全文获取类型
收费全文 | 3668篇 |
免费 | 853篇 |
国内免费 | 1298篇 |
专业分类
测绘学 | 243篇 |
大气科学 | 2077篇 |
地球物理 | 680篇 |
地质学 | 583篇 |
海洋学 | 1163篇 |
天文学 | 266篇 |
综合类 | 191篇 |
自然地理 | 616篇 |
出版年
2024年 | 24篇 |
2023年 | 91篇 |
2022年 | 146篇 |
2021年 | 182篇 |
2020年 | 185篇 |
2019年 | 284篇 |
2018年 | 186篇 |
2017年 | 225篇 |
2016年 | 196篇 |
2015年 | 211篇 |
2014年 | 285篇 |
2013年 | 305篇 |
2012年 | 296篇 |
2011年 | 292篇 |
2010年 | 221篇 |
2009年 | 295篇 |
2008年 | 233篇 |
2007年 | 289篇 |
2006年 | 240篇 |
2005年 | 207篇 |
2004年 | 173篇 |
2003年 | 168篇 |
2002年 | 162篇 |
2001年 | 115篇 |
2000年 | 121篇 |
1999年 | 95篇 |
1998年 | 85篇 |
1997年 | 59篇 |
1996年 | 91篇 |
1995年 | 71篇 |
1994年 | 58篇 |
1993年 | 62篇 |
1992年 | 50篇 |
1991年 | 34篇 |
1990年 | 15篇 |
1989年 | 14篇 |
1988年 | 11篇 |
1987年 | 10篇 |
1986年 | 4篇 |
1985年 | 9篇 |
1984年 | 5篇 |
1983年 | 3篇 |
1982年 | 2篇 |
1981年 | 2篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1971年 | 1篇 |
1954年 | 2篇 |
排序方式: 共有5819条查询结果,搜索用时 265 毫秒
21.
用北太平洋(含赤道太平洋区)1949~1979年的COADS资料,通过矢量EOF分解得到北太平洋异常风场的分布型及其时间变化规律。分析表明,EOF1~5场与大气活动中心、海洋相互作用有联系,具有明显的天气学意义。此外,还讨论了EOF异常风场间的转换及其季节性差异。 相似文献
22.
23.
We have examined wind-induced circulation in the Sea of Okhotsk using a barotropic model that contains realistic topography
with a resolution of 9.25 km. The monthly wind stress field calculated from daily European Centre for Medium-Range Weather
Forecasting (ECMWF) Re-Analysis data is used as the forcing, and the integration is carried out for 20 days until the circulation
attains an almost steady state. In the case of November (a representative for the winter season from October to March), southward
currents of velocity 0.1–0.3 m s−1 occur along the bottom contours off the east of Sakhalin Island. The currents are mostly confined to the shelf (shallower
than 200 m) and extend as far south as the Hokkaido coast. In the July case (a representative for the summer season from April
to September), significant currents do not occur, even in the shallow shelves. The simulated southward current over the east
Sakhalin shelf appears to correspond to the near-shore branch of the East Sakhalin Current (ESC), which was observed with
the surface drifters. These seasonal variations simulated in our experiments are consistent with the observations of the ESC.
Dynamically, the simulated ESC is interpreted as the arrested topographic wave (ATW), which is the coastally trapped flow
driven by steady alongshore wind stress. The volume transport of the simulated ESC over the shelf reaches about 1.0 Sv (1
Sv = 106 m3s−1) in the winter season, which is determined by the integrated onshore Ekman transport in the direction from which shelf waves
propagate.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
24.
To study ice-induced vibration of a compliant conical structure,a series of model tests were performed from 2004 to 2005.In the tests,the ice sheet before the compliant conical structure was found to fail in two-time breaking.From 2005 to 2006,this type of ice failure was studied through more groups of tests.The tests show that two-time breaking is the typical failure of ice before steep conical structures,and is controlled by other factors at the same time,such as ice speed and the angle of the cone. 相似文献
25.
Spatial and Temporal Variations of Sound Speed at the PN Section 总被引:3,自引:0,他引:3
Gridded sound speed data were calculated using Del Grosso's formulation from the temperature and salinity data at the PN section
in the East China Sea covering 92 cruises between February 1978 and October 2000. The vertical gradients of sound speed are
mainly related to the seasonal variations, and the strong horizontal gradients are mainly related to the Kuroshio and the
upwelling. The standard deviations show that great variations of sound speed exist in the upper layer and in the slope zone.
Empirical orthogonal function analysis shows that contributions of surface heating and the Kuroshio to sound speed variance
are almost equivalent.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
26.
27.
28.
Phytoplankton variability on the Faroe Shelf 总被引:2,自引:2,他引:2
29.
30.