全文获取类型
收费全文 | 687篇 |
免费 | 54篇 |
国内免费 | 1篇 |
专业分类
测绘学 | 14篇 |
大气科学 | 50篇 |
地球物理 | 251篇 |
地质学 | 227篇 |
海洋学 | 23篇 |
天文学 | 118篇 |
综合类 | 10篇 |
自然地理 | 49篇 |
出版年
2024年 | 2篇 |
2023年 | 2篇 |
2022年 | 6篇 |
2021年 | 12篇 |
2020年 | 13篇 |
2019年 | 11篇 |
2018年 | 51篇 |
2017年 | 46篇 |
2016年 | 64篇 |
2015年 | 48篇 |
2014年 | 51篇 |
2013年 | 58篇 |
2012年 | 27篇 |
2011年 | 30篇 |
2010年 | 34篇 |
2009年 | 33篇 |
2008年 | 29篇 |
2007年 | 28篇 |
2006年 | 26篇 |
2005年 | 20篇 |
2004年 | 12篇 |
2003年 | 12篇 |
2002年 | 10篇 |
2001年 | 4篇 |
2000年 | 10篇 |
1999年 | 6篇 |
1998年 | 11篇 |
1997年 | 4篇 |
1996年 | 13篇 |
1995年 | 6篇 |
1994年 | 4篇 |
1993年 | 6篇 |
1992年 | 2篇 |
1991年 | 8篇 |
1990年 | 3篇 |
1989年 | 3篇 |
1988年 | 2篇 |
1986年 | 4篇 |
1985年 | 3篇 |
1984年 | 4篇 |
1983年 | 4篇 |
1982年 | 2篇 |
1981年 | 3篇 |
1979年 | 2篇 |
1976年 | 1篇 |
1974年 | 1篇 |
1973年 | 3篇 |
1971年 | 2篇 |
1970年 | 1篇 |
1969年 | 2篇 |
排序方式: 共有742条查询结果,搜索用时 312 毫秒
391.
Strontium isotope identification of water mixing and recharge sources in a river system (Oder River,central Europe): A quantitative approach
下载免费PDF全文
![点击此处可从《水文研究》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Mateusz Zieliński Jolanta Dopieralska Zdzislaw Belka Aleksandra Walczak Marcin Siepak Michał Jakubowicz 《水文研究》2018,32(16):2597-2611
This study uses Sr isotope composition (87Sr/86Sr) and Sr content of waters of the Oder, one of the largest rivers in central Europe, to fingerprint natural and anthropogenic contributions to its Sr budget and to evaluate water mixing processes in its hydrological system. It also demonstrates a simple method of quantifying natural and anthropogenic Sr inputs in the watershed. The method has potential for environmental and archaeological research because past Sr geochemistry of river water can easily be reconstructed. For the first time, a catchment‐scale impact of anthropogenic sources on the Sr budget of a middle‐size river is shown in a quantitative way. The water of the Oder is characterized by a relatively uniform Sr isotope composition, from 0.7100 to 0.7108, contrasting with strong variations in Sr concentration, from 0.25 to 1.27 mg/L. There is a general seasonal trend in variability, with waters becoming more radiogenic and dilute with respect to the Sr in the spring time. This Sr systematics differs significantly from the Sr budgets of the majority of the Oder tributaries that exhibit more radiogenic composition and systematically lower Sr concentrations. A mixing scenario in the Oder involves Sr contribution from four principal water sources: (a) shallow ground waters with Sr derived from near‐surface weathering of silicates, (b) moderately radiogenic mine waters from the Upper Silesian Coal Basin, (c) unradiogenic mine waters from the Permian sequence of the copper district, and (d) unradiogenic ground waters from shallow‐seated Palaeogene, Neogene, and Mesozoic aquifers. The Sr budget of the Oder is primarily controlled by inputs of dissolved Sr from anthropogenic sources, which overprint the natural background, controlled by geology. Thus, about 47.5% of Sr originates from agriculture, industrial, and municipal additions, 31.5% from mine water inputs, and only 21% from natural sources, that is, rock weathering and atmospheric precipitation. Reconstruction of the past Sr chemistry of the Oder reveals that its present‐day Sr isotope composition is temporary and significantly different from that of the preindustrial times. 相似文献
392.
This article presents an equivalent stress approach that can be used in many elastoplastic constitutive models for unsaturated soils. The use of the equivalent stress leads to a modified yield locus that is independent of the suction. In addition, the equivalent stress becomes the major stress variable, with suction required only as an additional variable in calculations. The model on the basis of equivalent stress predicts exactly the same soil behaviour, with the sole difference being the use of equivalent stress instead of original stress variables. This article also presents the equivalent stress formulations of several constitutive models for unsaturated soils, including the Barcelona Basic Model. The predictions from these models remain unchanged, with the only difference being in their implementation. Finally, the equivalent stress approach and the net stress approach are compared for the Barcelona Basic Model. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
393.
