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61.
Lawrence M. Mayer Peter T. Rahaim William Guerin Stephen A. Macko Les Watling Franz E. Anderson 《Estuarine, Coastal and Shelf Science》1985,20(4):491-503
A variety of measures of organic matter concentration and quality were made on samples collected from the top few mm of intertidal mudflat sediment over the course of a year, in order to assess the relative importance of biological and sedimentological influences on sedimentary organic matter. Winter and summer were times of relatively fine-grained sediment accumulation, caused by biological deposition or stabilization processes and resulting in higher organic matter concentrations. Stable carbon isotope and Br:C ratios indicated a planktonic source of bulk organic matter. Ratios of organic carbon to specific surface area of the sediments were consistent with an organic monolayer coverage of sediment grains. Correction for changing grain size during the year showed no change in the organic concentration per unit surface area, in spite of organic matter inputs by in situ primary production, buildup of heterotroph biomass and mucus coatings, and biodeposition of organic-rich seston. There were also no indications of changes in bulk organic quality, measured as hydrolyzable carbohydrates and amino acids, in response to these biological processes. It is concluded that biological processes on a seasonal time scale affect the bulk organic matter of these sediments via a modulation of grain size rather than creation or decay of organic matter. 相似文献
62.
M.D. Morrison 《Planetary and Space Science》1985,33(1):135-139
Laboratory measurements of the Å (3s' 3D° → 2p41D, 3s' 3D° → 2p43P) branching ratio have been made with a value of 1.5 × 10t-4 indicated. This value makes the branching transition at 1173 Å an order of magnitude stronger than the branch at 7990 Å (3s' 3D° → 3p 3P). The 1173 Å branching loss is still too weak a loss process for multiply scattered 989 Å photons to resolve the 989 Å intensity problem in the dayglow. 相似文献
63.
64.
We present new 1.45-1.75 μm spectra of Europa's dark non-ice material with a spectral resolution (λ/δλ) of 1200, obtained by using adaptive optics on the Keck telescope to spatially separate the spectrum of the non-ice material from that of the surrounding ice-rich regions. Despite the great increase in spectral resolution over the previous best spectra of the non-ice material, taken with Galileo's near-infrared mapping spectrometer (NIMS) with λ/δλ=66, no new fine-scale spectral structure is revealed. The smoothness of the spectra is inconsistent with available laboratory spectra of crystalline hydrated salts at Europa temperatures, but is more consistent with various combinations of non-crystalline hydrated salts and/or hydrated sulfuric acid, as have been matched to the lower-resolution NIMS spectra. 相似文献
65.
66.
67.
We present warm dark matter (WDM) as a possible solution to the missing satellites and angular momentum problem in galaxy
formation and introduce improved initial conditions for numerical simulations of WDM models, which avoid the formation of
unphysical haloes found in earlier simulations. There is a hint, that because of that the mass function of satellite haloes
has been overestimated so far, pointing to higher values for the WDM particle mass.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
68.
W.M. Napier 《Astrophysics and Space Science》2003,285(2):419-427
Claims that ordinary spiral galaxies and some classes of QSO show periodicity in their redshift distributions are investigated
using recent high-precision data and rigorous statistical procedures. The claims are broadly upheld. The periodicites are
strong and easily seen by eye in the datasets. Observational, reduction or statistical artefacts do not seem capable of accounting
for them.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
69.
JINFeng-jun 《中国地理科学(英文版)》2003,13(2):97-103
It is very important to establish cooperative mechanism to guarantee all members to develop their e-conomies in the Yellow Sea Rim. In this paper, the development strategies ofshipplng centers and transportation networkare discussed based on economic giobalization tendency. The results argue that a united transportation network should bebuilt in order to promote the economic competition of Northeast Asia in the world. As a key component of the economiccooperation, a hierarchical shipping centers network should be established with Hong Kong, Shanghai, Pusan, Koho,and Tokyo as cores. The authorities of China, Japan, R. O. Korea and D. P. B. Korea should make more efforts tobuild a set of cooperation institutions based on raising the transportation efficiency. 相似文献
70.
L. Makarova E. Grebel I. Karachentsev A. Dolphin V. Karachentseva M. Sharina D. Geisler P. Guhathakurta P. Hodge A. Sarajedini P. Seitzer 《Astrophysics and Space Science》2003,285(1):107-111
We present a quantitative star formation history derivation of the four suspected tidal dwarf galaxies in the M 81 group:
Holmberg IX, BK3N,Arp-loop (A0952+69) and Garland using HST/WFPC2 images of these galaxies. We construct a library of synthetic
Colour-Magnitude Diagrams(CMDs) based on theoretical isochrones and data-derived determinations of photometric errors. These
synthetic CMDs were combined linearly andχ2-compared to observed photometry. All the galaxies show continuous star formation between about 20 and 200 Myr ago with star
formation rates between 7.5⋅10-3 M⊙/yr and 7.67⋅10-4 M⊙/yr. The metallicity of the detected stars is spanning rather a wide range, being lower than solar abundance. We suppose,
that all the galaxies were formed out of material from metal-poor outer part of the giant spiral galaxy M81after tidal interaction
about 200 Myr ago. However, this suggestion requires significantly more deep color-magnitude diagrams to be sure with the
scenario of the galaxy evolution.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献