全文获取类型
收费全文 | 184篇 |
免费 | 11篇 |
国内免费 | 1篇 |
专业分类
大气科学 | 14篇 |
地球物理 | 25篇 |
地质学 | 72篇 |
海洋学 | 1篇 |
天文学 | 75篇 |
自然地理 | 9篇 |
出版年
2024年 | 1篇 |
2022年 | 1篇 |
2021年 | 2篇 |
2020年 | 6篇 |
2017年 | 3篇 |
2016年 | 2篇 |
2015年 | 6篇 |
2014年 | 5篇 |
2013年 | 37篇 |
2012年 | 9篇 |
2011年 | 10篇 |
2010年 | 13篇 |
2009年 | 7篇 |
2008年 | 5篇 |
2006年 | 4篇 |
2005年 | 9篇 |
2004年 | 6篇 |
2003年 | 2篇 |
2002年 | 7篇 |
2001年 | 1篇 |
2000年 | 1篇 |
1999年 | 1篇 |
1998年 | 2篇 |
1997年 | 13篇 |
1996年 | 1篇 |
1995年 | 2篇 |
1994年 | 2篇 |
1993年 | 2篇 |
1989年 | 3篇 |
1987年 | 2篇 |
1986年 | 1篇 |
1985年 | 3篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1982年 | 2篇 |
1981年 | 1篇 |
1979年 | 1篇 |
1978年 | 2篇 |
1977年 | 2篇 |
1975年 | 3篇 |
1974年 | 1篇 |
1973年 | 4篇 |
1972年 | 1篇 |
1971年 | 6篇 |
1969年 | 1篇 |
1951年 | 1篇 |
排序方式: 共有196条查询结果,搜索用时 15 毫秒
51.
52.
53.
J. M. PAQUE J. R. BECKETT H. A. ISHII A. ALÉON‐TOPPANI D. S. BURNETT N. TESLICH Z. R. DAI J. P. BRADLEY 《Meteoritics & planetary science》2009,44(5):665-687
Abstract— We used focused ion beam thin section preparation and scanning transmission electron microscopy (FIB/STEM) to examine the interfacial region between spinel and host melilite for spinel grains in type B1 inclusions from the Allende and Leoville carbonaceous chondrites. Boundary clinopyroxenes decorating spinel surfaces have compositions similar to those of coarser clinopyroxenes from the same region of the inclusion, suggesting little movement after formation. Host melilite displays no anomalous compositions near the interface and late‐stage minerals are not observed, suggesting that boundary pyroxenes did not form by crystallization of residual liquid. Allende spinels display either direct spinel‐melilite contact or an intervening boundary clinopyroxene between the two phases. Spinel‐melilite interfacial regions in a Leoville B1 are more complex, with boundary clinopyroxene, as observed in Allende, but also variable amounts of glass, secondary calcite, perovskite, and an Mg‐, Al‐, OH‐rich and Ca‐, Si‐poor crystalline phase that may be a layered double hydrate. One possible scenario of formation for the glass veins is that open system alteration of melilite produced a porous, hydrated aggregate of Mg‐carpholite or sudoite + aluminous diopside that was shock melted and quenched to a glass. The hydrated crystalline phase we observed may have been a shocked remnant of the precursor phase assemblage, but is more likely to have formed later by alteration of the glass. In the mantle, boundary clinopyroxenes may have been crystallized from Ti‐rich liquids formed by the direct dissolution of perovskite and an associated Sc‐Zr‐rich phase or as a reaction product between dissolving perovskite and liquid. In the core, any perovskite and associated Ti‐enriched liquids that may have originally been present disappeared before the growth of boundary clinopyroxene, and the observed boundary clinopyroxene may have nucleated and grown from the liquid, along with the larger core clinopyroxene. 相似文献
54.
ALEXIS GODET KARL B. FÖLLMI STÉPHANE BODIN ERIC
De KAENEL VIRGINIE MATERA THIERRY ADATTE 《Sedimentology》2010,57(4):1088-1125
Urgonian‐type carbonates are a characteristic feature of many late Early Cretaceous shallow‐marine, tropical and subtropical environments. The presence of typical photozoan carbonate‐producing communities including corals and rudists indicates the prevalence of warm, transparent and presumably oligotrophic conditions in a period otherwise characterized by the high density of globally occurring anoxic episodes. Of particular interest, therefore, is the exploration of relationships between Urgonian platform growth and palaeoceanographic change. In the French and Swiss Jura Mountains, the onset and evolution of the Urgonian platform have been controversially dated, and a correlation with other, better dated, successions is correspondingly difficult. It is for this reason that the stratigraphy and sedimentology of a series of recently exposed sections (Eclépens, Vaumarcus and Neuchâtel) and, in addition, the section of the Gorges de l’Areuse were analysed. Calcareous nannofossil biostratigraphy, the evolution of phosphorus contents of bulk rock, a sequence‐stratigraphic interpretation and a correlation of drowning unconformities with better dated sections in the Helvetic Alps were used to constrain the age of the Urgonian platform. The sum of the data and field observations suggests the following evolution: during the Hauterivian, important outward and upward growth of a bioclastic and oolitic carbonate platform is documented in two sequences, separated by a phase of platform drowning during the late Early Hauterivian. Following these two phases of platform growth, a second drowning phase occurred during the latest Hauterivian and Early Barremian, which was accompanied by significant platform erosion and sediment reworking. The Late Barremian witnessed the renewed installation of a carbonate platform, which initiated with a phase of oolite production, and which progressively evolved into a typical Urgonian carbonate platform colonized by corals and rudists. This phase terminated at the latest in the middle Early Aptian, due to a further drowning event. The evolution of this particular platform segment is compatible with that of more distal and well‐dated segments of the same northern Tethyan platform preserved in the Helvetic zone of the Alps and in the northern subalpine chains (Chartreuse and Vercors). 相似文献
55.
