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41.
42.
ágnes Horváth István Hermecz Marianna Pongor-Csákvári Zoltán Mészáros József Kökösi Gábor Tóth áron Szöllósy 《Journal of heterocyclic chemistry》1984,21(1):219-224
The structures of the title compounds bearing a five-, six- or seven-membered A ring have been investigated by uv and 1H and 13C nmr spectroscopy. The imine-enol-enamine (I-II-III) tautomerism of these compounds depends greatly on the ring size. A significant solvent-dependence is observed only for the five-membered-ring compounds 1 and 2 , which in ethanolic solution exist predominantly in the imine form I, and in chloroform solution in the enol form II. The compounds with a six-membered A ring, 3 and 4 , are mainly in the enamine form III. On protonation, 3 and 4 change into the E and Z isomeric mixture of the enol tautomer II. The seven-membered-ring compound 5 is a mixture of the imine I and the enamine III tautomers. 相似文献
43.
L. Szentmiklósi K. Gméling Zs. Révay 《Journal of Radioanalytical and Nuclear Chemistry》2007,271(2):447-453
Prompt gamma activation analysis (PGAA) is one of the most powerful analytical methods for the determination of boron because
of its very large neutron capture cross section. The peak of boron in the PGAA spectra is highly broadened due to the Doppler-effect.
An improved method is presented to fit the boron peak, and to resolve interference with the gamma-rays of sodium and other
matrix components. The method has been checked on test samples and on geological samples as well. 相似文献
44.
Istvn Hermecz Benjaminnyi Pod Zoltn Mszros Gyrgy Szsz Jzsef Kksi 《Journal of heterocyclic chemistry》1985,22(5):1373-1375
Fischer indolization of 6-arylhydrazono-6,7,8,9-tetahydro-11H-pyrido[2,1-b]quinazolin-11-ones 1 afforded substituted 7,8-dihydro-5H,13H-indolo[2′,3′:3,4]pyrido[2,1-b]quinazolin-5-ones 3-12 in high yields. 相似文献
45.
Summary Gas chromatographic chiral separation of several chiral 2-and 3-alkanols and diols was studied both in their free hydroxyl
and in their trimethylsilyl ether forms. First, the derivatization procedure was verified through the identification of the
trimethylsilyl ethers formed on the basis of their mass spectra and optimized to obtain quantitative reaction. The optimized
procedure was applied to the trimethylsilylation of racemic mixtures of various hydroxyl compounds. The silylation was found
to be highly effective in the improvement of the separation of the individual enantiomers. The major advantages of the derivatization
process can be summarized as: (i) excellent baseline separation of the enantiomers of the silyl ethers was achieved in contrast
to the parent OH-containing compounds, (ii) the sensitivity of detection highly increased, (iii) the separations do not show
any significant concentration dependence and finally (iv) the analysis time needed decreased significantly.
Presented at: Balaton Symposium on High-Performance Separation Methods, Siófok, Hungary, September 3–5, 1997 相似文献
46.
A case study is presented for the establishment of traceability for ammonium nitrogen determination in wastewater in a routine laboratory in order to fulfil the requirements of ISO/IEC standard 17025. The necessary relevant information was obtained from the method validation data, the quality control data and equipment calibration certificates. The method of measurement is described together with the measurement equation, selected traceable reference standards and the associated measurement uncertainty. The major sources of uncertainty of the result of measurement were identified and the combined uncertainty was calculated. Identification of the main uncertainty sources represents the basis for target operations for reducing the measurement uncertainty of this determination. 相似文献
47.
