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141.
本文选用 10× 15× 0 .4 4 m m3双抛 L a Al O3衬底上外延生长的优质双面钇系高温超导 (HTSC)薄膜的Yba2 Cu3O7(YBCO) ,设计并制作了结构紧凑的高温超导发夹线微波窄带滤波器。该滤波器工作温度在 90 K以下 ,77K时指标为 :中心频率 9.4 8GHz,3d B相对带宽 1.1% ,带内最小插损 0 .36 d B,带外抑制大于 4 5 d B。另外 ,本文还介绍了高温超导滤波器的精确设计方法 ,并对高温超导滤波器的功率容载、制作等问题进行了讨论 ,同时还研制了具有实用意义的全密封高温超导滤波器外壳 ,仅需液氮制冷即可进入工作状态 ,输入、输出采用 SMA密封接头。 相似文献
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Hongping Zhang Peiliang Xu Wenhui Han Maorong Ge Chuang Shi 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2013
Currently, ground-based Global Navigation Satellite System (GNSS) stations of the International GNSS Service (IGS) are distributed unevenly around the world. Most of them are located on the mainland, while only a small part of them are scattered on some islands in the oceans. As a consequence, many unreasonable zero values (in fact negative values) appear in Vertical Total Electron Content (VTEC) of European Space Agency (ESA) and Center for Orbit Determination in Europe (CODE) IONEX products, especially in 2008 and 2009 when the solar activities were rather quiet. To improve this situation, we directly implement non-negative physical constraints of ionosphere for global ionosphere maps (GIM) with spherical harmonic functions. Mathematically, we propose an inequality-constrained least squares method by imposing non-negative inequality constraints in the areas where negative VTEC values may occur to reconstruct GIM models. We then apply the new method to process the IGS data in 2008. The results have shown that the new algorithm efficiently eliminates the unwanted behavior of negative VTEC values, which could otherwise often be seen in the current CODE and ESA GIM products in both middle and high latitude areas of the Southern Hemisphere (45°S∼90°S) and the Northern Hemisphere (50°N∼90°N). About 64% of GPS receivers’ DCBs have been significantly improved. Finally, we compare the GIM results between with and without the inequality constraints, which has clearly shown that the GIM result with inequality constraints is significantly better than that without the inequality constraints. The inequality-constrained GIM result is also highly consistent with the final IGS products in terms of root mean squared (RMS) and mean VTEC. 相似文献
144.
针对目前膜生物反应器运行过程中膜易污染的问题,研制了一种新型的双功能陶瓷膜生物反应器.该生物反应器的主要特点是采用一种具有双重功能的陶瓷膜作为生物反应器的主要元件,陶瓷膜可以交替地进行曝气和过滤,将膜的在线反冲清洗和生物反应器的供氧曝气结合在一起.考察了不同运行条件下该反应器对COD、氨氮的去除效果.对陶瓷膜的充氧能力进行了实验,测得小孔陶瓷膜、大孔陶瓷膜、砂型曝气头的氧传递系数分别为:0.2315min-1,0.1587min-1,0.0991min-1. 相似文献
145.
Qile Zhao Jing Guo Zhigang Hu Chuang Shi Jingnan Liu Hua Cai Xianglin Liu 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2011
The GRACE (Gravity Recovery And Climate Experiment) monthly gravity models have been independently produced and published by several research institutions, such as Center for Space Research (CSR), GeoForschungsZentrum (GFZ), Jet Propulsion Laboratory (JPL), Centre National d’Etudes Spatiales (CNES) and Delft Institute of Earth Observation and Space Systems (DEOS). According to their processing standards, above institutions use the traditional variational approach except that the DEOS exploits the acceleration approach. The background force models employed are rather similar. The produced gravity field models generally agree with one another in the spatial pattern. However, there are some discrepancies in the gravity signal amplitude between solutions produced by different institutions. In particular, 10%–30% signal amplitude differences in some river basins can be observed. In this paper, we implemented a variant of the traditional variational approach and computed two sets of monthly gravity field solutions using the data from January 2005 to December 2006. The input data are K-band range-rates (KBRR) and kinematic orbits of GRACE satellites. The main difference in the production of our two types of models is how to deal with nuisance parameters. This type of parameters is necessary to absorb low-frequency errors in the data, which are mainly the aliasing and instrument errors. One way is to remove the nuisance parameters before estimating the geopotential coefficients, called NPARB approach in the paper. The other way is to estimate the nuisance parameters and geopotential coefficients simultaneously, called NPESS approach. These two types of solutions mainly differ in geopotential coefficients from degree 2 to 5. This can be explained by the fact that the nuisance parameters and the gravity field coefficients are highly correlated, particularly at low degrees. We compare these solutions with the official and published ones by means of spectral analysis. It is found that our solutions are, in general, consistent with others in the spatial pattern. The water storage variations of the Amazon, Chari and Ganges river basins have also been computed. The variations computed with the NPARB approach are closer to those produced by JPL and DEOS solutions, while the variations produced with the NPESS approach are in good agreement with those produced by the CSR and GFZ solutions. A simulation study is implemented with considering realistic noise and low-frequency error. The two approaches are used to recover the true model. The NPESS solution appears closer to the true one. Therefore we are inclined to estimate the nuisance parameters simultaneously with the geopential coefficients. 相似文献
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