全文获取类型
收费全文 | 392篇 |
免费 | 11篇 |
国内免费 | 3篇 |
专业分类
测绘学 | 18篇 |
大气科学 | 32篇 |
地球物理 | 66篇 |
地质学 | 170篇 |
海洋学 | 14篇 |
天文学 | 86篇 |
综合类 | 6篇 |
自然地理 | 14篇 |
出版年
2022年 | 5篇 |
2021年 | 3篇 |
2020年 | 3篇 |
2019年 | 2篇 |
2018年 | 9篇 |
2017年 | 4篇 |
2016年 | 11篇 |
2015年 | 10篇 |
2014年 | 10篇 |
2013年 | 24篇 |
2012年 | 9篇 |
2011年 | 14篇 |
2010年 | 16篇 |
2009年 | 26篇 |
2008年 | 21篇 |
2007年 | 14篇 |
2006年 | 19篇 |
2005年 | 24篇 |
2004年 | 18篇 |
2003年 | 21篇 |
2002年 | 17篇 |
2001年 | 9篇 |
2000年 | 7篇 |
1999年 | 8篇 |
1998年 | 12篇 |
1997年 | 6篇 |
1995年 | 2篇 |
1993年 | 3篇 |
1991年 | 2篇 |
1990年 | 2篇 |
1989年 | 2篇 |
1987年 | 2篇 |
1986年 | 2篇 |
1980年 | 5篇 |
1978年 | 3篇 |
1977年 | 2篇 |
1976年 | 2篇 |
1974年 | 5篇 |
1969年 | 2篇 |
1965年 | 2篇 |
1964年 | 2篇 |
1957年 | 3篇 |
1956年 | 4篇 |
1955年 | 2篇 |
1953年 | 2篇 |
1951年 | 3篇 |
1948年 | 5篇 |
1928年 | 2篇 |
1916年 | 1篇 |
1912年 | 1篇 |
排序方式: 共有406条查询结果,搜索用时 15 毫秒
1.
2.
3.
4.
5.
6.
Haubold Herbert Scholger Robert Kondopoulou Despina Mauritsch Hermann J. 《Geologie en Mijnbouw》1997,76(1-2):45-55
Various Oligocene formations from NE Greece (ignimbrites from the Medousa area, rhyolites from Zagradenia, granodiorites from Elatia) show discordant paleomagnetic signatures, in each case indicating small cw (clockwise) rotation and also inclination flattening. Marls from Pithion were partly remagnetized in a present-day field. Samples that contain ancient magnetization components also indicate small cw rotation and inclination flattening. However, the magnetization of andesites from Peplos reflects a considerably larger rotation, likely owing to local tectonics. In the context of previous work in the area, these results are used to propose a subdivision of NE Greece into four structural zones of distinctive rotational behaviour (from east to west): sites in zone 1, east of the Kavala-Xanthi-Komotini fault (KXK), show various cw and ccw (counterclockwise) rotation angles owing to complex kinematics resulting from the interaction of the KXK and the north-Anatolian fault zone. However, zone 2, between the KXK and the Strymon valley, is structurally homogeneous ( 10° cw rotation). The paleomagnetic signature of the Vertiskos massif (zone 3) implies a larger (> 30°) cw rotation, whereas sites in the Vardar basin (zone 4) contain a paleomagnetic signature similar to that of zone 2. This suggests a motion of the Vertiscos massif, a meta-ophiolitic nappe, relative to underlying strata. Indeed, zones 2 and 4 may be parts of the same structural unit which underlies this nappe. 相似文献
7.
Sub-solidus Oligocene zircon formation in garnet peridotite during fast decompression and fluid infiltration (Duria, Central Alps) 总被引:1,自引:0,他引:1
Summary A garnet peridotite lens from Monte Duria (Adula nappe, Central Alps, Northern Italy) contains porphyroblastic garnet and
pargasitic amphibole and reached peak metamorphic conditions of ∼830 C, ∼2.8 GPa. A first stage of near isothermal decompression
to pressures <2.0 GPa is characterised by domains where fine grained spinel, clinopyroxene, orthopyroxene and amphibole form.
The newly formed amphibole contains elevated levels of fluid mobile elements such as Rb, Ba and Pb indicating that recrystallization
was assisted by infiltration of a crustal-derived fluid. Further decompression and cooling to ∼720 °C, 0.7–1.0 GPa associated
with limited fluid influx is documented by the formation of orthopyroxene-spinel-amphibole symplectites around garnet.
Zircon separated from this garnet peridotite exhibits two distinct zones. Domain 1 displays polygonal oscillatory zoning and
high trace element contents. It contains clinopyroxene and amphibole inclusions with the same composition as the same minerals
formed during the spinel peridotite equilibration, indicating that this domain formed under sub-solidus conditions during
decompression and influx of crustal fluids. Domain 2 has no zoning and much lower trace element contents. It replaces domain
1 and is likely related to zircon recrystallization during the formation of the symplectites. SHRIMP dating of the two domains
yielded ages of 34.2 ± 0.2 and 32.9 ± 0.3 Ma, respectively, indicating fast exhumation of the peridotite within the spinel
stability field. We suggest that the Duria garnet peridotite originates from the mantle wedge above the tertiary subduction
of the European continental margin and that it was assembled to the country rock gneisses between 34 and 33 Ma.
