全文获取类型
收费全文 | 26154篇 |
免费 | 3735篇 |
国内免费 | 5525篇 |
专业分类
测绘学 | 1894篇 |
大气科学 | 4114篇 |
地球物理 | 5602篇 |
地质学 | 13209篇 |
海洋学 | 3680篇 |
天文学 | 2215篇 |
综合类 | 1962篇 |
自然地理 | 2738篇 |
出版年
2024年 | 129篇 |
2023年 | 363篇 |
2022年 | 1127篇 |
2021年 | 1436篇 |
2020年 | 1193篇 |
2019年 | 1369篇 |
2018年 | 1631篇 |
2017年 | 1534篇 |
2016年 | 1566篇 |
2015年 | 1275篇 |
2014年 | 1574篇 |
2013年 | 1640篇 |
2012年 | 1668篇 |
2011年 | 1758篇 |
2010年 | 1716篇 |
2009年 | 1554篇 |
2008年 | 1480篇 |
2007年 | 1470篇 |
2006年 | 1254篇 |
2005年 | 832篇 |
2004年 | 696篇 |
2003年 | 747篇 |
2002年 | 805篇 |
2001年 | 788篇 |
2000年 | 622篇 |
1999年 | 733篇 |
1998年 | 521篇 |
1997年 | 567篇 |
1996年 | 471篇 |
1995年 | 452篇 |
1994年 | 401篇 |
1993年 | 350篇 |
1992年 | 301篇 |
1991年 | 185篇 |
1990年 | 169篇 |
1989年 | 177篇 |
1988年 | 139篇 |
1987年 | 101篇 |
1986年 | 89篇 |
1985年 | 62篇 |
1984年 | 58篇 |
1983年 | 52篇 |
1982年 | 64篇 |
1981年 | 34篇 |
1980年 | 41篇 |
1979年 | 36篇 |
1978年 | 19篇 |
1976年 | 18篇 |
1975年 | 22篇 |
1973年 | 17篇 |
排序方式: 共有10000条查询结果,搜索用时 640 毫秒
231.
南日岛周围海域浮游植物的分布 总被引:1,自引:0,他引:1
南日岛1990~1991年4个季度月共鉴定浮游植物200种(包括变种、变型),隶属5门64属,硅藻种类最多,其次是甲藻;暖水性种65种,广温性种120种,温带种15种;年平均数量为263.15×104个/m3,5月最多为869.61×104个/m3,8、10月及1月依次减少。主要优势种有细齿角利藻、奇异菱形藻、中肋骨条藻、佛氏海毛藻等。文章初步分析了浮游植物与环境因子的关系。 相似文献
232.
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
233.
234.
Algorithm for HF radar vector current measurements 总被引:1,自引:0,他引:1
A new algorithm is proposed, called the stream function method (SFM) for producing vector current maps from radial data measured
by dual-site high frequency surface wave radar (HFSWR). In SFM, a scalar stream function is constructed under some oceanographic
assumptions. The function describes the two-dimensional (2-D) ocean surface water motion and is used to obtain the distribution
of vector currents. The performance of SFM is evaluated using simulated radial data, which demonstrates that SFM has advantages
over typical vectorial combination methods (VCM) both in error acceptance and robustness, and excels another method based
on least-squares fitting (LSF) in recovering the complicated current models. Furthermore, SFM is capable of providing the
total currents based on radials from single-site radar. We also test the assumptions of horizontal non-divergence in the simulation.
The new algorithm is applied to the field experiment data of Wuhan University’s ocean state measuring and analyzing radar
(OSMAR), collected in the coastal East China Sea during April 11–17, 2004. Quantitative comparisons are given between radar
results by three current algorithms and in-situ current meter measurements. Preliminary analysis of the vertical current shear is given based on the current meter measurements. 相似文献
235.
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
236.
The North Yellow Sea Basin ( NYSB ), which was developed on the basement of North China (Huabei) continental block, is a typical continental Mesozoic Cenozoic sedimentary basin in the sea area. Its Mesozoic basin is a residual basin, below which there is probably a larger Paleozoic sedimentary basin. The North Yellow Sea Basin comprises four sags and three uplifts. Of them, the eastern sag is a Mesozoic Cenozoic sedimentary sag in NYSB and has the biggest sediment thickness; the current Korean drilling wells are concentrated in the eastern sag. This sag is comparatively rich in oil and gas resources and thus has a relatively good petroleum prospect in the sea. The central sag has also accommodated thick Mesozoic-Cenozoic sediments. The latest research results show that there are three series of hydrocarbon source rocks in the North Yellow Sea Basin, namely, black shales of the Paleogene, Jurassic and Cretaceous. The principal hydrocarbon source rocks in NYSB are the Mesozoic black shale. According to the drilling data of Korea, the black shales of the Paleogene, Jurassic and Cretaceous have all come up to the standards of good and mature source rocks. The NYSB owns an intact system of oil generation, reservoir and capping rocks that can help hydrocarbon to form in the basin and thus it has the great potential of oil and gas. The vertical distribution of the hydrocarbon resources is mainly considered to be in the Cretaceous and then in the Jurassic. 相似文献
237.
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
238.
239.
E. A. Agafonov N. A. Sorokina Yu. A. Prokhorenko E. E. Pavlova 《Physical Oceanography》1995,6(5):395-397
This paper discussesin situ observational data on the directed light attenuation index in the near-surface layer, collected in September 1987. The absolute light attenuation index has been evaluated for a near-shore strip of water 10–15 miles in width. When multidisciplinary research is conducted in the open sea, this part of the sea surface remains unstudied, as the observational grid for it is made larger than the spatial-temporal parameters of the biophysical processes producing optical inhomogeneities.Translated by Vladimir A. Puchkin. 相似文献
240.
The finite-elements technique is applied to study the effect of a basin’s geometry (bays, harbours) and location of the characteristics
of seiche oscillations in the basin and in the gulf proper. An increase of the length of the bay is shown to contribute to
the periods of natural oscillations and to cause their restructuring.
Translated by Vladimir A. Puchkin. 相似文献