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991.
Monitoring of rice cropping intensity in the upper Mekong Delta,Vietnam using time-series MODIS data
C.F. Chen N.T. Son L.Y. Chang 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2012
Information on rice growing areas is important for policymakers to devise agricultural plans. This research explores the monitoring of rice cropping intensity in the upper Mekong Delta, Vietnam (from 2001 to 2007) using time-series MODIS NDVI 250-m data. Data processing includes three steps: (1) noise is filtered from the time-series NDVI data using empirical mode decomposition (EMD); (2) endmembers are extracted from the filtered time-series data and trained in a linear mixture model (LMM) for classification of rice cropping systems; and (3) classification results are verified by comparing them with the ground-truth and statistical data. The results indicate that EMD is a good filter for noise removal from the time-series data. The classification results confirm the validity of LMM, giving an overall accuracy of 90.1% and a Kappa coefficient of 0.7. The lowest producer and user accuracies were associated with single crop rain-fed rice class due to the mixed pixel problems. A strong yearly correlation at the district level was revealed in the MODIS-derived areas (R2 ? 0.9). Investigation of interannual changes in rice cropping intensity from 2001 to 2007 showed a remarkable conversion from double to triple crop irrigated rice from 2001 to 2003, especially in the Thoai Son and Phu Tan districts. A big conversion from triple crop rice back to double crop rice cultivation was also observed in Phu Tan from 2005 to 2006. These changes were verified by visual interpretation of Landsat images and examination of NDVI profiles. 相似文献
992.
M. I. Panasyuk S. I. Svertilov V. V. Bogomolov G. K. Garipov V. O. Barinova A. V. Bogomolov N. N. Veden’kin I. A. Golovanov A. F. Iyudin V. V. Kalegaev P. A. Klimov A. S. Kovtyukh E. A. Kuznetsova V. S. Morozenko O. V. Morozov I. N. Myagkova V. L. Petrov A. V. Prokhorov G. V. Rozhkov E. A. Sigaeva B. A. Khrenov I. V. Yashin S. I. Klimov D. I. Vavilov V. A. Grushin T. V. Grechko V. V. Khartov V. A. Kudryashov S. V. Bortnikov P. V. Mzhel’skiy A. P. Papkov S. V. Krasnopeev V. V. Krug V. E. Korepanov S. Belyaev A. Demidov Ch. Ferenz L. Bodnar P. Szegedi H. Rotkel M. Moravskiy Il Park Jin-A Jeon Ji-In Kim Jik Lee 《Cosmic Research》2016,54(5):343-350
We present the first experimental results on the observation of optical transients, gamma-ray bursts, relativistic electrons, and electromagnetic waves obtained during the experiment with the RELEC complex of scientific equipment on the Vernov satellite. 相似文献
993.
Evlanov E. N. Zubkov B. V. Nenarokov D. F. Linkin V. M. Zavjalov M. A. Tyuryukanov P. M. 《Cosmic Research》2001,39(5):453-458
A gas-discharge anemometer is designed for investigating the gas-flow dynamics in wind tunnels, and in experimental and space meteorology. The anemometer allows one to measure simultaneously the magnitude and direction of the gas-flow velocity vector and the gas pressure in the flow. The instrument consists of a gas-discharge chamber, an analyzer of scattered ions, a power supply unit, and a measuring unit. The anemometer weight does not exceed 0.1 kg, and the power consumption does not exceed 0.2 W. The instrument was put through preliminary tests in a wind tunnel that simulated, in particular, the conditions in the boundary layer of the Martian atmosphere and produced a directed gas (air or CO2) flow whose velocity could be varied from 0.5 to 50 m/s at pressures from 0.3 to 1.3 kPa and temperatures from –120 to +20°C. The anemometer sensitivity is no worse than 100 mV/(m/s). The method of calculating the gas-flow velocity on the basis of the measured ion-current distributions is developed. 相似文献
994.
