全文获取类型
收费全文 | 3199篇 |
免费 | 10篇 |
国内免费 | 5篇 |
专业分类
航空 | 1192篇 |
航天技术 | 1041篇 |
综合类 | 19篇 |
航天 | 962篇 |
出版年
2022年 | 15篇 |
2021年 | 37篇 |
2019年 | 16篇 |
2018年 | 128篇 |
2017年 | 102篇 |
2016年 | 116篇 |
2015年 | 41篇 |
2014年 | 111篇 |
2013年 | 135篇 |
2012年 | 118篇 |
2011年 | 158篇 |
2010年 | 127篇 |
2009年 | 192篇 |
2008年 | 190篇 |
2007年 | 122篇 |
2006年 | 74篇 |
2005年 | 101篇 |
2004年 | 94篇 |
2003年 | 106篇 |
2002年 | 83篇 |
2001年 | 113篇 |
2000年 | 36篇 |
1999年 | 53篇 |
1998年 | 61篇 |
1997年 | 42篇 |
1996年 | 43篇 |
1995年 | 80篇 |
1994年 | 61篇 |
1993年 | 34篇 |
1992年 | 45篇 |
1991年 | 10篇 |
1990年 | 19篇 |
1989年 | 41篇 |
1988年 | 11篇 |
1987年 | 17篇 |
1986年 | 16篇 |
1985年 | 70篇 |
1984年 | 56篇 |
1983年 | 48篇 |
1982年 | 42篇 |
1981年 | 82篇 |
1980年 | 25篇 |
1979年 | 16篇 |
1978年 | 14篇 |
1977年 | 17篇 |
1976年 | 13篇 |
1975年 | 13篇 |
1974年 | 11篇 |
1972年 | 13篇 |
1971年 | 11篇 |
排序方式: 共有3214条查询结果,搜索用时 0 毫秒
951.
R.A. Gowen A. Smith A.D. Fortes S. Barber P. Brown P. Church G. Collinson A.J. Coates G. Collins I.A. Crawford V. Dehant J. Chela-Flores A.D. Griffiths P.M. Grindrod L.I. Gurvits A. Hagermann H. Hussmann R. Jaumann A.P. Jones K.H. Joy O. Karatekin K. Miljkovic E. Palomba W.T. Pike O. Prieto-Ballesteros F. Raulin M.A. Sephton S. Sheridan M. Sims M.C. Storrie-Lombardi R. Ambrosi J. Fielding G. Fraser Y. Gao G.H. Jones G. Kargl W.J. Karl A. Macagnano A. Mukherjee J.P. Muller A. Phipps D. Pullan L. Richter F. Sohl J. Snape J. Sykes N. Wells 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2011
952.
D.V. Blagoveshchensky J.W. MacDougall D.D. Rogov 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2011
For the magnetospheric storm of May 14–16, 1997 geophysical data of satellites DMSP and IMP-8 are compared with data of radio propagation on the high-latitude HF radio path of Heiss Island – St. Petersburg and data from European ionosondes. Peculiarities of variations of the operational frequencies range MOF–LOF (maximum and lowest observed frequencies) on the path were considered. The range has been determined by the method of oblique ionospheric sounding (OIS). The latter is more informative for observations during a magnetic storm compared to the vertical sounding method. Nevertheless, an analysis of variations of the critical frequency of the ionospheric F2 layer from the chain of European ionosondes was carried out. For interpretation of results, data of magnetospheric parameters, AE-indexes and riometer data were used. The variations of both frequency range on the path and critical frequencies of the F2 layer through the ionosondes chain during the disturbed period had certain regularities of behaviour. These regularities are being explained from the physical point of view. The analysis of the satellite DMSP data has showed that a magnetospheric disturbance causes displacement equatorward of precipitation and some growth of its width and energy. 相似文献
953.
Hopper concepts for small body landers 总被引:3,自引:0,他引:3
S. Ulamec V. Kucherenko J. Biele A. Bogatchev A. Makurin S. Matrossov 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2011
The investigation of small bodies, comets and asteroids, can contribute substantially to our understanding of the formation and history of the Solar System. In situ observations by landers play an important role in this field. 相似文献
954.
M.V. Podzolko I.V. Getselev Yu.I. Gubar I.S. Veselovsky A.A. Sukhanov 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2011
Charged particle fluxes on the trajectory of future Russian space research mission to Jupiter and its satellite Europa are investigated. The existing experimental data and models of Jupiter’s main magnetic field and radiation belts are summarized. Preliminary results of computations of energetic particle fluxes and radiation doses for each stage of the flight are given. Special attention is paid to estimation of radiation conditions in Europa’s orbit and on its surface; influence of the satellite on spatial distribution of the fluxes of charged particles of various energies is studied. 相似文献
955.
