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991.
E. Beinrohr M. Németh P. Tsch?pel G. T?lg 《Fresenius' Journal of Analytical Chemistry》1992,343(7):566-575
Summary Three types of flow-through, three-electrode cells with porous working electrodes made of crushed vitreous carbon were tested. The electrochemical properties of the cells were studied by hydrodynamic and cyclic voltammetry using potassium ferrocyanide test solutions. Depending on the volume of the porous working electrode, Nernstian behaviour and electrochemical yields up to 100% were observed for flow rates 1 to 7 ml/min. In the stopped-flow regime the cells exhibit thin-layer cell properties. The utility of the cells is demonstrated for on-line coulometric detection, continuous removal of impurities and dissolved oxygen and for anodic stripping coulometry of trace copper.On leave from: Department of Analytical Chemistry, Slovak Technical University, CS-812 37 Bratislava, Czechoslovakia 相似文献
992.
Marián Kucharík František Šimko Vladimír Danielik Miroslav Boča Roman Vasiljev 《Monatshefte für Chemie / Chemical Monthly》2007,138(12):1211-1215
Summary. The phase diagram of the system Na3AlF6–NaVO3 was determined by means of thermal analysis. The system is a simple binary eutectic one. The eutectic point was estimated
at x(NaVO3) = 0.975 and t
eut = 617°C. The XRD patterns of samples after thermal analysis revealed the presence of cryolite and NaVO3 only supporting the above assumption of a simple eutectic binary system. 相似文献
993.
With the use of the tritium monitoring network the samples of river water, air humidity and precipitation are collected and analysed for HTO in the vicinity of Temelín nuclear power plant. 相似文献
994.
Jaroslav Šesták 《Journal of Thermal Analysis and Calorimetry》2005,81(2):501-502
S. E. J_rgensen and Yu. M. Svirezhev Towards a Thermodynamic Theory for Ecological Systems Elsevier, Amsterdam 2004, Price: paperback 85€; hardbound 140€, 350 (A4 size) pages 相似文献
995.
Syuji?Fujii Hideto?Minami Masayoshi?OkuboEmail author 《Colloid and polymer science》2004,282(6):569-574
Poly(methyl methacrylate) (PMMA) particles were produced by dispersion polymerization of methyl methacrylate in the presence of mercaptopropyl terminated poly(dimethylsiloxane) (MP-PDMS) in supercritical carbon dioxide at about 30 MPa for 24 h at 65 °C. The particle diameter could be controlled in a size range of submicron to micron by varying MP-PDMS concentration. The MP-PDMS worked as not only a chain transfer agent but also a colloidal stabilizer, which was named tran
stab.Part CCLI of the series Studies on suspension and emulsion 相似文献
996.
Lanying?Yang Yi?Zhang Qingqi?Chen Jin Shi?MaEmail author 《Monatshefte für Chemie / Chemical Monthly》2004,135(2):223-229
Summary. 1-(Dipyrrin-2-yl)-1-(dipyrrin-3-yl)methane, the N-confused analog of biladiene-ac, is prepared by condensation of 2,3-dipyrromethane with two molecules of 2-formylpyrrole in dichloromethane in the presence of hydrogen bromide. Self-assembly of the ligand with Zn(II) in dichloromethane and methanol offers a dinuclear dimeric complex with a ligand:metal ratio of 2:2. X-Ray crystal structure analysis reveals two ligands bound through a head-to-tail pattern to two zinc centers to form a severely distorted helical conformation, which has the shape of a rectangle. 相似文献
997.
Preparation and Some Characteristics of Copper(I)-Copper(II) Selenocyanates From the system Cu2+-H2O-en-SeCN-in dependence on the conditions two new complexes have been prepared: Cu3en2(SeCN)(CN)3· H2O(I) and Cu3en2(SeCN)2(CN)2· H2O(II). They were studied by the methods of infra-red and EPR spectra as well as by those of X-ray diffraction. It has been found that Cu2+ is coordinated in these complexes with two molecules of ethylene diamine and one molecule water. The anion ligands have a bridging function and coordinate the copper(I). The EPR spectra show that the two complexes exhibit around the atom Cu2+ have different ligand field symmetry. For complex (I) it is a typically axial spectrum with two values of the gfactor g⊥? 2.18 and g⊥? 2.05 while complex (II) has an asymmetrical isotropic spectrum with one g-factor value only g⊥? 2.07. 相似文献
998.
Summary Using the X-ray crystal structure of the human topoisomerase I (top1) – DNA cleavable complex and the Sybyl software package, we have developed a general model for the ternary cleavable complex formed with four protoberberine alkaloids differing in the substitution on the terminal phenyl rings and covering a broad range of the top1-poisoning activities. This model has the drug intercalated with its planar chromophore between the −1 and +1 base pairs flanking the cleavage site, with the nonplanar portion pointing into the minor groove. The ternary complexes were geometry-optimized and relative interaction energies, computed by using the Tripos force field, were found to rank in correct order the biological potency of the compounds; in addition, the model is also consistent with the top1-poisoning inactivity of berberine, a major prototype of the protoberberine alkaloids. The model might serve as a rational basis for elaboration of the most active compound as a lead structure, in order to develop more potent top1 poisons as next generation anti-cancer drugs. 相似文献
999.
A carbon paste electrode for drotaverine hydrochloride (DvCl) was prepared and fully characterized in terms of composition, life span, usable pH range, response time and temperature. The electrode was applied to the potentiometric determination of drotaverinium ions in pharmaceutical preparations and biological fluids in steady state and flow injection conditions (FIA). The electrode is based on a mixture of two ion exchangers, namely, drotaverinium-silicotungestate and drotaverinium-tetraphenylborate dissolved in tricresyl phosphate as pasting liquid. The modified electrode showed a near-Nernstian slope of 59.34±2mV over the concentration range of 5.0×10–7–1.0 × 10–2M. The electrode exhibits good selectivity for DvCl with respect to a large number of inorganic cations, organic cations, sugars and amino acids. Potentiometric titrations of DvCl with several titrants have been monitored using this modified carbon paste electrode as an end-point indicator electrode. The proposed electrode offers the advantages of simplicity, accuracy, automation feasibility and applicability to turbid and colored samples. 相似文献
1000.
I.?S.?TerekhovaEmail author a?A.?Yu.?Manakov V.?V.?Feklistov Yu.?A.?Dyadin V.?YU.?Komarov D.?Yu.?Naumov 《Journal of inclusion phenomena and macrocyclic chemistry》2005,52(3-4):207-211
X-ray powder diffraction studies were performed of the polyhydrates, formed at positive temperature in swelled grains of carboxylic cation-exchange resins in the form of tetraisoamylammonium (cross-linked tetraisoamylammonium polyacrylates, differing in the degree of cross-linking: 1, 2 and 3%). It was shown that the polyhydrates exist as the crystalline phase under specific conditions, determined earlier by DTA technique. Diffraction patterns of the samples, recorded at the temperature +3 ± 1 °C, indicate that the polyhydrates crystallize in hexagonal symmetry, the unit cell parameters are close to a=12.25 Å, c=12.72 Å and do not depend significantly upon the degree of cross-linking. The suppositions were made concerning the size of hydrate crystallites, formed in the swelled grains of the studied resins.This revised version was published online in July 2005 with a corrected issue number. 相似文献