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排序方式: 共有289条查询结果,搜索用时 15 毫秒
91.
Smith BA Soderblom L Beebe R Boyce J Briggs G Bunker A Collins SA Hansen CJ Johnson TV Mitchell JL Terrile RJ Carr M Cook AF Cuzzi J Pollack JB Danielson GE Ingersoll A Davies ME Hunt GE Masursky H Shoemaker E Morrison D Owen T Sagan C Veverka J Strom R Suomi VE 《Science (New York, N.Y.)》1981,212(4491):163-191
As Voyager 1 flew through the Saturn system it returned photographs revealing many new and surprising characteristics of this complicated community of bodies. Saturn's atmosphere has numerous, low-contrast, discrete cloud features and a pattern of circulation significantly different from that of Jupiter. Titan is shrouded in a haze layer that varies in thickness and appearance. Among the icy satellites there is considerable variety in density, albedo, and surface morphology and substantial evidence for endogenic surface modification. Trends in density and crater characteristics are quite unlike those of the Galilean satellites. Small inner satellites, three of which were discovered in Voyager images, interact gravitationally with one another and with the ring particles in ways not observed elsewhere in the solar system. Saturn's broad A, B, and C rings contain hundreds of "ringlets," and in the densest portion of the B ring there are numerous nonaxisymmetric features. The narrow F ring has three components which, in at least one instance, are kinked and crisscrossed. Two rings are observed beyond the F ring, and material is seen between the C ring and the planet. 相似文献
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Galileo multispectral imaging of the north polar and eastern limb regions of the moon 总被引:1,自引:0,他引:1
Belton MJ Greeley R Greenberg R Geissler P McEwen A Klaasen KP Heffernan C Breneman H Johnson TV Head JW Pieters C Neukum G Chapman CR Anger C Carr MH Davies ME Fanale FP Gierasch PJ Thompson WR Veverka J Sagan C Ingersoll AP Pilcher CB 《Science (New York, N.Y.)》1994,264(5162):1112-1115
Multispectral images obtained during the Galileo probe's second encounter with the moon reveal the compositional nature of the north polar regions and the northeastern limb. Mare deposits in these regions are found to be primarily low to medium titanium lavas and, as on the western limb, show only slight spectral heterogeneity. The northern light plains are found to have the spectral characteristics of highlands materials, show little evidence for the presence of cryptomaria, and were most likely emplaced by impact processes regardless of their age. 相似文献
94.
Steven S. Seefeldt Rick A. Boydston Phil N. Kaspari Mingchu Zhang Erin Carr Jeff Smeenk David L. Barnes 《American Journal of Potato Research》2013,90(3):239-244
Aminopyralid is used in Alaska to control certain invasive weed species; however it appears to have an extended soil half-life in interior Alaska resulting in carry-over injury in potatoes. Field studies at three experiment stations in Delta Junction, Fairbanks, and Palmer, Alaska were established to determine the dose–response of weeds and above and below ground potato growth to soil-applied aminopyralid (0, 8, 15, 31, 62, and 123 g ae ha?1) . Both prostrate knotweed and narrowleaf hawksbeard were susceptible to aminopyralid. At Delta Junction and Fairbanks, visual injury of potatoes greater than 25 % was observed at 15 g ae ha?1 aminopyralid, whereas at Palmer visual injury was greater than 40 % at 8 g ae ha?1, the lowest rate tested. Potato tuber production was reduced by aminopyralid at rates of 15 g ae ha?1 and above at both Delta Junction and Palmer. Sub-samples of potato tubers from Delta Junction and Palmer were analyzed for aminopyralid content and grown out to determine if aminopyralid in tubers would reduce subsequent growth. The aminopyralid concentration in potato tubers increased with increasing field application rates, with 30 ppb extracted from tubers grown at the highest application rate (123 g ae ha?1). All plants grown from daughter tubers except from control plots in Palmer exhibited injury symptoms. The number of emerged shoots, and shoot height decreased with increasing aminopyralid concentrations in the tuber, with injury rates greater than 70 % at 8 g ae ha?1. 相似文献
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Two individuals of the sub-Antarctic fur seal, Arctocephalus tropicalis, one of which was photographed, were seen on the beach 1 km south of the mouth of the Kwanza River, Angola, on 2 October 1983. This record represents a northerly extension by some 2 700 km of the previously recorded range. The nearest breeding colony is at Tristan da Cunha about 4 000 km south-west of this sighting. 相似文献
98.
Ivones Hernndez-Balmaseda Idania Rodeiro Guerra Ken Declerck Jos Alfredo Herrera Isidrn Claudina Prez-Novo Guy Van Camp Olivier De Wever Kethia Gonzlez Mayrel Labrada Adriana Carr Geovanni Dantas-Cassali Diego Carlos dos Reis Livan Delgado-Roche Roberto Rafael Nuez Ren Delgado-Hernndez Miguel David Fernndez Miriam T. Paz-Lopes Wim Vanden Berghe 《Marine drugs》2021,19(2)
99.
The physical and mechanical characteristics of hollow polyester fibres were compared with solid polyester fibres in order
to establish their processing behaviour and performance characteristics. The effects of hollow fibres on fabric properties
were investigated by using microscopy and tests of tensile and bursting strength, pilling, abrasion resistance, water vapour
permeability, and handle. The results show that tensile strength of hollow polyester fibres and yarns are negatively affected
by the cavity inside the fibre. Hollow fibres also have higher stiffness and resistance to bending at relaxed state. Fabrics
made from hollow polyester/wool blends and pure wool fabrics show three distinguishable steps in pilling. During pilling,
hollow fibres break before being pulled fully out of the structure, leading to shorter protruding fibres. Microscopy studies
showed that the breakdown of hollow fibres started during entanglement by splitting along the helical lines between fibrils.
KES results showed that the friction between fibres and the fibre shape are the most important parameters that determine the
fabric low stress mechanical properties. However, in some aspects, the hollow structure of the fibre does not have a significant
effect. 相似文献
100.