全文获取类型
收费全文 | 1336篇 |
免费 | 75篇 |
国内免费 | 87篇 |
专业分类
测绘学 | 959篇 |
大气科学 | 14篇 |
地球物理 | 119篇 |
地质学 | 95篇 |
海洋学 | 154篇 |
天文学 | 4篇 |
综合类 | 110篇 |
自然地理 | 43篇 |
出版年
2024年 | 1篇 |
2023年 | 16篇 |
2022年 | 30篇 |
2021年 | 50篇 |
2020年 | 59篇 |
2019年 | 67篇 |
2018年 | 38篇 |
2017年 | 89篇 |
2016年 | 81篇 |
2015年 | 87篇 |
2014年 | 87篇 |
2013年 | 115篇 |
2012年 | 86篇 |
2011年 | 76篇 |
2010年 | 70篇 |
2009年 | 66篇 |
2008年 | 81篇 |
2007年 | 93篇 |
2006年 | 55篇 |
2005年 | 44篇 |
2004年 | 46篇 |
2003年 | 32篇 |
2002年 | 35篇 |
2001年 | 19篇 |
2000年 | 21篇 |
1999年 | 20篇 |
1998年 | 13篇 |
1997年 | 13篇 |
1996年 | 2篇 |
1995年 | 2篇 |
1993年 | 1篇 |
1992年 | 3篇 |
排序方式: 共有1498条查询结果,搜索用时 15 毫秒
251.
252.
针对非下采样Contourlet变换(NSCT)在处理噪声影像中具有的优势,以及同极化SAR图像(HH、VV)之间的相关性与互补性,本文实验了一种基于非下采样Contourlet变换的极化图像融合方法。该方法首先对每个极化图像进行多尺度、多方向分解,然后对不同分解子带系数分别采用有利于斑点噪声去除和信息增强的融合规则进行融合,最终通过NSCT反变换得到融合图像。通过信息熵、相关系数以及等效视数等指标的评价,验证了该方法可以有效地实现信息增强,同时该方法也在一定程度上降低了斑点噪声的负面影响。 相似文献
253.
254.
利用地面激光扫描仪具有的数据获取速度快、精度高、实时性强、能全天候工作等优点,在快速获取三维点云的基础上,通过点云自动拼接、Hausdorff距离检测不同时期建筑物的三维模型变化,并改进了检测算法,提高了算法的执行效率。通过拟合平面构建Delaunay三角网求解变化区域的面积来评估灾害对建筑物的破坏程度,从而为灾害应急响应以及保险理赔等提供了可靠的决策依据。 相似文献
255.
使用数学形态学的"膨胀算子"对影像进行预处理,提出了一种改进的基于高斯拉普拉斯算子的面状特征提取和细化方法,并利用边界代数快速标注边界封闭的面状特征。在提取面状特征的基础上,利用奇异值分解算法,实现了基于面状质心的遥感影像匹配,进而完成精确配准。实验结果表明,与传统方法相比,此方法在速度与准确度上具有明显优势。 相似文献
256.
土地登记档案在基层土地管理活动中发挥着重要作用,是地籍档案中的重中之重。做好土地登记档案的规范化管理及有效开发利用,是档案管理工作的基础,也是国土资源管理工作的基础。工作中需制订合理的土地登记档案归档制度、规范档案管理工作流程,并积极开展档案的公开查询、做好档案宣传、汇编等工作。 相似文献
257.
258.
259.
S. Salvi S. Stramondo M. Cocco M. Tesauro I. Hunstad M. Anzidei P. Briole P. Baldi E. Sansosti G. Fornaro R. Lanari F. Doumaz A. Pesci A. Galvani 《Journal of Seismology》2000,4(4):479-499
In this study we analyse coseismic GPS displacements and DInSAR data to constrain a dislocation model for the three largest earthquakes of the 1997 Umbria-Marche seismic sequence. The first two events, which occurred on September 26 at 00:33 GMT (Mw 5.7) and 09:40 GMT (Mw 6.0) respectively, are investigated using both GPS displacements and DInSAR interferograms. We discuss and compare the results of previous studies which separately modeled a smaller subset of geodetic data. We provide a dislocation model for these two earthquakes which fits well both GPS and DInSAR data and agrees with the results of seismological and geological investigations. The first event consists of a unilateral rupture towards the southeast with a uniform dislocation. The strike, rake and dip angles are those resulting from the CMT solution. The second event consists of an unilateral rupture towards the northwest and a variable slip distribution on the fault plane. The strike and the rake are consistent with the CMT solution, but the dip angle has been slightly modified to improve the simultaneous fit of GPS and DInSAR data. While the second rupture (09:40 GMT) arrived very close to the surface, the fit to geodetic data shows that the first rupture (00:33 GMT) is deeper (2 km), despite the more evident surface geological effects. The analysis of new SAR interferograms allows the identification of a 5–6 cm additional displacement caused by the October 3 (Mw 5.2) and 6 (Mw 5.4) seismic events.We use data from a new DInSAR interferogram to model the displacement field of the Sellano earthquake of October 14, 1997. For this event significant GPS measurements were not available. We tested two different fault plane geometries: a blind, planar fault (top depth = 2.4 km), and a curved (listric) fault reaching the surface. The two models provide a generally similar fit to the data, and show that most of the slip was released at depths greater than 2.4 km along a gently dipping (40°–45°) fault surface. They also show that a unilateral rupture does not allow fitting the interferometric fringes since there is evident surface deformation to the northwest of the hypocenter. Moreover, we suggest that the concentration of high residuals in the southern part of our uniform slip model may in fact indicate a certain slip variability in this area.We conclude that, despite the moderate magnitudes and the lack of significant surface faulting, the space geodetic data allowed to constrain dislocation models giving new insights in the rupture process of the three largest events of the sequence. 相似文献
260.
I~IOXThe image technology of the synthetic aperture radar (SAR) is one of most important advances in spaceberne microwave remote sensing (Larson et al., 1976). It has extensive application in the ocean remote sensing, such as inversion of the sea subdue winds and currentS, reconstruction of underwater hatom topography and so on. Owing tO the high conductivity of sea water, an electromagnetic wave actually cannot penetrate into the sea water, with extremely smallPenetration depth (abbot 1 c… 相似文献