共查询到20条相似文献，搜索用时 31 毫秒
1.
夏商周先民在河洛地区蚕桑制衣,兴修水利,发明农耕工具,尝试水稻栽培,在良种选择、田间管理、兼作套种、窖藏和肥田领域取得技术突破,并创立独特的天文历法,留下不朽的农学专著,为世界文明的发展作出了巨大贡献。快速发展的河洛农业文明不断向域外扩散延伸,并随着一次次社会动荡和民族融合传入台湾地区,并生根生长,台湾农业文明根在河洛。 相似文献
2.
New and more powerful methods for eliminating background intensity are needed in order to make possible the development of neutrino astronomy into a new, far-reaching branch of science. 相似文献
3.
Progress in gamma-ray astronomy has been very encouraging in recent years. These observations provide the most direct means of studying the largest transfer of energy occurring in astrophysical processes: the dynamic effects of the energetic charged cosmic-ray particles, element synthesis, and particle acceleration. Gammaray astronomical observations also find important application in studies of the development of the planets from the primitive solar nebula and of the nature of high-energy processes in the sun's atmosphere and their relation to the basic problems of solar activity. 相似文献
4.
Maran SP 《Science (New York, N.Y.)》1967,158(3803):867-871
In stellar astronomy, the future of automation techniques lies in their application to the largest telescopes. In such a case, the cost of automation is small compared to that of the telescope project as a whole, and is well repaid in the savings in observing time. A "stand-alone" capability for manual operation in event of computer breakdown is usually provided for systems like this; an example is the 107-inch (272-cm) telescope under construction at the McDonald Observatory of the University of Texas, which will be associated with an IBM 1800 computer. 相似文献
5.
Ney EP 《Science (New York, N.Y.)》1977,195(4278):541-546
Infrared astronomy has shown that certain classes of stars are abundant producers of refractory grains, which condense in their atmospheres and are blown into interstellar space by the radiation pressure of these stars. Metallic silicates of the kind that produce terrestrial planets are injected by the oxygen-rich stars and carbon and its refractories by carbon stars. Much of the interstellar dust may be produced by this mechanism. A number of "infrared stars" are completely surrounded by their own dust, and a few of these exhibit a unique morphology that suggests the formation of a planetary system or a stage in the evolution of a planetary nebula. Certain novae also condense grains, which are blown out in their shells. In our own solar system, comets are found to contain the same silicates that are present elsewhere in the galaxy, suggesting that these constituents were present in the primeval solar nebula. 相似文献
6.
Halzen F 《Science (New York, N.Y.)》2007,315(5808):66-68
Neutrino astronomy beyond the Sun was first imagined in the late 1950s. A neutrino detector at the bottom of Lake Baikal, the deployment of detectors in the Mediterranean Sea, and the construction of a kilometer-scale neutrino telescope at the South Pole exemplify current efforts to realize this dream. 相似文献
7.
One of the long-standing problems in modern astronomy is the curious division of Galactic globular clusters, the "Oosterhoff dichotomy," according to the properties of their RR Lyrae stars. Here, we find that most of the lowest metallicity ([Fe/H] < -2.0) clusters, which are essential to an understanding of this phenomenon, display a planar alignment in the outer halo. This alignment, combined with evidence from kinematics and stellar population, indicates a captured origin from a satellite galaxy. We show that, together with the horizontal-branch evolutionary effect, the factor producing the dichotomy could be a small time gap between the cluster-formation epochs in the Milky Way and the satellite. The results oppose the traditional view that the metal-poorest clusters represent the indigenous and oldest population of the Galaxy. 相似文献
8.
Rubin VC 《Science (New York, N.Y.)》1980,209(4452):64-71
Our perception of the universe has been altered by recent discoveries in astronomy, discoveries of new objects and of new phenomena, coming from a wide range of observing techniques. By 1990 astronomers expect to know more about the distribution of mass in the universe, the physics of energetic sources, and the intricate interconnections of astrophysical processes on a variety of spatial and temporal scales. 相似文献
9.
1956年7月9日至12日,中国科学院召开中国自然科学史第一次科学讨论会,会议分:农业及生物组、医学组和数学天文组。本文旨通过对农、生物组的学术讨论会历程及相应问题进行回溯,阐述本次科学讨论会的意义和影响。 相似文献
10.
The planetary radio astronomy experiment on board the Voyager spacecraft has detected bursts of nonthermal radio noise from Saturn occurring near 200 kilohertz, with a peak flux density comparable to higher frequency Jovian emissions. The radiation is right-hand polarized and is most likely emitted in the extraordinary magnetoionic mode from Saturn's northern hemisphere. Modulation that is consistent with a planetary rotation period of 10 hours 39.9 minutes is apparent in the data. 相似文献
11.
Glanz J 《Science (New York, N.Y.)》1995,268(5219):1849-1850
Pittsburgh-Most everything in astronomy is big. But the truly outsized features of the universe-vast filaments of galaxies and its great dark voids-were highlighted when 772 researchers gathered here on 11-15 June for the 186th meeting of the American Astronomical Society. Talks included a new explanation for the large-scale "tapestry" of the universe and a new glimpse of what may fill its voids. 相似文献
12.
