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1.
色谱保留值与流动相组成间关系的研究一直是色谱工作者关心的课题[1,2].灰色模型对于处理具有不确定关系的两因素间的关系问题具有独到之处,在容量因子(k)与流动相组成(φ)关系的研究方面已得到了应用[3~8].传统GM(1,1)模型将k与φ之间的关...  相似文献   

2.
研究了核糖核酸酶A(RNaseA)在丁酸十二铵(DAB)-环己烷反胶束溶液中催化水解胞苷2',3'环单磷酸酯的动力学,数据符合Michaelis-Menten酶催化机理。以kcat/Km表示酶催化活性时,RNaseA在反胶束溶液中的催化活性是在水溶液中的14 ̄30倍。无论是固定DAB浓度还是固定H2O与DAB浓度之比,随增溶水量的增加,kcat/Km呈下降趋势。  相似文献   

3.
钯催化下共轭烯烃的Heck芳基化是立体选择性形成碳碳键的重要方法,在有机合成中广为应用[1].均相钯催化剂因难以从反应体系中分离回收,其实际应用受到限制.聚合物负载过渡金属催化剂因综合了均相和复相催化过程的优势,已越来越引起人们的关注,聚苯乙烯负载的膦钯配合物能有效地催化共轭烯烃的芳基化[2,3].Zhang等报道了聚合物负载菲咯啉钯(0)配合物催化丙烯酰胺的芳基化[4],但该催化剂的制备过程过于复杂.作者曾报道过聚γ巯丙基硅氧烷钯(0)配合物的合成,并证实其是苯乙烯、丙烯酸Heck芳基化反…  相似文献   

4.
用跳浓弛豫法测定了微扰体系在不同浓度[Ti ̄(4+)]时的弛豫时间τ,拟定了合理的反应机理,并根据此机理导出了1/τ的函数表达式为1/τ=k[H4R]_0/[H3O ̄+]_0-4k·A∞/ε·[H3O ̄+]0,获得了配位反应的表现稳定常数K、表观速率常数k及摩尔吸光系数ε;其中所得稳定常数K的值与用平衡移动法获得的结果相吻合,进一步证明了所拟机理的合理性。  相似文献   

5.
朱维晃  吴丰昌  黄廷林 《色谱》2008,26(2):237-241
采用反相离子对高效液相色谱法分离测定了金属配合物{Fe[3-(2-吡啶基)-5,6-二苯基-1,2,4-三嗪]3}2+ ([Fe(PDT)3]2+)的两种几何异构体,研究了流动相中有机改性剂(乙腈、甲醇)的含量、不同种类和浓度的离子对试剂(高氯酸钠和十二烷基硫酸钠(SDS))对色谱分离的影响。并在不同的试验条件下,对所获得的色谱参数(保留因子(k)、分离度、选择性因子等)进行了探讨。在不同种类及浓度的离子对试剂条件下,二元流动相中乙腈的含量与两种几何异构体的ln k之间均呈显著的线性关系。研究进一步发现SDS的浓度变化对异构体的保留因子影响程度更为显著。在上述实验的基础上,引入更能灵活调节洗脱强度和分离度的三元流动相(乙腈/甲醇/水),优化选择了三元流动相中有机改性剂的比例以及离子对试剂的种类和浓度,使得异构体的色谱分离得到了满意的结果。实验结果表明,异构体的峰面积(A)和浓度(C)之间的线性关系良好,面式和经式异构体的检测限分别为4.28和3.44 ng/mL (S/N=3)。  相似文献   

6.
用特性粘度([η])和羧值为参数,研究了双唑啉化合物(BOZ)对聚对苯二甲酸乙二酯(PET)的扩链反应动力学过程,表明BOZ是与PET中羧基反应,考察了不同工艺生产的PET的扩链效果,结果说明达到的[η]极大值取决于原始PET的[η]与羧值之比  相似文献   

