全文获取类型
收费全文 | 91篇 |
免费 | 12篇 |
国内免费 | 1篇 |
专业分类
大气科学 | 14篇 |
地球物理 | 46篇 |
地质学 | 19篇 |
海洋学 | 8篇 |
天文学 | 9篇 |
综合类 | 1篇 |
自然地理 | 7篇 |
出版年
2023年 | 1篇 |
2021年 | 2篇 |
2020年 | 3篇 |
2019年 | 5篇 |
2018年 | 6篇 |
2017年 | 3篇 |
2016年 | 5篇 |
2015年 | 7篇 |
2014年 | 9篇 |
2013年 | 12篇 |
2012年 | 4篇 |
2011年 | 4篇 |
2010年 | 8篇 |
2009年 | 8篇 |
2008年 | 4篇 |
2006年 | 5篇 |
2005年 | 1篇 |
2004年 | 5篇 |
2003年 | 2篇 |
2002年 | 3篇 |
2001年 | 3篇 |
1999年 | 1篇 |
1998年 | 2篇 |
1991年 | 1篇 |
排序方式: 共有104条查询结果,搜索用时 31 毫秒
81.
Trans‐dimensional Bayesian inversion of controlled‐source electromagnetic data in the German North Sea
下载免费PDF全文
![点击此处可从《Geophysical Prospecting》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Romina A. S. Gehrmann Jan Dettmer Katrin Schwalenberg Martin Engels Stan E. Dosso Asli Özmaral 《Geophysical Prospecting》2015,63(6):1314-1333
This paper presents the first controlled‐source electromagnetic survey carried out in the German North Sea with a recently developed seafloor‐towed electrical dipole–dipole system, i.e., HYDRA II. Controlled‐source electromagnetic data are measured, processed, and inverted in the time domain to estimate an electrical resistivity model of the sub‐seafloor. The controlled‐source electromagnetic survey targeted a shallow, phase‐reversed, seismic reflector, which potentially indicates free gas. To compare the resistivity model to reflection seismic data and draw a combined interpretation, we apply a trans‐dimensional Bayesian inversion that estimates model parameters and uncertainties, and samples probabilistically over the number of layers of the resistivity model. The controlled‐source electromagnetic data errors show time‐varying correlations, and we therefore apply a non‐Toeplitz data covariance matrix in the inversion that is estimated from residual analysis. The geological interpretation drawn from controlled‐source electromagnetic inversion results and borehole and reflection seismic data yield resistivities of ~1 Ωm at the seafloor, which are typical for fine‐grained marine deposits, whereas resistivities below ~20 mbsf increase to 2–4 Ωm and can be related to a transition from fine‐grained (Holocene age) to unsorted, coarse‐grained, and compacted glacial sediments (Pleistocene age). Interface depths from controlled‐source electromagnetic inversion generally match the seismic reflector related to the contrast between the different depositional environments. Resistivities decrease again at greater depths to ~1 Ωm with a minimum resistivity at ~300 mbsf where a seismic reflector (that marks a major flooding surface of late Miocene age) correlates with an increased gamma‐ray count, indicating an increased amount of fine‐grained sediments. We suggest that the grain size may have a major impact on the electrical resistivity of the sediment with lower resistivities for fine‐grained sediments. Concerning the phase‐reversed seismic reflector that was targeted by the survey, controlled‐source electromagnetic inversion results yield no indication for free gas below it as resistivities are generally elevated above the reflector. We suggest that the elevated resistivities are caused by an overall decrease in porosity in the glacial sediments and that the seismic reflector could be caused by an impedance contrast at a thin low‐velocity layer. Controlled‐source electromagnetic interface depths near the reflector are quite uncertain and variable. We conclude that the seismic interface cannot be resolved with the controlled‐source electromagnetic data, but the thickness of the corresponding resistive layer follows the trend of the reflector that is inclined towards the west. 相似文献
82.
