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41.
Anthony PL Arnold RG Band HR Borel H Bosted PE Breton V Cates GD Chupp TE Dietrich FS Dunne J Erbacher R Fellbaum J Fonvieille H Gearhart R Holmes R Hughes EW Johnson JR Kawall D Keppel C Kuhn SE Lombard-Nelsen RM Marroncle J Maruyama T Meyer W Meziani Z Middleton H Morgenstern J Newbury NR Petratos GG Pitthan R Prepost R Roblin Y Rock SE Rokni SH Shapiro G Smith T Souder PA Spengos M Staley F Stuart LM Szalata ZM Terrien Y Thompson AK White JL Woods M Xu J Young CC Zapalac G 《Physical review D: Particles and fields》1996,54(11):6620-6650
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Sharon E. Navard John W. Seaman Jr. Dean M. Young 《Annals of the Institute of Statistical Mathematics》1993,45(4):603-614
Bertin and Theodorescu (1984,Statist. Probab. Lett.,2, 23–30) developed a characterization of discrete unimodality based on convexity properties of a discretization of distribution functions. We offer a new characterization of discrete unimodality based on convexity properties of a piecewise linear extension of distribution functions. This reliance on functional convexity, as in Khintchine's classic definition, leads to variance dilations and upper bounds on variance for a large class of discrete unimodal distributions. These bounds are compared to existing inequalities due to Muilwijk (1966,Sankhy, Ser. B,28, p. 183), Moors and Muilwijk (1971,Sankhy, Ser. B,33, 385–388), and Rayner (1975,Sankhy, Ser. B,37, 135–138), and are found to be generally tighter, thus illustrating the power of unimodality assumptions. 相似文献
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New boracites containing nitrato- or fluoroanions that appear to be true low-pressure phases have been synthesized at superatmospheric pressures. The M3B7O13NO3 compounds (M = Co, Ni, Cu, Zn, Cd) transform rapidly and reversibly in the temperature region 300–500°C between probable orthorhombic and face centered cubic symmetry, while the M3B7O13F compounds (M = Mg, Mn, Fe, Co, Zn) appear to maintain rhombohedral symmetry up to their decomposition temperatures of 800–900°C. True high-pressure boracite-like phases containing F and Cr, Mn, Fe, or Co that decompose upon heating to M3B7O13F have also been isolated. 相似文献
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The homoleptic magnesium carbamato complex Mg6(Et2NCO2)12, 1 (Et2NCO2- = diethylcarbamato anion), was prepared by the reaction of dibutylmagnesium with diethylamine, followed by carboxylation using gaseous carbon dioxide. Crystallographic characterization demonstrated that 1 has the standard M6(R2NCO2)12 structure and is a double helix of MgO(x)(x = 5, 6) coordination polyhedra with Delta or Lambda stereochemistry arising from the configuration around the six-coordinate Mg2+ cations. It crystallized in the orthorhombic space group Ccca with two molecules of Delta1 and two of Lambda1 per unit cell (a = 21.548 A, b = 25.094 A, c = 15.4485(11) A, alpha = beta = gamma = 90 degrees ). Extensive solution characterization of 1 by 1-dimensional proton and 13C NMR spectroscopy and by two-dimensional 1H-[13C] NMR correlation techniques verified that the helical structure is maintained in solution. Moreover, these measurements indicated that the intramolecular dynamics of 1 relating to motions of the ethyl groups was substantially hindered in solution. Correlation of the crystallographic and NMR structural studies indicated that this arises from a combination of hindered rotation about the carbamato C-N bond and efficient packing of the ethyl groups around the Mg6O24 core. The result is an inverted-micelle-like structure for 1 in which the hydrophobic ethyl groups form a sheath largely restricting access to the hydrophilic Mg6O24 core. 相似文献
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Gillitzer E Willits D Young M Douglas T 《Chemical communications (Cambridge, England)》2002,(20):2390-2391
Here we present generalized methods for chemically modifying the surface of a viral protein cage; this exploits the chemistry of native and engineered surface exposed functional groups for multivalent presentation of ligands. 相似文献
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Kang MS Kim JH Kim YJ Won J Park NG Kang YS 《Chemical communications (Cambridge, England)》2005,(7):889-891
The ionic conductivity of polymer electrolytes and their interfacial contact with dye-attached TiO2 particles were enhanced markedly by the addition of amorphous oligomer into polymer electrolytes, resulting in very high overall energy conversion efficiency. 相似文献
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The adaptation of a conventional atomic-absorption/flameemission spectrophotometer to the measurement of atomic-fluorescence in an air-acetylene flame is described. The determination of cadmium on the same instrument by both atomic-fluorescence and absorption shows that, even with a rather simple and inefficient means of exciting and measuring fluorescence, results can be obtained which indicate that the fluorescence technique is considerably more sensitive than atomic-absorbance and is equally free from inter-element interference. 相似文献