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排序方式: 共有155条查询结果,搜索用时 15 毫秒
71.
Lincoln Brum Leite Gusmão Pinheiro Francisco Carlos Serbena Carlos Eugênio Foerster Pedro Rodrigues Júnior Alcione Roberto Jurelo Adilson Luiz Chinelatto Jorge Luiz Pimentel Júnior 《Physica C: Superconductivity and its Applications》2011,471(5-6):179-184
The main objective of this paper is to report the room temperature hardness and elastic modulus of the RuSr2GdCu2O8 superconductor phase by instrumented indentation. Polycrystalline samples were produced by a solid state reaction technique. The samples were also characterized by scanning electron microscopy, X-ray diffraction and electrical resistivity measurements. The influence of porosity on the mechanical properties was avoided by considering only those indentations inside the grains. The hardness and elastic modulus were 8.6 GPa and 145 GPa, respectively. These values are comparable with those of Y-123. The indentation fracture toughness evaluated after conventional Vickers indentation was 1.9 MPa m1/2. 相似文献
72.
Kouakou TH Dué EA Kouadio NE Niamké S Kouadio YJ Mérillon JM 《Applied biochemistry and biotechnology》2009,157(3):575-592
Two peroxidases, cPOD-I and rPOD-II, have been isolated and purified from cotton cell suspension and their biochemical characteristics
studied. rPOD-II from R405-2000, a non-embryogenic cultivar, has higher activity than cPOD-I derived from Coker 312, which
developed an embryogenic structure. The cPOD-I and rPOD-II had molecular mass of 39.1 and 64 kDa respectively, as determined
by SDS-PAGE. Both enzymes showed high efficiency of interaction with the guaiacol at 25 mM. The optimal pH for cPOD-I and
rPOD-II activity was 5.0 and 6.0, respectively. The enzyme had an optimum temperature of 25 °C and was relatively stable at
20–30 °C. The isoenzymes were highly inhibited by ascorbic acid, dithiothreitol, sodium metabisulfite, and β-mercaptoethanol.
Their activities were highly enhanced by Al3+, Fe3+, Ca2+, and Ni2+, but they were moderately inhibited by Mn2+ and K+. The enzyme lost 50% to 62% of its activity in the presence of Zn2+ and Hg2+. 相似文献
73.
We introduce a new tuberculosis (TB) mathematical model, with 25 state-space variables where 15 are evolution disease states (EDSs), which generalises previous models and takes into account the (seasonal) flux of populations between a high incidence TB country (A) and a host country (B) with low TB incidence, where (B) is divided into a community (G) with high percentage of people from (A) plus the rest of the population (C). Contrary to some beliefs, related to the fact that agglomerations of individuals increase proportionally to the disease spread, analysis of the model shows that the existence of semi-closed communities are beneficial for the TB control from a global viewpoint. The model and techniques proposed are applied to a case-study with concrete parameters, which model the situation of Angola (A) and Portugal (B), in order to show its relevance and meaningfulness. Simulations show that variations of the transmission coefficient on the origin country has a big influence on the number of infected (and infectious) individuals on the community and the host country. Moreover, there is an optimal ratio for the distribution of individuals in (C) versus (G), which minimizes the reproduction number \(R_0\). Such value does not give the minimal total number of infected individuals in all (B), since such is attained when the community (G) is completely isolated (theoretical scenario). Sensitivity analysis and curve fitting on \(R_0\) and on EDSs are pursuit in order to understand the TB effects in the global statistics, by measuring the variability of the relevant parameters. We also show that the TB transmission rate \(\beta \) does not act linearly on \(R_0\), as it is common in compartment models where system feedback or group interaction do not occur. Further, we find the most important parameters for the increase of each EDS. 相似文献
74.