Tectonothermal history of the Holy Cross Mountains (Poland) in the light of low‐temperature thermochronology
下载免费PDF全文
![点击此处可从《地学学报》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Dariusz Botor Aneta A. Anczkiewicz István Dunkl Jan Golonka Mariusz Paszkowski Stanisław Mazur 《地学学报》2018,30(4):270-278
The low‐temperature thermal history of the Holy Cross Mountains (HCM) is investigated by apatite fission track and apatite and zircon (U–Th)/He thermochronology. Our results provide constraints on the deformation history of Palaeozoic basement rocks in the transition area from Precambrian to Palaeozoic Europe that are exposed from beneath Permian–Mesozoic sediments within the HCM. Late to post‐Variscan cooling of the Palaeozoic strata from maximum temperatures is shown to be a major feature of the HCM. This cooling likely followed a heating event related to burial and/or hot fluid circulation along the Holy Cross Fault in the late Carboniferous. The central part of the HCM shows a rapid cooling event caused by tectonic inversion, which started in the Late Cretaceous. However, this event was less pronounced in the western margin of the HCM, where slow cooling continued throughout the Mesozoic with only minor acceleration of the cooling rate since the latest Cretaceous. 相似文献
394.
Petra Hájková Ab Grootjans Mariusz Lamentowicz Eliška Rybníčková Mikuláš Madaras Věra Opravilová Dierk Michaelis Michal Hájek Hans Joosten Lesław Wołejko 《第四纪科学杂志》2012,27(3):233-243
In general, mires develop by autogenic succession from more groundwater‐fed to more rainwater‐fed. This study from a calcareous mire in the West Carpathians (Slovakia) describes a similar development in the Early Holocene, followed by a reverse development in the Middle and Late Holocene. Pollen, macrofossil and testate amoeba analyses show that the site started as a minerotrophic open fen woodland. After 10 700 cal a BP autogenic succession led to the accumulation of at least 1 m of Sphagnum fuscum peat. Around 9000 cal a BP, as climate could no longer sustain a stable water regime, the bog desiccated and a fire broke out. The fire removed part of the peat layer and as a consequence relative water levels rose, leading to the establishment of a wet minerotrophic swamp carr with Thelypteris palustris, Equisetum sp. and Alnus sp. with extremely slow peat accumulation. After 600 cal a BP, rapid peat accumulation with calcareous tufa formation resumed as a result of anthropogenic deforestation and hydrological changes in the catchment and resulting increased groundwater discharge. At present the mire still hosts a wealth of relict and endangered plant and animal species typical of calcareous fens and fen meadows. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
395.
Jacek Grabowski János Haas Emö Márton Andrzej Pszczółkowski 《Studia Geophysica et Geodaetica》2010,54(1):1-26
Jurassic-Cretaceous sediments of Transdanubian Range in Northern Hungary mostly retain their primary magnetizations and are
suitable for detailed bio- and magnetostratigraphic studies. The Lókút section, 13 m in thickness, is localized in the central
part of the Transdanubian Range. It contains the Jurassic/Cretaceous boundary in pelagic carbonate facies. Although the colour
of the rocks changes from reddish-pinkish in the bottom to almost white at the top of the section, magnetite was identified
as a magnetic carrier without evidence of hematite. Integrated bio- and magnetostratigraphical investigations resulted in
construction of chronostratigraphical scheme. The section, embraces magnetozones from M21r to M18r, of upper Lower Tithonian
(Parastomiosphaera malmica Zone) to Lower Berriasian age (Calpionella alpina Subzone). Sedimentation rate of pelagic limestones
increased from 1–3 m/My during Tithonian to 5–7 m/My during Berriasian. The sedimentation rate and its changes up the section
are comparable to those from the Jurassic/Cretaceous boundary sections of Trento plateau (Southern Alps, Italy) — sedimentary
environments of Trento plateau and central Transdanubian Range in that time might be similar. Sedimentation rate within Umbrian
Apennine basins and Križna unit in the Western Tatra Mts. seems significantly higher. Analysis of rock magnetic parameters
reveals that detrital input was much lower into the Lókút section than into Križna basin in the Tatra Mts. (Zliechov trough).
