全文获取类型
收费全文 | 407篇 |
免费 | 20篇 |
国内免费 | 5篇 |
专业分类
测绘学 | 4篇 |
大气科学 | 39篇 |
地球物理 | 116篇 |
地质学 | 144篇 |
海洋学 | 30篇 |
天文学 | 52篇 |
综合类 | 3篇 |
自然地理 | 44篇 |
出版年
2023年 | 3篇 |
2021年 | 4篇 |
2020年 | 5篇 |
2019年 | 6篇 |
2018年 | 8篇 |
2017年 | 11篇 |
2016年 | 21篇 |
2015年 | 5篇 |
2014年 | 7篇 |
2013年 | 28篇 |
2012年 | 13篇 |
2011年 | 15篇 |
2010年 | 16篇 |
2009年 | 26篇 |
2008年 | 19篇 |
2007年 | 12篇 |
2006年 | 6篇 |
2005年 | 18篇 |
2004年 | 6篇 |
2003年 | 12篇 |
2002年 | 9篇 |
2001年 | 17篇 |
2000年 | 11篇 |
1999年 | 13篇 |
1998年 | 7篇 |
1997年 | 17篇 |
1996年 | 8篇 |
1995年 | 5篇 |
1994年 | 7篇 |
1993年 | 4篇 |
1992年 | 4篇 |
1991年 | 5篇 |
1990年 | 6篇 |
1988年 | 4篇 |
1986年 | 3篇 |
1985年 | 4篇 |
1984年 | 4篇 |
1983年 | 4篇 |
1982年 | 3篇 |
1981年 | 4篇 |
1980年 | 6篇 |
1978年 | 4篇 |
1975年 | 3篇 |
1974年 | 4篇 |
1973年 | 3篇 |
1972年 | 3篇 |
1968年 | 3篇 |
1967年 | 2篇 |
1965年 | 2篇 |
1959年 | 2篇 |
排序方式: 共有432条查询结果,搜索用时 78 毫秒
71.
Viggo Hansen Niels Nielsen Ruth Helkiær Jensen Kaf Hansen Kaj Hansen Johannes Krüger 《Geografisk tidskrift / udgivet af Bestyrelsen for Det Kongelige danske geografiske selskab》2013,113(1):91-100
Christensen, Leif: Faststående og omlejrede Saale-morånelersaflejringer. Et eksempel fra Szdding-området, Vestjylland. Geografisk Tidsskrift 82: 91–94. Copenhagen, Dec. 1, 1982. In situ clayey till materials on the Skovbjerg Bakkea, western Jutland can be recognized by crop-marks revealing pseudomorphs of ice-wedge polygons in orthogonal, random orthogonal and hexagonal patterns. The tills inside these polygonal patterns have high shear-strength values as measured by vane tests. Remoulded fossil solifluction deposits of till origin reveal stripes and deformed polygonal patterns in the crops. High strength as measured by vane are encountered below fossil solifluction deposits 4 meters below ground. 相似文献
72.
Niels Nielsen Viggo Hansen Kaj Hansen Kr. M. Jensen Sten Folving Sofus Christiansen 《Geografisk tidskrift / udgivet af Bestyrelsen for Det Kongelige danske geografiske selskab》2013,113(1):101-118
Meyer, Marlene: Settlement Patterns and Land-use in Northern Ghana—A Study of the Changes during the period 1963–1991 based on Historical Surveys and recent SPOT-images. Geografisk Tidsskrift 92:101–104. Copenhagen 1992. A study by Hunter (1966) describes how large areas along the Red Volta River bank, have been abandoned due to river blindness. The mapping of current land-use status and settlements patterns, using multispectral SPOT-satellite images, shows how the border of settlements continue to retreat, whereas new land is being reclaimed for bush fields in the abandoned areas. 相似文献
73.
Morten Rasch Birger Hansen Ole Humlum Niels Nielsen Peter Funch Stephen D. Gurney 《Geografisk tidskrift / udgivet af Bestyrelsen for Det Kongelige danske geografiske selskab》2013,113(1):143-159
188 new and previously published radiocarbon dates on Holocene material from Disko Bugt, central West Greenland, are presented together with relevant informations (laboratory number, place name, dated material, geografic coordinates, altitude and δ13C-value) about the dates. In October 1990 an automatic weather station was established at the Arctic station (65 °15′N,53 °31′W), Qeqertarsuaq (Godhavn), Central West Greenland. The Station register parameters each 20 min., and the parameters have been described in an earlier paper in this journal by Nielsen et al. (1995). The present paper summarises main points of the climate during 1996. Open system, or more correctly, hydraulic pingos, are genetically poorly understood. A continuing problem concerns their need for a perennial groundwater supply (intra- or sub-permafrost). This has to be maintained despite the existence of continuous permafrost in many areas where they are located. Recent work on Disko Island has suggested a new type of hydraulic pingo developing only in a “marsh environment”. It is argued that the marsh setting is not relevant to the formation of these features and that they are simply hydraulic pingos. Abstract A group of marsh initiated open system pingo remnants from the Iterdlagssûp kûgssua valley mouth, in Mellemfjord, Disko Island, Central West Greenland was described in Christiansen (1995). Gurney and Worsley (1997) state that the location of this group of pingo remnants in the Iterdlagssûp kûgssua valley mouth is of no relevance to their genesis, and that they presumably were the result of an assumed late Holocene sea level regression, causing permafrost to be established in the valley bottom. In this reply the arguments by Gurney and Worsley (1997) on the Iterdlagssûp kûgssua valley pingos are commented, and it is argued by way of sea level information, frost penetration and water supply that the special setting must indeed have caused pingo initiation and growth. Furthermore, the area has experienced a relative sea level rise during the late Holocene. 相似文献
74.