Chebel FX Ratusznei SM Rodrigues JA Zaiat M Foresti E 《Applied biochemistry and biotechnology》2006,133(2):171-188
The performance of an anaerobic sequencing batch reactor (ASBR) was assessed when submitted to increasing organic load with different influent concentrations and cycle lengths. The 5-L mechanically stirred (75 rpm) ASBR contained 2 L of granular biomass and treated 2 L of synthetic wastewater per cycle. Volumetric organic loads (VOLs) from 0.66 to 2.88 g of chemical oxygen demand (COD)/(L x d) were applied by using influent concentrations from 550 to 3,600 mg of COD/L in 8- and 12-h cycles. Reactor stability was maintained for VOLs from 0.66 to 2.36 g of COD/(L x d), with organic matter removal efficiencies for filtered samples (epsilonF) between 84 and 88%. For VOLs from 0.78 to 2.36 g of COD/(L x d) at an influent concentration of 2,000 mg of COD/L, when cycle length was reduced from 12 to 8 h, epsilonF did not vary, yet showed a very distinct behavior from the other conditions. In addition, two operation strategies were studied for VOLs with approximately similar values of 2.36 and 2.08 g of COD/(L x d). One involved operation with an influent concentration of 2,000 mg of COD/L and an 8-h cycle, whereas the other involved an influent concentration of 2,600 mg of COD/L and a 12-h cycle. Only the former resulted in system stability and efficiency. These results indicate that besides organic load, influent concentration and cycle length play a significant role in ASBR systems. 相似文献
75.
Summary Heavy residues from the distillation of oils (SAFANYA) have been analyzed by inverse gas chromatography (IGC). The dispersive components of the surface energies of the residues could readily be determined. Acid/base characteristics could be appreciated using an original method developed in this Laboratory. 相似文献
76.
Leonard S Capote R Germonprez N Van Puyvelde L De Kimpe N Vermeersch H Rosier J Maes L Roets E Hoogmartens J 《Journal of chromatography. A》2003,1012(1):39-46
A liquid chromatographic method was developed for the separation of six related triterpenoid saponins in Maesa balansae extracts with different purity, active against leishmaniasis. As stationary phase a Hypersil BDS C18 column (3 microm), 100 x 4.6 mm was used. The mobile phase was a mixture of methanol, acetonitrile, 5% (m/v) ammonium acetate, pH 6.5 and water. A linear gradient was developed for the analysis of crude extracts. An isocratic method was developed to analyze purified samples that mainly contained saponins 3 and 4, the most active saponins. The isocratic LC method was optimized and the robustness was evaluated with an experimental design. The method showed good selectivity, repeatability, linearity and sensitivity. 相似文献
77.
Simultaneous determination of amino acids and neurotransmitters in plasma samples from schizophrenic patients by hydrophilic interaction liquid chromatography with tandem mass spectrometry
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Diego Soares Domingues Eduardo José Crevelin Luiz Alberto Beraldo de Moraes Jaime Eduardo Cecilio Hallak José Alexandre de Souza Crippa Maria Eugênia Costa Queiroz 《Journal of separation science》2015,38(5):780-787
A sensitive, reproducible, and rapid method was developed for the simultaneous determination of underivatized amino acids (aspartate, serine, glycine, alanine, methionine, leucine, tyrosine, and tryptophan) and neurotransmitters (glutamate and γ‐aminobutyric acid) in plasma samples using hydrophilic interaction liquid chromatography coupled to triple quadrupole tandem mass spectrometry. The plasma concentrations of amino acids and neurotransmitters obtained from 35 schizophrenic patients in treatment with clozapine (27 patients) and olanzapine (eight patients) were compared with those obtained from 38 healthy volunteers to monitor the effectiveness of treatment. The chromatographic conditions separated ten target compounds within 3 min. This method presented linear ranges that varied from (lower limit of quantification: 9.7–13.3 nmol/mL) to (upper limit of quantification: 19.4–800 nmol/mL), intra‐ and interassay precision with coefficients of variation lower than 10%, and relative standard error values of the accuracy ranged from –2.1 to 9.9%. The proposed method appropriately determines amino acids and neurotransmitters in plasma from schizophrenic patients. Compared with the control group (healthy volunteers), the plasma levels of methionine in schizophrenic patients treated with olanzapine are statistically significantly higher. Moreover, schizophrenic patients treated with clozapine tend to have increased plasma levels of glutamate. 相似文献
78.
79.
Eug Bamberger 《Fresenius' Journal of Analytical Chemistry》1887,26(1):640-641
Ohne Zusammenfassung 相似文献
80.
H. von Jüptner Francis Watts A. E. Hunt George Craig H. Rocholl V. Eggertz A. Tamm J. Oliver Arnold J. Lawrence Smith Magnus Troilius Albano Brand Eug Lundin Friedrich C. G. Müller A. Pourcel Brustlein H. Wedding und D. Sevoz 《Fresenius' Journal of Analytical Chemistry》1886,25(1):258-262
Ohne Zusammenfassung 相似文献