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601.
Caitlin J. Ahrens William M. Grundy Kathleen E. Mandt Paul D. Cooper Orkan M. Umurhan Vincent F. Chevrier 《Space Science Reviews》2018,214(8):130
This review of Pluto laboratory research presents some of the recent advancements and motivations in our understanding enabled by experimental simulations, the need for experiments to facilitate models, and predictions for future laboratory work. The spacecraft New Horizons at Pluto has given a large amount of scientific data already rising to preliminary results, spanning from the geology to the atmosphere. Different ice mixtures have now been detected, with the main components being nitrogen, methane, and carbon monoxide. Varying geology and atmospheric hazes, however, gives us several questions that need to be addressed to further our understanding. Our review summarizes the complexity of Pluto, the motivations and importance of laboratory simulations critical to understanding the low temperature and pressure environments of icy bodies such as Pluto, and the variability of instrumentation, challenges for research, and how simulations and modeling are complimentary. 相似文献
602.
This paper focuses on the advanced Forward Error Correction(FEC) based on LowDensity Parity-Check(LDPC) codes for remote control and data transmission of Aeronautic and Astronautic Vehicles(AAV). It shows that the nontransparent LDPC codes with odd row weights are able to resist phase inversion with a small computational overhead. To the best of our knowledge, it is the first time to use FEC to resist phase inversion. Then, a high hardware-efficient FEC design for AAV, which is capable of correcting random errors as well as phase inversion, is proposed based on circulant decomposition with circulant size of 2s. Such a(4096, 2048) LDPC code has been adopted in a data transmission system due to its excellent error performance and hardware efficiency. 相似文献
603.
Kai Shen K. A. Neusypin M. S. Selezneva A. V. Proletarskii 《Russian Aeronautics (Iz VUZ)》2018,61(2):279-286
High-precision measurement systems of modern aircraft are studied in this paper. A measurement system with correction in the structure of inertial navigation system is introduced for highprecision aircraft. In the correction algorithms, a linear error model of the navigation system is usually used. With the aim of increasing the accuracy of the navigation system, we propose a nonlinear correction algorithm based on the state dependent coefficient representation of the nonlinear model. 相似文献
604.
Andrea Kunder Elena Valenti Massimo Dall’Ora Pawel Pietrukowicz Chris Sneden Giuseppe Bono Vittorio F. Braga Ivan Ferraro Giuliana Fiorentino Giacinto Iannicola Marcella Marconi Clara E. Martínez-Vázquez Matteo Monelli Ilaria Musella Vincenzo Ripepi Maurizio Salaris Peter B. Stetson 《Space Science Reviews》2018,214(5):90
Here we review the efforts of a number of recent results that use old tracers to understand the build up of the Galaxy. Details that lead directly to using these old tracers to measure distances are discussed. We concentrate on the following: (1) the structure and evolution of the Galactic bulge and inner Galaxy constrained from the dynamics of individual stars residing therein; (2) the spatial structure of the old Galactic bulge through photometric observations of RR Lyrae-type stars; (3) the three-dimensional structure, stellar density, mass, chemical composition, and age of the Milky Way bulge as traced by its old stellar populations; (4) an overview of RR Lyrae stars known in the ultra-faint dwarfs and their relation to the Galactic halo; and (5) different approaches for estimating absolute and relative cluster ages. 相似文献
605.
Lifeng Qin Shuangsheng GuoWeidang Ai Yongkang TangQuanyong Cheng Guang Chen 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2013
Growing plants can be used to clean waste water in bioregenerative life support system (BLSS). However, NaCl contained in the human urine always restricts plant growth and further reduces the degree of mass cycle closure of the system (i.e. salt stress). This work determined the effect of NaCl stress on physiological characteristics of plants for the life support system. Amaranth (Amaranthus tricolor L. var. Huahong) and leaf lettuce (Lactuca sativa L. var. Luoma) were cultivated at nutrient solutions with different NaCl contents (0, 1000, 5000 and 10,000 ppm, respectively) for 10 to 18 days after planted in the Controlled Ecological Life Support System Experimental Facility in China. Results showed that the two plants have different responses to the salt stress. The amaranth showed higher salt-tolerance with NaCl stress. If NaCl content in the solution is below 5000 ppm, the salt stress effect is insignificant on above-ground biomass output, leaf photosynthesis rate, Fv/Fm, photosynthesis pigment contents, activities of antioxidant enzymes, and inducing lipid peroxidation. On the other hand, the lettuce is sensitive to NaCl which significantly decreases those indices of growth and physiology. Notably, the lettuce remains high productivity of edible biomass in low NaCl stress, although its salt-tolerant limitation is lower than amaranth. Therefore, we recommended that amaranth could be cultivated under a higher NaCl stress condition (<5000 ppm) for NaCl recycle while lettuce should be under a lower NaCl stress (<1000 ppm) for water cleaning in future BLSS. 相似文献
606.
Shuhui Li Junhuan Peng Weichao Xu Kun Qin 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2013
A 10.7 cm solar radio flux F10.7, geomagnetic planetary equivalent amplitude (Ap index), and period variations were considered in this paper to construct a linear model for daily averaged ionospheric total electron content (TEC). The correlation coefficient of the modeled results and International GNSS Service (IGS) observables was approximately 0.97, which implied that the model could accurately reflect the realistic variation characteristics of the daily averaged TEC. The influences of the different factors on TEC and its characteristics at different latitudes were examined with this model. Results show that solar activity, annual and semiannual cycles are the three most important factors that affect daily averaged TEC. Solar activity is the primary determinant of TEC during periods with high solar activity, whereas periodic factors primarily contribute to TEC during periods with minimum solar activity. The extent of the influences of the different factors on TEC exhibits obvious differences at varying latitudes. The magnitude of the semiannual variation becomes less significant with the increase in latitude. Furthermore, a geomagnetic storm causes an increase in TEC at low latitudes and a decrease at high latitudes. 相似文献
607.
Hasan Ranjous 《Russian Aeronautics (Iz VUZ)》2011,54(2):197-203
Some characteristic zones of parts shaped by the multi-pass rotary drawing are presented. Also given are the analytical relations
determining deformations in two directions within these zones and recommendations useful to calculate the values of stresses. 相似文献
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