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排序方式: 共有10000条查询结果,搜索用时 15 毫秒
981.
982.
Y.‐C. Wei C.‐M. Zhang Y.‐H. Zhao Q.‐H. Peng X.‐J. Wu J. Wang Y.‐Y. Pan H.‐X. Yin Y. Yan T.‐S. Yan H.‐J. Tian A. Esamdin A.L. Luo Y. Cai A. Taani 《Astronomische Nachrichten》2010,331(8):817-831
Under the two initial 1‐D one parameter velocity distribution forms (one is normal, the other is exponential), the z direction scale height evolution of normal neutron stars in the Galaxy is studied by numerical simulation. We do statistics for the cases at different time segments, also do statistics for the cumulative cases made of each time segment. The results show in the cumulative cases the evolution curves of the scale heights are smoother than in the each time segment, i.e., the cumulation improve the signal‐to‐noise ratio. Certainly the evolution cases are different at different Galactic disk locations, which also have very large difference from the average cases in the whole disk. In the initial stages of z evolution of normal neutron stars, after the beginning transient states, the cumulative scale heights increase linearly with time, and the cumulative scale height increasing rates have linear relationship with the initial velocity distribution parameters, which have larger fluctuation in the vicinity of the Sun than in the whole disk. We utilize the linear relationship of the cumulative scale height increasing rates vs. the initial velocity distribution parameters in the vicinity of the Sun to make comparison with the observation near the Sun. The results show if there is no magnetic decay, then the deserved initial velocity parameters are obvious lower than the present well known results from some authors; whereas if introducing magnetic decay, for the 1‐D normal case we can make consistence among concerning results using magnetic decay time values which are supported by some authors, while for the 1‐D exponential case the results show the lackness of young pulsar samples in the larger z in the vicinity of the Sun (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
983.
984.
Using 141 CME-interplanetary shock (CME-IPS) events and foF2 from eight ionosonde stations from January 2000 to September 2005, from the statistical results we find that there is a “same side?–?opposite side effect” in ionospheric negative storms, i.e., a large portion of ionospheric negative disturbances are induced by the same-side events (referring to the CMEs whose source located on the same side of the heliospheric current sheet (HCS) as the Earth), while only a small portion is associated with the opposite-side events (the CMEs source located on the opposite side of the HCS as the Earth); the ratio is 128 vs. 46, and it reaches 41 vs. 14 for the intense ionospheric negative storms. In addition, the ionospheric negative storms associated with the same-side events are often more intense. A comparison of the same-side event (4 April 2000) and the opposite-side event (2 April 2001) shows that the intensity of the ionospheric negative storm caused by the same-side event is higher than that by the opposite-side event, although their initial conditions are quite similar. Our preliminary results show that the HCS has an “impeding” effect to CME-IPS, which results in a shortage of energy injection in the auroral zone and restraining the development of ionospheric negative perturbations. 相似文献
985.
Ji Wu Guang-Wu Zhu Hua Zhao Chi Wang Lei Li Yue-Qiang Sun Wei Guo Cheng-Li Huang 《Chinese Astronomy and Astrophysics》2010
Compared with other planets, Mars is a planet most similar with the earth and most possible to find the extraterrestrial life on it, and therefore especially concerned about by human beings. In recent years, some countries have launched Mars probes and announced their manned Mars exploration programs. China has become the fifth country in the world to launch independently artificial satellites, and the third country able to carry out an independent manned space program. However, China is just at the beginning of deep space explorations. In 2007, China and Russia signed an agreement on a joint Mars exploration program by sending a Chinese micro-satellite Yinghuo-1 (YH-1) to the Mars orbit. Once YH-1 enters its orbit, it will carry out its own exploration, as well as the joint exploration with the Russian Phobos-Grunt probe. This paper summarizes the scientific background and objectives of YH-1 and describes briefly its payloads for realizing these scientific objectives. In addition, the main exploration tasks of YH-1 and a preliminary prospect on its exploration results are also given. 相似文献
986.
987.
