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Ohne Zusammenfassung 相似文献
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V. Ščasnár L. Beneš Š. Bezek T. Trnovec 《Journal of Radioanalytical and Nuclear Chemistry》1984,82(2):287-297
Simple and rapid extraction method for quantitative and selective isolation of the new local anesthetic pentacaine from biological materials is proposed. The technique of ion-pair formation was found to be more effective than usual access using the extraction of the nonionized species. The extraction yield of the unchanged molecule3H-pentacaine after double extraction and single scrubbing was found to be more than 90%. The radiochemical purity was over 90%. The method appears suitable for pharmacokinetic studies in the animal body. 相似文献
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V. Ščasnár M. Zemánek L. Šoltés M. Lukácsová 《Journal of Radioanalytical and Nuclear Chemistry》1989,134(2):433-436
An HPLC method was developed for studying the stability of [3H] stobadin stored in physiological saline or buffers at various pH. Optimum conditions for the separation of degradation products were elaborated. A high-performance liquid chromatograph equipped with a radioactivity detector was used. 相似文献
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A simple and rapid radiochemical method for the efficient and selective isolation of3H-stobadine from plasma, urine and organ homogenates has been developed. The method comprises the extraction of3H-stobadine from the biological matrix containing 2M Na2CO3 into n-hexane followed by scrubbing of partly coextracted metabolites into an equal volume of 2M Na2CO3. The specificity of the procedure presented is demonstrated by TLC and the comparison of distribution coefficients of authentic and apparent (isolated) substances. 相似文献
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Tomas Grinys Mantas Dmukauskas Mindaugas Ščiuka Saulius Nargelas Andrius Melninkaitis 《Applied Physics A: Materials Science & Processing》2014,114(2):381-385
Mg- and Si-doped GaN layers deposited by metalorganic chemical vapor deposition method were irradiated with femtosecond pulse duration laser of three different wavelengths 1,030, 515 and 343 nm. Both single and multiple shot laser induced damage thresholds of doped GaN layers were evaluated and discussed. The scanning electron microscopy employed with electron beam induced current and energy dispersive X-ray techniques were used to study laser damage morphology. It was observed that ablated area and laser-induced damage increased with irradiation fluence. The mechanism of damage generation by Gaussian beam profile laser was considered. 相似文献
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V. Ščasnár 《Journal of Radioanalytical and Nuclear Chemistry》1998,228(1-2):99-104
A simple and specific radiometric assay was developed for the determination of stobadine, a cardioprotective drug, in the serum of experimental animals. The assay is based on a single extraction step of the radioactively labeled drug from serum into the benzene solution of dicarbolide of cobalt followed by quantitation of the extracted radioactivity by using liquid scintillation counting. The extraction mechanism involves the ion-pair formation between the protonized molecule of stobadine and the hydrophobic, negatively charged molecule of dicarbolide of cobalt. The extraction yield of stobadine from 1 ml of serum was 95% in the concentration range from 1 to 6000 ng/ml. The co-extraction of metabolites was less than 5%. The method was applied to the determination of stobadine in serum of dogs and the data obtained were in a good agreement with those obtained by high performance liquid chromatography. 相似文献
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Jaroslav Ščudla Klaus-Jochen Eichhorn Miroslav Raab Pavel Schmidt Dieter Jehnichen Liane Häußler 《Macromolecular Symposia》2002,184(1):371-387
The molecular and supermolecular orientation, morphology and structural changes observed during cold drawing of injection moulded isotactic polypropylene modified by specific α, and β nucleating agents were studied by polarised photoacoustic FTIR spectroscopy, wide-angle X-ray diffraction and differential scanning calorimetry. Significantly lower molecular orientation was found in the core of the β-nucleated injection moulded specimens as compared to unmodified and α-nucleated materials. This has been ascribed to the fast growth of the β-crystallites which inevitably dislocates the flow-induced orientation within the crystalline regions and in their vicinity. Moreover, it was found that the presence of the developed β-crystallites distinctly diminishes the efficiency of the orientational solid-state drawing assessed on both levels of the hierarchical structure (molecular and crystalline). This structural observation is directly connected with macroscopic softening effect of the β-phase: lowering the yield stress and flattening the neck shoulder. Thus, the interrelation between the microstructural and macroscopic effects of the β-phase could be described as a feedback process. 相似文献
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Aluminium speciation in environmental samples: a review 总被引:2,自引:0,他引:2
Because of its toxic effects on living beings, Al may represent an environmental hazard, particularly under increased acidic
conditions. Growing environmental concern over the presence of increased Al concentrations in soil solutions and fresh waters
resulted in the development of numerous analytical techniques for the determination of Al species. Al has a very complex chemistry
that is significantly influenced by pH. Different Al species are present in environmental solutions, and many of them are
unstable. Contamination of samples and reagents by extraneous Al represents an additional problem in speciation of Al at trace
concentrations. Due to these reasons quantitative determination of particular chemical forms of Al is still a very difficult
task for analytical chemists. The most important analytical methodologies of the last decade and new trends for the speciation
of Al in environmental samples are comprehensively reviewed here. 相似文献