V. Iafolla D.M. Lucchesi S. Nozzoli M. Ravenna F. Santoli I.I. Shapiro E.C. Lorenzini M.L. Cosmo C. Bombardelli J. Ashenberg P.N. Cheimets S. Glashow 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2011
We presents the results of an activity concerning the test of the Einstein Weak Equivalence Principle with an accuracy of about 5 × 10−15. The experiment will be performed in an “Einstein elevator” using a differential accelerometer with a final sensitivity of about 10−14 g⊕/Hz1/2. The differential accelerometer is spun about an horizontal axis at a frequency in the range 0.5–1 Hz in order to modulate, during the free fall, the signal from a possible violation of the Equivalence Principle. In the paper the perturbing effects with the same signature of the possible violation are analyzed and constrained. The experimental results obtained in the laboratory with a first prototype of the differential accelerometer are discussed, comparing this results with those obtained using a new prototype. 相似文献
956.
I.A. Nesterov V.E. Kunitsyn 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2011
We discuss the specific features of the spatiotemporal radio tomography of ionospheric electron density based on the data from high orbiting global navigational satellite system (GNSS). The main peculiarities are four-dimensionality of the problem and essential incompleteness of input data. The approach suggested for the solution of this problem is based on the search for the solution with minimal Sobolev’s norm (the most smooth solution), which provides, in particular, smooth extension of the solution to the area where no input data is available. Methods and algorithms for the solution of the problem are developed, and the resolution of the proposed technique is estimated. Examples of global and regional radio tomographic imaging based on GNSS data are presented. The obtained results are compared with the data of ionosondes and with the results of radio tomography based on the radio transmissions from low-orbiting satellites. 相似文献
957.
P.R. Fagundes V. Klausner J.A. Bittencourt Y. Sahai J.R. Abalde 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2011
The occurrence of an additional F3-layer has been reported at Brazilian, Indian and Asian sectors by several investigators. In this paper, we report for the first time the seasonal variations of F3-layer carried out near the southern crest of the equatorial ionospheric anomaly (EIA) at São José dos Campos (23.2°S, 45.0°W; dip latitude 17.6°S – Brazil) as a function of solar cycle. The period from September 2000 to August 2001 is used as representative of high solar activity (HSA) and the period from January 2006 to December 2006 as representative of low solar activity (LSA). This investigation shows that during HSA there is a maximum occurrence of F3-layer during summer time and a minimum during winter time. However, during LSA, there is no seasonal variation in the F3-layer occurrence. Also, the frequency of occurrence of the F3-layer during HSA is 11 times more than during LSA. 相似文献
958.
L Narici V Bidoli M Casolino M P De Pascale G Furano A Morselli P Picozza E Reali R Sparvoli S Licoccia P Romagnoli E Traversa W G Sannita A Loizzo A Galper A Khodarovich M G Korotkov A Popov N Vavilov S Avdeev V P Salnitskii O I Shevchenko V P Petrov K A Trukhanov M Boezio W Bonvicini A Vacchi N Zampa R Battiston G Mazzenga M Ricci P Spillantini G Castellini P Carlson C Fuglesang 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2003,31(1):141-146
The ALTEA project participates to the quest for increasing the safety of manned space flights. It addresses the problems related to possible functional damage to neural cells and circuits due to particle radiation in space environment. Specifically it aims at studying the functionality of the astronauts' Central Nervous Systems (CNS) during long space flights and relating it to the peculiar environments in space, with a particular focus on the particle flux impinging in the head. The project is a large international and multidisciplinary collaboration. Competences in particle physics, neurophysiology, psychophysiology, electronics, space environment, data analyses will work together to construct the fully integrated vision electrophysiology and particle analyser system which is the core device of the project: an helmet-shaped multi-sensor device that will measure concurrently the dynamics of the functional status of the visual system and passage of each particle through the brain within a pre-determined energy window. ALTEA is scheduled to fly in the International Space Station in late 2002. One part of the multi-sensor device, one of the advanced silicon telescopes, will be launched in the ISS in early 2002 and serve as test for the final device and as discriminating dosimeter for the particle fluences within the ISS. 相似文献
959.
S I Bartsev V V Mezhevikin V A Okhonin 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2003,31(7):1823-1832
This paper is devoted to the consideration of possible viewpoint on CELSS development and design. If the aim to create practically applicable CELSS is accepted then the task to optimize the process of CELSS research and development in terms of minimum cost, hours, maximum applicability, scientific contribution, etc. becomes actual. Requirements of applicability and scientific significance are synergetic since understanding of general properties of CELSS gives an ability to create CELSS for different applications. To accomplish the task three main groups of parameters have to be optimized: i) configuration and operating parameters of developing CELSS itself; ii) organizational management of research and development of CELSS; iii) features of an area where CELSS is planned to be used (space missions, terrestrial applications, or biosphere investigation) and where requirements to CELSS characteristic come from. Given paper is a brief review presented some attempts to arrange mentioned above into some set of formalized and interacting criteria, and some progression of research stages derived from these criteria. 相似文献
960.