Éric Gilli 《Comptes Rendus Geoscience》2005,337(13):1208-1215
Collapses that affect cave speleothems have frequently been attributed to earthquakes, although this has not been proved. Observations after an earthquake and laboratory tests indicate that only slender speleothems break under coseismic solicitation. Other causes as subsidence, decompression and creeping of ice or cave sediments explain most of the breaks. Tectonics is also a major cause of speleothems breakages and it is possible to detect minute movements of faults. It seems possible to make the difference between brutal coseismic movements and aseismic slow ones. However, the interpretation is often difficult, as the damage can also be caused by gravity tectonics or glacitectonics. To cite this article: É. Gilli, C. R. Geoscience 337 (2005). 相似文献
56.
Didier Miallier Laurent Michon Jacques Évin Thierry Pilleyre Serge Sanzelle Gérard Vernet 《Comptes Rendus Geoscience》2004,336(15):1345-1353
On the basis of radiocarbon ages obtained on wood burned by base surges and tephrochronological observations, it has been possible to assess that the Puy Chopine, aged ca 9700 yr is older by a few centuries than both the Vasset and Kilian volcanoes. The last two have nearly the same age, ca 9300–9400 yr. Layers of trachytic tephra, most probably originated from Kilian or Vasset, can be observed overlapping those from the Pariou. This last volcano had been previously thought to be the younger of the area on the basis of the observation of trachytic tephra beneath its own tephra. However, new observations allow us to assume that those trachytes originated from the acid phase of the Pariou itself. Therefore, it can be assessed that the four volcanoes erupted according to the following sequence: Chopine/Pariou/?Vasset?/Kilian; the chronological situation of Vasset lies on poor arguments and it should be confirmed. To cite this article: D. Miallier et al., C. R. Geoscience 336 (2004). 相似文献
57.
Éric Chaumillon Hervé Gillet Nicolas Weber Michel Tesson 《Comptes Rendus Geoscience》2002,334(2):119-126
The evolution and the internal architecture of an estuary type sand ridge has been studied with a set of bathymetric data recorded during the last two centuries and with a dense grid of recent very high resolution seismic profiles. Bathymetric data of the so-called, Longe de Boyard sand ridge, displays sand losts due to wave and tide erosion. Internal geometry, through seismic profile analysis, indicates two main phases of deposition recording both, a recent high energy environment and an older low energy one, respectively. Such an evolution is believed to record changes in sedimentation processes mainly related to the end of the Holocene transgression (8 000–5 000 yr BP). To cite this article: É. Chaumillon et al., C. R. Geoscience 334 (2002) 119–126. 相似文献
58.
Thibaut Lery CÉline Combet Gareth Murphy Luke O. C. Drury 《Astrophysics and Space Science》2005,298(1-2):375-378
As network performance has outpaced computational power and storage capacity, a new paradigm has evolved to enable the sharing
of geographically distributed resources. This paradigm is known as Grid computing and aims to offer access to distributed
resource irrespective of their physical location. Many national, European and international projects have been launched during
the last years trying to explore the Grid and to change the way we are doing our everyday work. In Ireland, we have started
the CosmoGrid project that is a collaborative project aimed to provide high performance super-computing environments. This
will help to address complex problems such as magnetohydrodynamic outflows and jets in order to model and numerically simulate
them. Indeed, the numerical modeling of plasma jets requires massive computations, due to the wide range of spatial-temporal
scales involved. We present here the first jet simulations and their corresponding models that could help to understand results
from laboratory experiments. 相似文献
59.
Émilie Gaudry Philippe Sainctavit Farid Juillot Federica Bondioli Philippe Ohresser Isabelle Letard 《Physics and Chemistry of Minerals》2006,32(10):710-720
The best known cause for colors in insulating minerals is due to transition metal ions as impurities. As an example, Cr3+ is responsible for the red color of ruby (α-Al2O3:Cr3+) and the green color of eskolaite (α-Cr2O3). Using X-ray absorption measurements, we connect the colors of the Cr
x
Al2−x
O3 series with the structural and electronic local environment around Cr. UV–VIS electronic parameters, such as the crystal field and the Racah parameter B, are related to those deduced from the analysis of the isotropic and XMCD spectra at the Cr L2,3-edges in Cr0.07Al1.93O3 and eskolaite. The Cr–O bond lengths are extracted by EXAFS at the Cr K-edge in the whole Cr
x
Al2−x
O3 (0.07≤x< 2) solid solution series. The variation of the mean Cr–O distance between Cr0.07Al1.93O3 and α-Cr2O3 is evaluated to be 0.015 Å (≈1%). The variation of the crystal field in the Cr
x
Al2−x
O3 series is discussed in relation with the variation of the averaged Cr–O distances. 相似文献
60.