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排序方式: 共有126条查询结果,搜索用时 15 毫秒
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JPC – Journal of Planar Chromatography – Modern TLC - TLC and HPLC have been used for preliminary evaluation of the phenolic acids occurring in the leaves, inflorescences, and rhizomes... 相似文献
3.
Silica xerogels with different structures and morphology, synthesized using a sol-gel procedure, were used as a carrier of vanadium catalysts (VOCl3/AlEt2Cl) for ethylene polymerization. Two techniques of catalyst synthesis were applied: slurry impregnation and gas-phase adsorption and the relevant polymerization methods were then employed. The effect of the carrier structure and morphology on the vanadium loading in the catalysts, the catalyst’s activity and kinetic stability were investigated. 相似文献
4.
Prakash R Czaja AU Heinemann FW Sellmann D 《Journal of the American Chemical Society》2005,127(40):13758-13759
The new ruthenium compound [Ru(NO)(pysiS4)]Br (3) (pysiS4 = 2,6-bis(3-triphenylsilyl-2-sulfanylphenylthiomethyl)pyridine), containing sterically bulky SiPh3 groups ortho to the thiolate donors, has been synthesized. In solution, 3 releases NO efficiently on exposure to visible light (lambda >/= 455 nm) at room temperature to afford [Ru(Br)(pysiS4)] (4). Treatment of 4 with NO yielded exclusively 3 without any metal-bound side reaction. 相似文献
5.
A short-term aerobic stabilization of digested waste in the final methane phase was studied. The effect of aeration rate on
the reduction of leachate parameters and on the rate of CO2 production and O2 assimilation was investigated. Experimental simulation of aerobic landfill stabilization was carried out using lysimeters.
When testing the effect of aeration rate on the reduction of leachate indices (BOD5, COD, N-NH4+), it was reported that the most significant reduction was obtained at the highest rate of aeration and the smallest reduction
of leachate indices was attained not at the lowest but at medium aeration rates. Both the rate of CO2 production and the O2 assimilation reached their highest values in the lysimeters aerated at a high rate of aeration. The proposed mathematical
model which consists of a system of five differential equations describing CO2 production, O2 assimilation and the changes of organic carbon content in the leachate correspond well with the experimental data. 相似文献
6.
Dialkyl [2-hydroxy-5-(phenylazo)benzyl]phosphonates were prepared by a convenient procedure in good yield from Mannich base and trialkyl phosphite in benzene with the elimination of ammonium or morpholinium cation. 2-[(Dialkylamino)methyl]-4-(phenylazo)phenol methiodide is a new reagent in the Michaelis-Arbuzov reaction. 相似文献
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Radoslaw Pomecko Zouhair Asfari Véronique Hubscher-Bruder Maria Bochenska 《Supramolecular chemistry》2013,25(7):459-466
The synthesis and characterization of a new tetra (triphenylphosphonium) p-tert-butylcalix[4]arene 2 is presented. Its interactions with anions were studied by 1H and 31P NMR and UV absorption spectrophotometry, showing the biggest interaction with ClO4 ? , I? and SCN? . Anion selectivity in ion-selective PVC-membrane electrodes (ISEs) plasticized with o-NPOE containing ionophore 2 was also investigated. Compound 2 shows a potentiometric response for various anions with the following selectivity pattern: ClO4 ? > SCN? > I? > Cr2O7 2 ? > NO3 ? > Br? > Cl? . 相似文献
9.
Piotr Czaja 《Journal of Thermal Analysis and Calorimetry》2013,113(1):91-95
In this paper the technology of producing solid solutions of Csx(NH4)1?xLiSO4 using the slow evaporation method is presented. Appropriate conditions were chosen to grow large samples. The ammonium ion content in the solid solutions was determined using the Kjeldahl method. It was found that the real ammonium ion concentration is twice lower than the one applied in the initial substances. At room temperature, the base crystal, lithium cesium sulfate (CsLiSO4), is paraelastic, whereas lithium ammonium sulfate (NH4LiSO4) is ferroelectric. It is expected that as a result of substituting Cs+ ions with $ N{\text{H}}_{4}^{ + } $ N H 4 + ions, instead of the Cs+ ions, the modification of the ferroic properties of solid solutions of Csx(NH4)1?xLiSO4 will take place. Tests conducted with the use of the differential scanning calorimetry method (DSC) allowed the detection of the ferroelastic phase transition which takes place in these compounds. A gradual increase of temperature transition was observed from 202 K for the pure CsLiSO4 to 203.8 K for Cs0.90(NH4)0.10LiSO4 and 230.1 K for Cs0.85(NH4)0.15LiSO4 with the increase of $ N{\text{H}}_{4}^{ + } $ N H 4 + ions concentration. Using polarized light microscopy, a ferroelastic domain structure was detected in the examined solid solutions, which appeared below the structural phase transition temperature. 相似文献
10.
Paweł Mierczynski Piotr Kaczorowski Agnieszka Ura Waldemar Maniukiewicz Marcin Zaborowski Radoslaw Ciesielski Adam Kedziora Tomasz P. Maniecki 《Central European Journal of Chemistry》2014,12(2):206-212
Ternary CuO-ZrO2-Al2O3 catalysts promoted by palladium or gold were prepared and tested in CO hydrogenation reaction at 260°C under elevated pressure (4.8 MPa). The promotion effect of palladium or gold addition on the physicochemical and catalytical properties of CuO-ZrO2-Al2O3 catalysts in methanol synthesis (MS) was studied. The catalysts were characterized by BET, XRD, TPR-H2, TPD-NH3 methods. The BET results showed that the ternary system CuO-ZrO2-Al2O3 had the largest specific surface area, cumulative pore volume and average pore size in comparison with the promoted catalysts. The yield of methanol can be given through the following sequence: 5%Pd/CuO-ZrO2-Al2O3 > CuO-ZrO2-Al2O3 > 2%Au/CuO-ZrO2-Al2O3. We also found that the presence of gold or palladium on catalyst surface has strong influence on the reaction selectivity. The high selectivity of gold doped ternary catalyst is explained by the gold-oxide interface sites created on the catalyst surface and the acidity of those systems. The higher selectivity to methanol in the case of the palladium catalyst is explained by the spillover effect between Pd and CuO. 相似文献