全文获取类型
收费全文 | 5501篇 |
免费 | 1307篇 |
国内免费 | 1436篇 |
专业分类
测绘学 | 262篇 |
大气科学 | 2429篇 |
地球物理 | 2385篇 |
地质学 | 545篇 |
海洋学 | 1195篇 |
天文学 | 540篇 |
综合类 | 227篇 |
自然地理 | 661篇 |
出版年
2024年 | 23篇 |
2023年 | 107篇 |
2022年 | 188篇 |
2021年 | 247篇 |
2020年 | 253篇 |
2019年 | 311篇 |
2018年 | 263篇 |
2017年 | 275篇 |
2016年 | 249篇 |
2015年 | 295篇 |
2014年 | 353篇 |
2013年 | 350篇 |
2012年 | 365篇 |
2011年 | 382篇 |
2010年 | 316篇 |
2009年 | 387篇 |
2008年 | 325篇 |
2007年 | 412篇 |
2006年 | 368篇 |
2005年 | 331篇 |
2004年 | 308篇 |
2003年 | 299篇 |
2002年 | 261篇 |
2001年 | 186篇 |
2000年 | 201篇 |
1999年 | 171篇 |
1998年 | 164篇 |
1997年 | 121篇 |
1996年 | 139篇 |
1995年 | 125篇 |
1994年 | 88篇 |
1993年 | 100篇 |
1992年 | 71篇 |
1991年 | 52篇 |
1990年 | 31篇 |
1989年 | 35篇 |
1988年 | 19篇 |
1987年 | 16篇 |
1986年 | 8篇 |
1985年 | 11篇 |
1984年 | 9篇 |
1983年 | 5篇 |
1982年 | 2篇 |
1981年 | 3篇 |
1980年 | 6篇 |
1979年 | 3篇 |
1978年 | 2篇 |
1977年 | 6篇 |
1954年 | 2篇 |
排序方式: 共有8244条查询结果,搜索用时 15 毫秒
41.
Li Dashan Shen Ying Ren Rushu Chen Yao
Senior Engineer River Harbour Department Nanjing Hydraulic Research Institute Nanjing Engineer River Harbour Department Nanjing Hydraulic Research Institute Nanjing Associate Professor Hohai University Nanjing Master Hohai University Nanjing 《中国海洋工程》1997,(1)
In this paper,the characteristics of density current under the action of waves are describedwith the help of flume experiment and theoretical analysis.The study shows that turbid water under the ac-tion of the waves can present three types of motion,i.e.significant stratification,fragile stratification andstrong mixing.The motion of turbid water presents significant stratification when(H/D)/△ρ/ρ~(1/2)≤4.5,generally this state is known as density current.The formulas of motionvelocity,thickness,and discharge of density current moving on horizontal bottom are derived by use of ba-sic equations such as momemtum equation,equation of energy conservation and continuity equation offluid.The time-average velocity and the thickness of density current under the action of waves have a rela-tionship with such parameters as relative density(△ρ/ρ),wave height(H),and water depth(D).Whenthese parameters are determined,the time-average thickness and motion velocity of density current are al-so determined.The relat 相似文献
42.
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
43.
44.
45.
46.
47.
Phytoplankton variability on the Faroe Shelf 总被引:2,自引:2,他引:2
48.
49.
近海工程环境应用中各种风资料的平均时间分析 总被引:5,自引:0,他引:5
本文从近海工程设计应用的需要出发,对于通常使用的不同来源的测风资料平均时间进行了分析,这些资料来源包括:岸边及近海探查与生产设施上的气象台站、天气观测船、浮标、商船气象报、从受灾情况估计出的极大风速以及动力诊断模型估计出的海面风速。 相似文献
50.
青岛局地风特征的分析 总被引:8,自引:0,他引:8
本文根据位于胶州湾东岸的青岛沧口和流亭两机场气象台和唠山区气象台资料及现场实验资料对胶州湾东岸的海陆风气候特征,来自胶州湾与来自南面黄海水域的两支海陆风相互作用及其对沧口地区的影响,崂山西坡下坡风的气候特征及影响进行了分析。文中还提出了一种根据常规气象观测资料估算海陆风发生频率的方法。 相似文献