全文获取类型
收费全文 | 418篇 |
免费 | 25篇 |
国内免费 | 4篇 |
专业分类
测绘学 | 4篇 |
大气科学 | 30篇 |
地球物理 | 93篇 |
地质学 | 185篇 |
海洋学 | 14篇 |
天文学 | 102篇 |
自然地理 | 19篇 |
出版年
2020年 | 5篇 |
2019年 | 5篇 |
2018年 | 6篇 |
2017年 | 6篇 |
2016年 | 15篇 |
2015年 | 15篇 |
2014年 | 16篇 |
2013年 | 18篇 |
2012年 | 15篇 |
2011年 | 23篇 |
2010年 | 21篇 |
2009年 | 20篇 |
2008年 | 14篇 |
2007年 | 13篇 |
2006年 | 11篇 |
2005年 | 6篇 |
2004年 | 18篇 |
2003年 | 8篇 |
2002年 | 14篇 |
2001年 | 13篇 |
2000年 | 10篇 |
1999年 | 6篇 |
1998年 | 5篇 |
1997年 | 5篇 |
1996年 | 6篇 |
1995年 | 4篇 |
1994年 | 6篇 |
1993年 | 7篇 |
1992年 | 3篇 |
1991年 | 3篇 |
1990年 | 4篇 |
1989年 | 3篇 |
1988年 | 3篇 |
1986年 | 5篇 |
1985年 | 10篇 |
1984年 | 15篇 |
1983年 | 6篇 |
1982年 | 5篇 |
1980年 | 11篇 |
1979年 | 3篇 |
1977年 | 4篇 |
1976年 | 5篇 |
1975年 | 9篇 |
1974年 | 5篇 |
1973年 | 3篇 |
1971年 | 5篇 |
1970年 | 4篇 |
1967年 | 4篇 |
1964年 | 3篇 |
1962年 | 4篇 |
排序方式: 共有447条查询结果,搜索用时 0 毫秒
311.
Friedrich Lucassen Gerhard Franz Rolf L. Romer Dieter Pudlo Peter Dulski 《Contributions to Mineralogy and Petrology》2008,156(6):765-784
The isotopic composition of mafic small-volume intra-plate magmatism constrains the compositions of the sub-continental mantle
sources. The Nd, Pb, and Sr isotope signatures of widespread late Mesozoic to Quaternary intra-plate magmatism in NE Africa
(Sudan, South Egypt) are surprisingly uniform and indicate the presence of a high-μ (μ = 238U/204Pb) source in the mantle. The rocks are characterized by small ranges in the initial isotopic composition of Nd, Pb, and Sr
and most samples fall within ε Nd ca. 3–6, 206Pb/204Pb ca. 19.5–20.5, 207Pb/204Pb ca. 15.63–15.73, 208Pb/204Pb ca. 39–40 and 87Sr/86Sr ca. 0.7028–0.7034. We interpret this reservoir as lithospheric mantle that formed beneath the Pan-African orogens and magmatic
arcs from asthenospheric mantle, which was enriched in trace elements (U, Th, and light REE). Combining our new data set with
published data of intra-plate magmatic rocks from the Arabian plate indicates two compositionally different domains of lithospheric
mantle in NE-Africa–Arabia. The two domains are spatially related to the subdivision of the Pan-African orogen into a western
section dominated by reworked cratonic basement (NE-Africa; high-μ lithospheric mantle) and an eastern section dominated by
juvenile Pan-African basement (easternmost NE-Africa and Arabia; moderate μ lithospheric mantle). The compositions of the
Pan-African lithospheric mantle and the MORB-type mantle of the Red Sea and Gulf of Aden spreading centers could explain the
Nd–Pb-Sr isotopic compositions of the most pristine Afar flood basalts in Yemen and Ethiopia by mixtures of the isotopic composition
of regional lithospheric and asthenospheric sources.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
312.
