全文获取类型
收费全文 | 135810篇 |
免费 | 18612篇 |
国内免费 | 43043篇 |
专业分类
测绘学 | 5145篇 |
大气科学 | 27645篇 |
地球物理 | 32249篇 |
地质学 | 69540篇 |
海洋学 | 25313篇 |
天文学 | 26451篇 |
综合类 | 4266篇 |
自然地理 | 6856篇 |
出版年
2022年 | 1055篇 |
2021年 | 1790篇 |
2020年 | 3173篇 |
2019年 | 6707篇 |
2018年 | 8613篇 |
2017年 | 8192篇 |
2016年 | 8825篇 |
2015年 | 6427篇 |
2014年 | 7408篇 |
2013年 | 10249篇 |
2012年 | 7971篇 |
2011年 | 8505篇 |
2010年 | 8279篇 |
2009年 | 8713篇 |
2008年 | 7312篇 |
2007年 | 7222篇 |
2006年 | 6534篇 |
2005年 | 5327篇 |
2004年 | 5725篇 |
2003年 | 5286篇 |
2002年 | 4880篇 |
2001年 | 4360篇 |
2000年 | 3871篇 |
1999年 | 3386篇 |
1998年 | 3593篇 |
1997年 | 3560篇 |
1996年 | 2876篇 |
1995年 | 2765篇 |
1994年 | 2586篇 |
1993年 | 2290篇 |
1992年 | 2124篇 |
1991年 | 1847篇 |
1990年 | 1939篇 |
1989年 | 1575篇 |
1988年 | 1486篇 |
1987年 | 1492篇 |
1986年 | 1236篇 |
1985年 | 1508篇 |
1984年 | 1618篇 |
1983年 | 1370篇 |
1982年 | 1397篇 |
1981年 | 1154篇 |
1980年 | 1142篇 |
1979年 | 1035篇 |
1978年 | 1004篇 |
1977年 | 839篇 |
1976年 | 789篇 |
1975年 | 790篇 |
1974年 | 720篇 |
1973年 | 770篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
141.
142.
A spatial statistical method has been developed from the well-known Kriging technique in geostatistics, as a way of providing quantitative comparison between a pair of spatial data sets, and a measure for such a comparison. This residual analysis method is applied to oceanographic data in order to compare Iceland-Faeroes Front (IFF) model predictions against appropriate field observations, with an aim to assess the IFF model performance and its prediction accuracy. The method is also used to evaluate the model-generated dynamical variability within the model predictions, as well as the natural variability within the frontal observations. From the results, it has been found that the IFF model is highly robust, and gives better predictions at depth 150–350 m than elsewhere. Within such a depth (i.e. 250–350 m), there is also evidence to suggest that the main frontal region is most active above the IF Ridge. The natural variability obtained from the observations appears to be comparable to the model-generated dynamical variability after 20 days of integration, indicating a certain degree of accuracy in the model predictions. The method reported in this paper could also be extended for further use in model data assimilation. Thus, the work not only demonstrates how spatial statistics can be applied to oceanographic data, but also opens up new statistical tools for data handling in ocean modelling. 相似文献
143.
144.
Harpacticoida taxocen diversity in the silty-sandy littoral zone of Kandalaksha Bay of the White Sea
E. S. Chertoprud M. V. Chertoprud D. V. Kondar P. N. Kornev A. A. Udalov 《Oceanology》2006,46(4):492-500
The fauna composition, ecological groups, and life forms of Harpacticoids of soft littoral grounds from 15 sites off the Karelian coast in Kandalaksha Bay of the White Sea were studied. Six types of harpacticoid taxocens with different sets of dominating species are described. On silty sands with clear signs of desalination, the Stenchelia palustris taxocen is common; medium-grained sands are characterized by the Heterolaophonte minuta, Paraleptastacus kliei — Huntemannia jadensis, and Amphiascoides nanus — Scottopsyllus minor taxocens; while on coarse sands, the Ameira parvula and Ameira scotti — Mesochra lilljeborgi taxocens have developed. The diversity of the taxocens is partly explained by the differences in the grain-size composition and salinity at different sites. In addition, groups of various taxocens dwelling on the same type of the sediments were found in different minor bights of the coastline. 相似文献
145.
The wadic project: A comprehensive field evaluation of directional wave instrumentation 总被引:1,自引:0,他引:1
J. Allender T. Audunson S. F. Barstow S. Bjerken H. E. Krogstad P. Steinbakke L. Vartdal L. E. Borgman C. Graham 《Ocean Engineering》1989,16(5-6)
The results of a comprehensive field trial of nearly all commercially available directional wave measurement systems at the Edda field in the North Sea during winter 1985-86 are presented. The results summarize the accuracy of the principal engineering wave parameters from each system and the dependence on sea state. Limiting factors on system performance and operational problems are also included in the assessment. Overall experience has been good with systems utilizing widely different measurement principles returning consistent results. 相似文献
146.
147.
In this paper the peculiarities of compiled oceanographic data sets, which consist primarily in the presence of some characteristic information as well as in the planned incomplete filling of the files with observations, are discussed. A number of special ways are suggested which essentially improve the packing density of computerized data without applying special archiving algorithms. The effectiveness of these methods has been tested by treating thein situ hydrological/chemical data file compiled in the Black Sea in 1988.Translated by Vladimir A. Puchkin. 相似文献
148.
M. V. Ramana 《Geo-Marine Letters》1986,6(1):1-5
Satellite imagery and offshore magnetic data were analysed to correlate regional tectonic elements on the inner continental
shelf off Konkan and the adjacent Deccan plateau. Three statistically important lineament trends—N-S, WNW-ESE and ENE-WSW—that
prevail on land are correlatable well with the offshore trends. This positive correlation suggests simultaneous deformation.
The major magnetic lineament observed off Jaigad Bay, west coast of India, may be the extension of onshore lineaments. The
correlation of both the offshore and onshore trends indicates that the fracture pattern of the crystalline basement has also
controlled the offshore structural pattern. 相似文献
149.
150.
The properties of salinity in the South China Sea (SCS), a significant marginal sea connecting the Pacific andIndian Oceans, are greatly influenced by the transport of fresh water flux between the two oceans. However, the long-termchanges in the intermediate water in the SCS have not been thoroughly studied due to limited data, particularly in relationto its thermodynamic variations. This study utilized reanalysis data products to identify a 60-year trend of freshening in theintermediate waters of the northern South China Sea (NSCS), accompanied by an expansion of low-salinity water. Thestudy also constructed salinity budget terms, including advection and entrainment processes, and conducted an analysis ofthe salinity budget to understand the impacts of external and internal dynamic processes on the freshening trend of theintermediate water in the NSCS. The analysis revealed that the freshening in the northwest Pacific Ocean and theintensification of intrusion through the Luzon Strait at intermediate levels are the primary drivers of the salinity changes inthe NSCS. Additionally, a weakened trend in the intensity of vertical entrainment also contributes to the freshening in theNSCS. This study offers new insights into the understanding of regional deep sea changes in response to variations in boththermodynamics and oceanic dynamic processes. 相似文献