全文获取类型
收费全文 | 184篇 |
免费 | 8篇 |
国内免费 | 3篇 |
专业分类
大气科学 | 15篇 |
地球物理 | 28篇 |
地质学 | 88篇 |
海洋学 | 16篇 |
天文学 | 36篇 |
综合类 | 2篇 |
自然地理 | 10篇 |
出版年
2024年 | 1篇 |
2022年 | 1篇 |
2021年 | 3篇 |
2020年 | 2篇 |
2019年 | 4篇 |
2018年 | 5篇 |
2017年 | 8篇 |
2016年 | 7篇 |
2015年 | 9篇 |
2014年 | 8篇 |
2013年 | 8篇 |
2012年 | 8篇 |
2011年 | 12篇 |
2010年 | 7篇 |
2009年 | 9篇 |
2008年 | 17篇 |
2007年 | 9篇 |
2006年 | 7篇 |
2005年 | 13篇 |
2004年 | 5篇 |
2003年 | 7篇 |
2002年 | 5篇 |
2001年 | 2篇 |
2000年 | 2篇 |
1999年 | 3篇 |
1998年 | 4篇 |
1997年 | 2篇 |
1996年 | 3篇 |
1995年 | 2篇 |
1994年 | 1篇 |
1993年 | 1篇 |
1990年 | 3篇 |
1987年 | 2篇 |
1983年 | 4篇 |
1982年 | 3篇 |
1981年 | 1篇 |
1980年 | 2篇 |
1978年 | 1篇 |
1976年 | 2篇 |
1971年 | 1篇 |
1954年 | 1篇 |
排序方式: 共有195条查询结果,搜索用时 31 毫秒
41.
André Burnol Francis Garrido Philippe Baranger Catherine Joulian Marie-Christine Dictor Françoise Bodénan Guillaume Morin Laurent Charlet 《Geochemical transactions》2007,8(1):12
High levels of arsenic in groundwater and drinking water are a major health problem. Although the processes controlling the
release of As are still not well known, the reductive dissolution of As-rich Fe oxyhydroxides has so far been a favorite hypothesis.
Decoupling between arsenic and iron redox transformations has been experimentally demonstrated, but not quantitatively interpreted.
Here, we report on incubation batch experiments run with As(V) sorbed on, or co-precipitated with, 2-line ferrihydrite. The
biotic and abiotic processes of As release were investigated by using wet chemistry, X-ray diffraction, X-ray absorption and
genomic techniques. The incubation experiments were carried out with a phosphate-rich growth medium and a community of Fe(III)-reducing
bacteria under strict anoxic conditions for two months. During the first month, the release of Fe(II) in the aqueous phase
amounted to only 3% to 10% of the total initial solid Fe concentration, whilst the total aqueous As remained almost constant
after an initial exchange with phosphate ions. During the second month, the aqueous Fe(II) concentration remained constant,
or even decreased, whereas the total quantity of As released to the solution accounted for 14% to 45% of the total initial
solid As concentration. At the end of the incubation, the aqueous-phase arsenic was present predominately as As(III) whilst
X-ray absorption spectroscopy indicated that more than 70% of the solid-phase arsenic was present as As(V). X-ray diffraction
revealed vivianite Fe(II)3(PO4)2.8H2O in some of the experiments. A biogeochemical model was then developed to simulate these aqueous- and solid-phase results.
The two main conclusions drawn from the model are that (1) As(V) is not reduced during the first incubation month with high
Eh values, but rather re-adsorbed onto the ferrihydrite surface, and this state remains until arsenic reduction is energetically
more favorable than iron reduction, and (2) the release of As during the second month is due to its reduction to the more
weakly adsorbed As(III) which cannot compete against carbonate ions for sorption onto ferrihydrite. The model was also successfully
applied to recent experimental results on the release of arsenic from Bengal delta sediments. 相似文献
42.
