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171.
N. Cornilleau-Wehrlin P. Chauveau S. Louis A. Meyer J. M. Nappa S. Perraut L. Rezeau P. Robert A. Roux C. De Villedary Y. De Conchy L. Friel C. C. Harvey D. Hubert C. Lacombe R. Manning F. Wouters F. Lefeuvre M. Parrot J. L. Pinçon B. Poirier W. Kofman Ph. Louarn 《Space Science Reviews》1997,79(1-2):107-136
The Spatio-Temporal Analysis of Field Fluctuations (STAFF) experiment is one of five experiments which together comprise the Wave Experiment Consortium (WEC). STAFF consists of a three-axis search coil magnetometer to measure magnetic fluctuations at frequencies up to 4 kHz, and a spectrum analyser to calculate in near-real time aboard the spacecraft, the complete auto- and cross-spectral matrices using the three magnetic and two electric components of the electromagnetic field. The magnetic waveform at frequencies below either 10 Hz or 180 Hz is also transmitted. The sensitivity of the search coil is adapted to the phenomena theo be studied: the values 3 × 10-3 nT Hz-1/2 and 3 × 10-5 nT Hz-1/2 are achieved respectively at 1 Hz and 100 Hz. The dynamic range of the STAFF instruments is about 96 dB in both waveform and spectral power, so as to allow the study of waves near plasma boundaries. Scientific objectives of the STAFF investigations, particularly those requiring four point measurements, are discussed. Methods by which the wave data will be characterised are described with emphasis on those specific to four-point measurements, including the use of the Field Energy Distribution function. 相似文献
172.
173.
Kleczek J. van Gent R. H. Rutten Robert J. de Munck J. C. Slottje C. Severne G. Pecker Jean-Claude Postma H. Grishchuk L. P. Niewenhuijzen H. Schuiling R. D. van Beek H. F. Reijnen G. C. M. Heidmann Jean Lemaire J. Bleeker Johan Icke V. Neéman Y. Feast M. W. de Graaff W. 《Space Science Reviews》1986,43(3-4):383-396
Space Science Reviews - 相似文献
174.
175.
Jin Ho Kang Jeffrey A. Hinkley Keith L. Gordon Sheila A. Thibeault Robert G. Bryant Juan M. Fernandez W. Keats Wilkie Héctor E. Diaz Morales Donovan E. Mcgruder Ray S. Peterson Charlotte J. Brandenburg Evin L. Hill Nina R. Arcot 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2021,67(9):2727-2735
Deployable space structures are being built from thin-walled fiber-reinforced polymer composite materials due to their high specific strength, high specific stiffness, and designed bistability. However, the inherent viscoelastic behavior of the resin matrix can cause dimensional instability when the composite is stored under strain. The extended time of stowage between assembly and deployment in space can result in performance degradation and in the worst case, mission failure. In this study, the viscoelastic properties of candidate commercial polymers consisting of difunctional and tetrafunctional epoxies and thermoplastic and thermosetting polyimides were evaluated for deployable boom structures of solar sails. Stress relaxation master curves of the candidate polymers were used to predict the relaxation that would occur in 1 year at room temperature under relatively low strains of about 0.1%. A bismaleimide (BMI) showed less stress relaxation (about 20%) than the baseline novolac epoxy (about 50%). Carbon fiber composites fabricated with the BMI resin showed a 44% improvement in resistance to relaxation compared to the baseline epoxy composite. 相似文献
176.
Sergey A. Bulat Irina A. Alekhina Dominique Marie Jean Martins Jean Robert Petit 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2011
The objective was to estimate the genuine microbial content of ice samples from refrozen water (accretion ice) from the subglacial Lake Vostok (Antarctica) buried beneath the 4-km thick East Antarctic ice sheet. The samples were extracted by heavy deep ice drilling from 3659 m below the surface. High pressure, a low carbon and chemical content, isolation, complete darkness and the probable excess of oxygen in water for millions of years characterize this extreme environment. A decontamination protocol was first applied to samples selected for the absence of cracks to remove the outer part contaminated by handling and drilling fluid. Preliminary indications showed the accretion ice samples to be almost gas free with a low impurity content. Flow cytometry showed the very low unevenly distributed biomass while repeated microscopic observations were unsuccessful. 相似文献
177.
