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1.
Nelly A. Kachurovskaya Georgii M. Zhidomirov Rutger A. van Santen 《Research on Chemical Intermediates》2004,30(1):99-103
Periodical calculations of Zn(II) metal cation stabilization in cationic positions with distantly placed aluminium ions has been performed for high-silica ferrierite. It was found that decrease of the stabilization energy at large distances between Al ions (more than 10 Å) is about of 2 eV in comparison with nearest possible position of two Al ions in the zeolite lattice and weekly depended on following increase of the Al-Al distance. Main changes in stabilization energy occured within a 3-Å interval of these distances. Only for the localizations of both Al ions in one zeolite ring zinc cationic form is more stable than hydrogen form. 相似文献
2.
Tsibakhashvili NY Asatiani NV Abuladze MK Birkaya BG Sapojnikova NA Mosulishvili LM Holman HY 《Biomedical chromatography : BMC》2002,16(5):327-331
Rapid and effective separation of bacteria Arthrobacter oxydans was performed using capillary electrophoresis. For optimal separation of bacteria the influence of buffer concentration, pH and applied voltage were studied. It was found that the most appropriate conditions for electrophoretic mobility measurements are as follows: applied voltage 6-14 kV; buffer concentration 5-10 mM pH 6-8. At the stationary phase of growth there are always two main heterogeneous peaks. They are connected with the morphology of bacteria as well as with cell aggregation. The heterogeneity of samples may be explained by surface modifications of bacterial cells. 相似文献
3.
Peña-Alvarez A Díaz L Medina A Labastida C Capella S Vera LE 《Journal of chromatography. A》2004,1027(1-2):131-136
Steam distillation (SD) extraction-solid-phase microextraction coupled to GC-MS was developed for the determination of terpenes and Bligh-Dyer extraction-derivatization coupled with GC for the determination of fatty acids such as ethyl esters were used. It was found that the three different Agave species have the same profile of fatty acids; the quantity of these compounds is different in each Agave variety. On the other hand, different terpenes were identified in the three Agave plants studied: nine in A. salmiana, eight in A. angustifolia and 32 in A. tequilana Weber var. azul. 相似文献
4.
[reaction: see text] Regioselective metalation of pyrazines and cross-coupling reactions provides an easy access to botryllazines A and B and to an isomer of botryllazine A with good yields from chloropyrazine. 相似文献
5.
6.
Pierre Thuéry Nelly Keller Monique Lance Julien-Daniel Vigner Martine Nierlich 《Journal of inclusion phenomena and macrocyclic chemistry》1994,20(1):89-96
The doubly deprotonated form of calix[6]arene, with two protonated triethylamines as counter-ions, crystallizes in the monoclinic system: space groupP21/n,a=8.465(4),b=17.822(8),c=15.182(6) Å,=90.18(4)°,V=2291(2) Å3,Z=2. Refinement led to a final conventionalR value of 0.063 for 1046 reflections. The macrocycle conformation is not apinched cone, usual for freeR-calix[6]arene, but a distorted 1,2,3-alternate cone, since the molecule lies on a symmetry center. Furthermore, one of the torsion angles defined by the methylene bridges is near to zero, which is unusual in calixarene structures.
Supplementary Data relating to this article (atomic coordinates for hydrogen atoms, anisotropic displacement parameters for oxygen and nitrogen atoms, and observed and calculated structure factors) are deposited with the British Library as Supplementary Publication No. SUP 82182 (7 pages). 相似文献
7.
Nelly Konopik 《Monatshefte für Chemie / Chemical Monthly》1961,92(1):8-21
Zusammenfassung Analog der Brenzcatechingermaniumsäure geben die komplexen Germaniumsäuren von Pyrogallol und 2,3-Dihydroxynaphthalin-6-sulfonsäure in saurer Lösung (pH<4,0) an der Hg-Tropfelektrode relativ positiv liegende Reduktionsstufen, die in Abhängigkeit vom pH, von der Ionenstärke, von der o-Diphenol-sowie von der Ge-Konzentration untersucht wurden. Ferner wurde festgestellt, daß der Grenzstrom durch Diffusion kontrolliert wird und daß bei der Reduktion je Ge-Atom 4 Elektronen aufgenommen werden. Mit Hilfe derJ obschen Methode der kontinuierlichen Variation wurde potentiometrisch und spektrophotometrisch die Zusammensetzung der in Lösung befindlichen Komplexe zu 1 Ge: 3 Phenol bestimmt.Mit 13 AbbildungenHerrn Prof. Dr.J. Heyrovský zum. 70. Geburtstag gewidmet.Der elektrochemische Teil der Arbeit wurde beim 2. Seminar für Elektrochemie Ende Dezember 1960 in Karaikudi vorgetragen. 相似文献
8.
