全文获取类型
收费全文 | 389篇 |
免费 | 22篇 |
国内免费 | 2篇 |
专业分类
测绘学 | 11篇 |
大气科学 | 23篇 |
地球物理 | 98篇 |
地质学 | 128篇 |
海洋学 | 27篇 |
天文学 | 70篇 |
综合类 | 3篇 |
自然地理 | 53篇 |
出版年
2021年 | 3篇 |
2020年 | 6篇 |
2019年 | 11篇 |
2018年 | 11篇 |
2017年 | 3篇 |
2016年 | 15篇 |
2015年 | 10篇 |
2014年 | 9篇 |
2013年 | 19篇 |
2012年 | 7篇 |
2011年 | 27篇 |
2010年 | 20篇 |
2009年 | 22篇 |
2008年 | 20篇 |
2007年 | 15篇 |
2006年 | 22篇 |
2005年 | 10篇 |
2004年 | 12篇 |
2003年 | 18篇 |
2002年 | 13篇 |
2001年 | 11篇 |
2000年 | 11篇 |
1999年 | 8篇 |
1998年 | 7篇 |
1997年 | 4篇 |
1996年 | 3篇 |
1995年 | 6篇 |
1994年 | 5篇 |
1993年 | 2篇 |
1992年 | 8篇 |
1991年 | 3篇 |
1990年 | 2篇 |
1989年 | 3篇 |
1988年 | 7篇 |
1987年 | 5篇 |
1986年 | 3篇 |
1985年 | 5篇 |
1984年 | 4篇 |
1983年 | 2篇 |
1981年 | 3篇 |
1980年 | 9篇 |
1979年 | 4篇 |
1978年 | 5篇 |
1977年 | 2篇 |
1975年 | 3篇 |
1974年 | 4篇 |
1972年 | 1篇 |
1971年 | 1篇 |
1970年 | 1篇 |
1968年 | 2篇 |
排序方式: 共有413条查询结果,搜索用时 22 毫秒
131.
Distribution and sedimentary characteristics of tsunami deposits along the Cascadia margin of western North America 总被引:1,自引:0,他引:1
Tsunami deposits have been found at more than 60 sites along the Cascadia margin of Western North America, and here we review and synthesize their distribution and sedimentary characteristics based on the published record. Cascadia tsunami deposits are best preserved, and most easily identified, in low-energy coastal environments such as tidal marshes, back-barrier marshes and coastal lakes where they occur as anomalous layers of sand within peat and mud. They extend up to a kilometer inland in open coastal settings and several kilometers up river valleys. They are distinguished from other sediments by a combination of sedimentary character and stratigraphic context. Recurrence intervals range from 300–1000 years with an average of 500–600 years. The tsunami deposits have been used to help evaluate and mitigate tsunami hazards in Cascadia. They show that the Cascadia subduction zone is prone to great earthquakes that generate large tsunamis. The inclusion of tsunami deposits on inundation maps, used in conjunction with results from inundation models, allows a more accurate assessment of areas subject to tsunami inundation. The application of sediment transport models can help estimate tsunami flow velocity and wave height, parameters which are necessary to help establish evacuation routes and plan development in tsunami prone areas. 相似文献
132.
Numerical model simulations of sea-breeze circulations in the presence of idealized topography are subjected to dimensional
analysis in order to capture the dynamics of the sea-breeze circulation combined with an upslope-flow circulation. A secondary
objective is to reconcile previous results based on observations. The analysis is based on a scaling analysis of sea-breeze
speed, depth and volume flux. This study is motivated by the fact that the literature of sea breezes interacting with upslope
flows is generally qualitative. Results show clear scaling regimes and strong interaction between the two thermally driven
circulations. We distinguish three regimes, depending on slope length, slope angle, stability and surface heat flux. The first
and third regimes obey the scaling laws of pure sea-breeze scaling. The second regime shows a significant decrease in the
scaled volume flux relative to pure sea-breeze scaling. Dynamical relations in the second regime show a strong influence on
the circulation of upslope stable air advection. 相似文献
133.
134.
The purpose of this work is to study some characteristics of roundish features which are observed on Hα filtergrams, above the solar chromosphere, at the limb. The ‘Bulles’ - chromospheric bubbles - so called for their apparent shape, move upwards into the low corona and fade out when their material is completely ionised (Figures 1 to 3). The physical data for nine observed bubbles listed in Table I are: lifetime (2), average height (3), ascending velocity (4), lateral velocity (5), angle of the movement with the normal to the solar limb (6), intensity in Hα (7) and diameters (8). The time variations of some of these properties are pictured in Figure 4. It is noted that all measured velocities are super-sonic. We discuss the relation between the ascending velocity and the maximum height reached by the bubbles (Figure 5) and compare it with the one obtained by Rush and Roberts for spicules. The study of their diameters shows that the vertical diameter is generally greater than the horizontal one. Their ratio is a function of speed and becomes equal to unity when the bubble velocity reaches 70 km s?1 (Figure 6). The bubbles seem to diffuse in the corona as spicules do. We also compare the properties of bubbles with some already known chromospheric features (Table II) and there seems to be a link between bubbles and Becker's grains. Finally, we, however, propose two hypothesis regarding the origin of bubbles: (i) they are related to spicules, or (ii) they are accelerated in the low chromosphere by the divergence of the magnetic field. 相似文献
135.
