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71.
Pedersen Henrik Tønnesen-Friedman Christina Valent Galliano 《Letters in Mathematical Physics》1999,50(3):229-241
We write an ansatz for quasi-Einstein Kähler metrics and construct new complete examples. Moreover, we construct new compact generalized quasi-Einstein Kähler metrics on some ruled surfaces, including some of Guan's examples as special cases. 相似文献
72.
Water‐Soluble Gold Nanoparticles: From Catalytic Selective Nitroarene Reduction in Water to Refractive Index Sensing 下载免费PDF全文
Water‐soluble gold nanoparticles (Au NPs) stabilized by a nitrogen‐rich poly(ethylene glycol) (PEG)‐tagged substrate have been prepared by reduction of HAuCl4 with NaBH4 in water at room temperature. The morphology and size of the nanoparticles can be controlled by simply varying the gold/stabilizer ratio. The nanoparticles have been fully characterized by TEM, high‐resolution (HR) TEM, electron diffraction (ED), energy‐dispersive X‐ray spectroscopy (EDS), UV/Vis, powder XRD, and elemental analysis. The material is efficient as a recyclable catalyst for the selective reduction of nitroarenes with NaBH4 to yield the corresponding anilines in water at room temperature. Furthermore, the potential ability of the Au NPs as a refractive index sensor owing to their localized surface plasmon resonance (LSPR) effect has also been assessed. 相似文献
73.
Liu Ming Granados Albert Reyes-Mesa David Arosemena-Angulo E. Leonardo Calvo-Torras María Ángeles Pleixats Roser Vallribera Adelina 《Cellulose (London, England)》2022,29(16):8889-8905
Cellulose - The preparation of antifungal-functionalized silica nanoparticles by covalent attachment of several silylated derivatives based on the topical antifungal agent Micozanole is described.... 相似文献
74.
Galliano Valent 《Mediterranean Journal of Mathematics》2006,3(2):327-345
In the field of orthogonal polynomials theory, the classical Markov theorem shows that for determinate moment problems the
spectral measure is under control of the polynomials asymptotics.
The situation is completely different for indeterminate moment problems, in which case the interesting spectral measures are
to be constructed using Nevanlinna parametrization. Nevertheless it is interesting to observe that some spectral measures
can still be obtained from weaker forms of the Markov theorem.
The exposition will be illustrated by orthogonal polynomials related to elliptic functions: in the determinate case by examples
due to Stieltjes and some of their generalizations and in the indeterminate case by more recent examples. 相似文献
75.
Patrícia Valentão Rui F. Gonçalves Cristóvão Belo Paula Guedes de Pinho Paula B. Andrade Federico Ferreres 《Journal of separation science》2010,33(20):3168-3176
Piper betle is a species growing in South East Asia, where its leaves are economically and medicinally important. To screen the highest possible number of volatile and semivolatile components, the leaves were subjected to headspace solid‐phase microextraction, hydrodistillation and Soxhlet extraction, prior to analysis by GC/MS. Fifty compounds (identified by comparison with standard compounds or tentatively by National Institute of Standards and Technology database) were determined, 23 being described for the first time in this matrix. An aqueous extract was also analysed, in which only seven compounds were characterized. The organic acids' composition of this extract was determined by HPLC/UV and eight compounds are reported for the first time in P. betle. This extract also displayed acetylcholinesterase inhibitory capacity. 相似文献
76.
Lactase in Immobilized Cells of Watermelon 总被引:1,自引:0,他引:1
I. Tilemann E. Tokhtaeva E. Sedlarova A. Barth A. Valent P. Siekel M. Duricek 《Chemistry of Natural Compounds》2003,39(4):394-398
A cell suspension culture of Citrullus vulgaris Schrad cv. Samara was permeabilized by Tween 80 and immobilized by glutaraldehyde. The highest lactase activity was achieved at pH 4.3, the temperature optimum for cell suspension was at 50°C, while for the immobilized cells the optimum was at 58°C. The hydrolysis of substrate was linear for 3 h, reaching 60-67% conversion rate. The cells were characterized by high enzyme activity. The stability of the enzyme showed convenient physico-mechanical properties (physical protection from shear forces and easy separation of product from biocatalysts) in long-term storage. 相似文献
77.
13C NMR differences of chemical shifts (delta(X) - delta(H)) of allyl carbon atoms in a series of trans-(1-(diphenylphosphino)-2-(dimethylamino)ethane)(eta(3)-1-arylallyl)palladium tetrafluoroborates, X ranging from NO(2) to OMe, correlate very well with sigma Hammett constants for C-1 and with sigma(+) for C-3, this carbon atom being in a trans relationship with the positively charged nitrogen atom. 相似文献
78.
Alejandro Marcó Ramon Companyó Roser Rubio Maite Pueyo Eugeni Vilalta 《Mikrochimica acta》2007,159(3-4):387-393
The estimation of uncertainty in organic elemental analysis for C, H, N and S is reported. Both “bottom up” and “top down”
strategies are used for uncertainty calculations. The bottom up approach used the results of C, H, N, and S obtained from
the homogeneity study of two pure chemicals (toluene-4-sulfonamide and 4(6)-methyl-2-thiouracil). Two calibration systems,
K factor and calibration curve, were applied in this study and no significant differences were obtained. For the “top down”
approach, we used the data obtained from a proficiency test on both pure chemicals from among 45 Spanish laboratories. Both
approaches are compared and discussed below. 相似文献
79.
Galliano Valent 《General Relativity and Gravitation》2009,41(10):2433-2459
We present, for both Minkowskian and Euclidean signatures, short derivations of the diagonal Einstein metrics for Bianchi
type II, III and V. For the first two cases we show the integrability of the geodesic flow while for the third case a somewhat
unusual bifurcation phenomenon takes place: for Minkowskian signature elliptic functions are essential in the metric while
for Euclidean signature only elementary functions appear. 相似文献
80.