排序方式： 共有17条查询结果，搜索用时 93 毫秒
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Broadfoot AL Atreya SK Bertaux JL Blamont JE Dessler AJ Donahue TM Forrester WT Hall DT Herbert F Holberg JB Hunter DM Krasnopolsky VA Linick S Lunine JI McConnell JC Moos HW Sandel BR Schneider NM Shemansky DE Smith GR Strobel DF Yelle RV 《Science (New York, N.Y.)》1989,246(4936):1459-1466
Results from the occultation of the sun by Neptune imply a temperature of 750 +/- 150 kelvins in the upper levels of the atmosphere (composed mostly of atomic and molecular hydrogen) and define the distributions of methane, acetylene, and ethane at lower levels. The ultraviolet spectrum of the sunlit atmosphere of Neptune resembles the spectra of the Jupiter, Saturn, and Uranus atmospheres in that it is dominated by the emissions of H Lyman alpha (340 +/- 20 rayleighs) and molecular hydrogen. The extreme ultraviolet emissions in the range from 800 to 1100 angstroms at the four planets visited by Voyager scale approximately as the inverse square of their heliocentric distances. Weak auroral emissions have been tentatively identified on the night side of Neptune. Airglow and occultation observations of Triton's atmosphere show that it is composed mainly of molecular nitrogen, with a trace of methane near the surface. The temperature of Triton's upper atmosphere is 95 +/- 5 kelvins, and the surface pressure is roughly 14 microbars. 相似文献
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Actin-myosin interaction: inhibition of the myosin adenosine triphosphatase by actin 总被引：1，自引：0，他引：1
In the absence of magnesium ion, the addition of actin to myosin in a 1 :4 ratio has a strong inhibitory effect on the adenosine triphosphatase activity, in contrast to the well-known activating effect of actin in the presence of magnesium ion. This finding suggests that both effects result from a conformational change in the active site of the myosin adenosine triphosphatase. 相似文献
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A rocket-borne spectrograph detected H I Lyman alpha emission from the disk of Saturn and from the vicinity of the planet. The signal is consistent with an emission brightness of 700 rayleighs for the disk and 200 rayleighs for the vicinity of Saturn. The emission from the vicinity of the planet may be due to a hydrogen atmosphere associated with the saturnian ring system. 相似文献
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Kriss GA Shull JM Oegerle W Zheng W Davidsen AF Songaila A Tumlinson J Cowie LL Deharveng JM Friedman SD Giroux ML Green RF Hutchings JB Jenkins EB Kruk JW Moos HW Morton DC Sembach KR Tripp TM 《Science (New York, N.Y.)》2001,293(5532):1112-1116
The neutral hydrogen (H I) and ionized helium (He II) absorption in the spectra of quasars are unique probes of structure in the early universe. We present Far-Ultraviolet Spectroscopic Explorer observations of the line of sight to the quasar HE2347-4342 in the 1000 to 1187 angstrom band at a resolving power of 15,000. We resolve the He II Lyman alpha (Lyalpha) absorption as a discrete forest of absorption lines in the redshift range 2.3 to 2.7. About 50 percent of these features have H I counterparts with column densities N(H I) > 10(12.3) per square centimeter that account for most of the observed opacity in He II Lyalpha. The He II to H I column density ratio ranges from 1 to >1000, with an average of approximately 80. Ratios of <100 are consistent with photoionization of the absorbing gas by a hard ionizing spectrum resulting from the integrated light of quasars, but ratios of >100 in many locations indicate additional contributions from starburst galaxies or heavily filtered quasar radiation. The presence of He II Lyalpha absorbers with no H I counterparts indicates that structure is present even in low-density regions, consistent with theoretical predictions of structure formation through gravitational instability. 相似文献
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Broadfoot AL Sandel BR Shemansky DE Holberg JB Smith GR Strobel DF McConnell JC Kumar S Hunten DM Atreya SK Donahue TM Moos HW Bertaux JL Blamont JE Pomphrey RB Linick S 《Science (New York, N.Y.)》1981,212(4491):206-211
The global hydrogen Lyman alpha, helium (584 angstroms), and molecular hydrogen band emissions from Saturn are qualitatively similar to those of Jupiter, but the Saturn observations emphasize that the H(2) band excitation mechanism is closely related to the solar flux. Auroras occur near 80 degrees latitude, suggesting Earth-like magnetotail activity, quite different from the dominant Io plasma torus mechanism at Jupiter. No ion emissions have been detected from the magnetosphere of Saturn, but the rings have a hydrogen atmosphere; atomic hydrogen is also present in a torus between 8 and 25 Saturn radii. Nitrogen emission excited by particles has been detected in the Titan dayglow and bright limb scans. Enhancement of the nitrogen emission is observed in the region of interaction between Titan's atmosphere and the corotating plasma in Saturn's plasmasphere. No particle-excited emission has been detected from the dark atmosphere of Titan. The absorption profile of the atmosphere determined by the solar occultation experiment, combined with constraints from the dayglow observations and temperature information, indicate that N(2) is the dominant species. A double layer structure has been detected above Titan's limb. One of the layers may be related to visible layers in the images of Titan. 相似文献
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Broadfoot AL Belton MJ Takacs PZ Sandel BR Shemansky DE Holberg JB Ajello JM Atreya SK Donahue TM Moos HW Bertaux JL Blamont JE Strobel DF McConnell JC Dalgarno A Goody R McElroy MB 《Science (New York, N.Y.)》1979,204(4396):979-982
Observations of the optical extreme ultraviolet spectrum of the Jupiter planetary system during the Voyager 1 encounter have revealed previously undetected physical processes of significant proportions. Bright emission lines of S III, S IV, and O III indicating an electron temperature of 10(5) K have been identified in preliminary analyses of the Io plasma torus spectrum. Strong auroral atomic and molecular hydrogen emissions have been observed in the polar regions of Jupiter near magnetic field lines that map the torus into the atmosphere of Jupiter. The observed resonance scattering of solar hydrogen Lyman alpha by the atmosphere of Jupiter and the solar occultation experiment suggest a hot thermosphere (>/= 1000 K) wvith a large atomic hydrogen abundance. A stellar occultation by Ganymede indicates that its atmosphere is at most an exosphere. 相似文献
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Fastie WG Feldman PD Henry RC Moos HW Barth CA Thomas GE Donahue TM 《Science (New York, N.Y.)》1973,182(4113):710-711
An ultraviolet spectrometer aboard the Apollo 17 orbiting spacecraft attempted to measure ultraviolet emissions from the lunar atmosphere. The only emissions observed were from a transient atmosphere introduced by the lunar landing engine. The absence of atomic hydrogen implies that solar wind protons are converted to hydrogen molecules at the lunar surface. 相似文献
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Daub Matthias Hakl Ulrike Maressa Beira Hailu Dehne Heinz-Wilhelm Hallmann Johannes Kiewnick Sebastian Eberlein Caroline Heuer Holger Moos Jan H Paulsen Hans M Westphal Andreas Sturhan Dieter Kiewnick Sebastian Wolf Stefanie Bühlmann Andy Frey Jürg Nuaima Rasha Heuer Holger Westphal Andreas 《植物病害和植物保护杂志》2014,121(4):187-189
Journal of Plant Diseases and Protection - 相似文献