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101.
The preparation of 4a-methyl-substituted bicyclic enones in high enantiomeric purity is described, involving a Michael alkylation of (R)- or (S)-1-phenylethyl imines of the corresponding (±)-2-methylcyclopentanone, 2-methyl-cyclohexanone, 2-methylcycloheptanone, and 2-methylcyclooctanone with methyl vinyl ketone. 相似文献
102.
103.
Eliot P. Botosoa Virginie Silvestre Richard J. Robins Jose Manuel Moreno Rojas Claude Guillou Gérald S. Remaud 《Journal of chromatography. A》2009,1216(42):7043-7048
Quantitative isotopic 13C NMR at natural abundance has been used to determine the site-by-site 13C/12C ratios in vanillin and a number of related compounds eluted from silica gel chromatography columns under similar conditions. Head-to-tail isotope fractionation is observed in all compounds at the majority of carbon positions. Furthermore, the site-specific isotope deviations show signatures characteristic of the position and functionality of the substituents present. The observed effects are more complex than would be obtained by simply summing the individual effects. Such detail is hidden when only the global 13C content is measured by mass spectrometry. In particular, carbon positions within the aromatic ring are found to show site-specific isotope fractionation between the solute and the stationary phase. These interactions, defined as non-covalent isotope effects, can be normal or inverse and vary with the substitution pattern present. 相似文献
104.
105.
Virginie Papadopoulou Meng-Xing Tang Costantino Balestra Robert J. Eckersley Thodoris D. Karapantsios 《Advances in colloid and interface science》2014
Bubbles can form in the body during or after decompression from pressure exposures such as those undergone by scuba divers, astronauts, caisson and tunnel workers. Bubble growth and detachment physics then becomes significant in predicting and controlling the probability of these bubbles causing mechanical problems by blocking vessels, displacing tissues, or inducing an inflammatory cascade if they persist for too long in the body before being dissolved. By contrast to decompression induced bubbles whose site of initial formation and exact composition are debated, there are other instances of bubbles in the bloodstream which are well-defined. Gas emboli unwillingly introduced during surgical procedures and ultrasound microbubbles injected for use as contrast or drug delivery agents are therefore also discussed. After presenting the different ways that bubbles can end up in the human bloodstream, the general mathematical formalism related to the physics of bubble growth and detachment from decompression is reviewed. Bubble behavior in the bloodstream is then discussed, including bubble dissolution in blood, bubble rheology and biological interactions for the different cases of bubble and blood composition considered. 相似文献
106.
Olive Recombinant Hydroperoxide Lyase,an Efficient Biocatalyst for Synthesis of Green Leaf Volatiles
107.
The following are notes on the geometry of the bidisk, H 2 × H 2. In particular, we examine the properties of equidistant surfaces in the bidisk. 相似文献
108.
Virginie Breau James A. Ibers 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(5):584-586
The title compounds, bis(diethoxyselenophosphinoyl) triselenide, [P(OEt)2Se]Se3[P(OEt)2Se], and bis(diisopropoxyselenophosphinoyl) diselenide, [P(OiPr)2Se]Se2[P(OiPr)2Se], comprise an Se3 chain or an Se2 chain bridging two (RO)2PSe groups. 相似文献
109.
Virginie Konlack Socgnia Olivier Menoukeu-Pamen 《Journal of Mathematical Analysis and Applications》2015
In the present work, a stochastic maximum principle for discounted control of a certain class of degenerate diffusion processes with global Lipschitz coefficient is investigated. The value function is given by a discounted performance functional, leading to a stochastic maximum principle of semi-couple forward–backward stochastic differential equation with non-smooth coefficients. The proof is based on the approximation of the Lipschitz coefficients by smooth ones and the approximation of the infinite horizon adjoint process. 相似文献
110.
Blanc R Héran V Rahmani R Commeiras L Parrain JL 《Organic & biomolecular chemistry》2010,8(24):5490-5494
An efficient synthesis of deoxy-lambertellols was reported through a highly chemo- and diastereoselective intermolecular Diels-Alder cycloaddition between trans-1,2-disiloxybenzocyclobutenes and 2-methylprotoanemonine. Such transformation with δ-substituted γ-alkylidenebutenolides, to prepare new analogues of these tricyclic spirolactones, which would be very difficult to prepare by other ways, was also studied. 相似文献