7.
单茂钛催化剂的苯乙烯间规聚合和乙烯聚合的比较   总被引:2,自引:0,他引:2  
考察三甲基铝(TMA) 部分水解法制备固体改性甲基铝氧烷(m MAO) 时,反应物H2O 和TMA 的摩尔比对m MAO 的产量及m MAO 中TMA 含量的影响;以五甲基茂基三苄氧基钛[Cp * Ti(OBz)3]/m MAO 组成的均相催化体系,分别考察m MAO 的用量[ 即Al/Ti 摩尔比] 及m MAO 中TMA 含量对苯乙烯间规聚合和乙烯聚合的影响.通过分析Cp * Ti(OBz)3/m MAO 催化体系钛氧化态的分布,发现Ti( Ⅲ) 活性中心有利于合成间规聚苯乙烯;而Ti( Ⅳ) 活性中心有利于合成聚乙烯.苯乙烯间规聚合时,外加三异丁基铝(TIBA) ,将提高催化活性,同时可节省MAO 用量.  相似文献   

8.
用特性粘度([η])和羧值为参数,研究了双恶唑啉化合物(BOZ)对聚对苯二甲酸乙二酯(PET)的扩链反应动力学过程,表明BOZ是与PET中羧基反应,考察了不同工艺生产的PET的扩链效果,结果说明达到的[η]极大值取决于原始PET的[η]与羧值之比。  相似文献   

9.
磷钼杂多酸-罗丹明B荧光体系研究及分析应用   总被引:4,自引:0,他引:4  
在0 .08 m ol/ L H2 S O4 介质中, P O[ 3 - ]4 、 Mo O[ 2 - ]4 与罗丹明 B 形成三元磷钼杂多酸·罗丹明 B 荧光缔合物,其λex /λe m 为325 n m/650 n m ,磷浓度在0 .3 ~30 μg/l 范围内与荧光强度呈良好线性关系。实验结果表明,本法具有灵敏度高,选择性好,操作简便等特点;用于水、铜合金、茶叶试样中磷的测定,结果令人满意。  相似文献   

10.
采用pH-电位滴定法研究了乙醇溶液中RE(Ⅲ)与新型荧试剂H2L[5-(2'-羧基苯偶氮)]绕丹宁(Br-RACP)、5-(4'-氯代-2'-羧基苯偶氮)绕丹宁(Cl-RACP)、5-(4'-溴代-2'-羧基苯偶氮)绕丹宁定常数大小为RACP>Cl-RACP>Br-RACP。而与Nd(Ⅲ)的累积生成常数lgβmlh随原子序数Z增大时,研究了浓度对lgβmlh的影响,测定了15种稀土与RACP的ig  相似文献   

11.
The spectral-polarization characteristics of absorption and phosphorescence of molecules of the initial form of nitro-substituted indolinospirobenzothiopyran were studied in oriented polyethylene films and in solutions with different polarity. An oscillator model of the electron transitions responsible for the formation of absorption and luminescence spectra was suggested. It was established that the principal differences in the spectral and photophysical properties of the compound studied and its oxygen-containing analog are associated with the fact that the electronegativity of the S atom is lower than that of the O atom. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1143–1146, June, 1997.  相似文献   

12.
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   

13.
Two vanilloids, (5E)-8-(4-hydroxy-3-methoxyphenyl)oct-5-en-4-one (1) and 4-[3-hydroxydecyl]-2-methoxyphenol (2), isolated from the dried seeds of Grains of Paradise (Aframomum melegueta), were synthesized; the latter compound was made as the S-enantiomer and the material derived from the seeds was found to be a 1:1.7 mixture of the R and S isomers. The synthetic route used should allow the preparation of analogs having extended alkyl chains and consequently different lipophilicity, and 3, a homolog of 2, was also prepared.  相似文献   