沈阳长白乡-观音阁断裂、抚顺浑河断裂的定位和活动性研究 总被引:3,自引:0,他引:3
本文基于对沈阳长白乡-观音阁断裂,以及抚顺浑河断裂开展的1:10000地质地貌填图工作,获得了这两条断裂在最老第四纪地层热释光的测年结果,它们分别为(112±6.7)ka和(150±9.0)ka。长白乡-观音阁断裂为一沿丘陵山地前缘分布的断裂,由2—3条分支断裂组成,最新的断面活动显示为压扭性正断层性质。断裂在晚更新世坡洪积扇堆积形成以来没有活动显示。3条浅层人工地震测线探测结果表明,其上断点均未错断第四系上更新统底界。断裂为中更新世活动断裂,晚更新世以来没有活动。浑河断裂为一沿丘陵山地前缘分布的断裂,由3—4条分支断裂组成,最新的断面活动显示为压扭性正断层性质。断裂在晚更新世坡洪积扇堆积形成以来没有活动显示。5条浅层人工地震测线探测结果表明,其上断点均在第四系上更新统底界以下。断裂为中更新世活动断裂,晚更新世以来没有活动。 相似文献
988.
T.S. Peretyazhko J.M. Zachara D.W. Kennedy J.K. Fredrickson B.W. Arey J.P. McKinley C.M. Wang A.C. Dohnalkova Y. Xia 《Geochimica et cosmochimica acta》2010,74(13):3751-60
The reductive biotransformation of 6-line ferrihydrite located within porous silica (intragrain ferrihydrite) by Shewanella oneidensis MR-1 was investigated and compared to the behavior of 6-line ferrihydrite in suspension (free ferrihydrite). The effect of buffer type (PIPES and NaHCO3), phosphate (P), and an electron shuttle (AQDS) on the extent of reduction and formation of Fe(II) secondary phases was investigated under anoxic conditions. Electron microscopy and micro X-ray diffraction were applied to evaluate the morphology and mineralogy of the biogenic precipitates and to study the distribution of microorganisms on the surface of porous silica after bioreduction. Kinetic reduction experiments with free and intragrain ferrihydrite revealed contrasting behavior with respect to the buffer and presence of P. The overall amount of intragrain ferrihydrite reduction was less than that of free ferrihydrite [at 5 mmol L−1 Fe(III)T]. Reductive mineralization was not observed in the intragrain ferrihydrite incubations without P, and all biogenic Fe(II) concentrated in the aqueous phase. Irrespective of buffer and AQDS addition, rosettes of Fe(II) phosphate of approximate 20-30 μm size were observed on porous silica when P was present. The rosettes grew not only on the silica surface but also within it, forming a coherent spherical structure. These precipitates were well colonized by microorganisms and contained extracellular materials at the end of incubation. Microbial extracellular polymeric substances may have adsorbed Fe(II) promoting Fe(II) phosphate nucleation with subsequent crystal growth proceeding in different directions from a common center. 相似文献
989.
新疆贝勒库都克A型花岗岩锆石U-Pb年龄、地球化学及锡成矿 总被引:1,自引:0,他引:1
新疆东准噶尔卡拉麦里地区是一个重要的锡成矿带,分布有多种类型花岗岩。贝勒库都克岩体位于锡成矿带中部,由黑云母正长花岗岩和黑云母二长花岗岩组成。本文通过精确的LA-ICP-MS锆石U-Pb测年获得贝勒库都克含锡黑云母正长花岗岩年龄为283±2Ma,MSWD=0.14(95%置信度),时代属于早二叠世,这与东准噶尔后碰撞深成岩浆活动的范围(330~265Ma)相吻合。岩石地球化学研究表明,贝勒库都克岩体富硅(SiO2=75.25%~76.67%),低铝(Al2O3=11.91%~12.86%),贫镁(MgO=0.02%~0.18%)和钙(CaO=0.39%~0.89%),富碱(Na2O+K2O=8.08%~8.97%),K2O>Na2O,NK/A=0.86~0.95(平均0.92),A/NCK=0.97~1.02,富集Rb、K等大离子亲石元素及Zr、Hf等高场强元素,Ba,Nb,Sr强烈亏损,δEu=0.01~0.11,其FeOt/MgO(12.71~84.51,平均34.55)和10000Ga/A1(2.97~4.20)值大,HFSE元素(Zr+Nb+Ce+Y=191.8×10-6~353.3×10-6)含量高,明显不同于典型的I型和S型花岗岩,基本属于典型的铝质A型花岗岩。年代学和地球化学综合研究表明,贝勒库都克铝质A型花岗岩是壳幔混合成因,是准噶尔地区后碰撞幔源岩浆底侵作用导致大陆地壳垂向生长过程的记录者。贝勒库都克铝质A型花岗岩Sn的含量高(6.0×10-6~19.5×10-6,个别为80.0×10-6),铝质A型花岗岩是成矿热液的直接母体,而富Sn的流体相最终形成了贝勒库都克锡矿床,锡矿与铝质A型花岗岩是同期地质事件的产物。 相似文献
990.