全文获取类型
收费全文 | 306篇 |
免费 | 26篇 |
国内免费 | 4篇 |
专业分类
测绘学 | 9篇 |
大气科学 | 23篇 |
地球物理 | 69篇 |
地质学 | 164篇 |
海洋学 | 16篇 |
天文学 | 34篇 |
综合类 | 1篇 |
自然地理 | 20篇 |
出版年
2024年 | 1篇 |
2023年 | 2篇 |
2022年 | 3篇 |
2021年 | 11篇 |
2020年 | 8篇 |
2019年 | 14篇 |
2018年 | 12篇 |
2017年 | 18篇 |
2016年 | 19篇 |
2015年 | 17篇 |
2014年 | 17篇 |
2013年 | 20篇 |
2012年 | 12篇 |
2011年 | 31篇 |
2010年 | 30篇 |
2009年 | 20篇 |
2008年 | 14篇 |
2007年 | 11篇 |
2006年 | 8篇 |
2005年 | 6篇 |
2004年 | 8篇 |
2003年 | 5篇 |
2002年 | 11篇 |
2001年 | 2篇 |
2000年 | 2篇 |
1999年 | 2篇 |
1998年 | 2篇 |
1997年 | 2篇 |
1996年 | 4篇 |
1995年 | 4篇 |
1994年 | 3篇 |
1992年 | 2篇 |
1991年 | 1篇 |
1987年 | 1篇 |
1986年 | 2篇 |
1985年 | 1篇 |
1978年 | 1篇 |
1976年 | 1篇 |
1975年 | 2篇 |
1974年 | 3篇 |
1973年 | 2篇 |
1928年 | 1篇 |
排序方式: 共有336条查询结果,搜索用时 140 毫秒
21.
Summary Thaumasite from the manganese mine of Tschwinning, South Africa, has the formula Ca3.097 Si1.062OH6.372(CO3)0.994(SO4)1.000·11.596 H2O. Unit cell parameters (a=11.013(2) Å,c=10.379(5) Å,V=1090.1(6) Å3) and refraction indices (ne=1.458(2),n
o=1.498(2)) compare well with the best ones available in the literature. The IR spectrum and DT-TG profiles are given. Contradictions between the IR spectrum, a recent structural refinement and the DT-TG are discussed, but cannot be explained satisfactorily.
With 2 Figures 相似文献
Thaumasit aus der Mangan-Mine von Tschwinning, Süd-Afrika
Zusammenfassung Thaumasit aus der Mangan-Mine von Tschwinning, Süd-Afrika, besitzt die Formel Ca3.097 Si1.062OH6.372(CO3)0.994(SO4)1.000·11.596 H2O. Die Parameter der Elementarzelle (a=11.013(2) Å,c=10.379(5) Å,V=1090.1(6) Å3) und die Brechungsindizes (n e=1.458(2),n o=1.498(2)) zeigen gute Übereinstimmung mit verfügbaren Literaturdaten. Es werden ein IR-Spektrum und DT-TG-Profile präsentiert. Gegensätze zwischen dem IR-Spektrum, einer neueren Strukturverfeinerung und dem DT-TG werden diskutiert, können jedoch nicht zufriedenstellend erklärt werden.
With 2 Figures 相似文献
22.
23.
Guillaume Favreau Christian Leduc Christelle Marlin Abdou Guéro 《Comptes Rendus Geoscience》2002,334(6):395-401
In southwest Niger, the Continental Terminal water table displays a natural hollow shape about 10 m in depth over an area of 4000 km2. A 10-year survey of this hollow aquifer has shown that current recharge is above . The water table has risen continuously since the 1950–1960s as a result of land clearance. This shows a disequilibrium in the aquifer balance. The long-term recharge rate is estimated by radioisotopes to be around . This figure fits with the only possible origin of the piezometric depression, i.e. evapotranspiration losses in its centre. To cite this article: G. Favreau et al., C. R. Geoscience 334 (2002) 395–401. 相似文献
24.
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
25.
Andre Guillaume 《Tectonophysics》1978,48(1-2)
This work discusses the state of knowledge (mainly tectonic and geophysical data) about the Tonale line and other “peri-Adriatic” lines in the Central and Eastern Alps. The chain is here cut into a mosaic of independent blocs, separated by faults with basic injections in some places. The Tonale fault had a dextral movement in Oligo-Miocene times; it is connected with the Austrian “Thermenlinie”, and not to the Pusteria—Gail line. An attempt at chronology is presented.
Résumé
Ce travail fait le point des connassiances, principalement tectoniques et géophysiques, sur la linge du Tonale et les accidents “péri-adriatiques” récents des Alpes centrales et Orientales. Dans cette région, la chaine est découpée en une mosaïque de blocs indépendants, séparés par des accidents injectés ça et là de masses basiques. L'accident du Tonale, Qui a joué en décrochement dextre à l'Oligo-Miocéne, est relié à la Thermenlinie d'Autriche Et non à la linge Pusteria—Gail. Un essai de chronologie est présenté. 相似文献26.