Delphine Yeghicheyan Cécile Bossy Martine Bouhnik Le Coz Chantal Douchet Guy Granier Alexie Heimburger Francois Lacan Aurélie Lanzanova Tristan C. C. Rousseau Jean‐Luc Seidel Mickaël Tharaud Frédéric Candaudap Jérôme Chmeleff Christophe Cloquet Sophie Delpoux Marie Labatut Rémi Losno Catherine Pradoux Yann Sivry Jeroen E. Sonke 《Geostandards and Geoanalytical Research》2013,37(4):449-467
The natural river water certified reference material SLRS‐5 (NRC‐CNRC) was routinely analysed in this study for major and trace elements by ten French laboratories. Most of the measurements were made using ICP‐MS. Because no certified values are assigned by NRC‐CNRC for silicon and 35 trace element concentrations (rare earth elements, Ag, B, Bi, Cs, Ga, Ge, Li, Nb, P, Rb, Rh, Re, S, Sc, Sn, Th, Ti, Tl, W, Y and Zr), or for isotopic ratios, we provide a compilation of the concentrations and related uncertainties obtained by the participating laboratories. Strontium isotopic ratios are also given. 相似文献
43.
James W. Beletic Sean Adkins Barry Burke Robert Reich Bernie Kosicki Vyshnavi Suntharalingham Charlie Bleau Ray DuVarney Richard Stover Jerry Nelson Francois Rigaut 《Experimental Astronomy》2005,19(1-3):103-109
All of the extremely large telescopes (ELTs) will utilize sodium laser guide star (LGS) adaptive optics (AO) systems. Most of these telescopes plan to use the Shack-Hartmann approach for wavefront sensing. In these AO systems, the laser spots in subapertures at the edge of the pupil will suffer from spot elongation due to the 10 km extent of the sodium layer and the large separation from the projection laser. This spot elongation will severely degrade the performance of standard geometry wavefront sensing systems. In this paper, we present a CCD with custom pixel morphology that aligns the pixels of each subaperture with the radial extension of the LGS spot. This CCD design will give better performance than a standard geometry CCDs for continuous wave lasers. In addition, this CCD design is optimal for a pulsed sodium laser. The pixel geometry enables each subaperture to follow a laser pulse traversing the sodium layer, providing optimal sampling of a limited number of detected photons. In addition to novel pixel layout, this CCD will also incorporate experimental JFET sense amplifiers and use CMOS design approaches to simplify the routing of biases, clocks and video output. This CCD will attain photon-noise limited performance at high frame rates, and is being incorporated in the plans for the Thirty Meter Telescope (TMT). 相似文献
44.
Landman Willem A. Engelbrecht Francois Hewitson Bruce Malherbe Johan van der Merwe Jacobus 《Theoretical and Applied Climatology》2018,132(3-4):1153-1163
Theoretical and Applied Climatology - Multi-decadal regional projections of future climate change are introduced into a linear statistical model in order to produce an ensemble of austral... 相似文献
45.
Bibhash Nath Doris Stüben Sukumar Basu Mallik Debashis Chatterjee Laurent Charlet 《Applied Geochemistry》2008
The present study demonstrates the importance of hydrogeochemical characteristics (groundwater flow and recharge) of an aquifer in the release of As to groundwater. The study area (∼20 km2) is located in Chakdaha block, Nadia district, West Bengal, which hosts groundwaters of variable As content. The spatial distribution pattern of As is patchy with areas containing groundwater that is high in As (>200 μg L−1) found in close vicinity to low As (<50 μg L−1) groundwaters (within 100 m). The concentration of groundwater As is found to decrease with depth. In addition, the data shows that there is no conspicuous relationship between high groundwater As concentration and high groundwater abstraction, although the central cone of depression has enlarged over 2 a and is extending towards the SE of the study area. The river Hooghly, which forms the NW boundary of the study site, shows dual behaviour (effluent and influent during pre- and post-monsoon periods, respectively), complicating the site hydrogeology. The observed groundwater flow lines tend to be deflected away from the high As portion of the aquifer, indicating that groundwater movement is very sluggish in the As-rich area. This leads to a high residence time for this groundwater package, prolonging sediment–water interaction, and hence facilitating groundwater As release. 相似文献
46.
