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661.
在GNSS接收机的实际应用中,多径是影响定位精度的主要因素之一。在车载应用条件下,多径的影响由于快速的多径信道变化而变得更加明显,车载接收机的GNSS信号接收处理部分会受到包含周围运动车辆及其自身结构影响在内的复杂多径干扰。针对接收机的各个组成部分分析了天线设计、多径估计、多频测量、传感器融合等多种可用的多径抑制方法,并根据分析和比较结果指出:信号处理方法、基于导航的方法以及传感器融合方法是实现车载接收机多径消除的首选方法。 相似文献
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LIANG Yuyang LI Jiabiao LI Shoujun RUAN Aiguo NI Jianyu YU Zhiteng ZHU Lei 《海洋学报(英文版)》2013,32(12):87-95
The morphotectonic features and their evolution of the central Southwest Indian Ridge (SWIR) are dis- cussed on the base of the high-resolution flfll-coverage bathyraetric data on the ridge between 49°-51°E. A comparative analysis of the topographic features of the axial and flank area indicates that the axial topogra- phy is alternated by the ridge and trough with en echelon pattern and evolved under a spatial-temporal mi- gration especially in 49°-50.17°E. It is probably due to the undulation at the top of the mantle asthenosphere, which is propagating with the mantle flow. From 50.17° to 50.7°E, is a topographical high terrain with a crust much thicker than the global average of the oceanic crust thickness. Its origin should be independent of the spreading mechanism of ultra-slow spreading ridges. The large numbers of volcanoes in this area indicate robust magmatic activity and may be related to the Crozet hot spot according to RMBA (residual mantle Bouguer anomaly). The different geomorphological feature between the north and south flanks of the ridge indicates an asymmetric spreading, and leading to the development of the OCC (oceanic core complex). The tectonic activity of the south frank is stronger than the north and is favorable to develop the OCC. The first found active hydrothermal vent in the SWIR at 37°47'S, 49°39'E is thought to be associated with the detach- ment fault related to the OCC. 相似文献
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ZHAO Jianhu ZHANG Hongmei John E. Hughes Clarke 《地球空间信息科学学报》2007,10(4):250-254
To overcome the shortcomings of the traditional multibeam survey and data processing, a new method is presented for the precise determination of the instantaneous height at the multibeam transducer by ... 相似文献
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海底底质分类对于海洋资源开发与利用、海洋科学研究等多方面具有重要意义。目前,多波束探测是实现大范围海底底质分类的有效手段之一,通常基于多波束反向散射强度提取角度响应(AR)特征及反向散射图像特征进行底质分类。由于特征来源较单一,分类器结构简单,往往分类精度不高。为此,本文提出了一种基于深层卷积神经网络(CNN)的多波束海底底质分类方法。除反向散射强度特征外,还利用地形特征,将特征向量转换为波形图,再输入卷积神经网络进行训练和分类。试验对比不同特征组合以及BP网络、支持向量机(SVM)、K近邻(KNN)、随机森林(RF)4种常规分类器,本文模型算法总体分类精度达到94.86%,Kappa系数为0.93,精度具有明显优势,效率也比较高。表明该方法有效利用两种数据类型所蕴含的海底底质信息,充分发挥卷积神经网络权值共享、高效率等特点,实现高分辨率海底底质分类,可对海底底质分类研究提供参考。 相似文献
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Swath mapping system processing: Bathymetry and cartography 总被引:1,自引:0,他引:1
J. F. Bourillet C. Edy F. Rambert C. Satra B. Loubrieu 《Marine Geophysical Researches》1996,18(2-4):487-506
668.
Larry A. Mayer 《Marine Geophysical Researches》2006,27(1):7-17
Over the past few years there have been remarkable and concomitant advances in sonar technology, positioning capabilities,
and computer processing power that have revolutionized the mapping, imaging and exploration of the seafloor. Future developments
must involve all aspects of the “seafloor mapping system,” including, sonars, ancillary sensors (motion sensors, positioning
systems, and sound speed sensors), platforms upon which they are mounted, and the products that are produced. Current trends
in sonar development involve the use of innovative new transducer materials and the application of sophisticated processing
techniques including focusing algorithms that dynamically compensate for the curvature of the wavefront in the nearfield and
thus allow narrower beam widths (higher lateral resolution) at close ranges . Future developments will involve “hybrid”, phase-comparison/beam-forming
sonars, the development of broad-band “chirp” multibeam sonars, and perhaps synthetic aperture multibeam sonars. The inability
to monitor the fine-scale spatial and temporal variability of the sound speed structure of the water column is often a limiting
factor in the production of accurate maps of the seafloor; improvements in this area will involve continuous monitoring devices
as well as improved ocean models and perhaps tomography. Remotely Operated Vehicles (ROV’s) and particularly Autonomous Underwater
Vehicles (AUV’s) will become more important as platforms for seafloor mapping systems. There will also be great changes in
the products produced from seafloor mapping and the processing necessary to create them. New processing algorithms are being
developed that take advantage of the density of multibeam sonar data and use statistically robust techniques to “clean” massive
data sets very rapidly. A range of approaches are being explored to use multibeam sonar bathymetry and imagery to extract
quantitative information about seafloor properties, including those relevant to fisheries habitat. The density of these data
also enable the use of interactive 3-D visualization and exploration tools specifically designed to facilitate the interpretation
and analysis of very large, complex, multi-component spatial data sets. If properly georeferenced and treated, these complex
data sets can be presented in a natural and intuitive manner that allows the simple integration and fusion of multiple components
without compromise to the quantitative aspects of the data and opens up new worlds of interactive exploration to a multitude
of users. 相似文献
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