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81.
Ketones can be homologated to α,gb-unsaturated esters or amides via their enol triflates by a palladium-catalyzed reaction with carbon monoxide and alcohols or amines. 相似文献
82.
83.
Ru-based oxidation catalysis 总被引:1,自引:0,他引:1
Ranging from the oxidative conversion of water to O(2) to the elegant hydroxylation of olefins and to oxidative dehydrogenation of alcohols Ru-mediated oxidations are finding increasing application due to the unique properties of this extremely versatile transition metal, whose oxidation state can vary from -II to +VIII. Covering recent developments in both homogeneously and heterogeneously catalysed oxidations (in liquid-phase as well as in novel reaction media), this tutorial review aims to provide investigators with a general picture of the chemical and structural origins of the excellent performance of many ruthenium catalysts and to promote further advancement that, it is envisaged, will soon benefit society at large. 相似文献
84.
Geng Y Romsted LS Froehner S Zanette D Magid LJ Cuccovia IM Chaimovich H 《Langmuir : the ACS journal of surfaces and colloids》2005,21(2):562-568
Sphere-to-rod transitions of cetyltrimethylammonium (CTA+) micelles with dichlorobenzoate counterions are remarkably substituent dependent. Simultaneous estimates of the interfacial molarities of H2O, MeOH, and Cl- and 2,6- and 3,5-dichlorobenzoate (2,6OBz and 3,5OBz) counterions were obtained by the chemical trapping method in mixed micelles of CTACl/CTA3,5OBz and CTACl/CTA2,6OBz without added salt. Increasing the CTA3,5OBz mole fraction produces a marked concurrent increase in interfacial 3,5OBz- and a decrease in interfacial H2O concentrations through the sphere-to-rod transition. No abrupt concentration changes are observed with increasing CTA2,6OBz mole fraction. Counterion-specific changes in the interfacial water concentration may be a major contributor to the delicate balance of forces governing micellar morphology. 相似文献
85.
Sandro Salsa 《Annali di Matematica Pura ed Applicata》1981,128(1):193-206
Sunto In questo lavoro vengono prese in considerazione soluzioni deboli non-negative di equazioni paraboliche lineari del secondo ordine in forma di divergenza in un dominio cilindrico diR
n×R. Per tali soluzioni si stabilisce un principio di tipo Harnach che si estende sino alla frontiera del dominio. Si prova poi che tale principio è équivalente ad una stima uniforme per la misura calorica associata ad ogni operatore del tipo suddetto. Per soluzioni continue nella chiusura del dominio è poi provata una versione più forte del prineipio di cut sopra.
Lavoro eseguito nell'ambito del G.N.A.F.A. 相似文献
Lavoro eseguito nell'ambito del G.N.A.F.A. 相似文献
86.
Sandro Mattarei 《Proceedings of the American Mathematical Society》2006,134(8):2189-2195
We prove that knowledge of the character degrees of a finite group and of their multiplicities determines whether has a Sylow -subgroup as a direct factor. An analogous result based on knowledge of the conjugacy class sizes is known. We prove variations of both results and discuss their similarities.
87.
We investigate the force acting between two parallel plates held at different temperatures. The force reproduces, as limiting cases, the well-known Casimir-Lifshitz surface-surface force at thermal equilibrium and the surface-atom force out of thermal equilibrium recently derived by M. Antezza et al., Phys. Rev. Lett. 95, 113202 (2005)10.1103/PhysRevLett.95.113202. The asymptotic behavior of the force at large distances is explicitly discussed. In particular when one of the two bodies is a rarefied gas the force is not additive, being proportional to the square root of the density. Nontrivial crossover regions at large distances are also identified. 相似文献
88.
Bianco A Dezzi S Bonadies F Romeo G Scarpati ML Uccella N 《Natural product research》2006,20(5):475-478
Aroma of olive oil is a very complex mixture of components. Analysis of head space of a series of virgin olive oil samples indicate a great variability of volatile substances composition in olives and these data probably should be related to the story of olives after collecting. 相似文献
89.
Sandro Mattarei 《Journal of Number Theory》2006,117(2):471-481
We prove that if the signed binomial coefficient viewed modulo p is a periodic function of i with period h in the range 0?i?k, then k+1 is a power of p, provided h is not too large compared to k. (In particular, 2h?k suffices). As an application, we prove that if G and H are multiplicative subgroups of a finite field, with H<G, and such that 1-α∈G for all α∈G?H, then G∪{0} is a subfield. 相似文献
90.
We transfer the whole geometry of PG(3, q) over a non-singular quadric Q4,q of PG(4, q) mapping suitably PG(3, q) over Q4,q. More precisely the points of PG(3, q) are the lines of Q4,q; the lines of PG(3, q) are the tangent cones of Q4,q and the reguli of the hyperbolic quadrics hyperplane section of Q4,q. A plane of PG(3, q) is the set of lines of Q4,q meeting a fixed line of Q4,q. We remark that this representation is valid also for a projective space
over any field K and we apply the above representation to construct maximal partial spreads
in PG(3, q). For q even we get new cardinalities for
For q odd the cardinalities are partially known. 相似文献