全文获取类型
收费全文 | 6454篇 |
免费 | 827篇 |
国内免费 | 680篇 |
学科分类
地球科学 | 7961篇 |
出版年
2024年 | 15篇 |
2023年 | 57篇 |
2022年 | 103篇 |
2021年 | 123篇 |
2020年 | 163篇 |
2019年 | 203篇 |
2018年 | 166篇 |
2017年 | 196篇 |
2016年 | 203篇 |
2015年 | 260篇 |
2014年 | 267篇 |
2013年 | 364篇 |
2012年 | 247篇 |
2011年 | 286篇 |
2010年 | 223篇 |
2009年 | 357篇 |
2008年 | 437篇 |
2007年 | 518篇 |
2006年 | 409篇 |
2005年 | 331篇 |
2004年 | 323篇 |
2003年 | 321篇 |
2002年 | 257篇 |
2001年 | 227篇 |
2000年 | 225篇 |
1999年 | 240篇 |
1998年 | 235篇 |
1997年 | 150篇 |
1996年 | 163篇 |
1995年 | 132篇 |
1994年 | 142篇 |
1993年 | 117篇 |
1992年 | 95篇 |
1991年 | 77篇 |
1990年 | 70篇 |
1989年 | 68篇 |
1988年 | 39篇 |
1987年 | 35篇 |
1986年 | 30篇 |
1985年 | 19篇 |
1984年 | 8篇 |
1983年 | 5篇 |
1982年 | 7篇 |
1981年 | 3篇 |
1980年 | 19篇 |
1979年 | 4篇 |
1978年 | 7篇 |
1977年 | 7篇 |
1954年 | 8篇 |
排序方式: 共有7961条查询结果,搜索用时 15 毫秒
101.
102.
Wave run-up, and flow visualization experiments were conducted with a 1:2 sloped sea wall model. The visualization experiments gave an overview of flow fields in reflected, non-breaking conditions. Maximum particle velocities were found to be significantly smaller than suggested in the literature. Downrush produced a fast sheet flow, extending down to the toe of the sea wall. This created a ‘reverse’ breaker during the retreat of the initially non-breaking wave, which explains the high-energy dissipation rates for non-breaking waves reported in the literature. Embankments may therefore be exposed to wave impact pressures in areas up to 1.18H0 below MWL. 相似文献
103.
Seasonal Variability of Near-Surface Heat Budget of Selected Oceanic Areas in the North Tropical Indian Ocean 总被引:1,自引:0,他引:1
The results obtained from an Ocean General Circulation Model (OGCM), the Modular Ocean Model 2.2, forced with the National
Center for Environmental Prediction/National Center for Atmospheric Research reanalysis data, and observational data have
been utilized to document the climatological seasonal cycle of the upper ocean response in the Tropical Indian Ocean. We address
the various roles played by the net surface heat flux and the local and remote ocean dynamics for the seasonal variation of
near-surface heat budget in the Tropical Indian Ocean. The investigation is based in seven selected boxes in the Arabian Sea,
Bay of Bengal and the Equatorial Indian Ocean. The changes of basin-wide heat budget of ocean process in the Arabian Sea and
the Western Equatorial Indian Ocean show an annual cycle, whereas those in the Bay of Bengal and the Eastern Equatorial Indian
Ocean show a semi-annual cycle. The time tendency of heat budget in the Arabian Sea depends on both the net surface heat flux
and ocean dynamics while on the other hand, that in the Bay of Bengal depends mainly on the net surface flux. However, it
has been found that the changes of heat budget are very different between western and eastern regional sea areas in the Arabian
Sea and the Bay of Bengal, respectively. This difference depends on seasonal variations of the different local wind forcing
and the different ocean dynamics associated with ocean eddies and Kelvin and Rossby waves in each regional sea areas. We also
discuss the comparison and the connection for the seasonal variation of near-surface heat budget among their regional sea
areas.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
104.
The paper is intended to extend the investigations about the nature of abnormal waves that have been reported in the work of Guedes Soares et al. (Characteristics of abnormal waves in North Sea states. Applied Ocean Research 25, [337–344]). The same dataset gathered at the oil platform North Alwyn in the North Sea during the November storm in 1997 is used along with the time series from the Draupner platform, in which an abnormal wave occurred. The data are reanalyzed from the viewpoint of the applicability of second-order models to fit large waves. The observed results confirm that the second-order approximation is not adequate to describe highly asymmetric and abnormal waves. 相似文献
105.
Crustal Structures of the Northernmost South China Sea: Seismic Reflection and Gravity Modeling 总被引:2,自引:0,他引:2
The South China Sea (SCS) is a marginal sea off shore Southeast Asia. Based on magnetic study, oceanic crust has been suggested in the northernmost SCS. However, the crustal structure of the northernmost SCS was poorly known. To elaborate the crustal structures in the northernmost SCS and off southwest Taiwan, we have analyzed 20 multi-channel seismic profiles of the region. We have also performed gravity modeling to understand the Moho depth variation. The volcanic basement deepens southeastwards while the Moho depth shoals southeastwards. Except for the continental margin, the northernmost SCS can be divided into three tectonic regions: the disturbed and undisturbed oceanic crust (8–12 km thick) in the southwest, a trapped oceanic crust (8 km thick) between the Luzon-Ryukyu Transform Plate Boundary (LRTPB) and Formosa Canyon, and the area to the north of the Formosa Canyon which has the thickest sediments. Instead of faulting, the sediments across the LRTPB have only displayed differential subsidence offset of about 0.5–1 s in the northeast side, indicating that the LRTPB is no longer active. The gravity modeling has shown a relatively thin crust beneath the LRTPB, demonstrating the sheared zone character along the LRTPB. However, probably because of post-spreading volcanism, only the transtension-shearing phenomenon of volcanic basement in the northwest and southeast ends of the LRTPB can be observed. These two basement-fractured sites coincide with low gravity anomalies. Intensive erosion has prevailed over the whole channel of the Formosa Canyon. 相似文献
106.
107.
S型海洋重力仪是目前海洋重力测量中较为常用的一种仪器,其产品性能也逐步得到提高。介绍了进行全自动化控制升级后,最新引进的SⅡ型海洋重力仪使用中出现的稳定平台颤动故障现象及排除办法。 相似文献
108.
109.
110.
The objective in this experimental work is to evaluate the capability of several cylindrical buoys to follow and measure waves. Eleven configurations have been studied, eight among which were furnished with disks of different diameters at the waterline. The experiments took place in the test basin at ISITV. On the one hand, we have obtained a set of transfer coefficients for each frequency and each configuration in regular waves. On the other hand, we have determined the corresponding transfer functions, then we have used the latter to measure irregular waves. The time signals as measured by the buoys with and without corrections have been compared with wave gage measurements and subjected to a wave-by-wave analysis. The results allow the conclusion that the buoy with a medium size disk constitutes the best compromise. In fact, it permits the buoy to follow the free surface while minimizing parasitic motions. 相似文献