全文获取类型
收费全文 | 61篇 |
免费 | 2篇 |
国内免费 | 1篇 |
专业分类
测绘学 | 5篇 |
大气科学 | 9篇 |
地球物理 | 22篇 |
地质学 | 21篇 |
海洋学 | 5篇 |
天文学 | 1篇 |
自然地理 | 1篇 |
出版年
2021年 | 2篇 |
2020年 | 3篇 |
2019年 | 1篇 |
2018年 | 3篇 |
2017年 | 5篇 |
2016年 | 4篇 |
2015年 | 2篇 |
2014年 | 1篇 |
2013年 | 3篇 |
2012年 | 2篇 |
2010年 | 2篇 |
2009年 | 1篇 |
2008年 | 3篇 |
2007年 | 2篇 |
2006年 | 1篇 |
2005年 | 1篇 |
2004年 | 1篇 |
2003年 | 2篇 |
2002年 | 1篇 |
1999年 | 1篇 |
1998年 | 1篇 |
1997年 | 1篇 |
1996年 | 2篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1985年 | 2篇 |
1984年 | 1篇 |
1983年 | 2篇 |
1982年 | 2篇 |
1980年 | 1篇 |
1978年 | 1篇 |
1976年 | 1篇 |
1972年 | 1篇 |
1969年 | 1篇 |
1968年 | 2篇 |
1967年 | 1篇 |
1966年 | 1篇 |
1958年 | 1篇 |
排序方式: 共有64条查询结果,搜索用时 31 毫秒
1.
Rita Borges Radhouan Ben-Hamadou M. Alexandra Chícharo Pedro R Emanuel J. Gonalves 《Estuarine, Coastal and Shelf Science》2007,71(3-4):412-428
There have been no previous studies of the composition of nearshore larval fish assemblages along the coast of Portugal. We aimed to describe the composition and horizontal distribution patterns of larval fish assemblages and their temporal dynamics near a rocky reef at depths shallower than 13 m (inshore) and at two miles (3.70 km) from shore (offshore), as well as along transects perpendicular to the shoreline, from the reef to 10 miles offshore (18.52 km). Samples were taken using 5 min sub-surface trawls at the rocky shore of the Arrábida Marine Park (W Portugal). A total of 1021 larvae were collected, belonging to 61 taxa inshore and to 29 taxa offshore. Along transects, 626 larvae of 52 taxa were collected. Most larvae belonged to coastal species associated with rocky reefs. Total larval abundance and diversity were higher from May to July, which is consistent with the spawning activity of adults. Diversity and total larval abundance decreased significantly with increasing distance from shore, both in the inshore/offshore comparison and in the transects, where this decrease was evident at a very small spatial scale (within the first mile from the reef). Species assemblages differed in the pattern of distribution, with most species clearly associated to the extreme nearshore. The distribution patterns obtained were independent of the spawning mode of species. Results are discussed in the light of the possible physical mechanisms that can potentially act at the Arrábida Marine Park to facilitate larvae retention and the role of larval behaviour. 相似文献
2.
Zhengzhao Luo Stephens G.L. Emanuel K.A. Vane D.G. Tourville N.D. Haynes J.M. 《Geoscience and Remote Sensing Letters, IEEE》2008,5(1):13-16
This letter presents preliminary results concerning the use of new observations from the A-Train Constellation for testing a new technique of remotely sensing hurricane intensity from space based on modeling a hurricane as a balanced, convectively neutral vortex. The key observational requirements are simultaneous, accurate measurements of cloud-top height, cloudtop temperature, and cloud profiling information across the center of the storm, although there are ways to bypass the need for cloud-top temperature. In this letter, the Moderate Resolution Imaging Spectroradiometer onboard Aqua provides an estimation of the cloud-top temperature, and the near-simultaneous CloudSat observations provide the essential cloud-top height and cloud profiling information. Initial results indicate that the new technique is a promising method for estimating storm intensity when compared post facto to the best track database. Potential uncertainties and room for further refinement of the technique are discussed. 相似文献
3.
Mrio Neto Cavalcanti de Araújo Fernando Csar Alves da Silva Emanuel Ferraz Jardim de S Rodney J. Holcombe Paulo Marcos de Vasconcelos 《Journal of Structural Geology》2003,25(12):2089-2107
The polyphase evolution of the Seridó Belt (NE-Brazil) includes D1 crust formation at 2.3–2.1 Ga, D2 thrust tectonics at 1.9 Ga and crustal reworking by D3 strike-slip shear zones at 600 Ma. Microstructural investigations within mylonites associated with D2 and D3 events were used to constrain the tectono-thermal evolution of the belt. D2 shear zones commenced at deeper crustal levels and high amphibolite facies conditions (600–650 °C) through grain boundary migration, subgrain rotation and operation of quartz c-prism slip. Continued shearing and exhumation of the terrain forced the re-equilibration of high-T fabrics and the switching of slip systems from c-prism to positive and negative a-rhombs. During D3, enhancement of ductility by dissipation of heat that came from syn-D3 granites developed wide belts of amphibolite facies mylonites. Continued shearing, uplift and cooling of the region induced D3 shear zones to act in ductile-brittle regimes, marked by fracturing and development of thinner belts of greenschist facies mylonites. During this event, switching from a-prism to a-basal slip indicates a thermal path from 600 to 350 °C. Therefore, microstructures and quartz c-axis fabrics in polydeformed rocks from the Seridó Belt preserve the record of two major events, which includes contrasting deformation mechanisms and thermal paths. 相似文献
4.
