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101.
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103.
Determination of tungsten with pyrocatechol violet by first-derivative solid-phase spectrophotometry
M. I. Pascual-Reguera A. Molina-Diaz M. C. Pacheco-Castillo M. C. Anguita-Fernández M. L. Fernández-de Córdova L. F. Capitán-Vallvey 《Mikrochimica acta》1994,112(5-6):225-235
Derivative spectrophotometry was applied to solid-phase spectrophotometry in order to enhance its sensitivity and remove the large background caused by the absorbance of the resin layer. Determination of micro-amounts of tungsten with pyrocatechol violet to form a 21 green complex in acid medium which is fixed on a dextran-type anion-exchange resin (Sephadex QAEA-25) is described as an example for the application of this technique. The absorbance of the resin packed in a 1-mm spectrophotometric cell, was measured directly. The characteristic peak amplitude of the signal at 674 nm in the first-derivative spectrum is useful for quantitative determination of tungsten (3–16 g 1–1; RSD 5.8%) in natural and industrial water samples. 相似文献
104.
It has been well-known that the heat distortion temperature of resin is effectively enhanced by the incorporation of a maleimide unit. However, an economical industrial production method for maleimide was not yet established. We have established a new industrial production method of maleimides based on a reaction model which was revealed by analyzing the reactions occurring in the dehydration of maleamic acid. Especially, we have developed a new re-usable catalyst which has high performance without corrosion problems and a new process having superior productivity of maleimide with a high yield. This method contains the following two features: (1) a new catalyst, supported orthophosphoric acid and its amine salt mixture; (2) employment of a reaction to change the by-product to maleimide. 相似文献
105.
Yan-zhongZhang Zhi-qiangFan Bai-gengWu Jun-tingXu QiWang 《高分子科学》2004,(3):231-238
Spherical polyethylene/polypropylene (PE/PP) in-reactor blend granules with various ethylene/propylene molar ratios and high porosity were synthesized using a high yield TiCl4/MgCl2 supported catalyst. A solution of benzoyl peroxide (BPO)/maleic anhydride (MAH)/xylene (interfacial reagent) or BPO/MAH/St (comonomer) was absorbed onto the PE/PP inreactor blend granules, and solid phase gratt polymerization of MAH on PE/PP was conducted. The amount of grafted MAH on PE/PP was measured through chemical titration. The results showed that solid phase graft polymerization of MAH in PE/PP in-reactor blend granules produced graft copolymer with high amount of grafted MAH, and the amount of grafted MAH was raised slightly when St was introduced as comonomer. The graft in-reactor blend was fractionated into five fractions through temperature-gradient extraction fractionation (TGEF), and the fractions were analyzed by FTIR. The results revealed that MAH is mainly grafted on the PE segments, whereas MAH was predominantly grafted on the PP segments when St was present in the graft polymerization system. In addition, the final product is still in the form of regular spherical granules, which is beneficial for industrial processing. 相似文献
106.
Charles Pedersen's career is reviewed from the time of his early life in Korea and Japan and scientific training in the United States to the present. His 42-year research career was practically and scientifically productive, leading finally to a share of the Nobel prize in chemistry for 1987. Commercially significant accomplishments included a large improvement in the yield of tetraethylead antiknock and discovery of the first oil soluble agents for inhibiting catalytic effects of copper in degradation of petroleum products and rubber. This led to a study of the interactions of metals with chelating agents and the resultant effects on oxidation reactions, thence to the behavior of peroxides and their reactions with substrates. He also discovered the antiknock activity of ferrocene. While studying the effects of ligands on the catalytic behavior of vanadium he discovered the crown compounds and their ability to include alkali metal ions. He devoted the last years of his career to elaborating their chemistry.Taken in part with permission fromCurrent Topics in Macrocyclic Chemistry in Japan, E. Kimura (ed.), Hiroshima University School of Medicine, Hiroshima, 1987. 相似文献
107.
《化学:亚洲杂志》2017,12(2):190-193
Synthetic chemistry remains a time‐ and labor‐intensive process of inherent hazardous nature. Our organic solvent disintegrating tablet (O‐Tab) technology has shown potential to make industrial/synthetic chemistry more efficient. As is the case with pharmaceutical tablets, our reagent‐containing O‐Tabs are mechanically strong, but disintegrate rapidly when in contact with reaction media (organic solvents). For O‐Tabs containing sensitive chemicals, they can be further coated to insulate them from air and moisture. 相似文献
108.
人口老龄化与区域产业结构——基于分位数回归的实证研究 总被引:1,自引:0,他引:1
基于2005-2016年的省级面板数据,运用分位数回归实证分析了人口老龄化背景下,产业结构优化升级的影响因素.结果表明:全部样本的老年抚养比对产业结构优化升级的阻碍作用十分明显,东部对产业结构的影响不显著,中部的阻碍作用与全国趋势相反,西部的阻碍作用与全国趋势相同,具有明显的区域差异性;全部样本和东中西部的人均GDP都是正向推动产业结构合理化和高度化;全部样本和西部的政府行为对产业结构调整的抑制作用在增强,而东中部对产业结构调整的促进作用在增强;全部样本和东部的创新效率对产业结构调整有不断增强地推动作用,中部对产业结构调整的促进作用在减弱,而西部对产业结构调整的阻碍作用在增强. 相似文献
109.
M. K. Deb C. Agarwal K. S. Patel R. K. Mishra 《International journal of environmental analytical chemistry》2013,93(4):417-419
Abstract A simple and rapid method for the spectrophotometric determination of traces of total arsenic present in industrial waste waters is described. It is based on the reaction of As(III) with I? in 5 –6 M HCl, and extraction of the iodo-arsenite complex formed into chloroform with amidines. The molar absorptivity of AsI4 ? with 11 different amidines is in the range (3.9 –7.9) × 103 lmol?1 cm?1 at λmax = 380 –395 nm; the simplest compound, N,N′-diphenylbenzamidine (DPBA) has been chosen for further studies. The limit of detection with DPBA is 0.1 μg As/ml. The method is highly selective with almost no interference from all anions and cations tested. 相似文献
110.
Ugur Ulusoy Meftuni Yekeler Cevdet Biçer Zeynep Gülsoy 《Particle & Particle Systems Characterization》2006,23(6):448-456
It is known that size of the individual particles is the predominant factor affecting the behavior of particulate materials, and that the size effects become increasingly important as the particles become finer. In this article, particle size distributions (PSDs) measured by different techniques, i.e. sieving and Andreasen pipette sedimentation, were combined for different mill (ball and rod) products of some industrial (talc and quartz) minerals. The corrected sedimentation data came closer to the sieving data. The apparent mean shape factors, r, determined from the corrected PSDs for the talc mineral ground by ball and rod mill were found to be 1.34, 0.62, whereas it was 1.00, 1.12 for the quartz mineral ground by ball and rod mill, respectively. The results show that the ball milled products of talc mineral have more regular (rounder in shape) particles than those of rod milled, but the rod milled products of quartz mineral studied were not more regular in shape than ball milled products of quartz mineral as confirmed by the SEM pictures and reviewed literature. 相似文献