Anne-Kathrin Schäffer Tom Jäpel Stefan Zaefferer Rainer Abart Dieter Rhede 《Physics and Chemistry of Minerals》2014,41(10):795-804
Cation exchange experiments between gem quality sanidine \((X_\mathrm{Or} = 0.85)\) and KCl melt produced chemical alteration of alkali feldspar starting at the grain surface and propagating inwards by highly anisotropic Na–K interdiffusion on the alkali sublattice. Diffusion fronts developing in b-direction are very sharp, while diffusion fronts within the a–c-plane are comparatively broad. Due to the composition dependence of the lattice parameters of alkali feldspar, the diffusion induced compositional heterogeneity induces coherency stress and elastic strain. Electron back-scatter diffraction combined with the cross-correlation technique was employed to determine the lattice strain distribution across the Na–K interdiffusion fronts in partially exchanged single crystals of alkali feldspar. The strain changes gradually across the broad fronts within the a–c-plane, with a successive extension primarily in a-direction conferring to the composition strain in unstressed alkali feldspar. In contrast, lattice strain characterised by pronounced extension in b-direction is localised at the sharp diffusion fronts parallel to b, followed by a slight expansion in a-direction in the orthoclase-rich rim. This strain pattern does not confer with the composition induced lattice strain in a stress-free alkali feldspar. It may rather be explained by the mechanical coupling of the exchanged surface layer and the mechanically strong substratum. The lattice distortion localised at the sharp diffusion front may have an influence on the diffusion process and appears to produce a self-sharpening feedback, leading to a local reduction of component mobilities. 相似文献
313.
Daniela Rubatto Dieter Gebauer Mark Fanning 《Contributions to Mineralogy and Petrology》1998,132(3):269-287
The Zermatt–Saas-Fee ophiolites (ZSFO) are one of the best preserved slices of eclogitic oceanic crust in the Alpine chain.
They formed during the opening of the Mesozoic Tethys and underwent subduction to HP/UHP conditions during Alpine compression. A cathodoluminescence-based ion microprobe (SHRIMP) dating of different zircon domains
from metagabbros and oceanic metasediments was carried out to constrain the timing of formation and subduction of this ophiolite,
two fundamental questions in Alpine geodynamics. The formation of the ophiolitic sequence is constrained by the intrusion
ages of the Mellichen and the Allalin metagabbros (164.0 ± 2.7 Ma and 163.5 ± 1.8 Ma) obtained on magmatic zircon domains.
These data are in line with the maximum deposition age for Mn-rich metasediments which overlie the mafic rocks at Lago di
Cignana (161 ± 11 Ma) and at Sparrenflue (ca. 153–154 Ma). An Eocene age of 44.1 ± 0.7 Ma was obtained for whole zircons and zircon rims from an UHP eclogite and two metasediments at Lago di Cignana. One of the Eocene zircons contains a rutile inclusion indicating formation
at HP conditions. As the temperature and pressure peak of these rocks nearly coincide, the Eocene zircons probably constrain the
age for the deepest subduction of the ZSFO. This Eocene age for the UHP metamorphism implies that the ZSFO were subducted later than the Adriatic margin (Sesia-Lanzo Zone) and before the Late Eocene
subduction of the European continental crust below Apulia. A scenario with three subduction episodes propagating in time from
SE to NW is proposed for the geological evolution of the Central and Western Alps.
Received: 1 December 1997 / Accepted: 8 April 1998 相似文献
314.
Thomas Christian Brachert Gerhard B. Brügmann Dieter F. Mertz Ottmar Kullmer Friedemann Schrenk Dorrit E. Jacob Immaculate Ssemmanda Heinrich Taubald 《International Journal of Earth Sciences》2010,99(7):1663-1675
The Neogene was a period of long-term global cooling and increasing climatic variability. Variations in African-Asian monsoon
intensity over the last 7 Ma have been deduced from patterns of eolian dust export into the Indian Ocean and Mediterranean
Sea as well as from lake level records in the East African Rift System (EARS). However, lake systems not only depend on rainfall
patterns, but also on the size and physiography of river catchment areas. This study is based on stable isotope proxy data
(18O/16O, 13C/12C) from tooth enamel of hippopotamids (Mammalia) and aims in unravelling long-term climate and watershed dynamics that control
the evolution of palaeolake systems in the western branch of the EARS (Lake Albert, Uganda) during the Late Neogene (7.5 Ma
to recent). Having no dietary preferences with respect to wooded (C3) versus grassland (C4) vegetation, these territorial, water-dependant mammals are particularly useful for palaeoclimate analyses. As inhabitants
of lakes and rivers, hippopotamid tooth enamel isotope data document mesoclimates of topographic depressions, such as the
rift valleys and, therefore, changes in relative valley depth instead of exclusively global climate changes. Consequently,
we ascribe a synchronous maximum in 18O/16O and 13C/12C composition of hippopotamid enamel centred around 1.5–2.5 Ma to maximum aridity and/or maximum hydrological isolation of
the rift floor from rift-external river catchment areas in response to the combined effects of rift shoulder uplift and subsidence
of the rift valley floor. Structural rearrangements by ~2.5 Ma within the northern segment of the Albertine Rift are well
constrained by reversals in river flow, cannibalisation of catchments, biogeographic turnover and uplift of the Rwenzori horst.
