》1998,4(3):293-297
采用电渗法研究了电解质溶液组分对铝阳极氧化多孔膜层界面电性能的影响。结果表明,多孔膜分别经含F^-,PO^3-4,SiO^2-3或单宁酸溶液浸泡处理后,膜在0.01mol/LKCl溶液中等电点由原来的pHIEP=9.20分别移至pHIEP=3.40,4.30,3.30display structure  相似文献   

2.
丝素膜上药物渗透量对溶液PH值的响应   总被引:4,自引:0,他引:4  
蚕丝丝素蛋白膜是一种具有弱碱性和弱酸性的两性荷电膜。因此在丝素膜-水溶液体系中,水溶液pH值变化会影响丝素膜上溶质的渗透速度和渗透量。丝素膜的等电点pH≈4.5。丝素膜上药物渗透实验的结果表明:在pH=3.0~9.0的范围内,当溶液的pH<4.5时,丝素膜带正电,正离子苄三甲氯化铵的渗透系数下降;当溶液的pH>4.5时,丝素膜带负电,负离子酚磺酸钠的渗透系数明显下降。中性分子间苯二酚在丝素膜上的透过不受外部溶液pH值变化的影响。当溶液的pH>8或pH>4.5时,离子化的药物5-氟尿嘧啶或维生素C的渗透系数明显变小,这是因为两者分别在pH=8(pKa=8.0)和pH=4.5(pKa=4.25)以上变成带电离子。这表明离子化药物在蚕丝丝素膜上的渗透速度和渗透量对溶液pH值变化有较好的响应特性。  相似文献   

3.
以不对称长链叔胺为中性载体的PVC膜PH电极的研究   总被引:2,自引:0,他引:2  
合成了一系列不对称长链叔胺类化合物作中性载体,研制成PVC膜pH电极。其中(2-羟基苄基)二正癸胺、(β-氰乙基)LA-2、(2-羟基苄基)LA-2的电极线性范围分别为pH2.5~12.5、pH2.5~12.5、pH3.0~12.5,斜率分别为56.6±0.4mV/pH、56.3±0.7mV/pH、55.9±0.3mV/pH(30℃)。这些pH电极内阻低,响应速度快,性能较稳定,可用于血清样中的pH值测量。此外,以(2-羟基辛基)LA-2为载体可制成流通式PVC膜pH内电极型氨气敏电极。  相似文献   

4.
纳米尺度TiO2/聚吡咯多孔膜电极光电化学研究   总被引:32,自引:4,他引:28  
用光电流作用谱,光电流-电势图和UV-Vis光说研究了TiO2/聚吡咯多孔膜电极在不含氧化还原对和含不同氧化还原体系电解质溶液中的光电转换过程。TiO2/聚吡咯多孔膜电极双层n型半导体结构,内层TiO2多孔膜的禁带宽度为3.26eV,外层聚吡咯膜的禁带宽度为2.2eV。  相似文献   

5.
以双核有机锡化合物为载体的PVC膜磷酸根离子敏感电极   总被引:2,自引:0,他引:2  
以双(三苄基锡)氧化物为载体制备了一种对磷酸氢根离子具有良好电位响应性能的溶剂聚合膜离子敏感电极。在pH为7.20±0.02的测试液中,电极的线性响应范围为5 ×10^-6 ̄10^-1mol/L,斜率为-30.1mV/dec..用分别溶液法测得其对于各种阴离子的选择性次序:HPO4^2- ̄I^-〉Br^-〉Cl^-〉Ac〉SO4^2-。膜相中荷电离子添加实验的结果表明,电极响应系中性载体作用机制。  相似文献   

6.
编者 《大学化学》1995,10(4):47-48
分析化学试题选登一、选择题1.标定盐酸溶液最适宜的基准物为()(1)苯二甲酸氢钾(2)氢氧化钠(3)氢氧化钾(4)碳酸钠2.1.00×10-3mol/LHClO4水溶液pH=3.0,1.00×1O7mol/LHClO4溶液pH为6.8,这是因为()(...  相似文献   