14.
Main hydration products of two cement pastes, i.e. CSH-gel, portlandite (P) (and specific surface S) were studied by static heating, and by SEM, TEM and XRD, as a function of cement strength (C-33 and C-43) hydration time (th) and subsequent hydration in water vapour.Total change in mass on hydration and air drying, Mo, increased with strength of cement paste and with hydration time. Content of water escaping at 110 to 220°C, defined as water bound with low energy, mainly interlayer and hydrate water, was independent on cement strength but its content increased with (th). Content of chemically bound (zeolitic) water in CSH-gel, escaping at 220-400°C, was slightly dependent on strength and increased with (th). It was possibly derived from the dehydroxylation of CSH-gel and AFm phase. Portlandite water, escaping at 400-500°C, was independent on cement strength and was higher on longer hydration. Large P crystals were formed in the weaker cement paste C-33. Smaller crystals were formed in C-43 but they increased with (th). Carbonate formated on contact with air (calcite, vaterite and aragonite), decomposed in cement at 600-700oC. It was high in pastes C-33(1 month) and C-43(1 month), i.e. 5.7 and 3.3%, respectively; it was less than 1% after 6 hydration months (low sensitivity to carbonation) in agreement with the XRD study showing carbonates in the air dry paste (1month), and its absence on prolonged hydration (6 months) and on acetone treatment. Water vapour treatment of (6 months) pastes or wetting-drying increased this sensitivity.Nanosized P-crystals, detected by TEM, could contribute to the cement strength; carbonate was observed on the rims of gel clusters.This revised version was published online in November 2005 with corrections to the Cover Date.  相似文献   

15.
Cotton cellulose was swollen in a sodium hydroxide solution and carboxymethylated by a two-bath method for different periods of time for each process. The kinetics of acid hydrolysis and the crystallinity of the swollen and carboxymethylated samples were measured. The proportion of broken bonds, rate constants for hydrolysis, and permeability of cellulose to hydrolyzing agents were calculated. The susceptibility of glycosidic linkages to acid hydrolysis was improved by carboxymethylation more than by swelling in alkali. The increased accessibility of carboxymethylcellulose to acid was regarded as a consequence of increased intra-and intercrystalline swelling and of the glycosidic bonds' weakness caused by the electron-attracting carboxymethyl group on the C-6 position.  相似文献   

16.
17.
翟宗玺  刘树深  夏树屏 《化学学报》1990,48(10):946-950
用氧化镁氯化镁水溶液制备了8水合氯氧化镁[nMg(OH)2·MgCl2·8H2O], 并测定了其在盐酸中的溶解热, 实验结果表明, 氯氧化镁溶解热与n值呈线性关系, 根据溶解热求出5Mg(OH)2·MgCl2·8H2O和3Mg(OH)2·MgCl2·8H2O的生成热分别为-7727.1和5888.1kJ·mol^1^-。  相似文献   

18.

The heats of detonation of 20 simple high explosives and explosive mixtures were determined by means of an adiabatic detonation calorimeter designed by the authors. The results indicated that the performance of the instrument was reliable and the experimental data were very accurate. For explosive mixtures, there was a linear accumulative relationship between the heats of detonation of the explosive mixture and its components. Accordingly, the heats of detonation of explosive mixtures could be calculated directly from the heats of detonation of simple explosives and the characteristic heats of other components. The experiments showed that the gold or brass shell of the cylindrical charge could be substituted by a thick-walled porcelain shell, which had the advantage of cheapness.

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19.
The aim of the presented work was the investigation of thermal oxidation of ilmenite in static air atmosphere. The investigations were carried out by use of a derivatograph (MOM, Hungary). The changes of crystallographic structure of investigated samples were identified by X-ray diffractometry on Philips PW-1710 diffractometer. In temperature above 500°C appears structure of hematite Fe2O3. On the basis of the thermogravimetric measurements, the contracting area and contracting volume models were found as the best fitting experimental data. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

20.
Cyclopropyl derivative of 2,6-di-tert-butylphenol is synthesized as a probe to investigate the mechanism of base-catalyzed autooxidation of phenol derivatives. Our study indicates that one electron reduction of molecular oxygen from phenolate gives phenoxyl radical 3, a key intermediate of autooxidation. The coupling of phenoxyl radical and superoxide radical gives peroxylate anion 4 and produces the final epoxy alcohol adduct 6.  相似文献   

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