全文获取类型
收费全文 | 293篇 |
免费 | 10篇 |
国内免费 | 2篇 |
专业分类
测绘学 | 9篇 |
大气科学 | 24篇 |
地球物理 | 61篇 |
地质学 | 139篇 |
海洋学 | 27篇 |
天文学 | 26篇 |
综合类 | 1篇 |
自然地理 | 18篇 |
出版年
2023年 | 1篇 |
2022年 | 1篇 |
2021年 | 3篇 |
2020年 | 9篇 |
2019年 | 8篇 |
2018年 | 6篇 |
2017年 | 10篇 |
2016年 | 10篇 |
2015年 | 7篇 |
2014年 | 12篇 |
2013年 | 19篇 |
2012年 | 8篇 |
2011年 | 26篇 |
2010年 | 14篇 |
2009年 | 18篇 |
2008年 | 17篇 |
2007年 | 16篇 |
2006年 | 16篇 |
2005年 | 17篇 |
2004年 | 20篇 |
2003年 | 12篇 |
2002年 | 15篇 |
2001年 | 5篇 |
2000年 | 3篇 |
1999年 | 1篇 |
1998年 | 5篇 |
1997年 | 4篇 |
1996年 | 2篇 |
1994年 | 4篇 |
1993年 | 2篇 |
1992年 | 3篇 |
1991年 | 2篇 |
1990年 | 1篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1979年 | 1篇 |
1977年 | 1篇 |
排序方式: 共有305条查询结果,搜索用时 15 毫秒
281.
In order to assess in fish the maternal transfer of alkylphenolic compounds to the progeny, the identification and quantification of the labelled compounds present in oocytes and embryos was conducted after dietary exposure of mature female mosquitofish to 14C-4n-nonylphenol during vitellogenesis and embryogenesis respectively. Radioactivity found in bile and liver extracts accounted for 0.9–0.6 and 0.2–0.1% of ingested radioactivity for females exposed during vitellogenesis and embryogenesis respectively. The amount of extractable radioactivity present in oocytes and embryos was 0.19 and 0.07% of the ingested dose respectively. The radio-HPLC profiles obtained from bile, liver, oocyte and embryo extracts were similar. They showed the presence of 4n-NP-glucuronide as the major metabolite and traces of unchanged 4n-NP. The other metabolites corresponded to 8-hydroxynonylphenol, 9-(4-hydroxyphenyl)-nonanoic acid and para-hydroxybenzoic acid which is the final product of the alkyl chain oxidation. Our results indicate that exposure of ovoviviparous female fish to 4-NP during vitellogenesis and embryogenesis leads to the contamination of the progeny by 4-NP and its metabolites. 相似文献
282.
Nicolas Paparoditis Jean-Philippe Souchon Gilles Martinoty Marc Pierrot-Deseilligny 《ISPRS Journal of Photogrammetry and Remote Sensing》2006,60(6):400
The IGN digital camera project was established in the early 1990s. The first research surveys were carried out in 1996 and the digital camera was first used in production in 2000. In 2004 approximately 10 French departments (accounting for 10% of the territory) were covered with a four-head camera system and since summer 2005 all IGN imagery has been acquired digitally. Nevertheless the camera system is still evolving, with tests on new geometric configurations being continuously undertaken. The progressive integration of the system in IGN production workflows has allowed IGN to keep the system evolving in accordance with production needs. Remaining problems are due to specific camera characteristics such as CCD format, the optical quality of off-the-shelf lenses, and because some production tools are ill-adapted to digital images with a large dynamic range. However, when considering the pros and cons of integrating these images into production lines, the disadvantages are largely balanced by the numerous benefits this technology offers. 相似文献
283.
