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101.
102.
Phillip S. Griffin 《Probability Theory and Related Fields》1988,78(2):293-319
Summary We study the law of the iterated logarithm for the partial sum of i.i.d. random variables when the r
n largest summands are excluded, where r
n=o(log logn). This complements earlier work in which the case log logn=O(rn) was considered. A law of the iterated logarithm is again seen to prevail for a wide class of distributions, but for reasons quite different from previously.Research supported in part by NSF Grant DMS-8501732 相似文献
103.
104.
Robert E. Stevens Phillip C.C. Liu Wayne L. Gladfelter 《Journal of organometallic chemistry》1985,287(1):133-143
The reaction of PP(NO2) with M4(CO)12 (M = Co, Rh) gives the nitrido clusters [M6N(CO)15]? in 13 and 21% yields, respectively. A high yield synthesis (77%) of [Rh6N(CO)15)]? directly from Rh6(CO)16 and PPN(NO2) is also presented. PPN(NO2) reacts with Ir4(CO)12 to give the new isocyanato cluster, [Ir4(NCO)(CO)11]? in 34% yield, while the direct synthesis of this isocyanate product occurs in 77% yield from PPN(N3) and Ir4(CO)12. Modifications of published procedures for the preparation of [N(C2H5)4]2 [Ir6(CO)15] and Ir6(CO)16 are reported that allow shorter reaction times and give higher yields. The reaction of Ir6(CO)16 with one equivalent of PPN(NO2) generates a new cluster, PPN[Ir6(CO)15(NO)], in 57% yield which is proposed to contain a bent nitrosyl ligand. An additional equivalent of PPN(NO2) gives (PPN)2[Ir6(CO)15] in 84% yield with the evolution of N2O as well as CO2. 相似文献
105.
We present an elementary proof of a transfinite symmetric form of Philip Hall's theorem on systems of distinct representatives and derive some wellknown mapping theorems from it to illustrate the ease with which this form of the theorem may be used. 相似文献
106.
107.
108.
Phillip J. Black 《Tetrahedron》2005,61(5):1363-1374
This paper describes the activation of 2-cyclohexen-1-ol (1) and 2-cyclopenten-1-ol (11) through the use of aluminium-catalysed transfer hydrogenation. The electronically activated substrates are demonstrated to undergo facile conjugate addition and, when the alcohol functional group is subsequently restored in a one-pot procedure, this leads to an indirect addition of nucleophiles to allylic alcohols. This novel methodology has been termed catalytic electronic activation.The aluminium tert-butoxide catalysed conversion of 2-cyclohexen-1-ol (1) into 2-(3-hydroxycyclohexyl)-2-methylmalononitrile (18) and 2-cyclopenten-1-ol (11) into 2-(3-hydroxycyclopentyl)-2-methylmalononitrile (16) in 90 and 60% yield, respectively has been demonstrated through an efficient domino Oppenauer/Michael addition/Meerwein-Ponndorf-Verley process. 相似文献
109.
Kidder MK Britt PF Zhang Z Dai S Hagaman EW Chaffee AL Buchanan AC 《Journal of the American Chemical Society》2005,127(17):6353-6360
Mesoporous silicas such as SBA-15 and MCM-41 are being actively investigated for potential applications in catalysis, separations, and synthesis of nanostructured materials. A new method for functionalizing these mesoporous silicas with aromatic phenols is described. The resulting novel hybrid materials possess silyl aryl ether linkages to the silica surface that are thermally stable to ca. 550 degrees C, but can be easily cleaved at room temperature with aqueous base for quantitative recovery of the organic moieties. The materials have been characterized by nitrogen physisorption, FTIR, NMR, and quantitative analysis of surface coverages. The maximum densities of 1,3-diphenylpropane (DPP) molecules that could be grafted to the surface were less than those measured on a nonporous, fumed silica (Cabosil) and were also found to decrease as a function of decreasing pore size (5.6-1.7 nm). This is a consequence of steric congestion in the pores that is magnified at the smaller pore sizes, consistent with parallel studies conducted using a conventional silylating reagent, 1,1,3,3-tetramethyldisilazane. Pyrolysis of the silica-immobilized DPP revealed that pore confinement leads to enhanced rates and altered product selectivity for this free-radical reaction compared with the nonporous silica, and the rates and selectivities also depended on pore size. The influence of confinement is discussed in terms of enhanced encounter frequencies for bimolecular reaction steps and pore surface curvature that alters the accessibility and resultant selectivity for hydrogen transfer steps. 相似文献
110.