全文获取类型
收费全文 | 326篇 |
免费 | 16篇 |
国内免费 | 3篇 |
专业分类
航空 | 14篇 |
航天技术 | 313篇 |
航天 | 18篇 |
出版年
2023年 | 11篇 |
2022年 | 2篇 |
2021年 | 14篇 |
2020年 | 15篇 |
2019年 | 15篇 |
2018年 | 16篇 |
2017年 | 1篇 |
2016年 | 2篇 |
2015年 | 5篇 |
2014年 | 18篇 |
2013年 | 26篇 |
2012年 | 18篇 |
2011年 | 26篇 |
2010年 | 22篇 |
2009年 | 27篇 |
2008年 | 20篇 |
2007年 | 13篇 |
2006年 | 6篇 |
2005年 | 17篇 |
2004年 | 10篇 |
2003年 | 8篇 |
2002年 | 7篇 |
2001年 | 10篇 |
2000年 | 1篇 |
1999年 | 3篇 |
1998年 | 4篇 |
1997年 | 2篇 |
1996年 | 5篇 |
1995年 | 4篇 |
1994年 | 3篇 |
1993年 | 3篇 |
1992年 | 4篇 |
1990年 | 6篇 |
1987年 | 1篇 |
排序方式: 共有345条查询结果,搜索用时 15 毫秒
161.
Gustavo A. Mansilla 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2011
In this short paper we examine the possible connection between atmospheric parameters measured at low and middle altitudes and geomagnetic storms occurred in 2000 and 2003. For that, from a chain of stations located near the meridian 60°W we compare the storm time values of temperature and wind speed with their standard deviation 2σ obtained from quiet time values. We observed statistically significant variations at several altitudes during the storm recovery phase and after it, both in neutral wind speed and temperature. The results obtained suggest that atmospheric parameters could be affected by geomagnetic storms. 相似文献
162.
E.I. Astafyeva E.L. Afraimovich S.V. Voeykov 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2008,41(9):1459-1462
By using data from GPS receivers we detected huge-amplitude solitary large-scale traveling acoustic-gravity waves (LS AGW) which manifested themselves as perturbations of total electron content (TEC) of duration of about 40 min. Originated in the auroral area after significant alterations of geomagnetic field intensity during geomagnetic storms on 29–30 October 2003, LS disturbances propagated with a velocity about 1000–1200 m/s and caused generation of secondary small-scale (SS) waves with time period of 2–10 min. Such SS structure followed the solitary intensive AGW at a distance more than 4000 km. However, we observed such phenomenon only within the territory with high values of “vertical” TEC and steep gradients of TEC. Apparently, these conditions are necessary for generation of SS waves due to propagation of LS AGW. 相似文献
163.
S. Watari 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2011
Long-term forecast of space weather allows in achieving a longer lead time for taking the necessary precautions against disturbances. Hence, there is a need for long-term forecasting of space weather. We studied the possibility for a long-term forecast of recurrent geomagnetic storms. Geomagnetic storms recur with an approximate 27-day period during the declining phase of a solar cycle. These disturbances are caused by the passage of corotating interaction regions, which are formed by interactions between the background slow-speed solar wind and high-speed solar wind streams from a coronal hole. In this study, we report on the performance of 27-day-ahead forecasts of the recurrent geomagnetic disturbances using Kp index. The methods of the forecasts are on the basis of persistence, autoregressive model, and categorical forecast using occurrence probability. The forecasts show better performance during the declining phase of a solar cycle than other phases. The categorical forecast shows the probability of detection (POD) more than 0.5 during the declining phase. Transition of the performance occurs sharply among the declining phases and other phases. 相似文献
164.
165.
