全文获取类型
收费全文 | 74753篇 |
免费 | 4749篇 |
国内免费 | 5455篇 |
专业分类
测绘学 | 2505篇 |
大气科学 | 7999篇 |
地球物理 | 15347篇 |
地质学 | 30068篇 |
海洋学 | 7349篇 |
天文学 | 13957篇 |
综合类 | 2608篇 |
自然地理 | 5124篇 |
出版年
2023年 | 489篇 |
2022年 | 1274篇 |
2021年 | 1694篇 |
2020年 | 1565篇 |
2019年 | 1701篇 |
2018年 | 2794篇 |
2017年 | 2584篇 |
2016年 | 3143篇 |
2015年 | 1941篇 |
2014年 | 3040篇 |
2013年 | 4105篇 |
2012年 | 2990篇 |
2011年 | 3592篇 |
2010年 | 3216篇 |
2009年 | 3830篇 |
2008年 | 3306篇 |
2007年 | 3336篇 |
2006年 | 2985篇 |
2005年 | 2453篇 |
2004年 | 2222篇 |
2003年 | 2178篇 |
2002年 | 2098篇 |
2001年 | 1875篇 |
2000年 | 1884篇 |
1999年 | 2010篇 |
1998年 | 1858篇 |
1997年 | 1837篇 |
1996年 | 1643篇 |
1995年 | 1478篇 |
1994年 | 1255篇 |
1993年 | 1117篇 |
1992年 | 993篇 |
1991年 | 885篇 |
1990年 | 860篇 |
1989年 | 679篇 |
1988年 | 683篇 |
1987年 | 657篇 |
1986年 | 595篇 |
1985年 | 688篇 |
1984年 | 728篇 |
1983年 | 642篇 |
1982年 | 603篇 |
1981年 | 530篇 |
1980年 | 511篇 |
1979年 | 507篇 |
1978年 | 473篇 |
1977年 | 379篇 |
1976年 | 356篇 |
1975年 | 374篇 |
1973年 | 351篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
V. A. Dulov S. I. Klyushnikov V. N. Kudryavtsev O. V. Shulgin O. G. Shcherbak 《Physical Oceanography》1991,2(4):269-282
An overview of experiments is given on the observation of the dependence of the intensity of wind wave breaking on large-scale
currents' inhomogeneities and atmospheric boundary layer stratification. The data were interpreted using a model in which
the variance of the wind wave breaking intensity reflects fluctuations in the influx of energy to wind waves due to various
factors.
Translated by V. Puchkin. 相似文献
992.
Large deposits of marine clays are encountered all along the Indian coastal belt. These clays are pleistocene to recent in origin, are considered to be young, and were deposited in a salt or brackish environment. These clays are very soft in consistency with low in-situ strength and high compressibility. The properties of these soil deposits depend mainly on the clay minerals present. In the present investigation, the mineralogical studies of some Cochin marine clays were carried out using XRD technique. The physical and chemical properties of these deposits were also reported. The test results were compared with some earlier reported works on marine clays. 相似文献
993.
S. G. Buynov 《Physical Oceanography》1992,3(6):471-473
The possibilities of measuring the temperature of seawater as a continuous medium are analysed. It is shown that contemporary thin-film platinum resistance thermometers are inadequate for seawater temperature measurements because of their lag and resolution. The following shortcomings of these thermometers are indicated: heat dissipation by the terminals and the need for them to be hermetically sealed. A prospective improved design is suggested for a thermomagnetic temperature transducer, which provides for the minimal possible lag for the required resolution.Translated by V. Puchkin. 相似文献
994.
995.
本文对青岛—石臼所沿岸潮流特征进行了分析。实际观测资料表明,这一带潮流具有典型的往复流性质,并有较明显的不对称性和较大的垂直变化。文中指出涨落潮流不对称性是由于余流和分潮流影响的结果。讨论了不对称性随余流和分潮流的变化和潮流垂直梯度的特征。不对称和垂直梯度对泥沙运动和污染扩散的影响在文中也作了阐述。 相似文献
996.
997.
The three-dimensional coupled behavior during the interaction of buoys with their mooring systems is numerically analyzed. A time-domain model was developed to predict the response of a tethered buoy subject to hydrodynamic loadings. External loadings include hydrodynamic forces, tethers tensions, wind loadings and weight. System nonlinearities include large rotational and translational motions, and non-conservative fluid loadings. The mooring problem is formulated as a combined nonlinear initial-value and two-point-boundary-value problem which is directly integrated both in time and space. Buoy equations of motion are derived using small Eulerian angles. Coupling between rotational and translational degrees of freedom is included and coupling between the buoy and cable is effected by adopting the buoy equations of motion as boundary conditions at one end for the mooring problem. Numerical examples are provided to validate the formulation and solution technique; predicted responses of three types of buoy (sphere, spar, and disc) are compared with experimental results. 相似文献
998.
莱州湾东部滨海水域第四纪沉积及古地理特征 总被引:5,自引:0,他引:5
本文通过对6个钻孔和461km浅层地震剖机测量获得的测年、微古、孢粉、藻类、古地磁以及岩持征和地震反射界面等资料的综合分析,将本区第四系划分为中更新统、上更新统和全新统,对各时期的沉积进行了较详细的阐述,并对不同时期的沉积相特征和古地理环境的变化进行了初步地揭示。 相似文献
999.
1000.
Data on East Australian Current (EAC) warm-core eddies were obtained over the period 1976–1978 by the Department of Defence and the Commonwealth Scientific and Industrial Research Organization (CSIRO). In that time we have learned that warm eddies form by pinch-off of poleward EAC meanders, can coalesce with the EAC and appear generally similar to Gulf Stream, Kuroshio and other current system eddies. Two eddies were tracked over 1977–1978 with satellite buoys and one (eddy B) was repeatedly studied over eleven months. A deep winter core formed by winter convective cooling and the following summer a new surface mixed layer formed on top of the core. The seasonal changes have been analysed for heat content and changes in dynamic relief. The eddy decayed with a time constant of 650 ± 150 days, due to upwelling below the seasonal thermocline. Surface cooling had little effect on eddy lifetime. The eddy contracted horizontally, possibly after some interaction with the EAC, giving rise to eddy spin-up with increasing age. Surface currents increased after eleven months to 2.0 m s?1. The dynamic relief during summer was also apparently boosted by contact with the EAC. Eddy B was observed to coalesce with a new meander of the EAC rather than drift away to the south. It is proposed that the formation of these eddies is governed by the westward propagation of the baroclinic Rossby wave known as the Tasman Front. Pinch-off of eddies adjacent to the coast and the variable flow of the EAC may be caused by the baroclinic wave ‘breaking’ on the coast. The eddy formation rate is about two per year and most eddies coalesce with the EAC and do not escape to the south. Eddies coalesce and re-separate, creating many subsurface isothermal layers from old cores south of 34°S. 相似文献