A.A. Sukhanov A.F.B.A. Prado 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2012
A simple and effective mathematical method to calculate optimal station-keeping manoeuvres by means of electric propulsion is suggested. The method is based on a linearization of the satellite motion near a reference orbit. Two versions of the method allow station keeping both in an assigned position and in any position of the orbit. The method is fully analytical for the two-body problem and takes a simpler form for the circular assigned orbit. The suggested method may also be used in the case when constraints are imposed on the thrust direction due to specific features of the satellite stabilization mode. An application of the method to any force field is shown. Illustrative examples of satellite station keeping in a circular orbit are given. Both cases of the station keeping, i.e., in an assigned position and in an assigned orbit, are considered without and with a constraint on the thrust direction. 相似文献
995.
996.
Discusses Phase I bids to study the feasibility of using MMW radar techniques to measure the amount of ice accumulated on aircraft wings and rotors. It appeared to the authors that this sensor technology might have the potential to solve some of the problems of sensors that are currently available. A proposal and program strategy was adopted capitalizing on the prior research in the area wherever it could be found from unclassified sources 相似文献
997.
The enormous benefits of a worldwide accurate location system can only be achieved if GPS and Galileo can be made truly interoperable. The technical issues involved are relatively easy to deal with but the political and legal problems require far greater attention, with military issues and enactment of legislation the chief difficulties. These are discussed using examples, notably from road traffic law. Given that the US DoD is unlikely to cede control of GPS to the civil sector and design a new, separate system, the best solution might be to set aside part of GPS for purely civil purposes. 相似文献
998.
E Chassefière J-L Bertaux J-J Berthelier M Cabane V Ciarletti G Durry F Forget M Hamelin F Leblanc M Menvielle M Gerasimov O Korablev S Linkin G Managadze A Jambon G Manhès Ph Lognonné P Agrinier P Cartigny D Giardini T Pike W Kofman A Herique P Coll A Person F Costard Ph Sarda Ph Paillou M Chaussidon B Marty F Robert S Maurice M Blanc C d'Uston J-Ch Sabroux J-F Pineau P Rochette 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2004,34(8):1702-1709
In view to prepare Mars human exploration, it is necessary to promote and lead, at the international level, a highly interdisciplinary program, involving specialists of geochemistry, geophysics, atmospheric science, space weather, and biology. The goal of this program will be to elaborate concepts of individual instruments, then of integrated instrumental packages, able to collect exhaustive data sets of environmental parameters from future landers and rovers of Mars, and to favour the conditions of their implementation. Such a program is one of the most urgent need for preparing human exploration, in order to develop mitigation strategies aimed at ensuring the safety of human explorers, and minimizing risk for surface operations. A few main areas of investigation may be listed: particle and radiation environment, chemical composition of atmosphere, meteorology, chemical composition of dust, surface and subsurface material, water in the subsurface, physical properties of the soil, search for an hypothesized microbial activity, characterization of radio-electric properties of the Martian ionosphere. Scientists at the origin of the present paper, already involved at a high degree of responsibility in several Mars missions, and actively preparing in situ instrumentation for future landed platforms (Netlander--now cancelled, MSL-09), express their readiness to participate in both ESA/AURORA and NASA programs of Mars human exploration. They think that the formation of a Mars Environment working group at ESA, in the course of the AURORA definition phase, could act positively in favour of the program, by increasing its scientific cross-section and making it still more focused on human exploration. 相似文献
999.
This paper proposes abandoning the use of multipurpose ATE for “horizontal” support of weapon systems in favor of returning to “vertical” support. An R&D effort is proposed to develop a software “hot mock-up” system for field testing weapon system assemblies 相似文献
1000.
F D Sack J M Schwuchow T Wagner V Kern 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2001,27(5):871-876
Moss protonemata are a valuable system for studying gravitropism because both sensing and upward curvature (oriented tip growth) take place in the same cell. We review existing evidence, especially for Ceratodon purpureus, that addresses whether the mass that functions in sensing is that of amyloplasts that sediment. Recent experiments show that gravitropism can take place in media that are denser than the apical cell. This indicates that gravity sensing relies on an intracellular mass rather than that of the entire cell and provides further support for the starch-statolith hypothesis of sensing. Possible mechanisms for how amyloplast mass functions in sensing and transduction are discussed. 相似文献