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排序方式: 共有538条查询结果,搜索用时 31 毫秒
91.
This paper develops semistability and uniform semistability analysis results for switched linear systems. Semistability is the property whereby the solutions of a dynamical system converge to Lyapunov stable equilibrium points determined by the system’s initial conditions. Since solutions to switched systems are a function of the system’s initial conditions as well as the switching signals, uniformity here refers to the convergence rate of the multiple solutions as the switching signal evolves over a given switching set. The main results of the paper involve sufficient conditions for semistability and uniform semistability using multiple Lyapunov functions and sufficient regularity assumptions on the class of switching signals considered. 相似文献
92.
Optical absorption bands at ~18772 and ~18807 cm-1, previously assigned to A2Δ-X2Π electronic origin band transitions of the linear carbon-chain radicals C5H and C5D, respec-tively, have been reinvestigated. The spectra have been recorded in direct absorption apply-ing cavity ring-down spectroscopy to a supersonically expanding acetylene/helium plasma. The improved spectra allow deducing a l-C5H upper state spin-orbit coupling constant A'=-0.7(3) cm-1 and a A2Δ lifetime of 1.6±0.3 ps. 相似文献
93.
Gregory B. Kharas William S. Schjerven Uriel A. Baray Samantha Chan Michael T. Cole Alexander F. Haddad 《高分子科学杂志,A辑:纯化学与应用化学》2016,53(4):191-195
Electrophilic trisubstituted ethylenes, ring-disubstituted butyl 2-cyano-3-phenyl-2-propenoates, RPhCH?C(CN)CO2C4H9 (where R is 2-fluoro-5-methoxy, 2-fluoro-6-methoxy, 3-fluoro-4-methoxy, 4-fluoro-3-methoxy, 5-fluoro-2-methoxy, 3-fluoro-2-methyl, 3-fluoro-4-methyl, 4-fluoro-2-methyl, 4-fluoro-3-methyl, 5-fluoro-2-methyl were prepared and copolymerized with styrene. The monomers were synthesized by the piperidine catalyzed Knoevenagel condensation of ring-disubstituted benzaldehydes and butyl cyanoacetate, and characterized by CHN analysis, IR, 1H and 13C-NMR. All the ethylenes were copoly-merized with styrene (M1) in solution with radical initiation (ABCN) at 70°C. The compositions of the copolymers were calculated from nitrogen analysis and the structures were analyzed by IR, 1H and 13C-NMR. Decomposition of the copolymers in nitrogen occurred in two steps, first in the 200–500°C range with residue (1.2–3.5% wt.), which then decomposed in the 500–800°C range. 相似文献
94.
The direct effect of ultrasound on the extraction of date syrup and its micro-organisms 总被引:2,自引:0,他引:2
In the date syrup industry, date fruits are mixed with a suitable amount of water at a temperature greater than 50 °C for about 1 h. This condition is not sufficient for killing the micro-organisms present in the fruit. In addition, Overheating for a long time can damages nutritious materials and also changes the final product's color. Ultrasound was applied for improving the quantity and quality of the extraction, and also to overcome the health problem. In this research, the following variables were examined: date fruit/water ratio, ultrasonic intensity and temperature. The results showed that sonication under the proper conditions can lead to a higher extraction in a shorter time with a better physical quality of the product. Most importantly, the sonication significantly decreased the microbial count in comparison to the classical method. This study also confirmed the presence of anti-microbial substances in date fruit, and that ultrasonic waves can accelerate their effects. 相似文献
95.
One of the problems with capillary electrophoresis is a lack of versatility regarding manipulation of the separation selectivity. A new and potentially universal concept is to introduce an ion-exchange component into a separation so that the migration of analyte ions is influenced by both their electrophoretic mobilities and their chromatographic properties. This may be accomplished by use of capillaries filled with or coated with solid ion-exchange polymers, or by addition of a soluble ionic polymer to the background electrolyte to create a pseudo-stationary phase. While each of these methods achieves the same result, they are not competitive, but rather complementary as the problems associated by one approach are overcome by the others. Recent highlights in the field are used to illustrate the flexibility that this approach provides to electrophoretic separation of ions. 相似文献
96.
Shahali Y Sutra JP Haddad I Vinh J Guilloux L Peltre G Sénéchal H Poncet P 《Electrophoresis》2012,33(3):462-469
Italian cypress (Cupressus sempervirens, Cups) pollen causes allergic diseases in inhabitants of many of the cities surrounding the Mediterranean basin. However, allergens of Cups pollen are still poorly known. We introduce here a novel proteomic approach based on double one‐dimensional gel electrophoresis (D1‐DE) as an alternative to the 2‐DE immunoblot, for the specific IgE screening of allergenic proteins from pollen extracts. The sequential one‐dimensional combination of IEF and SDS‐PAGE associated with IgE immunoblotting allows a versatile multiplexed immunochemical analysis of selected groups of allergens by converting a single protein spot into an extended protein band. Moreover, the method appears to be valuable for MS/MS identification, without protein purification, of a new Cups pollen allergen at 43 kDa. D1‐DE immunoblotting revealed that the prevalence of IgE sensitization to this allergen belonging to the polygalacturonase (PG) family was 70% in tested French allergic patients. In subsequent triple one‐dimensional gel electrophoresis, the Cups pollen PG was shown to promote lectin‐based protein‐protein interactions. Therefore, D1‐DE could be used in routine work as a convenient alternative to 2‐DE immunoblotting for the simultaneous screening of allergenic components under identical experimental conditions, thereby saving considerable amounts of sera and allergen extracts. 相似文献
97.
98.
Wenzhi Hu Paul R. Haddad Kyioshi Hasebe Helmy A. Cook James S. Fritz 《Analytical and bioanalytical chemistry》2000,367(7):641-644
The inability to separate fluoride, phosphate and sulfate by electrostatic ion chromatography (EIC) was overcome by using an ODS silica column coated with mixed zwitterionic-cationic surfactants as the stationary phase. The best results were obtained using the zwitterionic surfactant, 3-(N,N-dimethylmyristylammonium)-propanesulfonate (C19H41NO3S), and the cationic surfactant, myristyltrimethylammonium, CH3(CH2)13N+(CH3)3, in a 10:1 molar ratio in the column coating solution. With a dilute solution of sodium tetraborate as the eluent the model analyte anions were completely separated in the following elution order: F–, HPO4 2–, SO4 2–, Cl–, NO2 –, Br–, NO3 –. The very early elution of phosphate and sulfate is most unusual and is unique to this system. Detection limits better than 1.1 × 10–4 mM and linear calibration plots up to 7.0 mM were obtained with a suppressed conductivity system. 相似文献
99.
M. El Haddad M. Soukri S. Lazar A. Bennamara G. Guillaumet M. Akssira 《Journal of heterocyclic chemistry》2000,37(5):1247-1252
Pyrazolo‐[3,4‐d]pyrimidine‐4,6‐diones 5 and pyrazolo[4,3‐d]pyrimidine‐5,7‐diones 7 were synthesized by Curtius rearrangement of pyrazolic mono‐esters 2 and 3 followed by hetero‐cyclization via the ureas derivatives 4 and 6 under alkaline conditions. 相似文献
100.