Third author was Deceased 相似文献
8.
Potential of High-Resolution Satellite Data in the Context of Vulnerability of Buildings 总被引:1,自引:2,他引:1
High-resolution space-borne remote sensing data are investigated for their potential to extract relevant parameters for a
vulnerability analysis of buildings in European countries. For an evaluation of large earthquake scenarios, the number of
parameters in models for vulnerability is reduced to a minimum of relevant information such as the type of building (age,
material, number of storeys) and the geological and spatial context. Building-related parameters can be derived from remote
sensing data either directly (e.g. height) or indirectly based on the recognition of the urban structure type in which the
buildings are located. With the potential of a fully- or semi-automatic inventory of the buildings and their parameters, high-resolution
satellite data and techniques for their processing are a useful supporting tool for the assessment of vulnerability. 相似文献
9.
W. R. Skinner M. D. Flannigan B. J. Stocks D. L. Martell B. M. Wotton J. B. Todd J. A. Mason K. A. Logan E. M. Bosch 《Theoretical and Applied Climatology》2002,71(3-4):157-169
Summary
In Canada, the average annual area of burned forest has increased from around 1 million ha in the 1970’s to over 2.5 million
ha in the 1990’s. A previous study has identified the link between anomalous mid-tropospheric circulation at 500 hPa over
northern North America and wildland fire severity activity in various large regions of Canada over the entire May to August
fire season. In this study, a northern North American study region of the hemispheric gridded 5° latitude by 10° longitude
500 hPa dataset is identified and analysed from 1959 to 1996 for a sequence of six monthly periods through the fire season,
beginning in April and ending in September. Synoptic types, or modes of upper air behavior, are determined objectively by
the eigenvector method employing K-means cluster analysis. Monthly burned areas from the Canadian Large Fire Database (LFDB)
for the same period, 1959 to 1996, are analysed in conjunction with the classified monthly 500 hPa synoptic types. Relationships
between common monthly patterns of anomalous upper flow and spatial patterns of large fire occurrence are examined at the
ecozone level. Average occurrence of a monthly synoptic type associated with very large area burned is approximately 18% of
the years from 1959 to 1996. The largest areas burned during the main fire (May to August) season occur in the western Boreal
and Taiga ecozones – the Taiga Plains, Taiga Shield, Boreal West Shield and Boreal Plains. Monthly burned areas are also analysed
temporally in conjunction with a calculated monthly zonal index (Zim) for two separate areas defined to cover western and eastern Canada. In both western and eastern Canada, high area burned
is associated with synoptic types with mid-tropospheric ridging in the proximity of the affected region and low Zim with weak westerlies and strong meridional flow over western Canada.
Received April 3, 2001 Revised July 13, 2001 相似文献
10.
Sjoerd J. Kluiving J. H. Aleid Bosch Jan H. J. Ebbing Chris S. Mesdag Rogier S. Westerhoff 《Journal of Applied Geophysics》2003,53(4):249
High-resolution seismic data (onshore and offshore), geophysical borehole data as well as detailed lithofacies from airlift boreholes were acquired in northern Netherlands on and around the island of Ameland. Marine and land seismic data combined with information from land boreholes have been explored with the objective of providing a sedimentary model. Qualitative seismic facies analysis of the valley fill commonly shows a thin unit with high amplitude reflectors at the base. Thick units of variable seismic facies (transparent to high amplitude) occur higher up in the sequence. Onlap is common at mid–upper levels within the sandy valley fill (with clay in mm layering), and a transparent seismic facies, corresponding to firm clays, is common at the top. Almost all lithological unit boundaries recognised within core parameters correspond with seismic unconformities within error margins. Subunits contain multiple cyclical trends in gamma ray and grain size. Cyclical trends show lower order fluctuations in gamma radiation on a scale of less than 1 m. Gamma-ray pattern variability between units, e.g. in general coarsening-up or fining-up units, suggests migration of subaqueous outwash fans or ice margin fluctuations. Seismic results could support a headward excavation and backfilling process suggested by Praeg [Morphology, stratigraphy and genesis of buried Elsterian tunnel valleys in the southern North Sea basin [PhD thesis]: University of Edinburgh, 207 pp.; Journal of Applied Geophysics, (this volume)] as being responsible for the formation of buried valleys. On a lithological scale, a more complicated, detailed and cyclical pattern arises. Catastrophic processes are considered unlikely as being responsible for the infill sequence because of the observed small-scale facies variability and because of the presence of diamicton layers. Diamicton layers at the base of basal unconformities as well as higher in sequence could suggest subglacial deformation by grounded ice before and during the valley-fill process. 相似文献