Birger Ulf Hansen Ole Humlum Niels Nielsen Dorte P. Lundqvist Ditte L. Jansen Christian Christiansen 《Geografisk tidskrift / udgivet af Bestyrelsen for Det Kongelige danske geografiske selskab》2013,113(2):93-109
An automatic meteorological station has been operating at the Arctic Station (69°15'N, 53°31'W) in West Greenland since 1990. This paper summarises meteorological parameters during 2002, including snow cover, ground temperatures and active layer development, and air temperatures at the Station during the last 12 years are compared to large scale trends during the last century. A compilation of 93 sedimentation rate determinations based on 210Pb dating has been carried out for the North Sea-Baltic Sea transition area from a database containing 165 determinations carried out by Danish institutions. In the depositional parts of the area sedimentation rates generally range 25–6403 g m?2 y?1. An extreme rate of 13351 g m?2 y?1 is observed on a station in the Skagerrak. Sedimentation rates significantly increase with depth indicating that the Skagerrak and northern parts of the Kattegat as well as the deep basins in the Baltic Sea act as depocentres for fine-grained sediments. Apparently, sedimentation rates have increased in recent years. 相似文献
75.
Søren Munch Kristiansen Jacob Clement Yde Teresa Gómez Bárcena Bjarne Holm Jakobsen Jesper Olsen Niels Tvis Knudsen 《Geografiska Annaler: Series A, Physical Geography》2013,95(2):97-108
Groundwater in front of warm‐based glaciers is likely to become a more integrated part of the future proglacial hydrological system at high latitudes due to global warming. Here, we present the first monitoring results of shallow groundwater chemistry and geochemical fingerprinting of glacier meltwater in front of a warm‐based glacier in Southeast Greenland (Mittivakkat Gletscher, 65° 41′ N, 37° 48′ W). The groundwater temperature, electrical conductivity and pressure head were monitored from August 2009 to August 2011, and water samples were collected in 2009 and analyzed for major ions and water isotopes (δD, δ18O). The 2 yrs of monitoring revealed that major outbursts of glacier water during the ablation season flushed the proglacial aquifer and determined the groundwater quality for the next 2–8 weeks until stable chemical conditions were reached again. Water isotope composition shows that isotopic fractionation occurs in both groundwater and glacier meltwater, but fractionation due to evaporation from near‐surface soil moisture prior to infiltration has the most significant effect. This study shows that groundwater in Low Arctic Greenland is likely to possess a combined geochemical and isotopic composition, which is distinguishable from other water sources in the proglacial environment. However, the shallow groundwater composition at a given time is highly dependent on major outbursts of glacier water in the previous months. 相似文献
76.
Paleo- and Neoproterozoic magmatic and tectonometamorphic evolution of the Isla Cristalina de Rivera (Nico Pérez Terrane, Uruguay) 总被引:1,自引:0,他引:1
Pedro Oyhant?abal Martin Wagner-Eimer Klaus Wemmer Bernhard Schulz Robert Frei Siegfried Siegesmund 《International Journal of Earth Sciences》2012,101(7):1745-1762
The Isla Cristalina de Rivera crystalline complex in northeastern Uruguay underwent a multistage magmatic and metamorphic evolution. Based on SHRIMP U–Pb zircon, Th–U–Pb monazite (CHIME-EPMA method) and K–Ar age data from key units several events can be recognized: (1) multistage magmatism at 2,171–2,114?Ma, recorded on zircon of the granulitic orthogneisses and their 2,093–2,077?Ma overgrowths; (2) a distinct amphibolite facies metamorphism at ~1,980?Ma, recorded by monazite; (3) greenschist facies reworking and shearing at ca. 606?Ma (monazite and K–Ar on muscovite) along the Rivera Shear Zone, and finally (4) intrusion of the post-tectonic Sobresaliente and Las Flores granites at around 585?Ma. Lithological similarities, geographic proximity and coeval magmatic and metamorphic events indicate a similar tectonometamorphic evolution for the Isla Cristalina de Rivera, the Valentines Block in Uruguay and the Santa María Chico Granulitic Complex in southern Brazil, since at least 2.1?Ga. 相似文献
77.
