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991.
DISTRIBUTION OF THE MAIN CROP GERMPLASM RESOURCES IN CHINA 总被引:1,自引:0,他引:1
Cropgermplasmresourcesaretheindispensablematerialbaseforcropbreedingandagriculturalproduction.Theresearchondistributionofcropgermplasmr~urcesisofgreatimportanceinstudyingonorigin,evolutionandclassificationofcrops,expeditingandcollectinggermplasm,ascertainingofcentersofdiversity,protectinggermplasmr~urcesandmakingagriculturalproductiondivision.Since1949,researchesofexploration,collection,preservation,cha-racterizationandevaluationofcropgermplasmresourceshavebeendoneinChina.Atpresent,thenational… 相似文献
992.
During the 21st solar activity cycle the HXRBS aboard SMM satellite and the HXM on HINOTORI spacecraft detected several thousand hard X-ray solar flares. Studies of the temporal properties of these events had revealed hundreds of examples of fast spikes with durations of less than 1 sec. We analysed part of these observations and found that they have four common characteristics. Among these characteristics, quasi-periodic oscillations led us to believe the possibility of oscillations existing in the corona. We have studied the characteristics of the oscillations and derived their periods. The conditions of trapping the oscillations are also discussed. 相似文献
993.
994.
1 IntroductionOneofthemaintasksinstudyinggeodynamicprocessisevaluatingtherateofearthcrustmove ments.Normally ,themethodsforstudyingearthcrustmovementareestablishedonthebasisoftheobjectofstudyandtherequirementsfortheresultstobeobtainedasfollows.1 )Tostudythemovingprocessofcrustplatesinalargeareaandwithinacertaintectonicperiod ,geologicmethodsareusuallyused .2 )Geodeticmeasurementsarecarriedoutinanareacoveringfromsomekm2 totensofkm2 andal lowtodeterminethedisplacementoftheearthcrustwithinaperio… 相似文献
995.
Dust storms in Northeast China become more se-rious in recent years due to the global warming and local land use and cover change (LUCC) around the sand lands in western and northwestern Jilin Province. Field investigations and urban testing re-vealed that the amount of dusts brought by dust storm reaches a higher level in the past two years. According to an experiment on the “mud-snow”in April, 2000 and an observation in March, 2002, the dusts coming from the western Jilin and fall… 相似文献
996.
997.
重力滑动构造广泛发育,是豫西煤田构造格局显著特征之一。本文分析了导致煤田重力滑动构造形成的动力学条件、构造变形条件、岩性条件和流体介质条件,讨论了此类特殊构造现象与其所处的特殊构造环境之间的关系。 相似文献
998.
Minfeng Gu Xinwu Cao D. R. Jiang Y. Xu 《Monthly notices of the Royal Astronomical Society》2001,321(2):369-371
The low-frequency radio luminosity is believed to be an indicator of jet power, while the optical/ultraviolet (UV) emission is probably from accretion discs in the nuclei of steep-spectrum radio quasars. We present a correlation between the ratio of radio-to-optical luminosities and the continuum spectral index in blue/UV bands, which might indicate that the continuum shape in blue/UV bands is related to the ratio of jet to accretion power. The results may imply that the spectra and structure of accretion discs are probably affected by the interactions between jets and discs. 相似文献
999.
Cao Tian-jun 《Chinese Astronomy and Astrophysics》1983,7(4):305-308
We summarize the morphological features of spotless flares as observed by three Chinese observatories (Yunnan Purple Mountain and Beijing) during the peak years of the 21st solar cycle. On the basis of the Kippenhahn-Schluter model of solar prominences, we qualitatively interpret these observed features and propose a possible theoretical model of generating spotless flares. 相似文献
1000.
Cao Shenglin 《Astrophysics and Space Science》1990,174(2):165-171
According to our Paper I (Cao Shenglin, 1988), it could be supposed that the physical space-time is a Finsler space-time, characterized by the metric ds
4=g
ijkf
dx
i
dx
j
dx
k
dx
f
. If so, a new space-time transformation could be found by invariant ds
4 and the theory of relativity is discussed on this transformation.The project supported by National Natural Science Foundation of China. 相似文献