全文获取类型
收费全文 | 834篇 |
免费 | 63篇 |
国内免费 | 26篇 |
专业分类
测绘学 | 409篇 |
大气科学 | 17篇 |
地球物理 | 70篇 |
地质学 | 141篇 |
海洋学 | 39篇 |
天文学 | 17篇 |
综合类 | 57篇 |
自然地理 | 173篇 |
出版年
2024年 | 4篇 |
2023年 | 10篇 |
2022年 | 14篇 |
2021年 | 32篇 |
2020年 | 15篇 |
2019年 | 27篇 |
2018年 | 21篇 |
2017年 | 36篇 |
2016年 | 45篇 |
2015年 | 38篇 |
2014年 | 43篇 |
2013年 | 109篇 |
2012年 | 57篇 |
2011年 | 46篇 |
2010年 | 44篇 |
2009年 | 22篇 |
2008年 | 36篇 |
2007年 | 41篇 |
2006年 | 30篇 |
2005年 | 34篇 |
2004年 | 19篇 |
2003年 | 24篇 |
2002年 | 20篇 |
2001年 | 23篇 |
2000年 | 18篇 |
1999年 | 19篇 |
1998年 | 7篇 |
1997年 | 14篇 |
1996年 | 11篇 |
1995年 | 5篇 |
1994年 | 7篇 |
1993年 | 7篇 |
1992年 | 6篇 |
1991年 | 7篇 |
1990年 | 2篇 |
1989年 | 5篇 |
1988年 | 6篇 |
1987年 | 4篇 |
1986年 | 6篇 |
1985年 | 2篇 |
1984年 | 5篇 |
1983年 | 1篇 |
1977年 | 1篇 |
排序方式: 共有923条查询结果,搜索用时 15 毫秒
81.
湖南省传统聚落景观基因组图谱的空间形态与结构特征 总被引:2,自引:2,他引:2
传统聚落保有显著的价值,深入开展相关研究有利于促进经济社会的可持续发展和新型城镇化战略的实施。结合传统聚落景观基因组图谱,本文探讨了湖南省传统聚落景观的空间形态与结构特征。首先,根据传统聚落景观基因组的空间排列特征将湖南省传统聚落的空间形态归结为向心圆环式、扇形扩张式、多向扩张式、条带式、离散式和组团式等5种基本类型,并进一步归纳了各种形态类型的特征。其次,运用空间句法理论,通过构建传统聚落景观基因组的空间轴线模型,系统地剖析了湖南省传统聚落景观的空间结构特征,发现湖南省传统聚落的空间结构具有对称和平行等鲜明的几何特征,存在着“界域”和“街—巷—码头”等典型结构,还具有典型的风水意象特征。因此,结合传统聚落景观基因组图谱从地理学的视角揭示传统聚落的地学特征,有利于完善传统聚落景观基因理论,深化对传统聚落的认识,促进相关保护工作。 相似文献
82.
In this paper, we discuss the development of electronic atlas in China, with focus on the issues of visualization. We particularly categorise this development into four periods, and then analyse the characters in each period and discuss the visualization issues. The four periods are highlighted: 1) Infant period (<1990) characterized as computer assisted mapping with products of screen maps; 2) Starting period (1991-1995) characterized as object-oriented mapping with products of interactive maps/atlases; 3) Advancing period (1996-2000) characterized as integrated mapping with products of multimedia cartographic maps; 4) New era (> 2001) characterized as web mapping and adaptive map design with products of Internet maps and atlas as well as adaptive maps. It is obvious that the development follows the logical way from static to dynamic, and even real time visualization, from single user to multiple users, from presentation to exploration for effective communication and knowledge construction. Current research and development projects are focused on customisation of atlas information systems for real-time tasks, Internet operability, small displays and mobile environments. The major challenges involved in each of such customisation processes are identified and commented in relation to the further development of visualization. 相似文献
83.
84.
