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排序方式: 共有855条查询结果,搜索用时 109 毫秒
821.
Da-Qi Xu Guo-Qiang Ni Li-Li Jiang Yuan-Ting Shen Ting Li Shu-Le Ge Xian-Biao Shu 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2008,41(11):1800-1817
Reflectance spectra in the visible and near-infrared wavelengths provide a rapid and inexpensive means for determining the mineralogy of samples and obtaining information on chemical composition. Hydrocarbon microseepage theory establishes a cause-and-effect relation between oil and gas reservoirs and some special surface anomalies, which mainly include surface hydrocarbon microseepage and related alterations. Therefore, we can explore for oil, gas by determining reflectance spectra of surface anomalies. This idea has been applied to the R&D project of exploring for natural gas in Qinghai province of China using NASA EO-1 satellite with the Hyperion sensor (June 2005 to June 2006). In this project, in order to improve the accuracy of exploration targets of natural gas mapped in the field studied, an integrated practical system of exploration of oil and gas was built by the analysis of not only hyperspectral remote sensing data but also data provided from field work. In this paper, our efforts were focused on the analysis of the 799 reflectance spectra provided from the field work. In order to properly define the typical form of hydrocarbon microseepage with spectroscopy and fulfill the data analysis, it was necessary to build a spectral model. In this spectral model the most important features of hydrocarbon microseepage in the surface of our study area, i.e., diagnostic spectral macroscopic features and diagnostic spectral absorption features, were proposed and extracted, respectively. The distribution of coexisting anomalies, which results from both alteration minerals and hydrocarbons, is estimated by the diagnostic macroscopic features mainly using Spectral Angle Mapper (SAM) classifier. On the other hand, the diagnostic absorption features of two main absorption bands presented abundant local information, based on deep analysis of which, we are able to map the anomalies of alteration minerals and hydrocarbons, respectively. Additionally, a general framework of analysis and key classification algorithms applied to the Hyperion data have been introduced briefly. In our work, three exploration targets of natural gas were identified from the study area which covers 2100 km2. In the three exploration targets, three wildcats have been drilled by China National Petroleum Corporation (CNPC) since July 2006, and all the three wells have been proven some industrial reserves. 相似文献
822.
O.S. Oyekola Akin Ojo 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2008,41(9):1500-1509
The variability of the F2-layer even during magnetically quiet times are fairly complex owing to the effects of plasma transport. The vertical E × B drift velocities (estimated from simplified electron density continuity equation) were used to investigate the seasonal effects of the vertical ion drifts on the bottomside daytime ionospheric parameters over an equatorial latitude in West Africa, Ibadan, Nigeria (Geographic: 7.4°N, 3.9°E, dip angle: 6°S) using 1 year of ionsonde data during International Geophysical Year (IGY) of 1958, that correspond to a period of high solar activity for quiet conditions. The variation patterns between the changes of the vertical ion drifts and the ionospheric F2-layer parameters, especially; foF2 and hmF2 are seen remarkable. On the other hand, we observed strong anti-correlation between vertical drift velocities and h′F in all the seasons. We found no clear trend between NmF2 and hmF2 variations. The yearly average value of upward daytime drift at 300 km altitude was a little less than the generally reported magnitude of 20 ms−1 for equatorial F-region in published literature, and the largest upward velocity was roughly 32 ms−1. Our results indicate that vertical plasma drifts; ionospheric F2-layer peak height, and the critical frequency of F2-layer appear to be somewhat interconnected. 相似文献
823.
824.
针对耦合差分器件的散射参数测量,提出了一种使用对称反射标准件的混合模式TRL(Through-Reflect-Line)校准算法.根据过渡结构的多模散射矩阵元素之间的相位关系和散射矩阵的广义互易性,消除符号模糊性并得到过渡结构的混合模式转移矩阵.该算法要求的校准标准件类似于传统的单模式TRL算法,不需要非对称结构的反射标准件产生模式转换项.利用全波仿真方法得到了包含过渡结构的校准标准件和待测件的单模散射矩阵,并使用该算法对仿真数据进行处理,得到不包含过渡结构的待测件的混合模散射矩阵.将校准结果与不包含过渡结构的待测件的全波仿真结果进行比较,其一致性表明了该算法可有效地校准线性平衡器件. 相似文献
825.
基于粒子群算法的切削参数优化及其约束处理 总被引:1,自引:0,他引:1
切削参数优化问题通常是多约束、非线性的,通过对其目标函数进行分析,发现这类问题的最优解通常位于可行域边界上.针对该问题的求解,在约束处理方法上引入了非固定多段映射罚函数法和半可行域概念,并考虑到绝对半可行域宽度导致的不同约束条件难以同步得到满足问题,提出了相对半可行域设置方法,即将半可行域宽度与各约束许用值的相对误差相对应,应用于粒子群算法实现了切削参数优化,并通过实例计算对所提出的方法进行了验证. 相似文献
826.
Sudip Bhattacharyya 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2010
Measurement of at least three independent parameters, for example, mass, radius and spin frequency, of a neutron star is probably the only way to understand the nature of its supranuclear core matter. Such a measurement is extremely difficult because of various systematic uncertainties. The lack of knowledge of several system parameter values gives rise to such systematics. Low mass X-ray binaries, which contain neutron stars, provide a number of methods to constrain the stellar parameters. Joint application of these methods has a great potential to significantly reduce the systematic uncertainties, and hence to measure three independent neutron star parameters accurately. Here, we review the methods based on: (1) thermonuclear X-ray bursts; (2) accretion-powered millisecond-period pulsations; (3) kilohertz quasi-periodic oscillations; (4) broad relativistic iron lines; (5) quiescent emissions; and (6) binary orbital motions. 相似文献
827.
828.
系列图象分析和三维目标参数提取技术 总被引:3,自引:0,他引:3
系列图象分析是很有前途的崭新学科。本文把分析技术分成光流分析法和几何分析法两大类。在论述两类分析技术的基础上,重点研究了如何检测流速、提取三维几何参数和运动参数以及如何恢复物体的结构,也涉及到三维目标识别问题。文内比较详细地研究了线性的算法,并且提供了已经实现过的某些实验方案和结果。还提出了新方案,即“通用系列图象分析和三维目标参数自动探测装置”。最后,对发展趋势作出了估计,认为系列图象分析技术正朝着理论的完备性和应用的现实性推进。 相似文献
829.
830.
针对迭代制导完成后入轨参数或终端程序角修正问题,研究一种基于模型参考的自适应预测补偿迭代制导算法在运载火箭上的应用。该算法在经典迭代制导算法的基础上,根据预测的迭代终端程序角和飞行视加速度的参考模型,对关机点参数进行补偿,依据补偿后的终端指标重新规划飞行轨迹,进而得出满足入轨参数或终端程序角偏差修正的制导指令,提升迭代制导对入轨参数偏差或终端程序角的修正能力。此外,阐述了经典迭代制导的基本算法,概括了自适应预测补偿迭代制导算法的基本原理,并以大推力直接入轨、终端程序角大偏差以及满足终端程序角约束为例,给出相应工况的自适应预测补偿的迭代制导算法。仿真结果表明:该算法对入轨参数和终端程序角偏差具有一定的修正能力。 相似文献