全文获取类型
收费全文 | 20577篇 |
免费 | 2655篇 |
国内免费 | 4070篇 |
专业分类
测绘学 | 1243篇 |
大气科学 | 3248篇 |
地球物理 | 4271篇 |
地质学 | 10400篇 |
海洋学 | 2831篇 |
天文学 | 2014篇 |
综合类 | 1396篇 |
自然地理 | 1899篇 |
出版年
2024年 | 137篇 |
2023年 | 384篇 |
2022年 | 886篇 |
2021年 | 1160篇 |
2020年 | 998篇 |
2019年 | 1051篇 |
2018年 | 1279篇 |
2017年 | 1195篇 |
2016年 | 1206篇 |
2015年 | 914篇 |
2014年 | 1176篇 |
2013年 | 1217篇 |
2012年 | 1204篇 |
2011年 | 1313篇 |
2010年 | 1220篇 |
2009年 | 1176篇 |
2008年 | 1104篇 |
2007年 | 1132篇 |
2006年 | 1013篇 |
2005年 | 581篇 |
2004年 | 489篇 |
2003年 | 544篇 |
2002年 | 596篇 |
2001年 | 546篇 |
2000年 | 458篇 |
1999年 | 494篇 |
1998年 | 442篇 |
1997年 | 464篇 |
1996年 | 384篇 |
1995年 | 365篇 |
1994年 | 363篇 |
1993年 | 295篇 |
1992年 | 237篇 |
1991年 | 161篇 |
1990年 | 157篇 |
1989年 | 158篇 |
1988年 | 126篇 |
1987年 | 87篇 |
1986年 | 80篇 |
1985年 | 64篇 |
1984年 | 55篇 |
1983年 | 54篇 |
1982年 | 55篇 |
1981年 | 36篇 |
1980年 | 27篇 |
1979年 | 33篇 |
1978年 | 21篇 |
1976年 | 20篇 |
1975年 | 23篇 |
1973年 | 19篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
长江口及济州岛附近海域变性水团的初步分析 总被引:1,自引:0,他引:1
基于变性水团的概念,本文把聚类分析用于确定长江口及济州岛附近海域变性水团的边界。由聚类分析得到的结果表明,在该海区有十个水团。对它们的特征、分布与变化进行了初步分析。作者得出的结论是:1、在十个水团中,有四个大洋性水团,六个变性水团。2、该海域水团变性的特点为暧季增温、降盐、降氧,而冷季则相反。3、水团变性是由海区内、外因素综合作用而发生的,而后者在浅水区域起主要作用。4、水团边界的舌状分布与流向之间有明显关系。因之,海流的方向及强度,大致可依水团舌状分布而判断。5、底层中心渔场基本上位于各变性水团之间的混合区或其附近。 相似文献
82.
83.
This paper considers the relationship between multi-year air temperature and pressure fluctuations over the ocean, based on an approximate solution of the problem on the determination of large-scale seawater temperature anomalies from the conditions predominating at the sea surface. The dependence derived is numerically analysed using observations made in the North Atlantic. It is shown that the variability of annual mean air temperature anomalies is largely controlled by the air pressure field which has taken place during the preceding long-term period. The dependence derived may be applied to generate long-term forecasts of the ocean's hydrometeorological regime.Translated by Vladimir A. Puchkin. 相似文献
84.
Yu. A. Karpychev 《Oceanology》2007,47(6):857-864
The structure of the bottom sediments in Kara Bogaz Gol Bay is correlated with the history of the sea level fluctuations in the Caspian Sea during the Novocaspian time based on the radiocarbon geochronology of the coastal and bottom sediments. Instrumental observations of the sea level and the hydrochemical regime of the bay are considered to substantiate the correlations obtained. 相似文献
85.
D. S. Drozdov F. M. Rivkin V. Rachold G. V. Ananjeva-Malkova N. V. Ivanova I. V. Chehina M. M. Koreisha Yu. V. Korostelev E. S. Melnikov 《Geo-Marine Letters》2005,25(2-3):81-88
A set of digital maps including geology, Quaternary sediments, landscapes, engineering-geological, vegetation, geocryological and the series of regional sources have been selected to characterize the Russian Arctic coast. Based on this data, new maps of engineering geocryological zoning and zoning of the coast with respect to the intensity of exogenous geological processes and risk of technogenic impacts have been generated at the scales of 1:4,000,000–1:8,000,000. These maps are a tool to assess the impact of industry on the Arctic coast of the country. 相似文献
86.
87.
88.
Various measures including material experiments, centrifuge modeling tests and FEM numerical analyses were performed to study systematically the action mechanism of the geotextile-reinforced cushion under breakwater on soft ground and the effects of the strata characterization and the reinforcement condition on the stability of the breakwater-ground system. In the aspect of controlling the deformation, the geotextile-reinforced cushion under breakwater constrains the lateral displacement of both the embankment and the ground. From the viewpoint of stress, the reinforcement suppressed the range of high stress level in the system. In general, the weaker the ground is and the greater the modulus of the geotextile is, the more effective the reinforcement is. The tensile force in the geotextile is greater in the range of the main part of the embankment. 相似文献
89.
Zhang Jinshan Yu Guohua
Research Engineer River Harbour Department Nanjing Hydraulic Research Institute Nanjing Research Senior Engineer River Harbour Department Nanjing Hydraulic Research Institute Nanjing 《中国海洋工程》1995,(3)
- Based on field investigations, this paper analyzes three types of harbour basinns and navigation channel excavated on seabed in Jiaozhou Bay, get a general rule of deposition for excavated trough, it found that pollution is one of crucial factors resulting in the deposition of the excavated trough in the east shore of Jiaozhou Bay. With these results, it predicted the annual deposition thickness for the excavated trough and disclosed the fact that it can't be deposited deadly during one storm. At the same time, with two-dimensional numerical model, it studied the effects of the excavated trough and the reclamation near shore on tidal cureent and said that the excavated trough can decrease the current velocity passing through the trough about 10- 15%, but only limited inside and near the trough and there are no effect on other regions; reclamation can cut off the pollution sources and no obvious effect on the currents of the Jiaozhou Bay. Connecting the deep trough and Cangkou tidal channel with a new 相似文献
90.
本文采用黄海(35°N以北,124°E以西)断面调查资料,对海域表层盐度年变化进行谐波分析,讨论了年波与半年波位相与振幅在海区的分 布不同水系消长及运动的关系。 相似文献