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991.
The structure of an O(2)-sensitive Mn(II)-Mn(II) complex with an unsymmetrical perchlorate bridge is reported. This complex promotes an O(2)-dependent oxidative cleavage of ketones giving mixed carboxylate complexes. 相似文献
992.
Bearden IG Beavis D Besliu C Budick B Bøggild H Chasman C Christensen CH Christiansen P Cibor J Debbe R Enger E Gaardhøje JJ Germinario M Hagel K Hansen O Holm A Holme AK Ito H Jipa A Jundt F Jørdre JI Jørgensen CE Karabowicz R Kim EJ Kozik T Larsen TM Lee JH Lee YK Løvhøiden G Majka Z Makeev A Mikelsen M Murray M Natowitz J Nielsen BS Norris J Olchanski K Ouerdane D Płaneta R Rami F Ristea C Röhrich D Samset BH Sandberg D Sanders SJ Sheetz RA Staszel P Tveter TS Videaek F Wada R Yin Z 《Physical review letters》2005,94(16):162301
We have measured rapidity densities dN/dy of pi+/- and K+/- over a broad rapidity range (-0.1 < y < 3.5) for central Au + Au collisions at square root(sNN) = 200 GeV. These data have significant implications for the chemistry and dynamics of the dense system that is initially created in the collisions. The full phase-space yields are 1660 +/- 15 +/- 133 (pi+), 1683 +/- 16 +/- 135 (pi-), 286 +/- 5 +/- 23 (K+), and 242 +/- 4 +/- 19 (K-). The systematics of the strange to nonstrange meson ratios are found to track the variation of the baryochemical potential with rapidity and energy. Landau-Carruthers hydrodynamics is found to describe the bulk transport of the pions in the longitudinal direction. 相似文献
993.
Arsene I Bearden IG Beavis D Besliu C Budick B Bøggild H Chasman C Christensen CH Christiansen P Cibor J Debbe R Enger E Gaardhøje JJ Germinario M Hagel K Ito H Jipa A Jørdre JI Jundt F Jørgensen CE Karabowicz R Kim EJ Kozik T Larsen TM Lee JH Lee YK Lindal S Lystad R Løvhøiden G Majka Z Makeev A Mikelsen M Murray M Natowitz J Neumann B Nielsen BS Ouerdane D Płaneta R Rami F Ristea C Ristea O Röhrich D Samset BH Sandberg D Sanders SJ Sheetz RA Staszel P Tveter TS Videbaek F Wada R Yin Z 《Physical review letters》2005,94(3):032301
Charged-particle pseudorapidity densities are presented for the d + Au reaction at sqrt[s(NN)] = 200 GeV with -4.2 < or = eta < or = 4.2. The results, from the BRAHMS experiment at BNL Relativistic Heavy-Ion Collider, are shown for minimum-bias events and 0%-30%, 30%-60%, and 60%-80% centrality classes. Models incorporating both soft physics and hard, perturbative QCD-based scattering physics agree well with the experimental results. The data do not support predictions based on strong-coupling, semiclassical QCD. In the deuteron-fragmentation region the central 200 GeV data show behavior similar to full-overlap d+Au results at sqrt[s(NN)] = 19.4 GeV. 相似文献
994.
Laye RH Larsen FK Overgaard J Muryn CA McInnes EJ Rentschler E Sanchez V Teat SJ Güdel HU Waldmann O Timco GA Winpenny RE 《Chemical communications (Cambridge, England)》2005,(9):1125-1127
The synthesis and structure of new heterometallic wheels are reported, with preliminary studies of selected compounds. 相似文献
995.
Piestert F Fetouaki R Bogza M Oeser T Blümel J 《Chemical communications (Cambridge, England)》2005,(11):1481-1483
New synthetic routes to symmetric and unsymmetric dppm-type chelate linkers containing the ethoxysilane group are described and the compounds were characterized also by solid-state NMR spectroscopy and X-ray structures. 相似文献
996.