Ruiguang Wang 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2007,40(12):1835-1841
During extreme solar events such as big flares or/and energetic coronal mass ejections (CMEs) high energy particles are accelerated by the shocks formed in front of fast interplanetary coronal mass ejections (ICMEs). The ICMEs (and their sheaths) also give rise to large geomagnetic storms which have significant effects on the Earth’s environment and human life. Around 14 solar cosmic ray ground level enhancement (GLE) events in solar cycle 23 we examined the cosmic ray variation, solar wind speed, ions density, interplanetary magnetic field, and geomagnetic disturbance storm time index (Dst). We found that all but one of GLEs are always followed by a geomagnetic storm with Dst −50 nT within 1–5 days later. Most(10/14) geomagnetic storms have Dst index −100 nT therefore generally belong to strong geomagnetic storms. This suggests that GLE event prediction of geomagnetic storms is 93% for moderate storms and 71% for large storms when geomagnetic storms preceded by GLEs. All Dst depressions are associated with cosmic ray decreases which occur nearly simultaneously with geomagnetic storms. We also investigated the interplanetary plasma features. Most geomagnetic storm correspond significant periods of southward Bz and in close to 80% of the cases that the Bz was first northward then turning southward after storm sudden commencement (SSC). Plasma flow speed, ion number density and interplanetary plasma temperature near 1 AU also have a peak at interplanetary shock arrival. Solar cause and energetic particle signatures of large geomagnetic storms and a possible prediction scheme are discussed. 相似文献
166.
167.
B.J. Adekoya V.U. Chukwuma 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2018,61(1):274-286
Classification and quantification of the interplanetary structures causing intense geomagnetic storms (Dst?≤??100?nT) that occurred during 1997–2016 are studied. The subject of this consists of solar wind parameters of seventy-three intense storms that are associated with the southward interplanetary magnetic field. About 30.14% of the storms were driven by a combination of the sheath and ejecta (S?+?E), magnetic clouds (MC) and sheath field (S) are 26% each, 10.96% by combined sheath and MCs (S?+?C), while 5.48% of the storms were driven by ejecta (E) alone. Therefore, we want to aver that for storms driven by: (1) S?+?E. The Bz is high (≥10?nT), high density (ρ) (>10?N/cm3), high plasma beta (β) (>0.8), and unspecified (i.e. high or low) structure of the plasma temperature (T) and the flow speed (V); (2) MC. The Bz is ≥10?nT, low temperature (T?≤?400,000?K), low ρ (≤10?N/cm3), high V (≥450?km), and low β (≤0.8); (3) The structures of S?+?C are similar to that of MC except that the V is low (V?≤?450?km); (4) S. The Bz is high, low T, high ρ, unspecified V, and low β; and (5) E. Is when the structures are directly opposite of the one driven by MCs except for high V. Although, westward ring current indicates intense storms, but the large intensity of geomagnetic storms is determined by the intense nature of the electric field strength and the Bz. Therefore, great storms (i.e. Dst?≤??200?nT) are manifestation of high electric field strength (≥13?mV/m). 相似文献
168.
169.
A.D. Danilov A.V. Konstantinova 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2021,67(12):4066-4077
The foF2 deviations from quiet conditions during three days preceding a magnetic storm are considered. The data of the Juliusruh station for the period of 1976–2010 are analyzed, and the results are compared to the similar analysis of the Slough data published earlier. A seasonal dependence of the deviations (events) is found: the probability of the events occurrence is higher in winter than in summer. This probability also depends on solar activity (it decreases with an increase in the F10.7 index) and the magnetic storm intensity (it decreases with an increase in the magnitude of the negative Dst index). The dependence of the events number on the local time of the storm onset (SO) and the time of the event prior to the SO moment is also analyzed. The results for both stations are in a good agreement and confirm the initial concept that the aforementioned events could be considered as precursors of the coming magnetic storm. 相似文献
170.
《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2020,65(1):115-128
The ionospheric effects induced by the September 2017 storm have been exceptional compared to other events in the solar cycle 24. This paper gathers results of the ionospheric observations at the European middle latitude station Pruhonice. It consists of evaluation of ionospheric vertical and oblique sounding, Digisonde drift measurement, and data obtained from the Continuous Doppler Sounding System. We observed strong ionospheric response with an unusual stratification of ionospheric layers, Large Scale Traveling ionospheric disturbances, changes in electron density, and increase and oscillations in plasma drift velocity. 相似文献