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排序方式: 共有872条查询结果,搜索用时 15 毫秒
771.
Christophe Cantau Thierry Pigot Narayanapillai Manoj Esther Oliveros Sylvie Lacombe 《Chemphyschem》2007,8(16):2344-2353
The quantum yields of singlet oxygen ((1)O(2)) production (Phi(Delta)) and (1)O(2) lifetimes (tau(Delta)) at the gas-solid interface in silica gel material are determined. Different photosensitizers (PS) are encapsulated in parallelepipedic xerogel monoliths (PS-SG). PS were chosen according to their known photooxidation properties: 9,10-dicyanoanthracene (DCA), 9,10-anthraquinone (ANT), and a benzophenone derivative, 4-benzoyl benzoic acid (4BB). These experiments are mainly based on time-resolved (1)O(2) phosphorescence detection, and the obtained Phi(Delta) and tau(Delta) values are compared with those of a reference sensitizer for (1)O(2) production, 1H-phenalen-1-one (PN), included in the same xerogel. The trend between their ability to oxidize organic pollutants in the gas phase and their efficiency for (1)O(2) production is investigated through photooxidation experiments of a test pollutant dimethylsulfide (DMS). The Phi(Delta) value is high for DCA-SG relative to the PN reference, whereas it is slightly lower for 4BB-SG and for ANT-SG. Phi(Delta) is related to the production of sulfoxide and sulfone as the main oxidation products for DMS photosensitized oxidation. Additional mechanisms, leading to C--S bond cleaveage, appear to mainly occur for the less efficient singlet oxygen sensitizers 4BB-SG and ANT-SG. 相似文献
772.
773.
Cristina Draper Antonio Fernández López Esther García Miguel Gómez Lozano 《Journal of Algebra》2008,319(6):2372-2394
We define the socle of a nondegenerate Lie algebra as the sum of all its minimal inner ideals. The socle turns out to be an ideal which is a direct sum of simple ideals, and satisfies the descending chain condition on principal inner ideals. Every classical finite dimensional Lie algebra coincides with its socle, while relevant examples of infinite dimensional Lie algebras with nonzero socle are the simple finitary Lie algebras and the classical Banach Lie algebras of compact operators on an infinite dimensional Hilbert space. This notion of socle for Lie algebras is compatible with the previous ones for associative algebras and Jordan systems. We conclude with a structure theorem for simple nondegenerate Lie algebras containing abelian minimal inner ideals, and as a consequence we obtain that a simple Lie algebra over an algebraically closed field of characteristic 0 is finitary if and only if it is nondegenerate and contains a rank-one element. 相似文献
774.
Jeong Hun Kim Jin Hyoung Kim Esther Yang Jae-Hwan Park Young Suk Yu Kyu-Won Kim 《Experimental & molecular medicine》2009,41(4):236-242
The retinal activity for vision requires a precise synaptic connectivity. Shank proteins at postsynaptic sites of excitatory synapses play roles in signal transmission into the postsynaptic neuron. However, the correlation of Shank 2 expression with neuronal differentiation in the developing retina remains to be elucidated regardless of previous evidences of Shank 2 expression in retina. Herein, we demonstrated that with progression of development, Shank 2 is initially detected in the inner plexiform layer at P2, and then intensively detected in inner plexiform layer, outer plexiform layer, and ganglion cell layer at P14, which was closely colocalized to the neurofilament expression. Shank 2 was, however, not colocalized with glial fibrillary acidic protein. Shank 2 expression was increased in the differentiated retinoblastoma cells, which was mediated by ERK 1/2 activation. Moreover, Shank 2 expression was colocalized with neurofilament at the dendritic region of cells. In conclusion, our data suggests that Shank 2 is expressed in the neurons of the developing retina and could play a critical role in the neuronal differentiation of the developing retina. 相似文献
775.
Elisa Marenna Esther Fanelli Pasquale Pernice 《Journal of solid state chemistry》2009,182(5):1229-1234
With the final goal to obtain thin films containing stoichiometric lithium niobate nanocrystals embedded in an amorphous silica matrix, the synthesis strategy used to set a new inexpensive sol-gel route to prepare nanocomposite materials in the Li2O-Nb2O5-SiO2 system is reported. In this route, LiNO3, NbCl5 and Si(OC2H5)4 were used as starting materials. The gels were annealed at different temperatures and nanocrystals of several phases were formed. Futhermore, by controlling the gel compositions and the synthesis parameters, it was possible to obtain LiNbO3 as only crystallizing phase. LiNbO3-SiO2 nanocomposite thin films on Si-SiO2 and Al2O3 substrates were grown. The LiNbO3 average size, increasing with the annealing temperature, was 27 nm for a film of composition 10Li2O-10Nb2O5-80SiO2 heated 2 h at 800 °C. Electrical investigation revealed that the nanocrystals size strongly affects the film conductivity and the occurrence of hysteretic current-voltage curves. 相似文献
776.
777.
Chromatography in authenticity and traceability tests of vegetable oils and dairy products: a review 总被引:1,自引:0,他引:1
The new applications of various chromatographic techniques such as gas-liquid chromatography, high-performance liquid chromatography and electrophoretic methods employed for the analysis in macro- and micro-components in vegetable oils and dairy products are compiled and critically evaluated. The employment of these methods for authenticity tests and traceability is discussed. 相似文献
778.
Fraga MF Uriol E Borja Diego L Berdasco M Esteller M Cañal MJ Rodríguez R 《Electrophoresis》2002,23(11):1677-1681
A new approach to the evaluation of the relative degree of genomic DNA methylation through the quantification of 2'-deoxynucleosides is proposed. Detection and quantification of 5-methyl 2'-deoxycytidine in genomic DNA has been performed using micellar high-performance capillary electrophoresis (HPCE) with UV-Vis detection. This approach has been demonstrated to be more sensitive and specific than other HPCE methods for the quantification of DNA methylation degree and also to be faster than other HPLC-based methods. The detection and quantification of nucleosides through enzymatic hydrolyses notably increases the specificity of the technique and allows its exploitation in the analysis of poorly purified and/or concentrated DNA samples such as those obtained from meristematic plant regions and paraffin-embedded tissues. 相似文献
779.
Cserháti T Forgács E Darwish Y Morais H Mota T Ramos AC 《Journal of chromatography. A》2002,949(1-2):269-273
Multiwavelength spectrometry and reversed-phase high-performance liquid chromatography have been employed for the study of the effect of reduced glutathione and storage time on the pigments of paprika powders. The evaluation of the data by principal component analysis and cluster analysis proved that the storage time exerts the highest effect of the decomposition rate of pigments. The stability of some pigment fractions was modified in the presence of reduced glutathione. However, the effect was of secondary importance. Multiwavelength spectrometry combined with HPLC can be successfully used for the study of the stability of pigments of paprika powder. 相似文献
780.
Bröring M Tejero EC Pfister A Brandt CD Pérez Torrente JJ 《Chemical communications (Cambridge, England)》2002,(24):3058-3059
The metalation reactions of the 2,2'-bidipyrrin 4 with different rhodium(I) precursors yield the complexes 5 and 6 and the unusual corrinoid 7, depending only on the type of the ancillary ligand employed. 相似文献