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排序方式: 共有261条查询结果,搜索用时 62 毫秒
131.
Jitka Hubackova Marie Dvorackova Petr Svoboda Pavel Mokrejs Jan Kupec Iva Pozarova Pavol Alexy Peter Bugaj Michal Machovsky Marek Koutny 《Polymer Testing》2013
Research concentrated on the biodegradable capability of PCL blends with various types of starch in an anaerobic aqueous environment of mesophilic sludge from a municipal wastewater treatment plant. For blend preparation, use was made of a native starch Meritena from maize, another from Waxy – a genetically modified type of maize, as well as Gel Instant, a gelatinized starch, and an amaranth starch. Additional PCL/starch blends were prepared from the same starch types, but these were initially plasticized with glycerol. The biodegradability tests were supplemented with thermo gravimetric analysis (TGA), and differential scanning calorimetry (DSC); morphology was identified using scanning electron microscopy (SEM), plus mechanical properties were also tested. While mixtures of PCL with starches plasticized with glycerol exhibited improved mechanical properties and a higher degree of biodegradation in the anaerobic environment, mixtures of PCL with pure forms of starch were ascertained as rather resistant to the anaerobic aqueous environment. TGA and DSC analysis confirmed the removal of starch and glycerol from the PCL matrix. SEM then proved these results through the absence of starch grains in the samples following anaerobic biodegradation. 相似文献
132.
133.
For separation of enantiomers in presence of a chiral selector, data obtained with the 1D dynamic simulators SIMUL5complex and GENTRANS are compared to data predicted by PeakMaster 6, a recently released generalized model of the linear theory of electromigration. Four electrophoretic systems with stereoisomers of weak bases were investigated. They deal with the estimation of input data for complexation together with the elucidation of the origin of observed system peaks, the interference of analyte and system peak migration, the change of enantiomer migration order as function of the selector concentration and the inversion of analyte migration direction in presence of a multiply negatively charged selector. For all systems, data predicted with PeakMaster 6 are in agreement with those of the dynamic simulators and simulation data compare well with experimental data that were monitored with setups featuring conductivity and/or UV absorbance detection along the capillary. SIMUL5complex and GENTRANS provide the full dynamics of any buffer and sample arrangement and require very long execution time intervals. PeakMaster 6 is restricted to conventional CZE, is based on an approximate solution of the transport equations, provides data for realistic experimental conditions within seconds and represents a practical tool for an experimentalist. 相似文献
134.
Flash chromatography of the mixture obtained by reaction of L-rhamnose with methanol in the presence of cation-exchange resin, in addition to methyl α-L-rhamnofuranoside (3) and methyl rhamnopyranosides 1 and 2 gave methyl β-L-rhamnofuranoside (4) in 8% yield. 13C and 1H NMR spectra of 3 and 4 as well as their calculated conformation in solution are discussed. 相似文献
135.
Mária Lukáčová-Medviďová Jitka Saibertová Gerald Warnecke Yousef Zahaykah 《Applications of Mathematics》2004,49(5):415-439
The subject of the paper is the derivation and analysis of evolution Galerkin schemes for the two dimensional Maxwell and linearized Euler equations. The aim is to construct a method which takes into account better the infinitely many directions of propagation of waves. To do this the initial function is evolved using the characteristic cone and then projected onto a finite element space. We derive the divergence-free property and estimate the dispersion relation as well. We present some numerical experiments for both the Maxwell and the linearized Euler equations. 相似文献
136.
Jurček O Ikonen S Buřičová L Wimmerová M Wimmer Z Drašar P Horníček J Galandáková A Ulrichová J Kolehmainen ET 《Molecules (Basel, Switzerland)》2011,16(11):9404-9420
Synthesis, detailed structural characterization (X-ray, NMR, MS, IR, elemental analysis), and studies of toxicity, antioxidant activity and bioavailability of unique potent anti-atherosclerotic succinobucol-steroid conjugates are reported. The conjugates consist of, on one side, the therapeutically important drug succinobucol ([4-{2,6-di-tert-butyl-4-[(1-{[3-tert-butyl-4-hydroxy-5-(propan-2-yl)phenyl]sulfanyl}ethyl)sulfanyl]phenoxy}-4-oxo-butanoic acid]) possessing an antioxidant and anti-inflammatory activity, and on the other side, plant stanol/sterols (stigmastanol, β-sitosterol and stigmasterol) possessing an ability to lower the blood cholesterol level. A cholesterol-succinobucol prodrug was also prepared in order to enhance the absorption of succinobucol through the intestinal membrane into the organism and to target the drug into the place of lipid metabolism-The enterohepatic circulation system. Their low toxicity towards mice fibroblasts at maximal concentrations, their antioxidant activity, comparable or even higher than that of ascorbic acid as determined by direct quenching of the DPPH radical, and their potential for significantly altering total and LDL cholesterol levels, suggest that these conjugates merit further studies in the treatment of cardiovascular or other related diseases. A brief discussion of succinobucol's ability to quench the radicals, supported with a computational model of the electrostatic potential mapped on the electron density surface of the drug, is also presented. 相似文献
137.
Capillary electrophoresis (CE) is a powerful separation method based on the migration of charged species under the influence of electric field. The main merits of CE are high separation efficiency, short analysis time and small consumption of solvents and samples. However, the main drawbacks of CE are generally lower sensitivity compared to classical column-chromatographic methods.Selectivity and/or sensitivity of CE separation can be improved by forming complexes between analytes and a complex-forming reagent present as an additive in the background electrolyte (BGE). We focus this review primarily on the application of inorganic complex-forming reagents added to the BGE to separate organic ligands. We briefly mention common CE separations of inorganic analytes (mainly metal ions) using BGEs with organic ligands (e.g., hydroxycarboxylic or aminopolycarboxylic acids) as selectors.The review involves brief theoretical consideration of the significance of the effect of complex formation on separation selectivity and/or sensitivity in CE, but the major topic is critical evaluation of different inorganic complex-forming reagents used recently in the CE analysis of organic compounds, including:
- (i)
- borate, tungstate and molybdate in separating organic compounds possessing vicinal -OH groups;
- (ii)
- ligand-exchange CE and capillary electrochromatography in chiral analysis; and,
- (iii)
- the role of metal ions as central ions employed for selectivity enhancement of CE separation of various classes of organic compounds, including biopolymers.
138.
Antonov N. N. Baldin A. A. Viktorov V. A. Galoyan A. S. Gapienko V. A. Gapienko G. S. Gres’ V. N. Ilyushin M. A. Prudkoglyad A. F. Pryanikov D. S. Romanovskii V. A. Semak A. A. Solodovnikov I. P. Terekhov V. I. Ukhanov M. N. Shimanskii S. S. 《JETP Letters》2020,111(5):251-254
JETP Letters - The first data on the yield of the lightest nuclear fragments (protons p, deuterons d, and tritons t) with high transverse momenta pT at an angle of 40° in the laboratory... 相似文献
139.
Pospiskova Kristyna Mohr Gerhard J. Prochazkova Jitka Timko Milan Rajnak Michal Paulovicova Katarina Kopcansky Peter Giovannini Giorgia Boesel Luciano F. Safarik Ivo 《Cellulose (London, England)》2021,28(12):7675-7685
Cellulose - Fluorescent and magnetic nano- and microparticles have already been used for wide range of (bio)applications. Multimodal imaging as well as simultaneous control and monitoring of... 相似文献
140.