However, a growing rain shadow is not obvious in 18O/16O signatures of the hippopotamid teeth of the Albertine Rift. According to our interpretation, this is the result of the overriding
effect of evaporation on 18O/16O responding to aridification of the basin floor by a valley air circulation system through relative deepening of the valley.
On the other hand, a synchronous arid pulse is not so clearly recorded in palaeosol data and mammalian fauna of the eastern
branch of the EARS. This discrepancy indicates that rift mesoclimates may represent an underestimated aspect in previous palaeoclimate
reconstructions from rift valley data and represent a clear limitation to attempts at global climate reconstructions. The
results of this study also suggest that using 18O/16O data as a proxy to rain shadow evolution must take into account relative basin subsidence to properly document mountain
range uplift. 相似文献
315.
Myo Min Khin Khin LinDepartment of Geology University of Mandalay Mandalay MyanmarFeng Qinglai Faculty of Earth Sciences China University of Geosciences Wuhan Chongpan ChonglakmaniSchool of Geotechnology Suranaree University of Technology Na 《中国地质大学学报(英文版)》2001,12(3)
INTRODUCTIONDuringthepasttwodecades ,amajorityofgeoscientistshaveregardedmainlandSoutheastAsiaascomposedofGond wana derivedterraneswhichcrossed“Paleotethys”tocollidewiththeformerPaleoeurasiancontinentinLateTriassic/Juras sic (Metcalfe ,1999;ScoteseandGolonk… 相似文献
316.
Correlation of Tectono-Stratigraphic Units in Northern Thailand with Those of Western Yunnan (China)
Chongpan Chonglakmani School of Geotechnology Suranaree University of Technology Nakhon Ratchasima ThailandFeng Qinglai Faculty of Earth Sciences China University of Geosciences Wuhan Dieter Meischner Goettingen Center of Geosciences 《中国地质大学学报(英文版)》2001,12(3)
Thecorrelationoftectono stratigraphicunitsofNorthernThailandwiththoseofWesternYunnan (China)isstilllittleunderstood ,partlybecauseofthe paucityofgeologicaldatafromtheUnionofMyanmarandtheLaos,andpartlyduetotheconflictinggeodynamicconceptsadoptedbyvariousa… 相似文献
317.
K. M. Haase Colin W. Devey Dieter F. Mertz Peter Stoffers Dieter Garbe-Schönberg 《Contributions to Mineralogy and Petrology》1996,123(3):223-237
Mohns Ridge lavas between 71 and 72°30′N (∼360 km) have heterogeneous compositions varying between alkali basalts and incompatible-element-depleted
tholeiites. On a large scale there is a continuity of incompatible element and isotopic compositions between the alkali basalts
from the island Jan Mayen and Mohns Ridge tholeiites. The variation in isotopes suggests a heterogeneous mantle which appears
to be tapped preferentially by low degree melts (∼5%) close to Jan Mayen but also shows its signature much further north on
Mohns Ridge. Three lava types with different incompatible element compositions [e.g. chondrite-normalized (La/Sm)N<1 to >2] occur in the area at 72°N and were generated from this heterogeneous mantle. The relatively depleted tholeiitic
melts were mixed with a small degree melt from an enriched source. The elements Ba, Rb and K of the enriched melt were probably
buffered in the mantle by residual amphibole or phlogopite. That such a residual phase is stable in this region of oceanic
mantle suggests both high water contents and low mantle temperatures, at odds with a hotspot origin for Jan Mayen. Instead
we suggest that the melting may be induced by the lowered solidus temperature of a “wet” mantle. Mohns MORB (mid ocean ridge
basalt) and Jan Mayen area alkali basalts have high contents of Ba and Rb compared to other incompatible elements (e.g. Ba/La >10).
