全文获取类型
收费全文 | 42141篇 |
免费 | 607篇 |
国内免费 | 355篇 |
专业分类
测绘学 | 1305篇 |
大气科学 | 3067篇 |
地球物理 | 8613篇 |
地质学 | 13869篇 |
海洋学 | 3634篇 |
天文学 | 10300篇 |
综合类 | 114篇 |
自然地理 | 2201篇 |
出版年
2021年 | 333篇 |
2020年 | 376篇 |
2019年 | 459篇 |
2018年 | 990篇 |
2017年 | 911篇 |
2016年 | 1190篇 |
2015年 | 672篇 |
2014年 | 1123篇 |
2013年 | 2028篇 |
2012年 | 1231篇 |
2011年 | 1638篇 |
2010年 | 1484篇 |
2009年 | 2045篇 |
2008年 | 1795篇 |
2007年 | 1816篇 |
2006年 | 1700篇 |
2005年 | 1279篇 |
2004年 | 1308篇 |
2003年 | 1192篇 |
2002年 | 1239篇 |
2001年 | 1094篇 |
2000年 | 1027篇 |
1999年 | 897篇 |
1998年 | 891篇 |
1997年 | 892篇 |
1996年 | 715篇 |
1995年 | 669篇 |
1994年 | 626篇 |
1993年 | 544篇 |
1992年 | 478篇 |
1991年 | 488篇 |
1990年 | 470篇 |
1989年 | 486篇 |
1988年 | 434篇 |
1987年 | 505篇 |
1986年 | 457篇 |
1985年 | 537篇 |
1984年 | 662篇 |
1983年 | 569篇 |
1982年 | 562篇 |
1981年 | 509篇 |
1980年 | 441篇 |
1979年 | 434篇 |
1978年 | 445篇 |
1977年 | 384篇 |
1976年 | 341篇 |
1975年 | 353篇 |
1974年 | 328篇 |
1973年 | 365篇 |
1972年 | 262篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
861.
862.
G. Bergametti A.L. Dutot J.P. Quisefit R. Vie Le Sage 《Journal of Volcanology and Geothermal Research》1983,15(4):355-367
A statistical analysis of volcanic aerosol based on 1,083 variables including concentration, grain-size and site variabilities establishes correlations between sites and among chemical elements.Variation curves of element concentration show parallel behaviour. High coefficients of correlation between anions and cations confirm associations between elements. 相似文献
863.
Based on phosphorus, iron and manganese analyses in 16 cores (5 dated) from the crest and flanks of the East Pacific Rise and the Bauer Deep we estimate that phosphorus is being deposited about 20 times faster in metalliferous sediments near the rise crest than in adjacent flank deposits, and about 40 times faster on the crest than in the Bauer Deep. Almost all of the phosphorus on the rise crest is contained in poorly crystallized hydrothermal iron oxyhydroxides, supporting Berner's (1973) proposal of phosphate sorption by these phases. The phosphate is probably derived from seawater, but some hydrothermal contribution cannot be excluded at this time. Flux estimates indicate that metalliferous sedimentation could remove 15–40% of the pre-agricultural river input of dissolved phosphate. 相似文献
864.
865.
Many hydrothermal deposits are formed around the marine and terrestrial fumarolic vents of Vulcano island (Italy). Their genesis is related to the recombination of the elements brougth by the fumaroles and those liberated by the destruction of pre-existing minerals. 相似文献
866.
P. A. Mohr 《Bulletin of Volcanology》1962,24(1):421-428
Recent Quaternary faulting and vulcanicity accompanied by peculiar subsidence phenomena in the northern part of the Main Ethiopian Rift are described for the first time. A suggested sequence of geological events is given. 相似文献
867.
F. Zebender P. Zimmermann R. Märki A. Hörler H. Ambübl 《Aquatic Sciences - Research Across Boundaries》1961,23(1):296-308
Ohne Zusammenfassung 相似文献
868.
Mini-sosie consists in using a vibration-rammer as seismic source and changing the striking rate by varying the engine speed, resulting in a random impulse transmission. The recording instruments are made up of two seismic traces, two constant gain amplifiers and a two-channel sosie processor which performs the decoding in real time by using the actual transmission times supplied by a captor located on top of the vibration-rammer's plate. An idea of the possible penetration is given by the recording of a velocity survey. Other results obtained in seismic reflection and refraction are given. 相似文献
869.
870.
Ian Robson 《Astronomy& Geophysics》2007,48(4):4.30-4.30
IYA2009 will be a great opportunity for all of us working in astronomy (and space) to make an impact; certainly locally and nationally and, we hope, globally. So what is going on and how can you participate? Ian Robson has the answers. 相似文献