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排序方式: 共有272条查询结果,搜索用时 15 毫秒
61.
Catalina Cioates Negut Raluca‐Ioana Stefan‐van Staden Florian Harja Jacobus Frederick van Staden 《Electroanalysis》2020,32(1):7-10
New synthesized fatty acid amides (N‐(2‐(piperidin‐1‐yl)ethyl)oleamide, and N‐(2‐(pyrrolidin‐1‐yl)ethyl)oleamide) were used for the design of stochastic sensors based on nanographene paste. The stochastic sensors were used for pattern recognition of four amino acids: L‐histidine, L‐tyrosine, L‐ornithine, and L‐lysine in wines. The pattern recognition was performed based on the signatures recorded for each of the amino acids. The limits of determination allow the assay of amino acids in wine at very low concentrations faster, reliable, and more cost effective than other methods proposed to date. 相似文献
62.
We build Gaussian wave packets for the linear Schrödinger equation and its finite difference space semi-discretization and illustrate the lack of uniform dispersive properties of the numerical solutions as established in Ignat and Zuazua (2009) [6]. It is by now well known that bigrid algorithms provide filtering mechanisms allowing to recover the uniformity of the dispersive properties as the mesh size goes to zero. We analyze and illustrate numerically how these high frequency wave packets split and propagate under these bigrid filtering mechanisms, depending on how the fine grid/coarse grid filtering is implemented. 相似文献
63.
Raluca Popescu Diana Costinel Damian Axente 《Isotopes in environmental and health studies》2014,50(4):461-474
One of the most important tributaries of the Danube River in Romania, the Olt River, was characterized in its middle catchment in terms of the isotopic composition using continuous flow–isotope ratio mass spectrometry (CF–IRMS). Throughout a period of 10 months, from November 2010 to August 2011, water samples from the Olt River and its more important tributaries were collected in order to investigate the seasonal and spatial isotope patterns of the basin waters. The results revealed a significant difference between the Olt River and its tributaries, by the fact that the Olt River waters show smaller seasonal variations in the stable isotopic composition and are more depleted in 18O and 2H. The waters present an overall enrichment in heavy isotopes during the warm seasons. 相似文献
64.
Rosu T Pasculescu S Lazar V Chifiriuc C Cernat R 《Molecules (Basel, Switzerland)》2006,11(11):904-914
The synthesis of Cu(II) complexes derived from Schiff base ligands obtained by the condensation of 2-hydroxybenzaldehyde or terephtalic aldehyde with 4-amino-antipyrine (4-amino-2,3-dimethyl-1-phenyl-3-pyrazolin-5-one) is presented. The newly prepared compounds were characterized by( 1)H-NMR, UV-VIS, IR and ESR spectroscopy. The determination of the antimicrobial activity of the ligands and of the complexes was carried out on samples of Escherichia coli, Klebsiella pneumoniae, Acinetobacter boumanii, Pseudomonas aeruginosa, Staphylococcus aureus and Candida sp. The qualitative and quantitative antimicrobial activity test results proved that all the prepared complexes are very active, especially against samples of Ps. aeruginosa, A. Boumanii, E. coli and S. aureus. 相似文献
65.
Cho H Felmy AR Craciun R Keenum JP Shah N Dixon DA 《Journal of the American Chemical Society》2006,128(7):2324-2335
Evidence for nine new solution state silicate oligomers has been discovered by (29)Si NMR homonuclear correlation experiments of (29)Si-enriched samples. In addition to enhancing signal sensitivity, the isotopic enrichment increases the probability of the (29)Si-(29)Si two-bond scalar couplings that are necessary for the observation of internuclear correlations in 2-D experiments. The proposed assignments are validated by comparisons of experimental and simulated cross-peaks obtained with high digital resolution. The internuclear connectivity indicated by the NMR data suggests that several of these oligomers can have multiple stereoisomers, including conformers and/or diastereomers. The stabilities of these oligomers and their possible stereoisomers have been investigated by electronic structure calculations. 相似文献
66.
Porphyrins and metalloporphyrins fulfil a very important role in the metabolism of living organisms through biological pigments or biochromes and are therefore also employed in numerous applications in analytical chemistry. In flow-injection analysis the role of porphyrins and metalloporphyrins are centered as either that of analyte or that of a reagent or modifier in the determination of other species. This paper covers the attributes of porphyrin and metallophorphyrin complexes as enhancements in chemical analysis in flow-injection systems and points out the advantages and disadvantages in the implementation thereof. 相似文献
67.
The binding ability of a series of spiroacetal thiacrown ethers with Li+, Na+, K+, Cs+, Co2+, Cd2+, Ag+ and Pb2+ is reported. The thiacrown ethers showed an affinity for the heavy metals. The interaction of the three thiacrown ethers 1-3 and [Al(acac)3] 5, [Co(NH3)5NO2](BPh4)26 and [Co(en)3](BPh4)37 complexes is also investigated. 相似文献
68.
Malacea R Daran JC Duckett SB Dunne JP Godard C Manoury E Poli R Whitwood AC 《Dalton transactions (Cambridge, England : 2003)》2006,(27):3350-3359
Ir(CO)[CpFe{eta5-C5H3(PPh2)CH2SR}]Cl [R = Ph and (t)Bu], containing a kappa2:P,S ligand, undergoes H2 addition across the S-Ir-CO axis under kinetic control to form two distinct diastereoisomeric products, which then rearrange via S dissociation in a process that can be hijacked for useful catalysis, but ultimately form a single diastereoisomer of the thermodynamic product where the hydride ligands are trans to chloride and phosphine. 相似文献
69.
Philip W. Kletnieks Ann J. Liang Raluca Craciun Justin O. Ehresmann Dr. David M. Marcus Dr. Vinesh A. Bhirud Dr. Meghan M. Klaric Miranda J. Hayman Darryl R. Guenther Olesya P. Bagatchenko David A. Dixon Prof. Bruce C. Gates Prof. James F. Haw Prof. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2007,13(26):7267-7267
70.
Fluorescence contrast and threshold limit: implications for photodynamic diagnosis of basal cell carcinoma 总被引:3,自引:0,他引:3
Ericson MB Sandberg C Gudmundson F Rosén A Larkö O Wennberg AM 《Journal of photochemistry and photobiology. B, Biology》2003,69(2):121-127
This study was designed to evaluate what application time of delta-5-aminolaevulinic acid (ALA) results in highest contrast between tumour and normal skin, in the interval 1-4 h, when using photodynamic diagnosis (PDD) of basal cell carcinomas (BCC) located on the face. Moreover, a value of the demarcation limit has been derived based on the fluorescence variation in normal skin adjacent to the tumour. Forty patients were included in the study, randomly allocated to four different groups with varying ALA application time in the range 1-4 h. The contrast, defined as the ratio between the fluorescence intensity in ALA-treated tumour tissue and normal skin, was calculated for each patient, and the mean values in each group were evaluated as a function of ALA application time. In addition, the fluorescence intensity variation in ALA-treated normal skin adjacent to the tumour was assessed. The results from this study show a peak of the mean contrast values after 3 h ALA application, but due to large interpatient variation, the mean contrast did not differ significantly in the interval 2-4 h. After 2 h ALA application, the fluorescence intensity variation in the normal ALA-treated skin was found to be at a maximum, which suggests that 2 h ALA application is not preferable when using PDD. Based on data of the fluorescence variation in ALA-treated normal skin after 3 and 4 h ALA application, a tolerance interval was calculated implying that values above 1.4 times the mean normal fluorescence indicate an abnormal condition. This tolerance limit agrees well with results obtained in a former study. 相似文献