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排序方式: 共有540条查询结果,搜索用时 31 毫秒
1.
Vasile M. Loots H. Vercammen L. Bruggeman M. Verrezen F. 《Journal of Radioanalytical and Nuclear Chemistry》2022,331(8):3349-3357
Journal of Radioanalytical and Nuclear Chemistry - In this paper a study for the selection of an NPE (nonylphenol ethoxylates)—free cocktail is discussed in order to be used for our routine... 相似文献
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Sergiu Aizicovici Nikolaos S. Papageorgiou Vasile Staicu 《Journal of Differential Equations》2007,243(2):504-535
We consider a nonlinear periodic problem driven by the scalar p-Laplacian with a nonsmooth potential (hemivariational inequality). Using the degree theory for multivalued perturbations of (S)+-operators and the spectrum of a class of weighted eigenvalue problems for the scalar p-Laplacian, we prove the existence of at least three distinct nontrivial solutions, two of which have constant sign. 相似文献
4.
Cimpeanu V Parvulescu VI Amorós P Beltrán D Thompson JM Hardacre C 《Chemistry (Weinheim an der Bergstrasse, Germany)》2004,10(18):4640-4646
Heterogeneous catalytic oxidation of a series of thioethers (2-thiomethylpyrimidine, 2-thiomethyl-4,6-dimethyl-pyrimidine, 2-thiobenzylpyrimidine, 2-thiobenzyl-4,6-dimethylpyrimidine, thioanisole, and n-heptyl methyl sulfide) was performed in ionic liquids by using MCM-41 and UVM-type mesoporous catalysts containing Ti, or Ti and Ge. A range of triflate, tetrafluoroborate, trifluoroacetate, lactate and bis(trifluoromethanesulfonyl)imide-based ionic liquids were used. The oxidations were carried out by using anhydrous hydrogen peroxide or the urea-hydrogen peroxide adduct and showed that ionic liquids are very effective solvents, achieving greater reactivity and selectivity than reactions performed in dioxane. The effects of halide and acid impurities on the reactions were also investigated. Recycling experiments on catalysts were carried out in order to evaluate Ti leaching and its effect on activity and selectivity. 相似文献
5.
Vasile Dinoiu Bernard Tinant Jean-Philippe Bouillon 《Journal of fluorine chemistry》2006,127(1):101-107
The paper presents a one-pot conversion of γ-keto-α-pentafluoroethyl thioester into new pyridazin-3-ones and α,β-unsaturated lactams. The structures of all new compounds were ascribed using 1D (19F, 1H, 13C) and 2D (1H-15N) NMR data, and X-ray diffraction analysis. Two possible competitive reaction mechanisms for the synthesis of pyridazin-3-ones and lactams are presented. 相似文献
6.
W.E. Falconer G.R. Jones W.A. Sunder M.J. Vasile Annabel A. Muenter T.R. Dyke W. Klemperer 《Journal of fluorine chemistry》1974,4(2):213-234
Most known non-radioactive pentafluorides have been examined by molecular-beam mass spectrometry and by the deflection of molecular beams in inhomogeneous electric fields. Extensive association of the vapors occurs for all but the lighter pentafluorides and the interhalogens. The interhalogen pentafluorides are strongly polar, consistent with the accepted C4v symmetry. The transition-metal and Group V pentafluorides are all non-polar, except VF5 and CrF5 for which temperature-dependent polarity is observed. However, uncertainty exists as to whether these observations are applicable to monomeric pentafluorides in all cases. Mass-spectral cracking patterns are presented for all species. 相似文献
7.
The simultaneous isolation and determination of mitoxantrone (Novantrone) and its two known metabolites (the mono- and dicarboxylic metabolites) were carried out using a high-performance liquid chromatographic (HPLC) system equipped with an automatic pre-column-switching system that permits drug analysis by direct injection of biological samples. Plasma or urine samples were injected directly on to an enrichment pre-column flushed with methanol-water (5:95, v/v) as the mobile phase. The maximum amount of endogenous water-soluble components was removed from biological samples within 9 min. Drugs specifically adsorbed on the pre-column were back-flushed on to an analytical column (Nucleosil C18, 250 X 4.6 mm I.D.) with 1.6 M ammonium formate buffer (pH 4.0) (2.5% formic acid) containing 20% acetonitrile. Detection was effected at 655 nm. Chromatographic analysis was performed within 12 min. The detection limit of the method was about 4 ng/ml for urine and 10 ng/ml for plasma samples. The precision ranged from 3 to 11% depending on the amount of compound studied. This technique was applied to the monitoring of mitoxantrone in plasma and to the quantification of the unchanged compound and its two metabolites in urine from patients receiving 14 mg/m2 of mitoxantrone by intravenous infusion for 10 min. 相似文献
8.
Bogdan Tutunaru Adriana Samide Catalin Negrila 《Journal of Thermal Analysis and Calorimetry》2013,111(2):1149-1154
The influence of different ions NO3 ? and SO4 2? on the carbon steel corrosion in ammonium chloride was investigated using mass loss measurements and potentiodynamic polarization. Corrosion products were analyzed using X-ray photoelectron spectroscopy (XPS) and simultaneous thermal and differential scanning calorimetry (TG/DSC). XPS analysis shows that the main product of corrosion is a non-stoichiometric Fe3+ oxyhydroxide, consisting of a mixture of FeO(OH) and FeO(OH) containing inclusions of these anions, species such as Fe3+O(OH,Cl?); Fe3+O(OH,SO4 2?); and Fe3+O(OH,NO3 ?). TG/DSC confirms the decomposition of the rusty products formed by chemical corrosion, compounds like Fe3+ oxyhydroxides, with β-FeOOH as the major phase, crystal structure of which may contain Cl?, NO3 ?, and SO4 2?—e.g., akaganeite [Fe3+O(OH,A)]. 相似文献
9.
Nicoleta E. Mircescu Haibo Zhou Nicolae Leopold Vasile Chiş Natalia P. Ivleva Reinhard Niessner Andreas Wieser Christoph Haisch 《Analytical and bioanalytical chemistry》2014,406(13):3051-3058
Based on molecular-specific surface-enhanced Raman scattering (SERS) spectroscopy we were able to discriminate between rough and smooth strains of Escherichia coli and Proteus mirabilis bacteria. For this purpose, bacteria have been immobilized through electrostatic forces by inducing a positive charge on the glass slide. This way, SERS spectra on bacterial biomass and also on single bacteria could be recorded in less than 2 h, by using concentrated silver nanoparticles as SERS-active substrate. Single-bacterium SERS spectral fingerprints showed to be sensitive to the presence of the O-antigen at strain level and to the microorganisms growth phase. By using principal component analysis (PCA) on the SERS spectra recorded from E. coli and P. mirabilis, these two uropathogens could be fairly discriminated. 相似文献
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