共查询到20条相似文献,搜索用时 0 毫秒
1.
Bailey JM 《Science (New York, N.Y.)》1971,173(3999):812-813
Because of the small size and irregular orbits of the seven outer satellites of Jupiter, it is often assumed that they were derived by capture. The conditions whereby Jupiter can capture satellites have therefore been examined. Relationships derived on the basis of the three-body problem for planets in elliptical orbits enable the dimensions of the capture orbits around Jupiter to be calculated. It is found that Jupiter may capture satellites through the inner Lagrangian point when at perihelion or at aphelion. Captures at perihelion should give rise to satellites in direct orbits of 11.48 x 10(6) kilometers and capture at aphelion to retrograde orbits of 21.7 x 10(6) kilometers. The correspondence with the seven outer satellites suggests that Jupiter VI, VIl, and X in direct orbits at 11.47, 11.74, and 11.85 x 10(6) kilometers were captured at Jupiter perihelion, whereas Jupiter VIII, IX, XI, and XII in retrograde orbits of 23.5, 23.7, 22.5, and 21.2 x 10(6) kilometers were captured when Jupiter was at aphelion. Examination of the precapture orbits indicates that the seven outer satellites were derived from the asteroid belt. 相似文献
2.
Protonated methane, CH5+, has unusual vibrational and rotational behavior because its three nonequivalent equilibrium structures have nearly identical energies and its five protons scramble freely. Although many theoretical papers have been published on the quantum mechanics of the system, a better understanding requires spectral data. A complex, high-resolution infrared spectrum of CH5+ corresponding to the C-H stretching band in the 3.4-micrometer region is reported. Although no detailed assignment of the individual lines was made, comparison with other carbocation spectra strongly suggests that the transitions are due to CH5+. 相似文献
3.
Grating spectra of the North Equatorial Belt of Jupiter 4.5 and 5.1 microns, obtained with a nominal resolving power of 180, are presented. An absorption feature centered at 4.73 microns and not due to a known constituent has been found. Its possible identification is discussed. 相似文献
4.
[目的]优化苯酚—硫酸法液化松木层孔菌的工艺参数,分析液化前后松木层孔菌化学官能团变化,揭示其液化机理,为废弃松木层孔菌的高效利用开辟一条新途径.[方法]以松木层孔菌为原料、浓硫酸为催化剂、苯酚为液化剂,考察料液比(原料/苯酚)、液化温度、液化时间和催化剂用量对松木层孔菌液化率的影响,并通过红外光谱对松木层孔菌原料和液化残渣进行分析.[结果]4个因素对松木层孔菌液化率影响排序为料液比>液化时间>催化剂用量>液化温度,优化的液化工艺参数为:料液比1:6、液化温度170℃、液化时间75 min、催化剂用量0.30 g,在此条件下,松木层孔菌液化率为48.64%.液化前后松木层孔菌红外光谱特征峰的形状和吸收位置均发生明显变化,3366 cm-1的活泼氢吸收峰在液化后发生红移,酰胺羰基吸收峰则分别由1697和1657 cm-1移至1701 cm-1,由1554 cm-1移至1612和1512 cm-1.[结论]采用苯酚—硫酸法可有效液化松木层孔菌,松木层孔菌含氮主要成分几丁质发生脱乙酰化反应,液化产物含有大量酚类物质,可进一步用于制备高附加值化工产品,为高等真菌菌渣的综合利用开辟新途径. 相似文献
5.
The use of polyester fibers has grown more rapidly than that of any other man-made fiber. Many factors have contributed to this growth. Polyester's unique physical properties of strength, high modulus, elasticity, and durability are the basis for its success. The tailorability of the fiber makes it possible to generate a whole family of property variants for a wide variety of end uses. The ready availability and low cost of the raw materials, the continuing advances in polymerization technology, and the versatility of the melt spinning process have also been major factors in establishing polyester as the leading man-made fiber. New end uses have had a major impact on the growth of polyester. Most notable was the introduction of durable press fabrics for clothing and home furnishings. The consumer preference for easy-care fabrics and garments makes the durable press area one of continuing growth. Two relatively new areas where growth is expected to continue at a rapid rate are tire cord and textured knits for women's and men's outerwear. 相似文献
6.
珊瑚藻藻红蛋白分离纯化技术及光谱学特性 总被引:5,自引:2,他引:5
藻红蛋白(PE)具有特征性吸收光谱和荧光光谱,是一种新颖的荧光分子探针.经反复探索研究建立了盐析、离子交换层析、羟基磷灰石吸附层析和凝胶过滤层析的分离纯化方案,从珊瑚藻中分离纯化出R-藻红蛋白(R-PE),其纯度[D(565nm)/D(280nm)]高达11. 相似文献
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8.
The reflection spectrum for the integral disk of the planet Mercury was measured and was found to have a constant positive slope from 0.32 to 1.05 micrometers, except for absorption features in the infrared. The reflectivity curve matches closely the curve for the lunar upland and mare regions. Thus, the surface of Mercury is probably covered with a lunar-like soil rich in dark glasses of high iron and titanium content. Pyroxene is probably the dominant mafic mineral. 相似文献
9.
Brownlee DE Horz F Newburn RL Zolensky M Duxbury TC Sandford S Sekanina Z Tsou P Hanner MS Clark BC Green SF Kissel J 《Science (New York, N.Y.)》2004,304(5678):1764-1769
Images taken by the Stardust mission during its flyby of 81P/Wild 2 show the comet to be a 5-kilometer oblate body covered with remarkable topographic features, including unusual circular features that appear to be impact craters. The presence of high-angle slopes shows that the surface is cohesive and self-supporting. The comet does not appear to be a rubble pile, and its rounded shape is not directly consistent with the comet being a fragment of a larger body. The surface is active and yet it retains ancient terrain. Wild 2 appears to be in the early stages of its degradation phase as a small volatile-rich body in the inner solar system. 相似文献
10.
