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731.
732.
A V Shafirkin V M Petrov 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2002,30(4):995-998
This paper presents a new concept of radiation hazard assessment for spacecraft crew members during long term space missions on the basis of a generalized dosimetric function. This new dosimetric function enables a complicated nature of space radiation exposure to be reduced to the conditions of a standard irradiation. It can be obtained on the basis of mean-tissue equivalent dose values calculated for each space radiation source and transmission coefficients describing the influence of the complex spatial and temporal distribution of the absorbed dose in the cosmonaut's body on the radiobiological effects. The combination of cosmic ionizing radiation with other non-radiation nature factors in flight can also be accounted for. In terms of the generalized dose, it is possible to assess the nature and extent of lowering a crew working capacity, as well as radiation risk, both during a flight and post flight period. 相似文献
733.
J.R. Cecatto H.S. Sawant F.C.R. Fernandes V. Krishan J.A.C.F. Neri J.C. Moraes Filho 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2003,32(12):2533-2537
Type-III bursts are signatures of the electron beams accelerated during the solar flares, their observation and investigation provide information of the acceleration processes, the characteristics of the exciting agent and the acceleration site. The Brazilian Solar Spectroscope (BSS), in operation at INPE, Brazil, have recorded type-III radio bursts in decimetric range (2050–2250 MHz) with high time resolution of 20 ms. Decimetric reverse drift bursts are possibly generated in a dense loop by electron beams travelling towards the photosphere. Hence their time profiles should carry signatures of the density inhomogenities in the loop. Here the temporal and spectral characteristics of decimetric type-III bursts are presented. 相似文献
734.
The information technology (IT) revolution, combined with people's need to access information quickly, has resulted in the explosive growth of the Internet in the past decade. Ubiquitous access to the Internet has become an essential component of a mobile workforce, and multiple mechanisms are being devised to ensure seamless connectivity to corporate resources. An integrated security framework requires careful consideration of the security features of the network within an airplane. Potentially, the aircraft could consist of three kinds of networks, namely: passenger network, crew network, and control network. The security protocol implemented must ensure a proper separation of these networks and also watch for any security protocol violations. In this paper, the authors review existing aircraft data network standards, security provisioning, and security threats associated with the aircraft data networks. In addition, the authors also analyze the security threats associated with different network architectures. 相似文献
735.
N A Tikhomirova S A Ushakova N P Kovaleva I V Gribovskaya A A Tikhomirov 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2005,35(9):1589-1593
Use of halophytes (salt-tolerant vegetation), in a particular vegetable Salicornia europaea plants which are capable of utilizing NaCl in rather high concentrations, is one of possible means of NaCl incorporation into mass exchange of bioregenerative life support systems. In preliminary experiments it was shown that S. europaea plants, basically, could grow on urine pretreated with physicochemical processing and urease-enzyme decomposing of urea with the subsequent ammonia distillation. But at the same time inhibition of the growth process of the plants was observed. The purpose of the given work was to find out the influence of excessive quantities of some mineral elements contained in products of physicochemical processing of urine on the production process and NaCl accumulation by S. europaea plants. As the content of mineral salts in the human liquid wastes (urine) changed within certain limits, two variants of experimental solutions were examined. In the first variant, the concentration of mineral salts was equivalent to the minimum salt content in the urine and was: K - 1.5 g/l, P - 0.5 g/l, S - 0.5 g/l, Mg - 0.07 g/l, Ca - 0.2 g/l. In the second experimental variant, the content of mineral salts corresponded to the maximum salt content in urine and was the following: K - 3.0 g/l, P - 0.7 g/l, S - 1.2 g/l, Mg - 0.2 g/l, Ca - 0.97 g/l. As the control, the Tokarev nutrient solution containing nitrogen in the form of a urea, and the Knop nutrient solution with nitrogen in the nitrate form were used. N quantity in all four variants made up 177 mg/l. Air temperature was 24 degrees C, illumination was continuous. Light intensity was 690 micromoles/m2s of photosynthetically active radiation. NaCl concentration in solutions was 1%. Our researches showed that the dry aboveground biomass of an average plant of the first variant practically did not differ from the control and totaled 11 g. In the second variant, S. europaea productivity decreased and the dry aboveground biomass of an average plant totaled 8 g. The increase of K quantity in the experimental solutions resulted in an elevated content of the element in the plants. The increase of K uptake in the second experimental variant was accompanied by a 30-50% decrease of Na content in comparison with the other variants. Comparative Na content in the other variants was practically identical. N, Mg and P content in the control and experimental variants was also practically identical. The increase of S quantity in the second experimental variant also increased S uptake by the plants. But Ca quantity, accumulated in aboveground plants biomass in the experimental variants was lower than in the control. NaCl uptake by plants, depending on the concentration of mineral salts in the experimental solutions, ranged from 8 g (maximum salt content) up to 15 g (minimum salt content) on a plant growth area that totaled 0.032 m2. Thus, high concentrations of mineral salts simulating the content of mineral salts contained in urine did not result in a significant decrease of S. europaea productivity. The present work also considers the influence of higher light intensity concentrations on productivity and NaCl accumulation by S. europaea plants grown on experimental solutions with high salt content. 相似文献
736.