Cytotoxic activity against the P388 cell line was seen in a crude extract of the New Zealand shrub Lophomyrtus bullata(Myrtaceae). Bioactivity-guided isolation led to a compound with NMR spectra complicated by the presence of two isomers. These crystallised together and an X-ray structure showed them to be stereoisomeric hybrids of triketone, phloroglucinol and bullatenone units. NMR measurements on the mixed isomers, as well as a cyclic ether produced from them by acid catalysed dehydration, were consistent with these structures. The natural products, named bullataketals A and B, have cytotoxic activity against the P388 cell line (IC(50) 1 microg ml(-1)), and antimicrobial activity against Bacillus subtilis. 相似文献
997.
Brown HN Bunce G Carey RM Cushman P Danby GT Debevec PT Deile M Deng H Deninger W Dhawan SK Druzhinin VP Duong L Efstathiadis E Farley FJ Fedotovich GV Giron S Gray F Grigoriev D Grosse-Perdekamp M Grossmann A Hare MF Hertzog DW Hughes VW Iwasaki M Jungmann K Kawall D Kawamura M Khazin BI Kindem J Krienen F Kronkvist I Larsen R Lee YY Logashenko I McNabb R Meng W Mi J Miller JP Morse WM Nikas D Onderwater CJ Orlov Y Ozben CS Paley JM Polly C Pretz J Prigl R zu Putlitz G Redin SI Rind O 《Physical review letters》2001,86(11):2227-2231
A precise measurement of the anomalous g value, a(mu) = (g-2)/2, for the positive muon has been made at the Brookhaven Alternating Gradient Synchrotron. The result a(mu+) = 11 659 202(14) (6) x 10(-10) (1.3 ppm) is in good agreement with previous measurements and has an error one third that of the combined previous data. The current theoretical value from the standard model is a(mu)(SM) = 11 659 159.6(6.7) x 10(-10) (0.57 ppm) and a(mu)(exp) - a(mu)(SM) = 43(16) x 10(-10) in which a(mu)(exp) is the world average experimental value. 相似文献
998.
The first direct calorimetric measurements of the energetics of metal film growth on a semiconductor surface are presented. The heat of adsorption of Ag on Si(100)-(2 x 1) at 300 K decreases from approximately 347 to 246 kJ/mol with coverage in the first monolayer (ML) due to overlap of substrate strain from nearby Ag islands. It then rises quickly toward the bulk sublimation enthalpy (285 kJ/mol) as 3D particles grow. A wetting layer grows to 1.0 ML, but is metastable above approximately 0.55 ML and dewets when kinetics permit. This may be common when adsorbate islands induce a large strain in the substrate surface nearby. 相似文献
999.
Norrman K Papra A Kamounah FS Gadegaard N Larsen NB 《Journal of mass spectrometry : JMS》2002,37(7):699-708
Silicon grafted monodisperse poly(ethylene glycol) (PEG) silanes with various PEG chain lengths and mixtures of these were systematically analyzed with static time-of-flight secondary ion mass spectrometry (TOF-SIMS). The mass spectra show differences in the various relative signal intensities, an observation that was used to elucidate important aspects of the grafting process. The relationship between PEG-silane fragment ion abundances and Si(+) ion abundances were used to (i) qualitatively describe layer thicknesses of grafted mixtures of PEG-silanes on silicon, (ii) construct a calibration curve from which PEG chain length (or molecular mass) can be determined and (iii) quantitatively determine surface mixture compositions of grafted monodisperse PEG-silanes of different chain lengths (3, 7 and 11 PEG units). The results suggest that discrimination does take place in the adsorption process. The PEG-silane with the shorter PEG chain is discriminated for mixtures containing PEG3-silane, whereas the PEG-silane with the longer PEG chain is discriminated in PEG7/PEG11-silane mixtures. The origin of this difference in adsorption behavior is not well understood. Aspects of the grafting process and the TOF-SIMS analyses are discussed. 相似文献
1000.