Nelly Konopik 《Fresenius' Journal of Analytical Chemistry》1966,224(1):107-116
Zusammenfassung Germaniumsäure reagiert mit den Formen H4Y und H3Y- der Äthylendiamintetraessigsäure unter Bildung von 11-Komplexverbindungen mit den folgenden Stabilitätskonstanten: K
H4Y=6.27·104 bzw. K
H4Y=5.99·104 und K
H3Y=3,78·104 bzw. K
H3Y=2,35·104 (25°C; Ionenstarke 0,1 m), je nachdem, mit welchen Werten für die Dissoziationskonstanten der ÄDTE gerechnet wird.
Herrn Prof. Dr. M. von Stackelberg zum 70. Geburtstag gewidmet.
Herrn Prof. Dr. H. Nowotny danke ich für wertvolle Diskussionen. Bei der Ausführung der Experimente haben mich in dankenswerter Weise vor allem Herr A. Grumer, ferner Frl. L. Docekal, Frl. E. Hofmeister und Herr P. Angelbeger unterstützt. 相似文献
Summary Germanic acid reacts with the species H4Y and H3Y- of EDTA forming 11 complex compounds. The following stability constants have been obtained: K H4Y=6.27x104 resp. K H4Y=5.99x104 and K HaY=3.78x104 resp. K H2Y=2.35x104 (25°C; ionic strength 0.1 m), depending on the values inserted for the dissociation constants of the EDTA.
Herrn Prof. Dr. M. von Stackelberg zum 70. Geburtstag gewidmet.
Herrn Prof. Dr. H. Nowotny danke ich für wertvolle Diskussionen. Bei der Ausführung der Experimente haben mich in dankenswerter Weise vor allem Herr A. Grumer, ferner Frl. L. Docekal, Frl. E. Hofmeister und Herr P. Angelbeger unterstützt. 相似文献
9.
Araceli Vernica Flores Carlos Alberto Prez Marco Aurlio Zezzi Arruda 《Analytica chimica acta》2005,530(2):619-305
In the present work, scandium was determined in sediment slurry samples (from three different rivers) by electrothermal atomic absorption spectrometry (ETAAS). Slurries were prepared by weighting 100 mg of dry sediment samples (≤53 μm particle sizes) and adding 6 ml of HCl:HNO3:HF (3:1:2, v/v). Accurate results were only possible due to the synergetic effect between Rh as permanent chemical modifier and acetylacetone (Acac) as complexing agent. The same platform was used for 400 heating cycles. The performance of the chemical modification was evaluated by using scanning electron microscopy (SEM), synchrotron radiation X-ray fluorescence (SRXRF) and some figures of merit (precision and detectability). The best analytical conditions were attained using 1500 and 2550 °C as pyrolysis and atomization temperatures. The scandium content in the liquid phase of the slurries ranged from 61 to 73%, thus indicating, in this study, that both liquid and solid phases play an important role in slurry analyses. An amount of 5.0–20.0 μg l−1 Sc linear range as well as LOD and LOQ of 0.19 and 0.62 μg l−1, respectively, were obtained under these conditions. The accuracy was checked by using microwave-assisted decomposition, and the results compared to those obtained with the proposed methodology (slurry analysis). By checking both sets of the results, there is no statistical difference at the 95% confidence levels. 相似文献
10.
The synthesis of [Mn12O12(O2CMe)6(p-CO2-phenyl nitronyl nitroxide)10(H2O)4]· 4H2O, (1), by direct replacement of some of the acetate groups in [Mn12O12(O2CMe)16(H2O)4] · 4H2O · 2MeCO2H, (2), with the organic radical p-HO2C-phenyl nitronyl nitroxide, (3), is reported. E.p.r. spectra show exchange narrowing in (1) due to coupling between the manganese ions and radicals. The isotropic hyperfine splitting constant from the manganese ions is a = 96 Oe at 5.5K. The magnetic susceptibility indicates antiferromagnetic exchange interactions between the manganese ions and the radicals with the Weiss constant = -25 K. The spin was determined to be S = 6 from magnetization data in the 2--30 K temperature range at 50 kOe, suggesting a mixture of ground state with excited states. 相似文献