Tony C. Slaba Steve R. Blattnig Francis F. Badavi Nicholas N. Stoffle Robert D. Rutledge Kerry T. Lee E. Neal Zapp Tsvetan P. Dachev Borislav T. Tomov 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2011
Measurements taken in Low Earth Orbit (LEO) onboard the International Space Station (ISS) and transit vehicles have been extensively used to validate radiation transport models. Primarily, such comparisons were done by integrating measured data over mission or trajectory segments so that individual comparisons to model results could be made. This approach has yielded considerable information but is limited in its ability to rigorously quantify and differentiate specific model errors or uncertainties. Further, as exploration moves beyond LEO and measured data become sparse, the uncertainty estimates derived from these validation cases will no longer be applicable. Recent improvements in the underlying numerical methods used in HZETRN have resulted in significant decreases in code run time. Therefore, the large number of comparisons required to express error as a function of a physical quantity, like cutoff rigidity, are now possible. Validation can be looked at in detail over any portion of a flight trajectory (e.g. minute by minute) such that a statistically significant number of comparisons can be made. This more rigorous approach to code validation will allow the errors caused by uncertainties in the geometry models, environmental models, and nuclear physics models to be differentiated and quantified. It will also give much better guidance for future model development. More importantly, it will allow a quantitative means of extrapolating uncertainties in LEO to free space. In this work, measured data taken onboard the ISS during solar maximum are compared to results obtained with the particle transport code HZETRN. Comparisons are made at a large number (∼77,000) of discrete time intervals, allowing error estimates to be given as a function of cutoff rigidity. It is shown that HZETRN systematically underestimates exposure quantities at high cutoff rigidity. The errors are likely associated with increased angular variation in the geomagnetic field near the equator, the lack of pion production in HZETRN, and errors in high energy nuclear physics models, and will be the focus of future work. 相似文献
178.
Peter G. Roma Steven R. Hursh Robert D. Hienz Henry H. Emurian Eric D. Gasior Zabecca S. Brinson Joseph V. Brady 《Acta Astronautica》2011,68(9-10):1581-1588
Logistical constraints during long-duration space expeditions will limit the ability of Earth-based mission control personnel to manage their astronaut crews and will thus increase the prevalence of autonomous operations. Despite this inevitability, little research exists regarding crew performance and psychosocial adaptation under such autonomous conditions. To this end, a newly-initiated study on crew management systems was conducted to assess crew performance effectiveness under rigid schedule-based management of crew activities by Mission Control versus more flexible, autonomous management of activities by the crews themselves. Nine volunteers formed three long-term crews and were extensively trained in a simulated planetary geological exploration task over the course of several months. Each crew then embarked on two separate 3–4 h missions in a counterbalanced sequence: Scheduled, in which the crews were directed by Mission Control according to a strict topographic and temporal region-searching sequence, and Autonomous, in which the well-trained crews received equivalent baseline support from Mission Control but were free to explore the planetary surface as they saw fit. Under the autonomous missions, performance in all three crews improved (more high-valued geologic samples were retrieved), subjective self-reports of negative emotional states decreased, unstructured debriefing logs contained fewer references to negative emotions and greater use of socially-referent language, and salivary cortisol output across the missions was attenuated. The present study provides evidence that crew autonomy may improve performance and help sustain if not enhance psychosocial adaptation and biobehavioral health. These controlled experimental data contribute to an emerging empirical database on crew autonomy which the international astronautics community may build upon for future research and ultimately draw upon when designing and managing missions. 相似文献
179.
Paulino-Lima IG Janot-Pacheco E Galante D Cockell C Olsson-Francis K Brucato JR Baratta GA Strazzulla G Merrigan T McCullough R Mason N Lage C 《Astrobiology》2011,11(9):875-882
In this experimental study, cells of the radiation-resistant bacterium Deinococcus radiodurans were exposed to several different sources of radiation chosen to replicate the charged particles found in the solar wind. Naked cells or cells mixed with dust grains (basalt or sandstone) differing in elemental composition were exposed to electrons, protons, and ions to determine the probability of cell survival after irradiation. Doses necessary to reduce the viability of cell population to 10% (LD(10)) were determined under different experimental conditions. The results of this study indicate that low-energy particle radiation (2-4?keV), typically present in the slow component of the solar wind, had no effect on dehydrated cells, even if exposed at fluences only reached in more than 1000 years at Sun-Earth distance (1 AU). Higher-energy ions (200?keV) found in solar flares would inactivate 90% of exposed cells after several events in less than 1 year at 1 AU. When mixed with dust grains, LD(10) increases about 10-fold. These results show that, compared to the highly deleterious effects of UV radiation, solar wind charged particles are relatively benign, and organisms protected under grains from UV radiation would also be protected from the charged particles considered in this study. 相似文献
180.
A process is well underway in which the scientific, technical and cultural information vital to our society is stored in digital form within a limited number of computer facilities. This practice is vulnerable to a variety of catastrophes which would destroy our knowledge base in addition to the losses they caused to population and structures. The Alliance to Rescue Civilization (ARC) proposes that a staffed data backup facility be constructed in a secure location, with the Moon as the site of choice. If Earth's population were destroyed entirely, the lunar sanctuary could serve to repopulate the planet. 相似文献