Schilling G 《Science (New York, N.Y.)》2000,289(5477):238a-239a
Data from decades of observations by dozens of instruments may soon be accessible over the Internet, changing the way that astronomy is done around the world. The National Virtual Observatory will be an electronic web that gives astronomers access to terabytes of celestial data with the click of a mouse. The virtual observatory promises to make possible new analyses of the heavens by weaving together information from facilities around the world--and in space. 相似文献
13.
An array of problems in astronomy, cosmology, and particle physics is dependent on our understanding of the evolution and structure of stars. Stellar structure and evolution, in turn, depend on how the nuclear energy generated in the stellar center is transported to the surface. Energy transport by photons is a primary transfer mechanism. Recent improvements in the calculation of the radiative properties of stellar matter have helped resolve several long-standing discrepancies between observations and the predictions of theoretical models. 相似文献
14.
Lo KY 《Science (New York, N.Y.)》1986,233(4771):1394-1403
Studies of active galactic nuclei constitute one of the major efforts in astronomy. Massive black holes are the most likely source for the enormous energy radiated from such nuclei. Observations reviewed here suggest unusual activity and the possible existence of a massive black hole in the nucleus of our galaxy. Because of its proximity to Earth, our galactic nucleus can be observed in unsurpassed detail and may serve as the Rosetta stone both for deciphering active galactic nuclei and for confirming the existence of a massive black hole. 相似文献
15.
Dunlop JS 《Science (New York, N.Y.)》2011,333(6039):178-181
Major advances in observational astronomy over the past 20 years have revolutionized our view of cosmic history, transforming our understanding of how the hot, smooth, early universe evolved into the complex and beautiful universe of stars and galaxies in which we now live. I describe how astronomers have used a range of complementary techniques to map out the rise and fall of star formation over 95% of cosmic time, back to the current observational frontier only ~500 million years after the Big Bang. 相似文献
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17.
Sincell M 《Science (New York, N.Y.)》2000,289(5479):534-536
For the past decade, scientific ballooning has been in a steady decline, but a comeback is now in the works here at the National Scientific Balloon Facility (NSBF). This year's Decadal Review of astronomy has for the first time recommended that NASA increase support for this oft-neglected stepchild of the space program. And in June, the NSBF completed a milestone test flight of its Ultra-Long Duration Balloon, a sealed balloon capable of carrying several tons to 37,000 meters for 100 days that could make balloons competitive with satellites for doing research. 相似文献
18.
Mendillo M Baumgardner J Allen DP Foster J Holt J Ellis GR Klekociuk A Reber G 《Science (New York, N.Y.)》1987,238(4831):1260-1264
The Spacelab-2 Plasma Depletion Experiments were a series of studies to examine shuttle-induced perturbations in the ionosphere and their application to ground-based radio astronomy. The space shuttle Challenger fired its orbital maneuvering subsystem engines on 30 July and 5 August 1985, releasing large amounts of exhaust molecules (water, hydrogen, and carbon dioxide) that caused the electrons and ions in Earth's upper atmosphere to chemically recombine, thereby creating so-called "ionospheric holes." Two burns conducted over New England produced ionospheric peak depletions ranging from 25 to 50 percent, affected the ionosphere over a 200-kilometer altitude range, and covered 1 degrees to 2 degrees of latitude. Optical emissions associated with the hole spanned an area of several hundred thousand square kilometers. A third burn was conducted over a low-frequency radio observatory in Hobart, Australia, to create an "artificial window" for ground-based observations at frequencies normally below the natural ionospheric cutoff (penetration) frequency. The Hobart experiment succeeded in making high-resolution observations at 1.7 megahertz through the induced ionospheric hole. 相似文献
19.
The determination of chemical abundances of the interstellar medium is related to three different areas of astronomy: pregalactic conditions, stellar evolution, and chemical evolution of galaxies. The observed abundances permit the testing of theories associated with these areas. Knowledge of the abundances of helium, carbon, nitrogen, and neon relative to the abundance of hydrogen in the interstellar medium puts limits on current models of cosmology, stellar evolution, and galactic evolution. 相似文献
20.
Warwick JW Evans DR Romig JH Alexander JK Desch MD Kaiser ML Aubier M Leblanc Y Lecacheux A Pedersen BM 《Science (New York, N.Y.)》1982,215(4532):582-587
Planetary radio astronomy measurements obtained by Voyager 2 near Saturn have added further evidence that Saturnian kilometric radiation is emitted by a strong dayside source at auroral latitudes in the northern hemisphere and by a weaker source at complementary latitudes in the southern hemisphere. These emissions are variable because of Saturn's rotation and, on longer time scales, probably because of influences of the solar wind and Dione. The electrostatic discharge bursts first discovered by Voyager 1 and attributed to emissions from the B ring were again observed with the same broadband spectral properties and an episodic recurrence period of about 10 hours, but their occurrence frequency was only about 30 percent of that detected by Voyager 1. While crossing the ring plane at a distance of 2.88 Saturn radii, the spacecraft detected an intense noise event extending to above 1 megahertz and lasting about 150 seconds. The event is interpreted to be a consequence of the impact, vaporization, and ionization of charged, micrometer-size G ring particles distributed over a vertical thickness of about 1500 kilometers. 相似文献