Reuter DC Simon-Miller AA Lunsford A Baines KH Cheng AF Jennings DE Olkin CB Spencer JR Stern SA Weaver HA Young LA 《Science (New York, N.Y.)》2007,318(5848):223-225
Several observations of Jupiter's atmosphere made by instruments on the New Horizons spacecraft have implications for the stability and dynamics of Jupiter's weather layer. Mesoscale waves, first seen by Voyager, have been observed at a spatial resolution of 11 to 45 kilometers. These waves have a 300-kilometer wavelength and phase velocities greater than the local zonal flow by 100 meters per second, much higher than predicted by models. Additionally, infrared spectral measurements over five successive Jupiter rotations at spatial resolutions of 200 to 140 kilometers have shown the development of transient ammonia ice clouds (lifetimes of 40 hours or less) in regions of strong atmospheric upwelling. Both of these phenomena serve as probes of atmospheric dynamics below the visible cloud tops. 相似文献
11.
SOLTRAN is a flexible computer model for the direct solar beam intensity spectrum at the earth's surface. It has been derived by combining the extra-terrestrial solar spectrum with the atmospheric transmittance spectrum. Application of SOLTRAN to the calculation of the potential efficiency of photovoltaic cells demonstrates the effect of atmospheric absorption bands. These bands prevent unequivocal assignment of optimum energy gap values. 相似文献
12.
Maugh TH 《Science (New York, N.Y.)》1976,191(4233):1250-1251
13.
A spectrum of comet Austin (1988 c(1)) has been obtained from 910 to 1180 A. Three bright emission lines were detected, including a forbidden oxygen line (1128 A), which are attributable to radiative pumping of neutral oxygen by solar Lyman beta. The relative strengths of the observed features should prove to be a useful diagnostic of the physical conditions and radiation fields in cometary comae. In addition, the absence of strong spectral features from highly volatile species such as He, Ar, or N(2) can be used to place constraints on the thermal environment under which the comet was formed and has been processed. 相似文献
14.
A shuttle-borne radiometer containing ten channels in the reflective infrared has demonstrated that direct identification of carbonates and hydroxyl-bearing minerals is possible by remote measurement from Earth orbit. 相似文献
15.
2种储粮害虫活动声信号的检测及其功率谱分析 总被引:1,自引:1,他引:0
分别采集米象Sitophilus oryzae(L.)成虫、玉米象Sitophilus zeamais(Motschnlsky)成虫和米象幼虫在小麦、玉米、薏米中的活动声信号,并对其功率谱特征进行分析。结果表明:27℃时,小麦中米象成虫活动声功率谱谱峰所处频率分别为172.3、409.1、1 077.0Hz,小麦中玉米象成虫活动声功率谱谱峰所处频率分别为193.8、430.7、990.5Hz,玉米中玉米象成虫活动声功率谱谱峰所处频率分别为236.9Hz和1 012.0Hz,薏米中米象幼虫活动声功率谱谱峰所处频率分别为344.5Hz和990.5Hz。通过分析不同温度下储粮害虫活动声信号的特征,发现不同害虫和粮食种类都会影响储粮害虫的活动声信号,且其活动声功率谱谱峰所处的频段存在差异。 相似文献
16.
Chen JY Bottjer DJ Oliveri P Dornbos SQ Gao F Ruffins S Chi H Li CW Davidson EH 《Science (New York, N.Y.)》2004,305(5681):218-222
Ten phosphatized specimens of a small (<180 micrometers) animal displaying clear bilaterian features have been recovered from the Doushantuo Formation, China, dating from 40 to 55 million years before the Cambrian. Seen in sections, this animal (Vernanimalcula guizhouena gen. et sp. nov.) had paired coeloms extending the length of the gut; paired external pits that could be sense organs; bilateral, anterior-posterior organization; a ventrally directed anterior mouth with thick walled pharynx; and a triploblastic structure. The structural complexity is that of an adult rather than a larval form. These fossils provide the first evidence confirming the phylogenetic inference that Bilateria arose well before the Cambrian. 相似文献
17.
Measurements of body composition from serial, in vivo determinations of potassium-40 were made on 51 obese human subjects who were placed on a low calorie diet. Weight losses in the group averaged from 12 to 36 pounds. There was no change in potassium content or in lean body weight. Weight loss resulted from the loss of excess body fat. 相似文献
18.
以“题要分类法”研究了2008年版16种中文体育核心期刊2008-2011年载文(共15582篇)的特征
,把载文归纳成十大类型,简述了文章的意义并对其最终归属进行了预测研究。分类结果显示:不定式类
型文章最多,焦点争议类型文章最少,预测未来类型的文章比较薄弱。建议各期刊社尝试拟照十大类型进
行栏目选择设置,突出办刊亮点,既可使作者可根据自己的专业特点确定投稿方向,克服机动栏目变化大
的困难,同时可为读者及体育科研人员提供快速查找帮助。 相似文献
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Submarine pillow basalts from Kilauea Volcano contain excess radiogenic argon-40 and give anomalously high potassium-argon ages. Glassy rims of pillows show a systematic increase in radiogenic argon-40 with depth, and a pillow from a depth of 2590 meters shows a decrease in radiogenic argon40 inward from the pillow rim. The data indicate that the amount of excess radiogenic argon-40 is a direct function of both hydrostatic pressure and rate of cooling, and that many submarine basalts are not suitable for potassium-argon dating. 相似文献