Marcelo Roberto Barbosa Mario Guimarães Buratto Leonardo Santana de Oliveira Dias João Paulo Carvalho Raivel Flavio Lobos Martins 《International journal of geographical information science》2013,27(6):873-901
To increase the monitoring potential of forest fires, an alert classification methodology using satellite-mapped hotspots has been established to help forest managers in the prioritization of which hotspot to be verified in the field, thus potentially improving the distribution of fire-fighting resources. A computer application was developed based on web-distributed geographical information technology whose main function is to interact automatically generated satellite hotspots and risk areas indicated in fire-susceptibility maps and classify them into five alert levels. The location of the hotspots is available continuously every 4 h, and a susceptibility map is produced daily through map algebra algorithm, which uses static (topography, vegetation and land use) and dynamic (weather) variables. Every process runs through automated geoprocessing routines. The methodology was tested during the dry period of 2007 in the Carajás National Forest, in the Brazilian Amazon, within an area of 400,000 ha. It is a critical area constantly threatened by fires caused by invasions and deforestation owing to intense agribusiness advances and mining activities in its surroundings. This situation results in observations of many hotspots inside the study area for the same day and almost the same time period, in places of extreme opposites, demanding complex rapid analysis and hindering the decision of the displacement of fire-fighting teams. Further, a major mining company operates within the National Forest area, maintaining actions of protection as part of its environmental mining license. Results are presented under three aspects: (i) the credibility of the daily susceptibility map (algorithm), which showed strong correlation between areas of greatest risks and the confirmed forest fires; (ii) the reliability of hotspots (alert levels), confirming 71% of fires; (iii) accuracy in the decision of which hotspot to be checked, which revealed the same number of verifications at different alert levels, 82% confirmed alert 5 hotspots (maximum) and only 50% from alert 1 (minimum), resulting in faster fire-fighting actions, minimizing burned areas and, in some cases, allowing fire control before its spreading. Therefore, the methodology demonstrated that GIS routines are able to determine the relationship between a reality-based, interpreted susceptibility map of the area and satellite-generated hotspots, highlighting the ones of highest hazard level through the alert classification, becoming an important tool to help decisions from the fire-control center, especially for high-risk regions. The methodology may be extrapolated to other forested areas. 相似文献
85.
The effect of scattering in surface wave tomography 总被引:6,自引:1,他引:6
Jesper Spetzler Jeannot Trampert Roel Snieder 《Geophysical Journal International》2002,149(3):755-767
86.
87.
《GFF》2012,134(3):253-269
Abstract The fracturing of the crust in southern Sweden has been investigated by means of topographical data, presented by the National Land Survey as the Relief Map of Sweden. Rock blocks of 3 different orders are presented in maps. On the basis of these maps, four regions have been distinguished, based on the character of the fracture pattern; southeastern Sweden with fairly regular pseudo-orthogonal patterns, southwestern Sweden with lensoidal patterns, the central belt with a penetrative north-southerly trend, and Skåne in the Fennoscandian Border Zone. Southeastern Sweden is dominated by a N10W grain, while the other regions, west of a line c. 30 km east of Lake Vättern, have a N20E grain. Rock block boundaries have been separated into 6 sets, according to their orientation. All sets show an arrangement of fractures into megalenses. The rate of the relative uplift of Fennoscandia is symmetric across southern Sweden, although the seismi-city is mainly confined to the western part. This implies that the differential movements in southeastern Sweden are aseismic, suggesting that the fracture pattern can accommodate applied strain. In southwestern Sweden, however, slip cannot occur along displaced curved fractures. The occurrence here of a late pseudo-orthogonal pattern in seismic areas, implies that new fractures form, if the crust cannot deform along existing fractures. 相似文献
88.
89.
利用Rayleigh波群速度资料反演得到中国大陆及其临近海域的(70°E-145°E,10°N-55°N)15-120s周期的群速度分布图像. 塔里木盆地在15s处清楚地显示为低速,在16-33s左右没有显示,但在36-5s显示为高速,说明塔里木盆地有较深的根. 青藏高原块体是44s至120s图像中最为突出的低速块体,南面与印度板块的分界线以及与北面的塔里木盆地、柴达木盆地的分界清晰,其块体中西部的速度低于东部. 泰国清迈附近存在一尺度为1000km左右的低速带,可能是青藏高原块体的物质向东南方向迁移造成上地幔物质上涌的结果. 南北地震带表现为强烈的速度梯度带,西面为低速,东面为高速. 中国南海的中央、日本海中央、菲律宾海表现为海洋性地壳. 菲律宾海的图像与地形及地震带完全吻合. 环绕菲律宾海及日本海存在400km左右宽的低速带,可能是岩浆活动带. 相似文献
90.
交通不便、植被覆盖茂盛、地形险峻等因素导致无居民海岛开展综合地质调查研究极其困难。为了补充登岛调查人员不足,降低安全风险,提高作业效率,本文探索无人机倾斜摄影技术在无居民海岛综合地质调查中的应用。利用飞马D20无人机搭载5镜头D-OP3000模块,快速获取海岛低空(190 m)、多角度、高精度影像数据,影像平均地面分辨率优于0.03 m。对获取的影像数据应用Smart3D软件生成数字正射影像(DOM)、构建海岛实景三维模型,并基于实景三维模型实现对海岛进行全方位观测,提升对海岛的宏观认识。通过对数字正射影像及海岛实景三维模型进行综合研究,结合实地调查,获取了蜈支洲岛线性断裂特征,探讨了其成因;提取了蜈支洲岛土地开发利用现状信息;识别出岛岸崩塌、断裂活动及岛滩侵蚀等地质灾害隐患点15处,并提出了防治建议,为海岛开发利用、生态保护修复、地质灾害治理及海岛综合管理提供了科学依据。 相似文献