Ur?a?Opara?Kra?ovecEmail author Marko?Topi? Anneke?Georg Andreas?Georg Goran?Dra?i? 《Journal of Sol-Gel Science and Technology》2005,36(1):45-52
Nano-structured WO3-TiO2 layers were prepared by the sol-gel route. To obtain transparent, porous and crack free layers up to 0.8 μ m with a single dipping cycle a templating strategy was used. As a template three-dimensionally network based on organically modified silane was introduced to the WO3 and TiO2 sols. The WO3 layers were dip-coated onto the conductive glass substrate (TCO) and the TiO2 layers on the top of the WO3 layer. The morphology and the structure of the layers were determined by Scanning Electron Microscopy (SEM), High Resolution Transmission Electron Microscopy (HR-TEM), Energy Dispersive X-Ray Spectroscopy (EDXS), Auger and Infrared spectroscopy. SEM image of the WO3-TiO2 layer confirmed the nano-porosity of the layers and give the size of the particles of about 10 nm for TiO2 and 30 nm for WO3 layer. Further analysis indicated that the titanium sol penetrates the WO3 layer. Particles in the WO3 layer consist of a crystalline monoclinic WO3 core surrounded by a 5–10 nm amorphous phase consisting of WO3, TiO2 and SiO2. The WO3-TiO2 layers were used to assemble all solid state photoelectrochromic (PE) devices. Under 1 sun irradiation (1000 W/m2) the visible transmittance of the PE device changes from 62% to 1.6%. The colouring and bleaching processes last about 10 minutes. 相似文献
48.
Truong Son Pham Katalin Gönczi György Kardos Krisztina Süle László Hegedűs Mihály Kállay Miklós Kubinyi Pál Szabó Imre Petneházy László Tőke Zsuzsa Jászay 《Tetrahedron: Asymmetry》2013,24(24):1605-1614
Several cinchona based squaramide catalysts were applied to the asymmetric Michael addition of α-nitroethylphosphonates to acrylic acid aryl esters, resulting in high yields and enantioselectivities. The absolute configuration of one of the quaternary α-nitrophosphonate adducts was deduced from its experimental and calculated CD spectra. The adducts were reduced to their cyclic aminophosphonates by catalytic hydrogenation. 相似文献
49.
Mass action type deterministic kinetic models of ion channels are usually constructed in such a way as to obey the principle of detailed balance (or, microscopic reversibility) for two reasons: first, the authors aspire to have models harmonizing with thermodynamics, second, the conditions to ensure detailed balance reduce the number of reaction rate coefficients to be measured. We investigate a series of ion channel models which are asserted to obey detailed balance, however, these models violate mass conservation and in their case only the necessary conditions (the so-called circuit conditions) are taken into account. We show that ion channel models have a very specific structure which makes the consequences true in spite of the imprecise arguments. First, we transform the models into mass conserving ones, second, we show that the full set of conditions ensuring detailed balance (formulated by Feinberg) leads to the same relations for the reaction rate constants in these special cases, both for the original models and the transformed ones. 相似文献
50.
B. Schäffer L. Daróczi B. Keller Z. Szakály D. Lőrinczy 《Journal of Thermal Analysis and Calorimetry》2013,111(3):1891-1896
Due to the increasing consumers’ interest in up-to-date nutrition nowadays the production of main part of fermented dairy products (e.g. yogurt, kefir) is performed using probiotic microbes. The majority of this product group are the flavoured variations, the sweetener is, first of all, still refined sugar (e.g. saccharose). Honey of natural origin, consequently preferred from the nutrition-physiological point of view, could be proposed to replace this refined carbohydrate. To check its availability for this purpose the growth of microbes of the Hungarian culture of trade name Prebiolact-2 was examined. The probiotic properties of the culture are proved by clinical tests. At the determination of recipes of control and experimental samples we took into consideration that the milk composition and carbohydrate content of samples should have been the same, and they could differ only in carbohydrate-free component content of honey. During processing of the samples the minimum heat-treatment was applied to protect the biologically active components of honey to the greatest degree. Pasteurized-homogenized milk was used as raw material, in which granulated sugar and the honeys were solved, respectively, at 60 °C. The inoculation was made by Prebiolact-2 culture injected into the batch-wessel; the closed cells were agitated intensively for 10 s. General conclusion of thermal investigation is that the proliferation rate is longer lasting in case of honey treated milks. The acacia- honey resulted in the same probiotic proliferation as sugar did. In case of other herb-honeys the effect was smaller, very probably because of the strong bactericidal effect of herbs, which is very important from medical point of view. According to the results of the consumer survey over 85 % of them think that the consumption of herbs in the form of honey is especially beneficial from both dietary and market view. 相似文献