Influence of boundary conditions on the out‐of‐plane response of brick masonry walls in buildings with RC slabs
下载免费PDF全文
![点击此处可从《地震工程与结构动力学》网站下载免费的PDF全文](/ch/ext_images/free.gif)
In modern unreinforced masonry buildings with stiff RC slabs, walls of the top floor are most susceptible to out‐of‐plane failure. The out‐of‐plane response depends not only on the acceleration demand and wall geometry but also on the static and kinematic boundary conditions of the walls. This paper discusses the influence of these boundary conditions on the out‐of‐plane response through evaluation of shake table test results and numerical modelling. As a novum, it shows that the in‐plane response of flanking elements, which are orthogonal to the wall whose out‐of‐plane response is studied, has a significant influence on the vertical restraint at the top of the walls. The most critical configuration exists if the flanking elements are unreinforced masonry walls that rock. In this case, the floor slabs can uplift, and the out‐of‐plane load‐bearing walls loose the vertical restraint at the top. Numerical modelling confirms this experimentally observed behaviour and shows that slab uplift and the difference in base and top excitation have a strong influence on the out‐of‐plane response of the walls analysed. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
83.
Hermann Held Friedrich-Wilhelm Gerstengarbe Tobias Pardowitz Joaquim G. Pinto Uwe Ulbrich Kai Born Markus G. Donat Melanie K. Karremann Gregor C. Leckebusch Patrick Ludwig Katrin M. Nissen Hermann Österle Boris F. Prahl Peter C. Werner Daniel J. Befort Olaf Burghoff 《Climatic change》2013,121(2):195-207
We present projections of winter storm-induced insured losses in the German residential building sector for the 21st century. With this aim, two structurally most independent downscaling methods and one hybrid downscaling method are applied to a 3-member ensemble of ECHAM5/MPI-OM1 A1B scenario simulations. One method uses dynamical downscaling of intense winter storm events in the global model, and a transfer function to relate regional wind speeds to losses. The second method is based on a reshuffling of present day weather situations and sequences taking into account the change of their frequencies according to the linear temperature trends of the global runs. The third method uses statistical-dynamical downscaling, considering frequency changes of the occurrence of storm-prone weather patterns, and translation into loss by using empirical statistical distributions. The A1B scenario ensemble was downscaled by all three methods until 2070, and by the (statistical-) dynamical methods until 2100. Furthermore, all methods assume a constant statistical relationship between meteorology and insured losses and no developments other than climate change, such as in constructions or claims management. The study utilizes data provided by the German Insurance Association encompassing 24 years and with district-scale resolution. Compared to 1971–2000, the downscaling methods indicate an increase of 10-year return values (i.e. loss ratios per return period) of 6–35 % for 2011–2040, of 20–30 % for 2041–2070, and of 40–55 % for 2071–2100, respectively. Convolving various sources of uncertainty in one confidence statement (data-, loss model-, storm realization-, and Pareto fit-uncertainty), the return-level confidence interval for a return period of 15 years expands by more than a factor of two. Finally, we suggest how practitioners can deal with alternative scenarios or possible natural excursions of observed losses. 相似文献
84.
Katrin Stephan Ralf Jaumann Roland Wagner Dale P. Cruikshank Thomas Roatsch Robert H. Brown Bonnie J. Buratti Tom B. McCord Kevin H. Baines 《Icarus》2010,206(2):631-652
We present a detailed analysis of the variations in spectral properties across the surface of Saturn’s satellite Dione using Cassini/VIMS data and their relationships to geological and/or morphological characteristics as seen in the Cassini/ISS images. This analysis focuses on a local region on Dione’s anti-saturnian hemisphere that was observed by VIMS with high spatial resolution during orbit 16 in October 2005. The results are incorporated into a global context provided by VIMS data acquired within Cassini’s first 50 orbits. Our results show that Dione’s surface is dominated by at least one global process. Bombardment by magnetospheric particles is consistent with the concentration of dark material and enhanced CO2 absorption on the trailing hemisphere of Dione independent of the geology. Local regions within this terrain indicate a special kind of resurfacing that probably is related to large-scale impact process. In contrast, the enhanced ice signature on the leading side is associated with the extended ejecta of the fresh impact crater Creusa (∼49°N/76°W). Although no geologically active regions could be identified, Dione’s tectonized regions observed with high spatial resolution partly show some clean H2O ice implying that tectonic processes could have continued into more recent times. 相似文献
85.