Christophe Messager Hubert Gallée Olivier Brasseur Bernard Cappelaere Christophe Peugeot Luc Séguis Michel Vauclin Romain Ramel Gilles Grasseau Laurent Léger Denis Girou 《Climate Dynamics》2006,27(2-3):199-214
The forcing of a hydrologic model (ABC) by both observed and simulated precipitation from a regional climate model (MAR) has been performed over the Sirba watershed (39,000 km2) located in the Sahelian region. Two aspects have been more specifically examined: the spatial and temporal representations of precipitation. The comparison between simulated and observed discharges—using observed rainfall datasets as forcing of the hydrologic model—has shown that the representation of daily precipitation (which is mainly convective in the Sahelian region) was not sufficiently accurate to correctly simulate the hydrologic response of the watershed. Since this response drives the soil water budget and consequently the amount of evaporation in forthcoming coupling experiments, it is thus necessary to develop more realistic infra-daily precipitation associated with convective events. A new temporal disaggregation scheme has been then developed. Considering observed as well as simulated precipitation fields, this method has significantly improved the simulated discharge at the catchment outlet. The major role played by the temporal component compared to spatial component of the precipitation has been then underlined. In addition, the present study shows the unsuitability of the simulated precipitation from the RCM to directly force a hydrologic model at infra daily timescale even if the cumulative amount and the main features of the precipitation seasonal cycle are well simulated. 相似文献
284.
Roger F. Reinking A. Shelby Frisch Brad W. Orr David L. Korn Luc R. Bissonnette Gilles Roy 《Boundary-Layer Meteorology》2003,109(3):255-284
Trapped Kelvin–Helmholtz (K–H) waves and vortices were monitored as they were generated immediately upwind of a mountain and driven into the barrier by a low-level jet. A stratus cloud visually revealed the embedded, propagating, gravity-shear waves. Interactions of the waves with the mountain were deciphered using remote sensing measurements of the structure, motions, and microphysics within the cloud and conceptual models based on existing theories. The observations show that the mountain acted as a dam to the flow that was primed for, but did not spontaneously induce, the waves. In response to the blocking, the waves spatially developed a pattern of formation, amplification, and breakdown between the upstream flow and the barrier, and altered the associated clouds in the process. Notably, radar signatures of velocity variance depicted organized, intertwined ribbons of relatively large vorticity within the wave layer. These provided measured evidence of the vortex sheet and streamwise vortex tubes predicted by advanced K–Hinstability theory, the three-dimensional version of Scorer's `stripe', the layer of rotational fluid between opposed flows that led to the wave generation. A theory of resonant interaction of wave trains, but with blocking imposed, appears to explain the internal structure of the pile-up of the flow and wave amplification approaching the barrier. Evolution of the supporting atmospheric thermal structure and introduction of a boundary-layer flow reversal follow a current model of blocking, although some features may have developed more directly from wave-driven mixing. The remote sensors also measured the influence of the waves on the cloud liquid water, including a cumulative enlargement of droplets as they were carried through a series of waves. 相似文献
285.
286.
Hervé Gillet Gilles Lericolais Jean-Pierre Rehault Corneliu Dinu 《Comptes Rendus Geoscience》2003,335(12):907-916
The stratigraphy of the Black Sea western margin is revisited through seismic data acquired during two French-Romanian surveys. These data are calibrated by industrial and DSDP drillings; they display several major discontinuities regarded as Tertiary erosional surfaces. The major seismic discontinuity underlines the base of Miocene formations and corresponds to a composite surface including at least three erosional phases ranging from Oligocene to Pontian times. Moreover, a Messinian erosional surface is clearly identified. This is in agreement with the Hsü's proposition [Palaeogeogr. Palaeoclimatol. Palaeoecol. 29 (1979) 75–93] suggesting a Messinian sea-level drop of Black Sea related to the Messinian Salinity Crisis described in the Mediterranean Sea. To cite this article: H. Gillet et al., C. R. Geoscience 335 (2003). 相似文献
287.
Robert Temdjim Pierre Boivin Gilles Chazot Claude Robin Émilie Rouleau 《Comptes Rendus Geoscience》2004,336(14):1239-1244
Volcanic deposits from the lake Nyos (Cameroon) contain ultrabasic xenoliths: lherzolites, harzburgites and websterites, sometimes containing amphibole. Major and trace element compositions of clinopyroxene and amphibole allow the recognition of an old depletion event followed by two episodes of incompatible-element enrichment. One is high in light rare-earth elements, while the other one is low in these elements, but high in U and Th. Their relative chronology is not yet established. To cite this article: R. Temdjim et al., C. R. Geoscience 336 (2004). 相似文献
288.