Hendrik Lamert H. Geistlinger U. Werban C. Schütze A. Peter G. Hornbruch A. Schulz M. Pohlert S. Kalia M. Beyer J. Gro?mann A. Dahmke P. Dietrich 《Environmental Earth Sciences》2012,67(2):447-462
Potential pathways in the subsurface may allow upwardly migrating gaseous CO2 from deep geological storage formations to be released into near surface aquifers. Consequently, the availability of adequate methods for monitoring potential CO2 releases in both deep geological formations and the shallow subsurface is a prerequisite for the deployment of Carbon Capture and Storage technology. Geoelectrical surveys are carried out for monitoring a small-scale and temporally limited CO2 injection experiment in a pristine shallow aquifer system. Additionally, the feasibility of multiphase modeling was tested in order to describe both complex non-linear multiphase flow processes and the electrical behavior of partially saturated heterogeneous porous media. The suitability of geoelectrical methods for monitoring injected CO2 and geochemically altered groundwater was proven. At the test site, geoelectrical measurements reveal significant variations in electrical conductivity in the order of 15?C30?%. However, site-specific conditions (e.g., geological settings, groundwater composition) significantly influence variations in subsurface electrical conductivity and consequently, the feasibility of geoelectrical monitoring. The monitoring results provided initial information concerning gaseous CO2 migration and accumulation processes. Geoelectrical monitoring, in combination with multiphase modeling, was identified as a useful tool for understanding gas phase migration and mass transfer processes that occur due to CO2 intrusions in shallow aquifer systems. 相似文献
78.
Jana Just Bernhard Schulz Helga de Wall Fred Jourdan Manoj K. Pandit 《Gondwana Research》2011,19(2):402-412
The in-situ “chemical” Th–U–Pb dating of monazite with the electron microprobe is used to unravel the Neoproterozoic tectono-thermal history of the “Erinpura Granite” terrane in the foreland of the Delhi Fold Belt (DFB) in the NW Indian craton. These granitoids are variably deformed and show effects of shearing activity. Monazites from the Erinpura granitoids recorded two main events; (1) protolith crystallization at 863 ± 23 Ma and (2) recrystallization and formation of new Th-poor monazite at 775 ± 26 Ma during shear overprint. Some components of the Erinpura granitoids, such as the Siyawa Granite and granites exposed near Sirohi town, show evidence of migmatization. This migmatization event is documented by anatexis and associated monazite crystallization at 779 ± 16 Ma. The age data indicate an overlap in timing between anatectic event and ductile shear deformation. The end of the tectono-thermal event in the Sirohi area is constrained by a 736 ± 6 Ma Ar–Ar muscovite age data from the ductile shear zone. 相似文献
79.
The pre-Mesozoic, mainly Variscan metamorphic basement of the Col de Bérard area (Aiguilles Rouges Massif, External domain)
consists of paragneisses and micaschists together with various orthogneisses and metabasites. Monazite in metapelites was
analysed by the electron microprobe (EMPA-CHIME) age dating method. The monazites in garnet micaschists are dominantly of
Variscan age (330–300 Ma). Garnet in these rocks displays well developed growth zonations in Fe–Mg–Ca–Mn and crystallized
at maximal temperatures of 670°C/7 kbar to the west and 600°C/7–8 kbar to the east. In consequence the monazite is interpreted
to date a slightly pressure-dominated Variscan amphibolite-facies evolution. In mylonitic garnet gneisses, large metamorphic
monazite grains of Ordovician–Silurian (~440 Ma) age but also small monazite grains of Variscan (~300 Ma) age were discovered.
Garnets in the mylonitic garnet gneisses display high-temperature homogenized Mg-rich profiles in their cores and crystallized
near to ~800°C/6 kbar. The Ordovician–Silurian-age monazites can be assigned to a pre-Variscan high-temperature event recorded
by the homogenised garnets. These monazite age data confirm Ordovician–Silurian and Devonian–Carboniferous metamorphic cycles
which were already reported from other Alpine domains and further regions in the internal Variscides. 相似文献
80.
B. Panteleit K. Hamer R. Kringel W. Kessels H. D. Schulz 《Environmental Earth Sciences》2011,62(1):77-91
Geochemical processes, occurring in a stable transition zone between saltwater and freshwater, were simulated in a 2D, multi-layer
flow chamber experiment. Mixing, calcite dissolution, and oxidative degradation of organic matter were identified as the main
controlling factors. The results of the chamber experiment were compared to field data and verified by thermodynamic modeling.
Similarity in most ion distributions suggests the general applicability of the experimental method. Differences in the redox
conditions between field and experiment were reflected by the oxidants involved in the mineralization of organic carbon; while
field data show evidence of sulfate reduction, the presence of oxygen in the laboratory experiment resulted in the reoxidation
of sulfides. 相似文献