Sharaf R. Noureldin A. Osman A. El-Sheimy N. 《Aerospace and Electronic Systems Magazine, IEEE》2005,20(3):8-14
Most of the present navigation systems rely on Kalman filtering to fuse data from global positioning system (GPS) and the inertial navigation system (INS). In general, INS/GPS integration provides reliable navigation solutions by overcoming each of their shortcomings, including signal blockage for GPS and growth of position errors with time for INS. Present Kalman filtering INS/GPS integration techniques have some inadequacies related to the stochastic error models of inertial sensors, immunity to noise, and observability. This paper aims to introduce a multi-sensor system integration approach for fusing data from INS and GPS utilizing artificial neural networks (ANN). A multi-layer perceptron ANN has been recently suggested to fuse data from INS and differential GPS (DGPS). Although being able to improve the positioning accuracy, the complexity associated with both the architecture of multi-layer perceptron networks and its online training algorithms limit the real-time capabilities of this technique. This article, therefore, suggests the use of an alternative ANN architecture. This architecture is based on radial basis function (RBF) neural networks, which generally have simpler architecture and faster training procedures than multi-layer perceptron networks. The INS and GPS data are first processed using wavelet multi-resolution analysis (WRMA) before being applied to the RBF network. The WMRA is used to compare the INS and GPS position outputs at different resolution levels. The RBF-ANN module is then trained to predict the INS position errors and provide accurate positioning of the moving platform. Field-test results have demonstrated that substantial improvement in INS/GPS positioning accuracy could be obtained by applying the combined WRMA and RBF-ANN modules. 相似文献
737.
Kinsey G.S. King R.R. Edmondson K.M. Stavrides A.P. Hojun Yoon Fetzer C.M. Colter P.C. Ermer J.H. Gillanders M.S. Hebert P. Granata J.E. Karam N.H. 《Aerospace and Electronic Systems Magazine, IEEE》2003,18(3):8-10
Solar cells suitable for the space environment must combine high-efficiency, high energy density, and radiation hardness in a manufacturable design. As improvement in one performance parameter usually results in degradation in one or more of the remaining parameters, careful optimization is required to enhance overall performance. The ultra triple-junction cell developed builds upon the established success of the fully qualified improved triple-junction cell currently in production. In the ultra triple-junction cell configuration, improved robustness and efficiency after radiation exposure augment a cell design expected to deliver 28% beginning-of-life efficiency in production. 相似文献
738.
I. Yu. Skriabysheva 《Cosmic Research》2005,43(6):432-441
The main problems concerning the electric polarization of low-orbit spacecraft are considered, including the results of studying the structure of the Earth's upper ionosphere, the methods of calculating the electrophysical characteristics of construction materials for spacecraft, and the elaboration of recommendations to mitigate the negative effects due to processes of charging and discharging. 相似文献
739.
Examples of solar microwave precursors and estimates of their energetic characteristics are discussed based on spectral investigations of the preflare activity. 相似文献
740.
Cooperation between the Eveready Battery Company and the Environmental Protection Agency has already led to significant improvements for the environment. Eveready Battery Company, Inc. and the Environmental Protection Agency (EPA) have for many years worked successfully in partnership for the benefit of the environment. This article examines an example of successful cooperation and partnership between Eveready and the EPA. In the early 1980's, the environmental community began to focus its attention on the mercury in household batteries. Studies had been performed in the US, Japan and the United Kingdom regarding the potential environmental harm resulting from the disposal of household batteries containing mercury 相似文献