High‐resolution evolution of terrigenous sediment yields in the Provence Basin during the last 6 Ma: relation with climate and tectonics
下载免费PDF全文
![点击此处可从《Basin Research》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Estelle Leroux Marina Rabineau Daniel Aslanian Christian Gorini Stéphane Molliex Francois Bache Cécile Robin Laurence Droz Maryline Moulin Jeffrey Poort Jean‐Loup Rubino Jean‐Pierre Suc 《Basin Research》2017,29(3):305-339
Basin‐wide correlation of Messinian units and Plio‐Quaternary chronostratigraphic markers (5.3 Ma, 2.6 Ma, 0.9 Ma and 0.45 Ma), the mapping of total sediment thickness and the determination of overall sedimentary volumes enabled us to provide a high‐resolution quantitative history of sediment volumes for the last 6 Ma along the Gulf of Lions margin. The results point to (i) a dramatic increase in terrigenous sediment input during the Messinian Salinity Crisis. This increased sedimentation reflects enhanced regional fluvial erosion related to the dramatic fall of Mediterranean base‐level. Stronger weathering due to a regional wetter climate probably also increased erosional fluxes. (ii) A sediment input three times higher during the Plio‐Quaternary compared to the Miocene seems in agreement with published measurements from World's ocean. However, the timing of this increase being uncertain, it implies that the trigger(s) also remain(s) uncertain. (iii) A decrease in detrital volume around 2.6 Ma is attributed to a regional change in the drainage pattern of rivers in the northwestern Alps. (iv) This study also highlights the Mid‐Pleistocene Revolution around 0.9 Ma, which resulted in an almost doubling of sediment input in the Provencal Basin. 相似文献
47.
Cr(III) sorbed at the solid/water interface of latex and hectorite was studied by ESR spectroscopy in the presence of different inorganic ligands. The ESR spectra of the surface obtained in the presence of selenite, phosphate and fluoride can be explained in terms of ternary surface complex formation. This is contrasted by the behaviour of sulfate and selenate ions which were found to have no effect on the ligand field of Cr(III), either in the adsorbed state or in solution. 相似文献
48.
The possible uses of thermoluminescence in mineral exploration are summarised. The methodology is described and some applications for gold exploration are developed with regard to the district of St-Yrieix (Limousin, France), the district of Salsigne (Herault, France) and some occurrences in the Ardenne massif (Belgium). From these cases, different possibilities may be mentioned: the distinction of various types of mineralized structures (St-Yrieix); the evaluation of the potential of mineralized districts from samples collected in the old mining works or in the superficial formations, etc. (St-Yrieix; Ardenne massif), and the determination of a genetic affiliation between different types of mineralizations (e.g. between stratiform deposits and vein-type deposits: the comparison between the districts of St-Yrieix and Salsigne). Finally new possibilities using the TL sensitivity and the equation of the straight lines NTL (natural TL) and ATL (induced TL) are evaluated. 相似文献
49.
Roland Vanderspek Alia Atlas Tye M. Brady Geoffrey B. Crew John P. Doty Steven E. Kissel George R. Ricker Peter C. Tappan Francois Martel M. Tim Jones 《Astrophysics and Space Science》1995,231(1-2):479-482
The High Energy Transient Experiment (HETE), scheduled for launch this year, is a small satellite dedicated to multiwavelength observations of -ray and X-ray bursts. The HETE spacecraft will be equipped with gamma-ray detectors, X-ray detectors with a coded mask, and ultraviolet-sensitive CCD cameras. The UV cameras on HETE are wide-field imagers which will a) provide UV images of the regions in which -ray or X-ray bursts are detected, before, duringand after the burst, b) detect UV transients, whether associated with a high-energy transient or not, c) monitor the brightnesses of field stars for variability over a wide range of timescales, and d) serve as star trackers for HETE. In this poster, we describe the HETE UV instrumentation, control software, and data products. 相似文献
50.
European Union directives as well as national legislation are placing great emphasis on the inclusion of stakeholder perspectives in the governance of risks from natural hazards. This should help decision makers formulate better policies. However, to date, there is little information on stakeholders’ perspectives with respect to landslide risk governance. This paper addresses the gap by reporting on research in Nocera Inferiore, Italy. The research is based on a documentary analysis, 43 semi-structured interviews and a survey submitted to 373 residents. The political instability, the unfairness of national funding allocation across municipalities and the residents’ lack of knowledge about risk assessment and emergency planning are some of the main barriers to effective risk governance. Moreover, there are divergent, sometimes even opposite, stakeholders’ views on several issues, such as the relevance of illegal development in risky areas. The results highlight the importance of addressing these divergent views and including the plurality of voices as a prerequisite for inclusive risk governance. The research provided essential background information for a participatory process, which was designed to support decisions on landslide risk mitigation measures in Nocera Inferiore (Linnerooth-Bayer et al. this issue). The methodology will be of more general interest to researchers and policymakers intent upon including stakeholder perspectives in natural risk governance. 相似文献