全文获取类型
收费全文 | 220篇 |
免费 | 14篇 |
国内免费 | 1篇 |
专业分类
测绘学 | 2篇 |
大气科学 | 9篇 |
地球物理 | 86篇 |
地质学 | 100篇 |
海洋学 | 8篇 |
天文学 | 7篇 |
综合类 | 1篇 |
自然地理 | 22篇 |
出版年
2023年 | 1篇 |
2022年 | 2篇 |
2021年 | 2篇 |
2020年 | 3篇 |
2019年 | 5篇 |
2018年 | 11篇 |
2017年 | 8篇 |
2016年 | 12篇 |
2015年 | 12篇 |
2014年 | 15篇 |
2013年 | 8篇 |
2012年 | 5篇 |
2011年 | 13篇 |
2010年 | 12篇 |
2009年 | 15篇 |
2008年 | 8篇 |
2007年 | 10篇 |
2006年 | 14篇 |
2005年 | 12篇 |
2004年 | 16篇 |
2003年 | 6篇 |
2002年 | 5篇 |
2001年 | 5篇 |
2000年 | 2篇 |
1999年 | 1篇 |
1998年 | 3篇 |
1997年 | 3篇 |
1996年 | 2篇 |
1995年 | 3篇 |
1994年 | 2篇 |
1993年 | 1篇 |
1992年 | 1篇 |
1991年 | 3篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1985年 | 3篇 |
1984年 | 3篇 |
1982年 | 1篇 |
1973年 | 1篇 |
1942年 | 1篇 |
1941年 | 1篇 |
1940年 | 1篇 |
1937年 | 1篇 |
排序方式: 共有235条查询结果,搜索用时 785 毫秒
61.
62.
63.
Landslides in Emilia-Romagna region (Italy): strategies for hazard assessment and risk management 总被引:1,自引:2,他引:1
In Emilia-Romagna, over 32,000 landslide bodies cover one-fifth of the hilly and mountainous territory. The majority of them
originated as earth-flows after the last glacial maximum and grew during the rainiest periods of the Holocene through the
superimposition of new earth-flows. Reactivation of these large landslides is the main problem the geologists of Emilia-Romagna
are facing now. Intense and/or prolonged precipitation play a major role as triggering factors in reactivating landslide bodies,
but also the importance of snowmelt is suggested by the monthly distribution of landslide events. Almost all the present-day
landslide activity is due to the reactivation of pre-existing landslide bodies. Consequently, territorial planning and geo-thematic
cartography are fundamental tools for the reduction of risk. The Emilia-Romagna geo-thematic cartography (1:10,000) is legally
binding and regulates land use in regional, municipal and basin plans. 相似文献
64.
65.
66.
67.
Earthquake-induced deformation structures in lake deposits: A Late Pleistocene to Holocene paleoseismic record for Central Switzerland 总被引:1,自引:0,他引:1
68.
Typical pump-and-treat (PAT) optimization problems involve design of pumping schemes, while minimizing cost and meeting a set of constraints. Due to scarcity of information about the hydrogeological system, stochastic modeling approaches can be used to assess tradeoffs between optimality and reliability. Using a stochastic approach, the constrained, single-objective problem may be turned into a multiobjective problem by substituting constraint inequalities with an additional objective function (OF) that accounts for the reliability of the PAT process. In this work, two approaches are analyzed: in one case, the additional OF consists of the probability of failure of a given remediation policy; in another, the OF additional is represented by the recourse, namely the penalty cost induced by the violation of constraints. In order to overcome the overwhelming computational cost required by stochastic simulation, surrogate forms of the OFs are introduced. In the test case under investigation, such functions are estimated by a kriging interpolation of the OF over a series of data points obtained from stochastic simulations of flow and transport, and calibrated against stochastic optimization solutions. The analysis of the two approaches for addressing the tradeoff of cost vs. reliability indicates that recourse accounts not only for the frequency of constraint violations, as the probability of failure does, but also for the intensity with which these occur. Ultimately, the recourse method allows considering less restrictive policies, although these may be highly sensitive to the choice of penalty functions. 相似文献
69.
Giovanni Chiodini Stefano Caliro Giorgio Caramanna Domenico Granieri Carmine Minopoli Roberto Moretti Lavinia Perotta Guido Ventura 《Pure and Applied Geophysics》2006,163(4):759-780
The marine sector surrounding Panarea Island (Aeolian Islands, South Italy) is affected by widespread submarine emissions
of CO2 -rich gases and thermal water discharges which have been known since the Roman Age. On November 3rd, 2002 an anomalous degassing event affected the area, probably in response to a submarine explosion. The concentrations of
minor reactive gases (CO, CH4 and H2) of samples collected in November and December, 2002 show drastic compositional changes when compared to previous samples
collected from the same area in the 1980s. In particular the samples collected after the November 3rd phenomenon display relative increases in H2 and CO and a strong decrease in the CH4 contents, while other gas species show no significant change. The interaction of the original gas with seawater explains
the variable contents of CO2, H2S, N2, Ar and He which characterize the different samples, but cannot explain the large variations of CO, CH4 and H2 which are instead compatible with changes in the redox, temperature and pressure conditions of the system. Two models, both
implying an increasing input of magmatic fluids are compatible with the observed variations of minor reactive species. In
the first one, the input of magmatic fluids drives the hydrothermal system towards atypical (more oxidizing) redox conditions,
slowly pressurizing the system up to a critical state. In the second one, the hydrothermal system is flashed by the rising
high-T volcanic fluid, suddenly released by a magmatic body at depth. The two models have different implications for volcanic
surveillance and risk assessment: In the first case, the November 3rd event may represent both the culmination of a relatively slow process which caused the overpressurization of the hydrothermal
system and the beginning of a new phase of quiescence. The possible evolution of the second model is unforeseeable because
it is mainly related to the thermal, baric and compositional state of the deep magmatic system that is poorly known. 相似文献
70.
Andrea Brogi Antonio Lazzarotto Domenico Liotta Giorgio Ranalli 《Tectonophysics》2003,363(1-2):127-139
The Larderello geothermal field is located in the Inner Northern Apennines, in an area which has been subject to extension since the Early Miocene. The latest extensional episode (Pliocene–Present) has resulted in the formation of NW-trending, NE-dipping listric normal faults, whose geometry is controlled down to 3 km by borehole data. In this paper, we integrate a new interpretation of seismic reflection lines with existing seismic, field, and borehole data to analyse the relations among listric normal faults, the top of the brittle–ductile transition, and the migration of geothermal fluids.In accordance with previous interpretations, we consider the strong reflector (K-horizon) marking the top of the reflective mid-lower crust, and located at a depth of 3–5 km in the geothermal area, to represent the top of the brittle–ductile transition. Its reflectivity most probably derives from the presence of overpressured fluids. We identify three main NW-trending, NE-dipping extensional brittle shear zones, showing listric geometry and soling out in the vicinity of the K-horizon. The latter appears to be dislocated in correspondence of the soling out of the shear zones. These shear zones, because of the associated intense fracturing, represent the most natural channels of upward migration of geothermal fluids from the magmatic sources located below the K-horizon.We suggest that these two conclusions—that listric normal faults root at or near the brittle–ductile transition, and that they act as preferential upward migration paths for magmatic fluids—may be of general validity for geothermal fields located in extensional settings. 相似文献