全文获取类型
收费全文 | 1059篇 |
免费 | 61篇 |
国内免费 | 5篇 |
专业分类
测绘学 | 15篇 |
大气科学 | 88篇 |
地球物理 | 321篇 |
地质学 | 391篇 |
海洋学 | 62篇 |
天文学 | 192篇 |
综合类 | 2篇 |
自然地理 | 54篇 |
出版年
2023年 | 7篇 |
2022年 | 7篇 |
2021年 | 13篇 |
2020年 | 16篇 |
2019年 | 8篇 |
2018年 | 45篇 |
2017年 | 38篇 |
2016年 | 63篇 |
2015年 | 38篇 |
2014年 | 69篇 |
2013年 | 87篇 |
2012年 | 60篇 |
2011年 | 50篇 |
2010年 | 47篇 |
2009年 | 59篇 |
2008年 | 44篇 |
2007年 | 32篇 |
2006年 | 29篇 |
2005年 | 41篇 |
2004年 | 36篇 |
2003年 | 17篇 |
2002年 | 19篇 |
2001年 | 15篇 |
2000年 | 10篇 |
1999年 | 12篇 |
1998年 | 10篇 |
1997年 | 11篇 |
1996年 | 16篇 |
1995年 | 20篇 |
1994年 | 13篇 |
1993年 | 6篇 |
1992年 | 4篇 |
1991年 | 9篇 |
1990年 | 5篇 |
1989年 | 5篇 |
1988年 | 4篇 |
1985年 | 10篇 |
1984年 | 13篇 |
1983年 | 14篇 |
1982年 | 12篇 |
1981年 | 17篇 |
1980年 | 7篇 |
1979年 | 12篇 |
1978年 | 15篇 |
1977年 | 7篇 |
1976年 | 4篇 |
1975年 | 8篇 |
1974年 | 4篇 |
1972年 | 4篇 |
1969年 | 7篇 |
排序方式: 共有1125条查询结果,搜索用时 0 毫秒
991.
992.
Milinkovitch T Lucas J Le Floch S Thomas-Guyon H Lefrançois C 《Marine pollution bulletin》2012,64(4):865-871
This study evaluated the toxicity of dispersant application which is, in nearshore area, a controversial response technique to oil spill. Through an experimental approach with juveniles of Liza aurata, the toxicity of five exposure conditions was evaluated: (i) a chemically dispersed oil simulating dispersant application; (ii) a single dispersant as an internal control of chemically dispersed oil; (iii) a mechanically dispersed oil simulating natural dispersion of oil; (iv) a water soluble fraction of oil simulating an undispersed and untreated oil slick and (v) uncontaminated seawater as a control exposure condition. The relative concentration of PAHs (polycyclic aromatic hydrocarbons) biliary metabolites showed that the incorporation of these toxic compounds was increased if the oil was dispersed, whether mechanically or chemically. However, toxicity was not observed at the organism level since the aerobic metabolic scope and the critical swimming speed of exposed fish were not impaired. 相似文献
993.
The basement of Montagne Noire (South France), as represented by the orthogneisses of the axial zone, has been dated by means of whole rocks isochron at 530 m.y. This age is discussed with the assistance of petrographic observations and compared to similar results obtained by other authors in the Massif Armoricain and eastern Pyrénées ranges. The high initial ratio 87Sr/86Sr allows one to hypothesize that these igneous masses were originated from a segment of a preexisting crust.
Contribution I.P.G.N.S. No 8. 相似文献
Contribution I.P.G.N.S. No 8. 相似文献
994.
Jean-Gabriel Bréhéret Micheline Hanzo Abderrazzak El Albani Agnès Iatzoura 《Comptes Rendus Geoscience》2004,336(15):1355-1362
The study of calcareous nodules from four organic-rich black shale series allows us to suggest a prominent part for benthic organisms in creating heterogeneities in the sediment, thus favouring microbially mediated early diagenesis based on organic matter consumption. To cite this article: J.-G. Bréhéret et al., C. R. Geoscience 336 (2004). 相似文献
995.
996.
Spatio‐temporal variations in demersal fish assemblages and diversity in the northern Gulf of St. Lawrence (Canada) 下载免费PDF全文
Species diversity is generally considered one of the key factors of ecosystem resilience in response to anthropogenic pressures, including fishing. In this context, the spatial and temporal changes in demersal fish assemblages and species diversity were investigated in the northern Gulf of St. Lawrence (Canada), over a 20‐year period (1990–2010). Data were obtained from the summer research survey conducted by the Department of Fisheries and Oceans, and include commercial and non‐commercial species. The study covers the period of groundfish fishery collapse, the moratorium period, and the post‐moratorium period, and reflects various modifications in management. Multivariate statistical methods revealed two communities. A coastal community corresponds to strata located above 200 m depth and a deeper community located in the deep channels. Interannual differences in the composition of fish assemblages were observed and are mainly due to the changes in the relative biomass of some dominant species. Three diversity indices (Shannon–Wiener, Simpson's Index of Diversity and Motomura's constant) indicate a slight but significant increase of the diversity over time. This trend is due to the increase of the relative biomass of low‐rank species, which may have been favoured by the prohibition of groundfish trawling after 1997 in that region. The geographical distribution of the Shannon–Wiener index also shows temporal dynamics reflecting the biomass distribution of dominant demersal species. 相似文献
997.
Gisèle Schmid 《Climate Policy》2013,13(6):722-740
Technology transfer is not an explicit objective of the Clean Development Mechanism (CDM). However, it constitutes a potential co-benefit by helping to improve living conditions in developing countries. Understanding the drivers and barriers of technology transfer in CDM projects is therefore essential to direct investment flows in host countries and enhance the current CDM framework. In this respect, the contribution of this article is twofold. First, it identifies stepping stones and stumbling blocks to technology transfer in the CDM. Higher applied tariff rates on environmental goods and services as well as burdensome administrative procedures to start a new business are found to be negatively associated with the likelihood of a technology transfer. The results are robust to the exclusion of large host countries such as China and India from the sample. Second, as an extension, the article analyses the correspondence of these supporting factors and barriers with the likelihood of a transfer of the different types of technology (equipment, knowledge, or both). The article concludes with policy recommendations for non-Annex I governments, and suggestions for improvements to the CDM to better assess technology transfer in offsetting projects. 相似文献
998.
The intensity of Jupiter's He 584 Å airglow has been measured by the Voyager U.V. spectrometers. The disc-averaged brightness is about 4 Rs and limb darkening is present. The intensity probably varies with longitude, the variation being out of phase with the H Lyman-α intensity bulge. Modelling of resonance scattering of the solar He 584 Å line by Jupiter's atmosphere has shown that the hydrogen and helium emissions can be explained about equally well by at least two self-consistent scenarios involving the structure (temperature and eddy diffusion coefficient) and excitation of the atmosphere. All our evidence points to a dramatic change of conditions in the Jovian atmosphere in the time between Pioneer and Voyager encounters. 相似文献
999.
1000.
Prof. G. Pasquarè 《International Journal of Earth Sciences》1971,60(3):900-911
The outlines of the Cenozoic volcanism developed between the Pontian and Taurian orogenic belts in the Erzurum area, are described. The following volcanic units are recognized, from the oldest ones: andesiticbasaltic fissurai strato-volcanoes; rhyodacitic and dacitic domes; andesitic domes followed by strong ejective activity; basaltic domes and flow-domes; basaltic fissure volcanoes. The relationships between these units and the main tectonic phases, which developed in this region during the latest periods of the Alpine orogenesis, are discussed. 相似文献