全文获取类型
收费全文 | 2480篇 |
免费 | 519篇 |
国内免费 | 600篇 |
专业分类
测绘学 | 226篇 |
大气科学 | 421篇 |
地球物理 | 448篇 |
地质学 | 1499篇 |
海洋学 | 345篇 |
天文学 | 117篇 |
综合类 | 205篇 |
自然地理 | 338篇 |
出版年
2024年 | 3篇 |
2023年 | 31篇 |
2022年 | 99篇 |
2021年 | 102篇 |
2020年 | 82篇 |
2019年 | 103篇 |
2018年 | 125篇 |
2017年 | 110篇 |
2016年 | 93篇 |
2015年 | 113篇 |
2014年 | 99篇 |
2013年 | 131篇 |
2012年 | 115篇 |
2011年 | 145篇 |
2010年 | 178篇 |
2009年 | 156篇 |
2008年 | 133篇 |
2007年 | 129篇 |
2006年 | 124篇 |
2005年 | 90篇 |
2004年 | 109篇 |
2003年 | 105篇 |
2002年 | 142篇 |
2001年 | 128篇 |
2000年 | 119篇 |
1999年 | 129篇 |
1998年 | 108篇 |
1997年 | 83篇 |
1996年 | 100篇 |
1995年 | 86篇 |
1994年 | 74篇 |
1993年 | 53篇 |
1992年 | 46篇 |
1991年 | 33篇 |
1990年 | 35篇 |
1989年 | 21篇 |
1988年 | 13篇 |
1987年 | 7篇 |
1986年 | 9篇 |
1985年 | 9篇 |
1984年 | 7篇 |
1983年 | 8篇 |
1982年 | 7篇 |
1981年 | 1篇 |
1980年 | 2篇 |
1979年 | 1篇 |
1977年 | 2篇 |
1958年 | 1篇 |
排序方式: 共有3599条查询结果,搜索用时 15 毫秒
111.
Mesozoic-Cenozoic tectonic transition in Kuqa Depression-Tianshan, Northwest China: Evidence from sandstone detrital and geochemical records 总被引:2,自引:0,他引:2
LI Zhong GUO Hong WANG Daoxuan & LIN Wei . Institute of Geology Geophysics Chinese Academy of Sciences Beijing China . Tarim Oilfield Branch CNPC Korla China . Hefei University of Industry Tunxilu Hefei China 《中国科学D辑(英文版)》2005,48(9):1387-1402
Succeeding to multiply collisions of different blocks in Late Paleozoic[1―5], complex intracontinental structural deformation occurred in the Tianshan area during Mesozoic-Cenozoic[6―16], which controlled coeval basin-range evolution and resulted in intensive modi- fication and adjustment of the Paleozoic oil-gas reser- voirs[17―19]. The Kuqa Depression is a secendary struc- tural unit of the Tarim basin, in which Mesozoic- Ce- nozoic deposits occur in thickness of 6000―7000 m. The Kuq… 相似文献
112.
城市缺水是目前带有普遍性的重大问题 ,但在城市建设过程中 ,宝贵的地下水资源遭到浪费的现象又大量存在 ,解决好施工降水与环境保护问题是关系到城市发展的重要问题之一 ,结合郑州市的工程实践 ,谈谈施工降水中的环境保护及水资源合理利用问题。 相似文献
113.
114.
Modelling post-glacial rebound with lateral viscosity variations 总被引:2,自引:0,他引:2
115.
Analysis of rock structure stability in coal mines 总被引:1,自引:0,他引:1
In this paper, the theory of limit point instability is used to analyse the stability of rock structures in coal mines. A general method of analysing stability of rock structures is put forward and a uniform instability condition of rock structures is set up. Some instability phenomena, such as rock bursts in circular roadways, pillars and long walls, and the outburst of coal and gas from circular roadways, are discussed analytically. At a later stage, the critical point of rock structure instability is determined. The influence of relative parameters (such as the mechanical properties of rock, coal, and the geometric sizes) on the stability of the rock structures is carefully analysed. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
116.
117.
118.
The interaction between twin‐parallel tunnels affects the tunnelling‐induced ground deformation, which may endanger the nearby structures. In this paper, an analytical solution is presented for problems in determining displacements and stresses around deforming twin‐parallel tunnels in an elastic half plane, on the basis of complex variable theory. As an example, a uniform radial displacement was assumed as the boundary condition for each of the two tunnels. Special attention was paid to the effects of tunnel depth and spacing between the two tunnels on the surface movement to gain deep insight into the effect of the interaction between twin‐parallel tunnels using the proposed analytical approach. It is revealed that the influence of twin tunnel interaction on surface movements diminishes with both the increase of the tunnel depth and the spacing between the two tunnels. The presented analytical solution manifests that, similar to most of the existing numerical results, the principle of superposition can be applied to determine ground deformation of twin‐parallel tunnels with a certain large depth and spacing; otherwise, the interaction effect between the two tunnels should be taken into account for predicting reliable ground movement. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
119.
The integration of Sensor Web Enablement services with other Open Geospatial Consortium (OGC) Web Services as Geospatial Processing Workflows (GPW) is essential for future Sensor Web application scenarios. With the help of GPW technology, distributed and heterogeneous OGC Web Services can be organized and integrated as compound Web Service applications that can direct complicated earth observation tasks. Under the Sensor Web environment, asynchronous communications between Sensor Web Services are common. We have proposed an asynchronous GPW architecture for the integration of Sensor Web Services into a Web Service Business Process Execution Language workflow technology. We designed a Sensor Information Accessing and Processing workflow, an asynchronous GPW instance, to take an experiment of observing and mapping ozone over Antarctica. Based on our results, our proposed asynchronous workflow method shows the advantages of taking environmental monitoring and mapping tasks. 相似文献
120.
Is the long-term variation of the estimated GPS differential code biases associated with ionospheric variability? 总被引:1,自引:0,他引:1
The global positioning system (GPS) differential code biases (DCB) provided by the International GNSS Service (IGS) show solar-cycle-like variation during 2002–2013. This study is to examine whether this variation of the GPS DCBs is associated with ionospheric variability. The GPS observations from low earth orbit (LEO) satellites including CHAMP, GRACE and Jason-1 are used to address this issue. The GPS DCBs estimated from the LEO-based observations at different orbit altitudes show a similar tendency as the IGS DCBs. However, this solar-cycle-like dependency is eliminated when the DCBs of 13 continuously operating GPS satellites are constrained to zero-mean. Our results thus revealed that ionospheric variation is not responsible for the long-term variation of the GPS DCBs. Instead, it is attributed to the GPS satellite replacement with different satellite types and the zero-mean condition imposed on all satellite DCBs. 相似文献