7.
胶束电动毛细管色谱法测定大气中的甲醛、乙醛和丙酮   总被引:10,自引:0,他引:10  
 用胶束电动毛细管色谱法同时测定了大气污染物甲醛、乙醛和丙酮。样品经2,4-二硝基苯肼衍生。采用47cm(到检测窗口40cm)×50μmi.d.毛细管柱,以50mmol/L十二烷基硫酸钠-20mmol/L四硼酸钠溶液(pH9.00)为操作缓冲溶液,电压30kV,检测波长214nm,7.5min内甲醛、乙醛和丙酮的2,4-二硝基苯腙衍生物可获得良好的分离。用峰面积定量,线性范围为0.01~0.5g/L,最小检出浓度均为2mg/L,变异系数在8.7%以内。  相似文献   

8.
纳米尺度TiO2聚苯胺多孔膜电极光电化学研究   总被引:12,自引:0,他引:12  
柳闽生  李永舫 《电化学》1998,4(3):246-251
用光电流作用谱,光电流-电势图等光电化学方法研究了TiO2/聚本胺复合多孔膜电极在不含氧化还原和含有没氧化还原对体系中的光电转换过程。结果说明,TiO2/聚苯胺复合多孔膜电极为双层m-型半导体结构,TiO2多孔膜的禁带宽度为3.2eV,外层聚苯胺膜的禁带宽度为2.88eV。  相似文献   

9.
将硫堇共价键合到自组装在金电极表面的半胱胺单分子层上,制成了衍生化自组装单分子膜修饰电极,并用电化学方法研究了它的电化学性质,循环伏安图显示其在pH=7.7的磷酸盐缓冲液中,于-0.45~+0.50V(vs.SCE)范围内有2对氧化还原峰,峰电位分别为Epa=214mV,Epc=82mV,E^2pa=-75mV,E^2pc--160mV(vs.SCE),pH在5.0~9.0范围内,峰1有2个质子参  相似文献   

10.
锌镀层表面混合稀土转化膜的研究   总被引:27,自引:2,他引:25  
利用浸液法在匀底层上获得混合稀土转化膜,研究了处理溶液的浓度,pH,温度,促进剂H2O2的含量及处理时间等因素对膜层耐蚀性的影响,从而是确定了适宜的工艺条件。用俄歇电子能谱对膜层的组成,厚度进行了测定。  相似文献   

11.
The reaction of malonothioamides with benzene-sulfonyl azide and 2-azido-3-ethylbenzthiazolium tetrafluoroborate gave amides of 2-diazothiomalonic acid, which underwent cyclization to a mixture of 5-N-R-amino-1,2,3-thiadiazole-4-carbothioamides and 5-amino-1,2,3-thiadiazole-4-N-R-carbothioamides. The ratio of the isomeric thiadiazoles formed in this reaction is the same as in the reactions of 2-diazo-2-cyanoacetamides, 5-amino-1,2,3-thiadiazole- and 5-mercapto-1,2,3-triazole-4-carboxamides with P4S10 and of 5-amino-1, 2,3-thiadiazole-4-carbonitriles with H2S; it is characteristic of the influence of substituents on the reactivity of -diazothioacetamides. It was found that the cyclization of the diazo compounds is accelerated when electron-acceptor substituents are attached to the nitrogen atom of the carbothioamide group.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1106–1112, August, 1992.  相似文献   

12.
利用手持技术改进测定乙醇分子结构实验   总被引:1,自引:0,他引:1  
利用压强传感器代替排水集气法,改进测定乙醇分子结构实验的仪器装置,并探索最佳反应条件。另外,设计两个空白实验,结合压强变化曲线对实验误差进行相关讨论。  相似文献   