Yarrow Axford Camilla S. Andresen John T. Andrews Simon T. Belt Áslaug Geirsdóttir Guillaume Massé Gifford H. Miller Sædís Ólafsdóttir Lindsay L. Vare 《第四纪科学杂志》2011,26(6):645-656
Geochemical, mineralogical and biological indicators preserved in sediments are widely used to reconstruct past climate change, but proxies differ in the degree to which their utility as climate indicators has been validated via laboratory experiments, modern spatial calibrations, or down‐core comparisons with instrumental climate data. Multi‐proxy studies provide another means of evaluating interpretations of proxies. This paper presents a multi‐proxy assessment comparing 19 sub‐centennially resolved late Holocene proxy records, covering the period 300–1900 AD, from seven Icelandic marine and lacustrine core sites. We employ simple statistical comparisons between proxy reconstructions to evaluate their correlations over time and, ultimately, their utility as proxies for regional climate. Proxies examined include oxygen isotopic composition of benthic and planktonic foraminifera, abundance of the sea‐ice biomarker IP25, allochthonous quartz in marine sediments (a proxy for drift ice around Iceland), marine carbonate abundance, total organic carbon concentration, chironomid assemblages, lacustrine biogenic silica and carbon/nitrogen ratios in lake sediments. Most of the examined proxy records, including temperature and sea‐ice proxies, correlate strongly with each other over multi‐centennial timescales, and thus do appear to record changes in regional climate. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
27.
Sophie Raous Thierry Becquer Jérémie Garnier Éder de Souza Martins Guillaume Echevarria Thibault Sterckeman 《Applied Geochemistry》2010
An understanding of the biogeochemical behaviour of metals in mine spoil materials is a prerequisite to rehabilitate Ni mining sites. The objective of this study was to characterize the fate of metals in different Ni ore spoil materials as influenced by hydrological conditions and fertilisation practices. In tropical ultramafic complexes, the different stages of lateritic weathering lead to two types of ores, and therefore, to two spoil types. They are mainly either a clay-rich saprolite, so-called “garnierite”, enriched in phyllosilicates, or a limonitic material, enriched in Fe oxides. Lysimeter columns were designed to monitor leaching waters through both spoil materials. The garnieritic spoil released higher concentrations of Mg (mean = 2.25 mg L−1), Ni (0.39 mg L−1) and Cr (1.19 mg L−1) than the limonitic spoil (Mg = 0.5 mg L−1; Ni = 0.03 mg L−1 and Cr = 0.25 mg L−1). Chromium was mainly in an anionic form in leaching solutions. As exchangeable pools of Cr(VI) in limonite (980 mg kg−1 of KH2PO4-extractable Cr) are considerable its release in water may still occur in the case of a pH increase. In mixed spoil, metal concentrations were almost as low as in the limonitic one. The effect of mineral-N fertilisation was a strong release of cations (Ni, Mg) into the leachate. Phosphate amendment did not affect the soil solution composition under experimental conditions. 相似文献
28.
Adnand Bitri Jean-Pierre Brun Denis Gapais Florence Cagnard Charles Gumiaux Jean Chantraine Guillaume Martelet Catherine Truffert 《Comptes Rendus Geoscience》2010,342(6):448-452
We present results and interpretation of a 72 km long deep seismic reflection profile acquired across the internal zone of the Hercynian belt of South Brittany. The profile is of excellent quality, most of the crust being highly reflective. The “ARMOR 2 South” profile, is correlated with the “ARMOR 2 North” profile that was published in 2003. Correlation of the main subsurface reflections with surface geological and structural data provides important information about the crustal structure that resulted from thickening during Late Devonian and regional-scale extension during Late Carboniferous. In particular, seismics image shows a very high reflectivity zone, lying flat over more than 40 km at about 10–12 km depth. This zone is interpreted as a major zone of ductile crustal thinning. 相似文献
29.
Towards Stochastic Time-Varying Geological Modeling 总被引:3,自引:1,他引:2
Guillaume Caumon 《Mathematical Geosciences》2010,42(5):555-569
The modeling of subsurface geometry and properties is a key element to understand Earth processes and manage natural hazards
and resources. In this paper, we suggest this field should evolve beyond pure data fitting approaches by integrating geological
concepts to constrain interpretations or test their consistency. This process necessarily calls for adding the time dimension
to 3D modeling, both at the geological and human time scales. Also, instead of striving for one single best model, it is appropriate
to generate several possible subsurface models in order to convey a quantitative sense of uncertainty. Depending on the modeling
objective (e.g., quantification of natural resources, production forecast), this population of models can be ranked. Inverse
theory then provides a framework to validate (or rather invalidate) models which are not compatible with certain types of
observations. We review recent methods to better achieve both stochastic and time-varying geomodeling and advocate that the
application of inversion should rely not only on random field models, but also on geological concepts and parameters. 相似文献
30.
The paper discusses the development of economic techniques for dealing with uncertainties in economic analysis of planting trees to mitigate climatic change. In consideration of uncertainty, time preference and intergenerational equity, the traditional cost-benefit analysis framework is challenged with regard to the discounting/non-discounting of carbon uptake benefits, and because it usually uses a constant and positive discount rate. We investigate the influence of various discounting protocols on the outputs of economic analysis. The idea of using the declining discount rate is also considered. Several numerical examples dealing with the analysis of afforestation for carbon sequestration in Scotland and Ukraine are provided. We show that the choice of discounting protocols have a considerable influence on the results of economic analysis, and therefore, on the decision-making processes related to climate change mitigation strategies. The paper concludes with some innovative insights on accounting for uncertainties and time preference in tackling climate change through forestry, several climate policy implications of dealing with uncertainties, and a brief discussion of what the use of different discounting protocols might imply for decision making. 相似文献