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71.
We describe in the space of binary forms of degree d the strata of forms having a given rank. We also give a simple algorithm for determining the rank of a given form. 相似文献
72.
73.
Danièle Vidril-Robert Marie-Thérèse Maurette Esther Oliveros Michel Hocquaux Bernard Jacquet 《Tetrahedron letters》1984,25(5):529-532
The oxidation of 1,2 and 1,3-dihydroxynaphtalenes with potassium superoxide in aprotic media is a heterogeneous to reaction at the solid-liquid interface, leading to the 2-hydroxy-1,4-naphtoquinone with good yields even if the addition of crown-ether is omitted. 相似文献
74.
Reine Sakellariou-Fargues Marie-Therese Maurette Esther Oliveros Monique Riviere Armand Lattes 《Tetrahedron》1984,40(12):2381-2384
Study of the photodimerization of coumarin in micellar media and microemulsions shows that the orientation and the concentration of molecu- les in the interfacial film can favor reactions involving just one of the excited states (the singlet state in this case). 相似文献
75.
Patricia Murasecco-Suardi Ernst Gassmann Andr M. Braun Esther Oliveros 《Helvetica chimica acta》1987,70(7):1760-1773
The quantum yield of intersystem crossing (Φisc) of a sensitizer is related to the quantum yield of singlet-oxygen production (Φ(1O2)) by the efficiency of the energy transfer (φet) and is an important parameter in the evaluation of potential applications of sensitized photo-oxidations. Using two different laser photolysis techniques, the energy-transfer method and the partial saturation method, Φisc of rose bengal has been determined in MeOH and in aqueous solutions. The results confirm that with Φisc(H2O) = 1.05(± 0.06) and Φisc(MeOH)=0.90(±0.08), the generally assumed relation Φisc · φet = Φ(1O2), with φet = 1, cannot be maintained any longer (Φ(1O2, H2O) = 0.75 and Φ(1O2, MeOH) = 0.76). During these experiments, a second intermediate has been observed which is produced from the triplet state of rose bengal and, stabilized in a anionic micellar solution, has been shown to be the radical cation of the sensitizer. The efficiency of the electron transfer has been evaluated from transient absorption and bleaching recordings, and it seems conclusive to attribute the results to the difference between Φisc and Φ(1O2). 相似文献
76.
Synthesis of light alkenes on manganese promoted iron and iron-cobalt Fischer-Tropsch catalysts 总被引:1,自引:0,他引:1
Sergio L. González-Cortés Serbia M. A Rodulfo-Baechler Alberto Oliveros José Orozco Bernardo Fontal Asiloé J. Mora Gerzon Delgado 《Reaction Kinetics and Catalysis Letters》2002,75(1):3-12
The Perkin reaction is accompanied by competitive transformations of the intermediate carbanions. These transformations are found to be inhibited by the reacting aldehydes. The limiting stage of the Perkin reaction is NACC attack (nucleophilic attack at carbonyl carbon) of amines on the anhydride. 相似文献
77.
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79.
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
80.
Introducing a new infrared cut-off for the holographic dark-energy, we study the correspondence between the quintessence, tachyon, K-essence and dilaton energy density with this holographic dark energy density in the flat FRW universe. This correspondence allows to reconstruct the potentials and the dynamics for the scalar fields models, which describe accelerated expansion. 相似文献