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IA Simpson R Bol ID Bull RP Evershed K Petzke SJ Dockrill 《Rapid communications in mass spectrometry : RCM》1999,13(13):1315-1319
Compound specific stable isotope analyses of managed soils using isotope ratio mass spectrometry have been undertaken as a means of determining early land use practices. delta (15)N amino acid signals demonstrate differences between manured grassland, unmanured grassland and continuous cereal cultivation under long-term experimental land use control conditions, with delta (15)N in hydrophobic amino acids providing the most distinctive signals. Analysis of early modern/medieval and of Bronze age anthropogenic soils from Orkney demonstrates that such signals are retained in archaeological contexts. delta (13)C analyses of n- alkanoic acid components of the fossil, Bronze Age, anthropogenic soils suggest a major terrestrial input to these soils, with uniform composition of formation materials. Surficial soils demonstrate the assimilation of isotopically lighter carbon, providing a means of assessing the mobility of the n- alkanoic acids within soils and sediments. Copyright 1999 John Wiley & Sons, Ltd. 相似文献
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We have performed extensive small-angle neutron scattering (SANS) diffraction studies of the vortex lattice in single crystal
YNi2B2C for B‖c. High-resolution SANS, combined with a field-oscillation vortex lattice preparation technique, allows us to separate Bragg
scattered intensities from two orthogonal domains and accurately determine the unit cell angle, β. The data suggest that upon increasing field there is a finite transition width where both low- and high-field distorted
hexagonal vortex lattice phases, mutually rotated by 45°, coexist. The smooth variation of diffracted intensity from each
phase through the transition corresponds to a redistribution of populations between the two types of domains. 相似文献
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G. A. Souliotis A. L. Keksis B. C. Stein M. Veselsky M. Jandel D. V. Shetty S. N. Soisson S. Wuenschel S. J. Yennello 《The European physical journal. Special topics》2007,150(1):325-327
Recent efforts to produce and separate neutron-rich rare
isotopes in peripheral collisions below the Fermi energy are
presented. The experiments have been performed at the Cyclotron
Institute of Texas A&M University employing beams from the K500
Superconducting Cyclotron. Two magnetic separators were used: the
MARS recoil separator and the Superconducting Solenoid Line (BigSol
Line). An enhanced production of neutron-rich nuclides in comparison
with high-energy fragmentation mechanisms has been observed and
attributed to the role of the N/Z and the nuclear periphery of the
target. From a practical viewpoint, these reactions below or around
the Fermi energy offer a novel way to access very neutron-rich rare
isotopes. The experience obtained in the production of rare isotope
beams (RIB) below the Fermi energy will be exploited in the ongoing
RIB upgrade of the Cyclotron Institute that will involve production,
stopping and reacceleration of rare isotopes. 相似文献
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New first- and high-order centred methods for conservation lawsare presented. Convenient TVD conditions for constructing centredTVD schemes are then formulated and some useful results areproved. Two families of centred TVD schemes are constructedand extended to nonlinear systems. Some numerical results arealso presented. 相似文献