全文获取类型
收费全文 | 1065篇 |
免费 | 176篇 |
国内免费 | 257篇 |
专业分类
测绘学 | 101篇 |
大气科学 | 225篇 |
地球物理 | 226篇 |
地质学 | 505篇 |
海洋学 | 145篇 |
天文学 | 77篇 |
综合类 | 112篇 |
自然地理 | 107篇 |
出版年
2024年 | 10篇 |
2023年 | 21篇 |
2022年 | 35篇 |
2021年 | 44篇 |
2020年 | 30篇 |
2019年 | 34篇 |
2018年 | 50篇 |
2017年 | 50篇 |
2016年 | 43篇 |
2015年 | 58篇 |
2014年 | 59篇 |
2013年 | 55篇 |
2012年 | 45篇 |
2011年 | 63篇 |
2010年 | 57篇 |
2009年 | 56篇 |
2008年 | 43篇 |
2007年 | 47篇 |
2006年 | 45篇 |
2005年 | 37篇 |
2004年 | 43篇 |
2003年 | 44篇 |
2002年 | 67篇 |
2001年 | 87篇 |
2000年 | 47篇 |
1999年 | 53篇 |
1998年 | 35篇 |
1997年 | 32篇 |
1996年 | 34篇 |
1995年 | 34篇 |
1994年 | 36篇 |
1993年 | 21篇 |
1992年 | 17篇 |
1991年 | 14篇 |
1990年 | 18篇 |
1989年 | 7篇 |
1988年 | 8篇 |
1987年 | 10篇 |
1985年 | 4篇 |
1984年 | 1篇 |
1983年 | 2篇 |
1982年 | 1篇 |
1964年 | 1篇 |
排序方式: 共有1498条查询结果,搜索用时 31 毫秒
961.
知识创新工程重大项目在大庆油田的技术成果要览 总被引:13,自引:8,他引:5
在国家自然科学基金委员合和大庆油田的长期支持与资助下,我国陆相油储地球物理历经十余年的广泛探索,在理论认识上取得长足进步。据此,中国科学院第一批知识创新工程重大项目启动时,就以“油气勘探二次创业的前导研究”为题,列项研究。本文着重介绍在该重大项目推动下,近三年来参于大庆油气储量探到实践过程中,所摧熟的若干地球物理关键技术及软件系统功能。 相似文献
962.
YOU Hongjian LI Shukai 《地球空间信息科学学报》2003,6(3):25-31
1 IntroductionAutomaticbuildingextractionistheresearchfocustoobtainthree dimensional (3D)informationofcity .Therearetwomainapproachestoextractbuildingsbyremotesensing :oneisbasedonaerialphotosandtheotherisbasedonstereophotosordigitalsurfacemodels (DSM) .Man madebuildingsgenerallyhavesuchcharacteristicsaslimitedarea ,evidentandregularboundary ,heightdifferencebetweenbuildingandground ,etc .Somemethodsareproposedtoextractbuildingsbyusingremotesensingbasedonthesecharacteristics .Inthe 1 980s ,… 相似文献
963.
Based on data of questionnaire and field survey and two developing models of Business As Usual (BAU) and the Intensive Urbanization
(IU), this article, taking Wuwei City, a medium size city and typical oasis arid area in Gansu Province with very vulnerable
and sensitive natural environment but long history of oasis economy, as an example, evaluated the sustainability of its environment
and analyzed the scenarios of Wuwei’s household energy consumption, waste discharge in transportation industry, primary industry,
secondary industry, tertiary industry, by the integration of the systematical dynamics model Stella and Polestar language
to simulate the future development of the research area. The results showed that, first, the developing model of IU was propitious
to Wuwei City named for oasis economy and vulnerable natural environment. The strategy of "Intensive Urbanization" can change
the structure of energy utilization, and improve the efficiency of energy utilization. Second, the proportion of domestic
energy consumption will decrease with industrialization and economic development, while that of tertiary industry, secondary
industry and transportation will gradually grow up according to strategy of "Intensive Urbanization". Third, the Wuwei City
is facing a severe eco-environmental crisis under the conventional patterns of development and a better future under a sustainable
urbanization scenario, in the next 10 to 20 years. The different developing trends were clarified and the relative countermeasures
were put forward for the policy makers according to the driving forces.
