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排序方式: 共有271条查询结果,搜索用时 15 毫秒
1.
The process of thermal degradation of poly(vinyl chloride)/poly(methyl methacrylate-butadiene-styrene) (PVC/MBS) blends was
investigated by means of isothermal thermogravimetry in nitrogen. The total mass loss was determined after 120 min. The kinetic
parameters of the degradation process were determined by applying two kinetic models: the model which assumes autocatalytic
degradation (Prout-Tompkins) and the model of two-dimensional diffusion. It was established that the thermal degradation at
lower degrees of conversion (α<0.20) was well described by the former model, but the latter model was applicable at higher
degrees of conversion. The thermal stability of blends at a certain temperature of isothermal degradation depends on the blend
composition and the shell/core ratio in MBS, and on the adhesion in the boundary layer in PVC/MBS blends.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
2.
The protected 2-formyl-L-arabinal 2 reacted with thiourea and cyanamide in the presence of sodium hydride to afford via ring transformations the 5-[1R,2S-1,2- bis(benzyloxy)-3-hydroxypropyl]-1,2-dihydropyrimidines 3 and 4, respectively. Similarly, treatment of 2 with 3-amino-2H-1,2,4-triazole yielded 6-[1R,2S-1,2- bis(benzyloxy)-3-hydroxypropyl][1,2,4]-triazolo[1,5-a]pyrimidine (5). 相似文献
3.
N. Filipović-Vinceković D. Barišić N. Mašić S. Lulić 《Journal of Radioanalytical and Nuclear Chemistry》1991,148(1):53-62
The distribution of137Cs through soil layers has been investigated by field sampling. The investigation deals with137Cs concentration found after the Chernobyl accident. The relationship between important soil characteristics, total precipitation and cesium distribution are analyzed. Cesium is strongly sorbed in the top soil layer and its migration downward is limited. Measurements performed over a 3-year period revealed that approximately 20–38 per cent of total137Cs is located in the upper soil layer. 相似文献
4.
Mohammed A. Bari Siddiqui Shakeel Ahmed Musaed S. Al-Gharami Chistopher F. Dean 《Reaction Kinetics and Catalysis Letters》2007,91(1):61-67
Sulfur reduction ability of alumina supported zinc, gallium and zinc-gallium additives for fluid catalytic cracking catalysts
was evaluated in a micro-activity test unit (MAT). Gallium/alumina showed the highest sulfur reduction of 31%, but the cracking
activity of the catalyst was decreased. Zinc-gallium/alumina reduced sulfur in 24 wt.% without decreasing the base catalyst
activity. 相似文献
5.
Database analysis and molecular mechanics were used to determine the conformational flexibility of tridentate scorpionate ligands. The tris(pyrazolyl)methane and tris(pyrazolyl)borate ligands act like molecular vises, opening their tripodal structure for larger metals and closing around smaller metal ions. Tris(3-tert-butylpyrazolyl)methane has significant preference for larger metal ions than its unsubstituted parent compound. Tris(pyrazolyl)methanes and tris(pyrazolyl)borates have similar conformational flexibilities. Placing sterically hindered groups on the central carbon or boron has only a minor effect on the geometry of the tris(pyrazolyl)methanes and tris(pyrazolyl)borates. However, it does influence the flexibility of the ligands, particularly when they have to open far from their ideal geometry, which commonly occurs. 相似文献
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8.
Sylvain Maclot Michael Capron Rémi Maisonny Arkadiusz Ławicki Dr. Alain Méry Dr. Jimmy Rangama Prof. Dr. Jean‐Yves Chesnel Sadia Bari Prof. Dr. Ronnie Hoekstra Dr. Thomas Schlathölter Prof. Dr. Bruno Manil Prof. Dr. Lamri Adoui Dr. Patrick Rousseau Prof. Dr. Bernd A. Huber 《Chemphyschem》2011,12(5):881-881
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10.
Nikica Šprem Ivan Babić Domagoj Barišić Delko Barišić 《Journal of Radioanalytical and Nuclear Chemistry》2013,298(1):513-517
The aim of this study was to investigate 137Cs and 40K load in large mammal game species in the mountain forest region of Gorski Kotar in Croatia approximately a quarter of century after the Chernobyl accident. 137Cs and 40K activity were determined by the gamma-spectrometric method in 49 meat samples of five large game species: brown bear (Ursus arctos), wild boar (Sus scrofa), roe deer (Capreolus capreolus), red deer (Cervus elaphus), and chamois (Rupicapra rupicapra). The results indicated that herbivore game species (roe deer, red deer and chamois) show significantly lower 137Cs concentrations than omnivore species (brown bear, wild boar), thereby confirming the hypothesis that different dietary strategy impact caesium concentrations in meat. The measured caesium load in brown bear meat was in the range of two orders of magnitude, while caesium load in wild boar meat was found in the range of one order of magnitude. The estimated effective equivalent dose showed that uptake of the highest caesium doses would be from consumption of omnivore species meat, while much lower doses could be taken in with the consumption of meat from herbivore species. 相似文献