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91.
针对目前城市众多管理部门对城市GIS数据共享交换平台不同层次的共享需求,在分析文件级、数据平台级、系统功能级以及Web服务级四种共享交换模式特点的基础上,本文采用业务流技术设计了一种集成多级共享交换模式的数据模型。结合无锡市地理信息共享交换平台项目的建设,给出了模型在城市GIS数据交换平台系统中的具体应用过程,以期对其他城市同类系统的建设提供一定的参考价值。 相似文献
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93.
A component (s-factor) with obvious promoting effect on hydrogen evolution of hydrogenase has been isolated and extracted
from a cell-free preparation ofSpirulina platensis. The effect of the s-factor in the reaction system is similar to that of Na2S2O4, but is coupled with light. The s-factor has the maximum absorption peak at 620 nm in the oxidized state, at 590 nm in the
reduced state. The partially purified s-factor showed two bands by SDS-PAGE and is distinctly different from phycocyanin,
which has no change of oxidized state and reduced state absorption spectra, and also has no promoting effect on hydrogenase
ofSpirulina platensis under the light.
The research supported by the NSFC. 相似文献
94.
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96.
The optical variability of 29 flat spectrum radio quasars in SDSS Stripe 82 region are investigated by using DR7 released multi-epoch data. All FSRQs show variations with overall amplitude ranging from 0.24 mag to 3.46 mag in different sources. About half of FSRQs show a bluer-when-brighter trend, which is commonly observed for blazars. However, only one source shows a redder-when-brighter trend, which implies it is rare in FSRQs. In this source, the thermal emission may be responsible for the spectral behaviour. 相似文献
97.
98.
M. Guélin N. Brouillet J. Cernicharo F. Combes A. Wooten 《Astrophysics and Space Science》2008,313(1-3):45-51
High angular resolution mm-wave observations of the Orion-KL region, made with the IRAM Plateau de Bure interferometer (PdBI),
reveal the presence of several cores of size 103 AU, which have distinct spectral signatures. Complex molecules such as ethanol, vinyl cyanide and dimethyl ether show different
distributions and their relative abundance varies from core to core by orders of magnitude. The molecular column densities
derived in the cores also differ widely from the beam-averaged column densities observed with large single-dish telescopes.
Obviously, the predictions of hot core chemistry models must be checked against high resolution observations. ALMA, which
allies sensitivity and high angular resolution, will be a key instrument for this type of studies.
The PdBI observations were part of a search for interstellar glycine, also carried out with the IRAM 30-m telescope and the
Green Bank Telescope. We derive a 3σ upper limit on the column density of glycine of 1×1015 cm−2 per 2″×3″ beam in the Orion Hot Core and Compact Ridge.
Based on observations made with the IRAM PdB Interferometer, the IRAM 30-m telescope and the NRAO Green-Bank telescope. IRAM
is supported by CNRS, MPG and IGN. 相似文献
99.
We perform a linear analysis to investigate the dynamical response of a non-synchronized hot Jupiter to stellar irradiation. In this work, we consider the diurnal Fourier harmonic of the stellar irradiation acting at the top of a radiative layer of a hot Jupiter with no clouds and winds. In the absence of the Coriolis force, the diurnal thermal forcing can excite internal waves propagating into the planet's interior when the thermal forcing period is longer than the sound crossing time of the planet's surface. When the Coriolis effect is taken into consideration, the latitude-dependent stellar heating can excite weak internal waves (g modes) and/or strong baroclinic Rossby waves (buoyant r modes) depending on the asynchrony of the planet. When the planet spins faster than its orbital motion (i.e. retrograde thermal forcing), these waves carry negative angular momentum and are damped by radiative loss as they propagate downwards from the upper layer of the radiative zone. As a result, angular momentum is transferred from the lower layer of the radiative zone to the upper layer and generates a vertical shear. We estimate the resulting internal torques for different rotation periods based on the parameters of HD 209458b. 相似文献
100.
The formation and evolution of elliptical galaxies (EGs) are still an open question. In particular, recent observations suggest that EGs are not only simple spheroidal systems of old stars. In this paper, we analyse a sample of EGs selected from the Sloan Digital Sky Survey in order to study the star-forming activity in local EGs. Among these 487 ellipticals, we find that 13 EGs show unambiguous evidence of recent star formation activity betrayed by conspicuous nebular emission lines. Using the evolutionary stellar population synthesis models and Lick absorption line indices, we derive stellar ages, metallicities and α-element abundances, and thus reconstruct the star formation and chemical evolution history of the star-forming elliptical galaxies (SFEGs) in our sample.
We find that SFEGs have relative younger stellar population age, higher metallicity and lower stellar mass, and that their star formation history can be well described by a recent minor and short starburst superimposed on old stellar component. We also detect 11 E+A galaxies whose stellar population properties are closer to those of quiescent (normal) ellipticals than to star-forming ones. However, from the analysis of their absorption line indices, we note that our E+A galaxies show a significant fraction of intermediate-age stellar populations, remarkably different from the quiescent galaxies. This might suggest an evolutionary link between E+As and star-forming ellipticals. Finally, we confirm the relations between age, metallicity, α-element abundance and stellar mass for local EGs. 相似文献
We find that SFEGs have relative younger stellar population age, higher metallicity and lower stellar mass, and that their star formation history can be well described by a recent minor and short starburst superimposed on old stellar component. We also detect 11 E+A galaxies whose stellar population properties are closer to those of quiescent (normal) ellipticals than to star-forming ones. However, from the analysis of their absorption line indices, we note that our E+A galaxies show a significant fraction of intermediate-age stellar populations, remarkably different from the quiescent galaxies. This might suggest an evolutionary link between E+As and star-forming ellipticals. Finally, we confirm the relations between age, metallicity, α-element abundance and stellar mass for local EGs. 相似文献