Increase of sedimentation rate occurs in both sections in the Upper Tithonian — Lower Berriasian. It coincides with the onset
of calpionellid limestone facies and is related to increased productivity of calcareous micro- and nannoplankton. Detailed
correlation of both sections basing on rock magnetic parameters and susceptibility changes is, however, not possible. They
are dependent mostly on the local sedimentary conditions (Bakony Mts. — deep water plateau; Križna unit — deep water trough)
and correlation with any “global” paleoenvironmental (climatic, eustatic) trends is not straightforward. 相似文献
396.
New Methods for Modeling Laterolog Resistivity Corrections 总被引:1,自引:1,他引:0
Jadwiga Anna Jarzyna Adam Cichy Dezső Drahos Attila Galsa Maria Joanna Bała Andrzej Ossowski 《Acta Geophysica》2016,64(2):417-442
The paper presents methods for laterolog response modeling. In Coulomb’s charges method, Laplace’s equation is solved for the electric field distribution in rock medium with internal boundaries between different resistivity layers. There, the boundary problem is reduced to Fred-holm integral equation of the second kind. The second method uses a finite element array to model apparent resistivity from laterolog. The task is treated as DC problem and the Laplace equation is solved numerically. The presented methods were applied to borehole data covering a typical stratigraphie section of the Fore-Sudetic Monocline in southwestern Poland. Apparent resistivity was calculated using the Coulomb’s charges method and alternatively modeled using a finite element method which gave similar results. Then, a series of linear corrections for borehole, shoulder bed, and filtration effects for apparent resistivity obtained by the Coulomb’s charges method demonstrated the feasibility of calculating true resistivity of virgin and invaded zones. The proposed methods provide a flexible solution in modeling which can be adapted to other logs. 相似文献
397.
Prospects for Solar and Space Weather Research with Polish Part of the LOFAR Telescope 总被引:1,自引:1,他引:0
Bartosz P. Dąbrowski Andrzej Krankowski Leszek Błaszkiewicz Hanna Rothkaehl 《Acta Geophysica》2016,64(3):825-840
The LOw-Frequency ARray (LOFAR) is a new radio interferometer that consists of an array of stations. Each of them is a phase array of dipole antennas. LOFAR stations are distributed mostly in the Netherlands, but also throughout Europe. In the article we discuss the possibility of using this instrument for solar and space weather studies, as well as ionosphere investigations. We are expecting that in the near future the LOFAR telescope will bring some interesting observations and discoveries in these fields. It will also help to observe solar active events that have a direct influence on the near-Earth space weather. 相似文献
398.
Stanisław R. Ćmiel 《Acta Geophysica》2012,60(2):438-448
The paper presents the results of studies of fault zones carried out in the Upper Silesian Coal Basin. Three types of changes
of the coal were distinguished: degradative changes connected with a deterioration in the quality of the coal; aggradational
changes connected with an increase in the quality of coal; and the type of coal which shows no significant change in the values
of its parameters. 相似文献
399.
Iwona S. Stachlewska Michał Piądłowski Szymon Migacz Artur Szkop Anna J. Zielińska Paweł L. Swaczyna 《Acta Geophysica》2012,60(5):1386-1412
Jenoptik’s CHM 15k ceilometer was used to monitor the vertical structure of the atmospheric boundary layer (ABL) over Warsaw, from 2008 until 2011, on Mondays and Thursdays, in 24h periods. Hereby, we present an assessment of the signal-to-noise ratio along with a sensitivity study of signal smoothing methods developed in-house. With the proposed averaging, ceilometer attenuated-backscatter signals reached the high troposphere, which makes this sensor competitive to a single-wavelength elastic lidar. The smoothed signals were employed as an input for algorithms developed to automatically detect the ABL height, clouds, fog, and precipitation in the lower troposphere. The classification of weather conditions was validated by the METAR reports from the Warsaw Airport. The obtained ABL heights were compared to those assessed from radio-soundings from a nearby meteorological station WMO12374 in Legionowo. An inter-comparison of the ABL heights, derived by using the Jenoptik’s automated routine against the in-house developed algorithms, is in favor of the latter. The presented four annual cycles of the ABL height, obtained with various derivative-based methods, are the first such long-term results reported using the CHM 15k sensor in Eastern Europe. 相似文献
400.
Monika B. Kalinowska Paweł M. Rowiński Janusz Kubrak Dorota Mirosław-Świątek 《Acta Geophysica》2012,60(1):214-231
The problem of two-dimensional mathematical modelling of heated cooling water discharges into running waters is considered
in the paper. Two models — one for the evaluation of 2D turbulent velocity field and the other, developed by authors of the
study, for 2D heat transport in open-channels — were used in the calculations. Relevant scenarios of the spread of heated
water discharged from a designed gas-stem power plant to be constructed at the Vistula River were presented. Environmentally
most friendly variant of the discharge of the thermal pollution was selected from among four various variants. 相似文献