Katrin J. Meissner Michael Eby Andrew J. Weaver Oleg A. Saenko 《Climate Dynamics》2008,30(2-3):161-174
We present several equilibrium runs under varying atmospheric CO2 concentrations using the University of Victoria Earth System Climate Model (UVic ESCM). The model shows two very different
responses: for CO2 concentrations of 400 ppm or lower, the system evolves into an equilibrium state. For CO2 concentrations of 440 ppm or higher, the system starts oscillating between a state with vigorous deep water formation in
the Southern Ocean and a state with no deep water formation in the Southern Ocean. The flushing events result in a rapid increase in atmospheric temperatures, degassing of CO2 and therefore an increase in atmospheric CO2 concentrations, and a reduction of sea ice cover in the Southern Ocean. They also cool the deep ocean worldwide. After the
flush, the deep ocean warms slowly again and CO2 is taken up by the ocean until the stratification becomes unstable again at high latitudes thousands of years later. The
existence of a threshold in CO2 concentration which places the UVic ESCM in either an oscillating or non-oscillating state makes our results intriguing.
If the UVic ESCM captures a mechanism that is present and important in the real climate system, the consequences would comprise
a rapid increase in atmospheric carbon dioxide concentrations of several tens of ppm, an increase in global surface temperature
of the order of 1–2°C, local temperature changes of the order of 6°C and a profound change in ocean stratification, deep water
temperature and sea ice cover. 相似文献
86.
AbstractMulti-stakeholder sustainability certification schemes have become a favorite instrument for applying good governance, though studies indicate their inefficiency at the producer level. In this study, we used a mixed-method approach to first, map the institutional context of independent oil-palm smallholders in rural Sumatra while, second, reflecting upon the impact of the Smallholder Standard proposed by the Roundtable on Sustainable Palm Oil on smallholder management practices. We hold that non-recognition of micro-scale perspectives within governance processes may partially explain noncompliance with certification principles among smallholders. The Smallholder Standard appears unable to mitigate challenges important for smallholders, who in turn cannot properly comply with it, due to problems including weather instability and high management costs. We suggest that certification schemes need to work on some overlooked but essential preconditions of good governance, namely gaining micro-level visibility and acceptance. 相似文献
87.
88.
Reservoirs as sentinels of catchments: the Rappbode Reservoir Observatory (Harz Mountains, Germany) 总被引:2,自引:2,他引:0
Karsten Rinke Burkhard Kuehn Serghei Bocaniov Katrin Wendt-Potthoff Olaf Büttner Jörg Tittel Martin Schultze Peter Herzsprung Helmut Rönicke Karsten Rink Kristine Rinke Maren Dietze Marco Matthes Lothar Paul Kurt Friese 《Environmental Earth Sciences》2013,69(2):523-536
Reservoirs can be viewed as sentinels of their catchments and a detailed monitoring of reservoir systems informs about biogeochemical and hydrological processes at the catchment scale. We developed a comprehensive online monitoring system at Rappbode reservoir, the largest drinking water reservoir in Germany, and its inflows. The Rappbode Reservoir Observatory comprises of a set of online-sensors for the measurement of physical, chemical, and biological variables and is complemented by a biweekly limnological sampling schedule. Measurement stations are deployed at the four major inflows into the system, at the outlets of all pre-reservoirs, as well as in the main reservoir. The newly installed monitoring system serves both scientific monitoring and process studies, as well as reservoir management. Particular emphasis is paid to the monitoring of short-term dynamics and many variables are measured at high temporal resolution. As an example, we quantitatively documented a flood event which mobilised high loads of dissolved organic carbon and changed the characteristics of the receiving reservoir from eutrophic to dystrophic within a few days. This event could have been completely missed by conventional biweekly sampling programs, but is relevant for biogeochemical fluxes at the catchment scale. We also show that the high frequency data provide a deeper insight into ecosystem dynamics and lake metabolism. The Rappbode Reservoir Observatory; moreover, offers a unique study site to apply, validate, and develop state of the art lake models to improve their predictive capabilities. 相似文献
89.
In this article, we contribute to a better understanding of contextual differences related to residential segregation. We illuminate one specific contextual factor—housing oversupply—and how it intersects with historically inherited patterns of socio-spatial differentiation and other drivers of residential segregation. The study is based on an analysis of how segregation has developed over the last 20 years in the city of Leipzig, Germany. This case offers the rare possibility of studying the impact of city-wide housing oversupply on residential segregation, rather than concentrating on decline or decay in specific areas. We examine how oversupply emerged at the meeting point of changes in market structures, housing preferences, welfare state interventions, and migration trends in the post-socialist transition. Using existing statistical data, we demonstrate how oversupply has fostered a fast and thorough reshuffling of residential patterns. After a period of resolving segregation patterns from the socialist era, oversupply acts as a catalyst for recently emerging residential segregation patterns. 相似文献
90.