Foundation item: Under the auspices of Key Program of the National Natural Science Foundation of China (No. 90102013) and
Key Innovation Sub-project of Chinese Academy of Sciences (No. KZCX1-10-07-04)
Biography: YOU Fei (1972–), male, a native of Pianguan of Shanxi Province, Ph.D., assistant professor, specialized in regional
sustainable development and ecological economy. E-mail: yofae@sina.com 相似文献
964.
应用线性回归、符号检验等数理统计方法研究了1993年完成的跨青藏高原首期GPS网39条基线的数据处理结果。通过对单基线观测中误差、重复观测基线互差及异步环闭合差的精度分析,认为由16个观测点组成的跨青藏高原GPS监测网的基线平均相对精度达0.1ppm。 相似文献
965.
三峡二期工程蓄水后的垂直形变场 总被引:16,自引:12,他引:4
根据三峡地区的数字高程模型(DEM),模拟三峡二期工程蓄水位达到135m后的水体负载,利用Farrell提出的质量负荷产生的地球形变理论,推算三峡水库水位达到135m后整个库区的垂直形变,与三峡库区GPS形变监测网获得的蓄水前后的垂直形变图像进行对比分析,结果显示:在三斗坪-巴东库段,两者中都出现了3个相同的、明显的垂直形变集中区。在三峡大坝附近,模拟结果比观测结果大8~15mm,说明坝址附近的花岗岩具有较强的刚性;而在香溪,模拟结果比观测结果要小23mm,且GPS观测到长江两岸的垂直变化差异达到22mm,说明该段地质构造的特殊性和复杂性。综合分析表明,三峡大坝坝址所在地的地质构造和地壳是稳定的。 相似文献
966.
中国大陆地壳现今运动的GPS测量结果与初步分析 总被引:9,自引:8,他引:1
利用中国大陆及周边地区 1991~ 2 0 0 0年间一系列全球定位系统 (GPS)观测资料 ,计算了 340个GPS站点的位移速率 ,得到了统一的中国大陆现今地壳运动速率场。这些站主要集中于青藏高原及其周缘的喜马拉雅、川滇、河西走廊、阿尔金、天山 ,以及华北、福建东南沿海等主要构造活动区。固定测站速率精度优于 1mm/a ,流动测站速率精度优于 3mm/a。根据GPS结果对中国大陆现今地壳运动的状况进行了分析。 相似文献
967.
Based on a lot of experiment results, it is put forward that the elastic part and plastic part of deformation of general metal material, and isotropic homogeneous, and continuous rock material follow a law—the relative law of elastic and plastic deformation. The law results from testing study and is partly proved theoretically. 相似文献
968.
长江三峡工程诱发地震监测系统中的GPS监测网及其观测结果 总被引:1,自引:1,他引:0
阐述长江三峡工程诱发地震监测系统中的 GPS监测网的设计思路 ,并介绍了该网的第一、二期观测情况及数据处理结果。认为该网无论是技术设计还是运行质量 ,均达到世界一流的先进水平 ,其站间基线长度及其分量的测定精度优于 5mm。 相似文献
969.
970.
Dynamic stiffness matrix of a poroelastic multi-layered site and its Green's functions 总被引:3,自引:1,他引:2
Few studies of wave propagation in layered saturated soils have been reported in the literature. In this paper, a general solution of the equation of wave motion in saturated soils, based on one kind of practical Biot‘s equation,was deduced by introducing wave potentials. Then exact dynamic-stiffness matrices for a poroelastic soil layer and halfspace were derived, which extended Wolf‘s theory for an elastic layered site to the case of poroelasticity, thus resolving a fundamental problem in the field of wave propagation and soil-structure interaction in a poroelastic layered soil site. By using the integral transform method, Green‘s functions of horizontal and vertical uniformly distributed loads in a poroelastic layered soil site were given. Finally, the theory was verified by numerical examples and dynamic responses by comparing three different soil sites. This study has the following advantages: all parameters in the dynamic-stiffness matrices have explicitly physical meanings and the thickness of the sub-layers does not affect the precision of the calculation which is very convenient for engineering applications. The present theory can degenerate into Wolf‘s theory and yields numerical results approaching those for an ideal elastic layered site when porosity tends to zero. 相似文献