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131.
132.
Gordana Marković Suzana Samaržija-Jovanović Vojislav Jovanović Milena Marinović-Cincović 《Journal of Thermal Analysis and Calorimetry》2010,100(3):881-888
The properties of filled polymers depend on the properties of the matrix and the filler, the concentration of the components and their interactions. In this research we investigated the rheological and mechanical properties and thermal stability of polychloroprene/chlorosulfonated polyethylene (CR/CSM) rubber blends filled with nano- and micro-silica particles. The density of the nano-silica filled CR/CSM rubber blends was lower than that of the micro-silica filled samples but the tensile strength and elongation at break were much higher. The nano-silica filled CR/CSM rubber blend has higher V r0/V rf values than micro-silica composites and show better polymer–filler interaction according to Kraus equation. The nano-silica filled CR/CSM rubber blends were transparent at all filler concentration, and have higher glass transition values than micro-silica filled compounds. The higher values of the glass transition temperatures for the nano- than the micro-filled cross-linked systems are indicated by DMA analysis. The nano-filled cross-linked systems have a larger number of SiO–C links than micro-filled cross-linked systems and hence increased stability. 相似文献
133.
JPC – Journal of Planar Chromatography – Modern TLC - A simple and reliable HPTLC method has been developed for simultaneous determination of antimycotics (bifonazole and econa-zole... 相似文献
134.
A simple structure is suggested for modelling unobserved heterogeneity in multivariate duration models which avoids the “curse
of dimensionality” and numerical integration of the likelihood function. 相似文献
135.
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137.
The benzimidazole compounds and benzoannulated cyclic benzimidazole analogues, such as benzimidazo[1,2-a]quinolines, are a part of our wider investigation on biologically active compounds, potential antitumor drugs. Here, we present
the synthesis of two compounds, [2-(1H-benzimidazol-2-yl)-3-(4-bromophenyl)-acrylonitrile, 5] and [2-bromo-benzimidazo[1,2-a]quinoline-6-carbonitrile, 7] and their crystal structures revealed by X-ray single crystal diffractometry. We also report the molecular and crystal structures
of two additional compounds [2-(1H-benzimidazol-2-yl)-3-(4-cyanophenyl)-acrylonitrile, 4] and [benzimidazo[1,2-a]quinoline-2,6-dicarbonitrile, 6], whose synthesis and spectroscopic characterization have been published earlier by us too (Hranjec and Karminski-Zamola,
Molecules 12:1817, 2007). The compounds 4 and 5 crystallize as monohydrates. The dihedral angles calculated between phenyl and benzimidazole ring reflect not significant
deviation from molecular planarity in the crystalline state for 4 and 5, while benzoannulated cyclic benzimidazole derivatives 6 and 7 are essentially planar. The crystal structures of 4 and 5 are characterized by O–H···N and N–H···O hydrogen bonds between water molecule of crystallization and imidazole NH group
as well as CN group, while in 6 and 7 only weak C–H···N intermolecular hydrogen bonds exist. Although, crystal packings are analogous in 4 and 5, the molecular conformations differ slightly. In 6 there is one C–H···N hydrogen bond that do not exist in 7. 相似文献
138.
A study of the neighbouring group effects on the 1H and 13C chemical shifts and the results of NOE experiments have allowed the identification of the stereoisomers of alkylidene cylopentenones. Various long range coupling constants have been measured and their signs determined by selective decoupling. The mechanisms and angular dependences of these couplings have been discussed. The Π contributions are predominant and the absolute value of 4Jtransoid associated with a dihedral angle of 30° is higher than the corresponding value of 4Jcisoid. 相似文献
139.
Violeta D. Mitic Marija D. Ilic Vesna P. Stankov-Jovanovic Gordana S. Stojanovic Marija V. Dimitrijevic 《Natural product research》2018,32(2):222-224
The essential oil isolated from Erica spiculifolia Salisb. by hydrodistillation was analysed by GC-MS. One hundred compounds representing 92.6% of total oil were identified. Among the detected compounds 38 were monoterpenoids (46.2%), 30 were sesquiterpenoids (31.7%), 2 diterpene (0.4%) and 30 compounds (14.3%) were with various non-terpenoid structures. Oxygenated monoerpenes were by far the main class (45.3%) with α-terpineol (7.5%) endo-borneol (7.2%), pinocarveol (5.9%) and thymol (3.7%) as the major compounds. The predominant components of sesquiterpenes were caryophyllene oxide (5.0%), caryophyllene (4.2%), τ –murrolol (3.5%), spathulenol (2.9) and α-cadinol (2.3%). 相似文献
140.
Snezana S. Mitic Gordana Z. Miletic Aleksandra N. Pavlovic Snezana B. Tosic 《Monatshefte für Chemie / Chemical Monthly》2004,56(12):927-936
A new selective, sensitive, and simple kinetic method is developed for the determination of trace amounts of chromium (VI). The method is based on the catalytic effect of Cr(VI) on the reaction of sodium pyrogallol-5-sulphonate (PS) with hydrogen peroxide. The reaction is followed spectrophotometrically by tracing the oxidation product at 437nm within 1min after addition of H2O2. The optimum reaction conditions are PS (1.32·10–3mol·dm–3), H2O2 (0.32mol·dm–3), HClO4 (2.6·10–3mol·dm–3) at 25°C. Following this procedure, chromium (VI) can be determined with a linear calibration graph up to 0.25ng·cm–3 and a detection limit of 0.024ng·cm–3, based on the 3 criterion. The interference effect of several species was also investigated and it was found that the most common cations and anions do not interfere with the determination. The developed procedure was successfully applied to the determination of Cr(VI) and total Cr in river waters and total Cr in herbal samples. 相似文献