5.
6.
Emanuel Procházka 《Studia Geophysica et Geodaetica》1969,13(2):105-124
Summary In adjusting a bilaterally connected polygonal traverse, whether to positionally accurate or inaccurate points of departure,
the mean errors are the problem of primary importance. Hitherto, the mean errors of lengths and angles were chosen; the procedure
was such that the weights of both quantities were determined from the mean errors chosen, and this fixed the ratio of the
mean errors. This ratio did not change as a result of the adjustment, but the absolute values of the mean errors did. Provided
the adjustment was carried out on a polygonal traverse with fixed points of departure, this change did not matter. In the
case of ellipses of errors in the points of departure, this change is not permissible, because it would include the change
of the semi-axes of the ellipses of errors and, therefore, also of the positional rigidity of the points of departure.
The contribution of this paper is in the exact method by which it is possible to compute a coefficientc, pertaining to the mean angular error selected (in the case of positionally inaccurate pointsd), which determines the mean errorm=±e √s (orm=±d √s) of the lengthss. The solution is based on the definition of the mean error of a unit weight founded on the work of deformation. In the calculus
of observations, the work of deformation has so far been determined as the deformation work of internal forces from the corrections
of the individual quantities after the adjustment is concluded. However, it is possible, as was demonstrated in this paper,
to express it as the deformation work of external forces, which act during the adjustment in pointO (Fig. 1) on the auxiliary static system in the shape of a console, and which provide it with the necessary deformation. If
the external forces are expressed by means of the tensor of the auxiliary system, the equation for the mean error of the unit
weight will provide a relation between this error and the coefficientc, ord. If the mean angular error is selected and if its weight is put equal to one, an equation of the fourth degree is obtained
in terms ofc (ord), from which it is possible to compute this coefficient.
From the external forces, necessary to produce the deformation of the auxiliary system during its adjustment, the corrections
of the individual elements of this system may be determined. If we want to determine the ellipse of errors in one of the polygonal
points, it is necessary to investigated the shifts of this point, which occur if the point is acted upon by a unit force first
in one and then in another direction, perpendicular to the first. Both shifts represent conjugate radii of the deformation
ellipse. From this ellipse we proceed to the ellipse of errors.
The general solution is supplemented by a numerical example of adjusting a polygonal traverse with positionally inaccurate
points and, for sake of comparison, also by the adjustment of this traverse with positionally accurate points.
Anschrift: Husova 5, Praha 1-Staré Město 相似文献
Anschrift: Husova 5, Praha 1-Staré Město 相似文献
7.
8.
Four major processes are observed to take place in the coastal aquifer of Israel, detectable even in the short times of water contact with the carbonate-containing host rocks. Three are chemical reactions, Ca2+-Mg2+ exchange, Na+-Ca2+ or Na+-Mg2+ base exchange, SO2?4 reduction and the fourth is dilution by freshwater. These reactions and their effects on the chemical composition of the waters were demonstrated experimentally. The range of chemical changes observed in the laboratory experiments overlap the range of the studied natural waters. This indicates that simulation of geologically long-term rock-water interaction could be achieved in laboratory experiments even at low temperatures. 相似文献
9.
10.
Understanding coastal wetland hydrology with a new regional‐scale,process‐based hydrological model 下载免费PDF全文
Yu Zhang Wenhong Li Ge Sun Guofang Miao Asko Noormets Ryan Emanuel John S. King 《水文研究》2018,32(20):3158-3173
Coastal wetlands represent an ecotone between ocean and terrestrial ecosystems, providing important services, including flood mitigation, fresh water supply, erosion control, carbon sequestration, and wildlife habitat. The environmental setting of a wetland and the hydrological connectivity between a wetland and adjacent terrestrial and aquatic systems together determine wetland hydrology. Yet little is known about regional‐scale hydrological interactions among uplands, coastal wetlands, and coastal processes, such as tides, sea level rise, and saltwater intrusion, which together control the dynamics of wetland hydrology. This study presents a new regional‐scale, physically based, distributed wetland hydrological model, PIHM‐Wetland, which integrates the surface and subsurface hydrology with coastal processes and accounts for the influence of wetland inundation on energy budgets and evapotranspiration (ET). The model was validated using in situ hydro‐meteorological measurements and Moderate Resolution Imaging Spectroradiometer (MODIS) ET data for a forested and herbaceous wetland in North Carolina, USA, which confirmed that the model accurately represents the major wetland hydrological behaviours. Modelling results indicate that topographic gradient is a primary control of groundwater flow direction in adjacent uplands. However, seasonal climate patterns become the dominant control of groundwater flow at lower coastal plain and land–ocean interface. We found that coastal processes largely influence groundwater table (GWT) dynamics in the coastal zone, 300 to 800 m from the coastline in our study area. Among all the coastal processes, tides are the dominant control on GWT variation. Because of inundation, forested and herbaceous wetlands absorb an additional 6% and 10%, respectively, of shortwave radiation annually, resulting in a significant increase in ET. Inundation alters ET partitioning through canopy evaporation, transpiration, and soil evaporation, the effect of which is stronger in cool seasons than in warm seasons. The PIHM‐Wetland model provides a new tool that improves the understanding of wetland hydrological processes on a regional scale. Insights from this modelling study provide benchmarks for future research on the effects of sea level rise and climate change on coastal wetland functions and services. 相似文献