Paul McMillan Gilles Peraudeau John Holloway Jean -Pierre Coutures 《Contributions to Mineralogy and Petrology》1986,94(2):178-182
We have measured the water solubility between 1 atmosphere and 5 kilobars for a calcium aluminosilicate melt of molar composition CaO 0.28, Al2O3 0.06, SiO2 0.66 (An9Wo38Qz53). The water contents were measured via thermogravimetric analysis of isobarically quenched glasses, and range from 0.121 wt% H2O near 1 aim to 9.25 wt% H2O at 5 kilobars. The molar water solubility lies between those of SiO2 and albite melts below around three kilobars, and crosses the albite solubility curve above this pressure. The present results are compared with data in the literature on related calcium aluminosilicate melts. There seems to be little variation of water solubility with composition for calcium aluminosilicate melts, unlike analogous alkali aluminosilicate compositions. Examination of the data suggests that there may be a maximum in molar water solubility along the albite-anorthite join. 相似文献
289.
An XPS and SEM study of gold deposition at low temperatures on sulphide mineral surfaces: Concentration of gold by adsorption/reduction 总被引:1,自引:0,他引:1
Gilles E. Jean 《Geochimica et cosmochimica acta》1985,49(4):979-987
Using X-ray photoelectron spectroscopy (XPS or ESCA) and scanning electron microscopy (SEM), we have examined the mechanism of adsorption and reduction of gold solutions on sulphides. KAuIIICl4 solutions are quickly adsorbed on the sulphide surfaces, and the Au(III) is quickly reduced to Au(0). Monolayer Au coverage is attained within one minute. The reduction is auto-catalyzed and Au metal grows on the surface. SEM photographs clearly show agglomerates of gold unevenly distributed on the surface. Specific sites of abnormally high Au concentration are found. We propose possible mechanisms for the adsorption and reduction. Our results suggest that adsorption of Au(III) and Au(I) by sulphide minerals, followed by reduction, could play an important role in the deposition of gold in natural systems especially at low temperature and low gold solution concentrations. 相似文献
290.
Christian Amblard Télesphore Sime-Ngando Saad Rachiq Gilles Bourdier 《Aquatic Sciences - Research Across Boundaries》1993,55(1):1-9
The abundance and the biomass of bacterial, phytoplanktonic, and ciliate communities were estimated at different depths during the spring planktonic development in an oligo-mesotrophic lake (the Pavin lake).The bacterial population, which consists mainly of free bacteria (94% of the total bacterial abundance), displays only low cell densities (0.6 to 7 × 105 cells · ml–1) and represents low biomass values (0.9 to 11.5 µgC·l–1) The bacteria represent from 0.9 to 23.8% (M = 9.7%) of the microplanktonic biomass (with the exclusion of heterotrophic nanoflagellates, i.e. bacteria + phytoplankton + ciliates, size range 0.2–160 µm). The abundance of the phytoplankton varies between 0.5 and 1.8 × 106 cells·l–1, and the biomass values between 12 and 118 µC·l–1. The phytoplankton population constitutes the largest part of the microplanktonic biomass (51.9 to 96.6%, M = 80.6%), and the diatomMelosira italica subsp.subarctica is the largely dominant species of this community. The population of ciliates, essentiallyOligotrichida andScuticociliatida, displays densities between 1.3 and 38.3 × 103 cells·l–1 (M = 6.7 × 103 cells·l–1), and biomass values vary from 0.10 to 16.30 µgC·l–1 (M = 6.01 µgC·l–1). The ciliates constitute thus from 0.1 to 26.4% (M = 9.8%) of the microplanktonic biomass. Whereas the oligotrichs are best represented in the euphotic zone, the small-sized scuticociliates dominate in the hypolimnion. Besides, species having symbionts and considered to be mixotrophic (Strobilidium gyrans, Strombidium viride, Stokesia vernalis) develop preferentially in the epilimnion and constitute more than 50% of the total ciliate biomass. 相似文献