These ratios reflect the signature of the mantle source. Ratios of Ce/Pb and Rb/Cs are normal MORB mantle ratios of 25 and
80, respectively, thus the enrichments of Ba and Rb are not indicative of a sedimentary component added to the mantle source
but were probably generated by the influence of a metasomatizing fluid, as supported by the presence of hydrous phases during
the petrogenesis of the alkali basalts. Geophysical and petrological models suggest that Jan Mayen is not the product of hotspot
activity above a mantle plume, and suggest instead that it owes its existence to the unique juxtaposition of a continental
fragment, a fracture zone and a spreading axis in this part of the North Atlantic.
Received: 3 May 1995 / Accepted: 6 November 1995 相似文献
318.
Rainer Thomas Paul Davidson Dieter Rhede Michael Leh 《Contributions to Mineralogy and Petrology》2009,157(4):505-523
In this paper, we show that the crystallization of miarolitic pegmatites at K?nigshain started at about 700°C, in melts containing
up to 30 mass% water. Such high water concentration at low pressures (1–3 kbar) is only possible if the melts are peralkaline.
Such peralkaline melts are highly corrosive, and reacted with the wall rock—here the granite host—forming the graphic granite
zone, in part via a magmatic–metasomatic reaction. With cooling, the water concentration in some melt fractions increased
up to 50 mass% H2O. The melt-dominated system ends below 600°C and passes into a fluid-dominated system, the beginning of which is characterized
by strong pressure fluctuations, caused by the change of OH and CO3
2− in the melt, to molecular water and CO2. We note two generations of smoky quartz, one crystallized above the β–α-transition of quartz (≈573°C), and one below, both
of which contain melt inclusions. This indicates that some melt fraction remains during at least the higher-temperature portion
of the growth of minerals into the miarolitic cavity, contradicting the view that minerals growing into a pegmatite chamber
only do so from aqueous fluids. We show that the K?nigshain miarolitic pegmatites are part of the broad spectrum of pegmatite
types, and the processes active at K?nigshain are representative of processes found in most granitic pegmatites, and are thus
instructive in the understanding of pegmatite formation in general, and constraining the composition and characteristics of
pegmatite-forming melts.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
319.
Dr. Dieter Ortlam 《International Journal of Earth Sciences》1974,63(3):850-884
In the central European Permo-Triassic, eight Violet Horizons (VH 0, VH 1, VH 2, VH 3, VH 4, VH 5, VH 6, and VH A) are recognized as fossil autochthonous soil complexes. The criteria for soil formation and the significance of the Violet Horizons for paleoclimate, paleogeography, and stratigraphy are presented. New proposals are made for the drawing of the Saxonian to Thuringian, Lower to Middle Bunter, and Middle to Upper Bunter boundaries in areas of central Europe. Comparison of the vertebrate fauna of Violet Horizon 5 with the strata of the “Grenzbitumen-Zone” (boundary Bituminous Zone) in the Tessin region (southern Switzerland) indicates a probable correlation of the Upper Bunter with the Anisian and the lower parts of the Muschelkalk with the Ladinian of the Tethys classification. 相似文献
320.
Andreas Schlatter Dieter Schneider Alain Geiger Hans-Gert Kahle 《International Journal of Earth Sciences》2005,94(4):507-514
The southern end of the Upper Rhine Graben is one of the zones in Switzerland where recent crustal movements can be expected because of ongoing seismotectonic processes as witnessed by seismicity clusters occurring in this region. Therefore, in 1973 a control network with levelling profiles across the eastern Rhine Graben fault was installed and measured in the vicinity of the city of Basel in order to measure relative vertical movements and investigate their relationship with seismic events. As a contribution to EUCOR-URGENT, the profiles were observed a third time in the years 2002 and 2003 and connected to the Swiss national levelling network. The results of these local measurements are discussed in terms of accuracy and significance. Furthermore, they are combined and interpreted together with the extensive data set of recent vertical movements in Switzerland (Jura Mountains, Central Plateau and the Alps). In order to be able to prove height changes with precise levelling, their values should amount to at least 3–4 mm (1). The present investigations, however, have not shown any significant vertical movements over the past 30 years. 相似文献