Influence of injection conditions on field tracer experiments 总被引:2,自引:0,他引:2
Calibration of ground water transport models is often performed using results of field tracer experiments. However, little attention is usually paid to the influence, on resulting breakthrough curves, of injection conditions and well-aquifer interactions, more particularly of the influence of the possible trapping of the tracer in the injection wellbore. Recently, a new mathematical and numerical approach has been developed to model injection conditions and well-aquifer interactions in a very accurate way. Using an analytical solution derived from this model, a detailed analysis is made of the evolution of the tracer input function in the aquifer. By varying injection conditions from one simulation to another, synthetic breakthrough curves are generated with the SUFT3D ground water flow and transport finite-element simulator. These tests show clearly that the shape of the breakthrough curves can be dramatically affected by injection conditions. Using generated breakthrough curves as "actual" field results, a calibration of hydrodispersive parameters is performed, neglecting the influence of injection conditions. This shows that neglecting the influence of actual injection conditions can lead to (1) errors on fitted parameters and (2) misleading identification of the active transport processes. Conclusions and guidelines are drawn in terms of proposed methodologies for better controlling the tracer injection in the field, in order to minimize risk of misinterpretation of results. 相似文献
136.
137.
Franck Humbert Guy Libourel Christian France-Lanord Laurent Zimmermann Bernard Marty 《Geostandards and Geoanalytical Research》2000,24(2):255-260
A new installation for the analysis of picomole quantities of nitrogen has been designed and constructed. It permits the simultaneous analysis of N and rare gases extracted from silicates by heating. The extraction procedure involves the use of a CO2 laser as a heater, and the analysis is made by static mass spectrometry using a high sensitivity, high resolution mass spectrometer. Procedural blanks of 2 picomoles N2 (60 picogram N) allow us to analyse routinely N in mg-sized samples such as mantle-derived and meteoritic minerals, and Lunar soil grains. 相似文献
138.
A review of low‐cost space‐borne data for flood modelling: topography,flood extent and water level 下载免费PDF全文
Kun Yan Giuliano Di Baldassarre Dimitri P. Solomatine Guy J.‐P. Schumann 《水文研究》2015,29(15):3368-3387
During the last two decades, remote sensing data have led to tremendous progress in advancing flood inundation modelling. In particular, low‐cost space‐borne data can be invaluable for large‐scale flood studies in data‐scarce areas. Various satellite products yield valuable information such as land surface elevation, flood extent and water level, which could potentially contribute to various flood studies. An increasing number of research studies have been dedicated to exploring those low‐cost data towards building, calibration and evaluation, and remote‐sensed information assimilation into hydraulic models. This paper aims at reviewing these recent scientific efforts on the integration of low‐cost space‐borne remote sensing data with flood modelling. Potentials and limitations of those data in flood modelling are discussed. This paper also introduces the future satellite missions and anticipates their likely impacts in flood modelling. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
139.
Potential evidence for slab detachment from the flexural backstripping of a foredeep: Insight on the evolution of the Pescara basin (Italy) 下载免费PDF全文
Paolo Mancinelli Cristina Pauselli Giorgio Minelli Massimiliano R. Barchi Guy Simpson 《地学学报》2018,30(3):222-232
The discrepancy between the size of the Apenninic chain and the depth of the Adriatic foredeep is investigated using 2D flexural backstripping on well‐constrained depth‐converted cross‐sections in the Pescara basin (Central Italy). The procedure consisted of removal, uplift, unfolding and unfaulting of the Pliocene–Pleistocene foreland deposits to produce a palaeogeographic map of the basin at the end of the Messinian and to constrain sedimentary rates since the Miocene. Results are found to support the contribution of an external load to the foreland evolution together with the Apenninic chain load. The interplay of the two types of loads resulted in spatial and temporal variations of the foredeep evolution that are quantified by palaeogeographic maps and sedimentation rates obtained through backstripping. Results are interpreted as representing the effects of a southward‐migrating wave linked to slab detachment beneath the Adriatic foredeep. This procedure can be useful to investigate similar problems on other chains worldwide. 相似文献