全文获取类型
收费全文 | 7980篇 |
免费 | 2036篇 |
国内免费 | 2564篇 |
专业分类
测绘学 | 332篇 |
大气科学 | 1573篇 |
地球物理 | 1777篇 |
地质学 | 5646篇 |
海洋学 | 859篇 |
天文学 | 79篇 |
综合类 | 1098篇 |
自然地理 | 1216篇 |
出版年
2024年 | 80篇 |
2023年 | 177篇 |
2022年 | 304篇 |
2021年 | 357篇 |
2020年 | 337篇 |
2019年 | 387篇 |
2018年 | 346篇 |
2017年 | 416篇 |
2016年 | 402篇 |
2015年 | 426篇 |
2014年 | 562篇 |
2013年 | 496篇 |
2012年 | 662篇 |
2011年 | 621篇 |
2010年 | 577篇 |
2009年 | 561篇 |
2008年 | 522篇 |
2007年 | 584篇 |
2006年 | 581篇 |
2005年 | 507篇 |
2004年 | 420篇 |
2003年 | 389篇 |
2002年 | 359篇 |
2001年 | 366篇 |
2000年 | 285篇 |
1999年 | 300篇 |
1998年 | 250篇 |
1997年 | 232篇 |
1996年 | 189篇 |
1995年 | 173篇 |
1994年 | 140篇 |
1993年 | 143篇 |
1992年 | 101篇 |
1991年 | 74篇 |
1990年 | 63篇 |
1989年 | 45篇 |
1988年 | 46篇 |
1987年 | 23篇 |
1986年 | 10篇 |
1985年 | 15篇 |
1984年 | 6篇 |
1983年 | 1篇 |
1982年 | 3篇 |
1981年 | 4篇 |
1980年 | 9篇 |
1979年 | 4篇 |
1978年 | 11篇 |
1977年 | 13篇 |
1976年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 9 毫秒
221.
西太平洋暖池变异及其对西太平洋次表层海温场的影响 总被引:9,自引:0,他引:9
应用热带太平洋上层XBT温度资料,分析研究了西太平洋暖池区(0°~16°N,125°~145°E)上层海洋的变化特征以及与西太平洋次表层海温场之间的关系.研究表明,西太平洋暖池区的垂向温度存在显著的年际变化,尤其在次表层(120~200m)的变化最为明显.西太平洋暖池区的次表层冷暖信号明显早于西太平洋次表层的海温异常.分析发现,西太平洋暖池区的海温异常是导致整个西太平洋次表层海温场变异的关键区,当西太平洋暖池区的次表层冷暖信号加强时,3~4个月后西太平洋海温场出现大范围的冷暖异常. 相似文献
222.
An applied Fourier transform computation for the hydrodynamic wave-resistance coefficient is shown, oriented to potential flows with a free surface and infinity depth. The presence of a ship-like body is simulated by its equivalent pressure disturbance imposed on the un-perturbed free surface, where a linearized free surface condition is used. The wave-resistance coefficient is obtained from the wave-height downstream. Two examples with closed solutions are considered: a submerged dipole, as a test-case, and a parabolic pressure distribution of compact support. In the three dimensional case, a dispersion relation is included which is a key resource for an inexpensive computation of the wave pattern far downstream like fifteen ship-lengths. 相似文献
223.
A system of numerical tools to predict the non-local long-term impact of large-scale constructions on the environment is described. The predictions have to be results of successive examination of free water oscillations, turbulent boundary layers on the sea bottom, and turbulent pulsation effects on sediment transport. Numerical results related to free water oscillations in diverse gulfs are shown, and non-local effects of the dam construction are found for an example of the Baltic Sea. Feasibility of suggested tools for turbulent flow is manifested. 相似文献
224.
海洋生物技术前沿领域研究进展 总被引:3,自引:0,他引:3
根据近期国际海洋生物技术研究发展的有关信息资料,介绍了海洋生物技术研究的现状、前沿领域和最新研究进展,并展望了今后的发展趋势及我国应采取的措施。 相似文献
225.
A tether management system of a winch module in a marine environment is proposed. For the purpose of this study the subsea body is considered as a mass attached at the free end of a long tether which is wrapped around a circular drum controlled by an external torque. The winch is considered mounted on a heaving platform. The effect of the heaving platform on the motions of the drum, tether and attached mass are studied with respect to the longitudinal vibrations of the tether in one dimension. The hydrodynamic effects are considered on the deployed portion of the tether and the tethered mass, both of which are assumed submerged in otherwise still water. The resulting nonlinear system of equations of motion is developed and solved numerically for an example of a marine tether system. The effect of the tether extensibility on the operation threshold of the system is identified. Comparison with an inextensible tether case is provided. The numerical results and their analysis for the retrieval/deployment of the system are presented. 相似文献
226.
南沙海域万安盆地地质构造特征 总被引:1,自引:3,他引:1
利用在南沙海域万安盆地所采集的地震、重磁资料及钻井、地质资料,对该盆地的地震反向特征,沉积特征、区域地质、构造特征及构造发展史进行了的简要的论述,本文以该区Tg深度资料为基础,并利用CCOP年刊发表的新生代基底深度资料,初步圈定了万安盆地的边界,并对盆地二级构造单元进行了划分,将盆地划分为5坳3隆、坳隆相间的构造格局。 相似文献
227.
228.
Temperature data at different layers of the past 45 years were studied and we found adiploe mode in the thermocline layer (DMT): anomalously cold sea temperature off the coast of Sumatra and warm sea temperature in the western Indian Ocean. First, we analyzed the temperature and the temperature anomaly (TA) along the equatorial Indian Ocean in different layers. This shows that stronger cold and warm TA signals appeared at subsurface than at the surface in the tropical Indian O-cean. This result shows that there may be a strong dipole mode pattern in the subsurface tropical Indian Ocean. Secondly we used Empirical Orthogonal Functions (EOF) to analyze the TA at thermocline layer. The first EOF pattern was a dipole mode pattern. Finally we analyzed the correlations between DMT and surface tropical dipole mode (SDM), DMT and Nino 3 SSTA, etc. and these correlations are strong. 相似文献
229.
230.