13.
14.
由于石化行业的生产需要,其材质的使用具有多样性和广泛性,经常会出现顾客委托的测试样品的一个或几个元素跨越光谱仪现有测试程序测量范围的情况。本法通过对光谱仪测试原理的认识,根据光谱仪的测试能力及标样的采集,实现了一个或几个元素测量范围的扩展,并对其测量的影响因素进行了研究。  相似文献   

15.
Sets of hydrogen molecule equivalents have been developed which permit the calculation of hydrogenation of different types of carbon-carbon bonds from ab initio total energies (3-21G and 6-31G* basis sets, and, to a more limited extent, for MP2/6-31G* data) of reactants and products. The calculated enthalpies of hydrogenation are in good agreement with experiment for unstrained molecules, with average errors on the order of 2 kcal/mol. The 6-31G* equivalents allow the enthalpies for strained molecules to be calculated accurately, but the 3-21G equivalents do not. The equivalents for both basis sets have been tested by calculating the enthalpies of hydrogenation of carbon-carbon bonds in nitrogen- and oxygen-containing organic molecules, free radicals, and classical carbocations. The results are in good agreement with experiment in most cases.  相似文献   

16.
非那雄胺能抑制5α-还原酶的活性,明显降低二氢睾酮水平,是一种治疗良性前列腺增生的有效药品。该合成工艺以甾烯酮酸为原料,将其与氯化亚砜反应,无须分离即与叔丁胺反应得17β-酰胺化合物,再氧化开环,环合,氢化,脱氢合成了非那雄胺。经元素分析、IR、1HNMR、13CNMR、MS分析表征了其结构。该法无须使用昂贵的2,2-二吡啶二硫化物和剧毒药品苯亚硒酸酐,且以乙酸铵代替氨气,降低了对设备的要求和腐蚀,更适用于工业生产。  相似文献   

17.
18.
实验教学目的是从解决实际问题出发,以实验技术训练和实验设计思想培养为目标。介绍了将单一的物质分配系数测定实验改进为综合实验,提高了实验效果及实验资源利用率。  相似文献   

19.
The compositions of the neutral diterpenoids of the oleoresins of five species of conifers growing in the Transcarpathia have been studied. It has been found that the oleoresins ofAbies alba M.,Larix decidua M., andPicea excelsa L. contain more than 50% of neutral diterpenoids. The group and qualitative compositions of the oxygen-containing diterpenoids have been determined. In the oleoresins ofAbies alba,Picea excelsa, andPicea abies tertiary alcohols — cis-abienol and isocembrol — predominate, while inLarix decidua the main component is the hydroxy ester larixyl acetate. Primary alcohols related to the resin acids have been found in all the oleoresins investigated. Features of the distribution of diterpenoids according to the species of conifers have been revealed. The results obtained are necessary for the chemotaxonomy of conifers of the family Pinceae.  相似文献   

20.
The compositions of the neutral diterpenoids of the oleoresins of five species of conifers growing in the Transcarpathia have been studied. It has been found that the oleoresins ofAbies alba M.,Larix decidua M., andPicea excelsa L. contain more than 50% of neutral diterpenoids. The group and qualitative compositions of the oxygen-containing diterpenoids have been determined. In the oleoresins ofAbies alba,Picea excelsa, andPicea abies tertiary alcohols — cis-abienol and isocembrol — predominate, while inLarix decidua the main component is the hydroxy ester larixyl acetate. Primary alcohols related to the resin acids have been found in all the oleoresins investigated. Features of the distribution of diterpenoids according to the species of conifers have been revealed. The results obtained are necessary for the chemotaxonomy of conifers of the family Pinceae.Novosibirsk Institute of Organic Chemistry, Siberian Branch, Academy of Sciences of the USSR. Translated from Khimiya Prirodynkh Soedinenii, No. 6, pp. 812–816, November–December, 1988.  相似文献   

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