全文获取类型
收费全文 | 258篇 |
免费 | 9篇 |
国内免费 | 2篇 |
专业分类
测绘学 | 13篇 |
大气科学 | 21篇 |
地球物理 | 72篇 |
地质学 | 99篇 |
海洋学 | 31篇 |
天文学 | 17篇 |
自然地理 | 16篇 |
出版年
2023年 | 2篇 |
2022年 | 2篇 |
2021年 | 5篇 |
2020年 | 9篇 |
2019年 | 8篇 |
2018年 | 9篇 |
2017年 | 13篇 |
2016年 | 11篇 |
2015年 | 14篇 |
2014年 | 12篇 |
2013年 | 15篇 |
2012年 | 16篇 |
2011年 | 22篇 |
2010年 | 20篇 |
2009年 | 26篇 |
2008年 | 12篇 |
2007年 | 12篇 |
2006年 | 10篇 |
2005年 | 9篇 |
2004年 | 4篇 |
2003年 | 3篇 |
2002年 | 4篇 |
2001年 | 2篇 |
2000年 | 3篇 |
1998年 | 2篇 |
1997年 | 2篇 |
1996年 | 1篇 |
1995年 | 1篇 |
1993年 | 1篇 |
1992年 | 2篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1988年 | 2篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1982年 | 1篇 |
1981年 | 2篇 |
1980年 | 2篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1965年 | 1篇 |
1964年 | 1篇 |
1962年 | 1篇 |
1954年 | 1篇 |
排序方式: 共有269条查询结果,搜索用时 15 毫秒
261.
Dale Dominey-Howes Paula Dunbar Jesse Varner Maria Papathoma-Köhle 《Natural Hazards》2010,53(1):43-61
The Cascadia margin is capable of generating large magnitude seismic-tsunami. We use a 1:500 year tsunami hazard flood layer
produced during a probabilistic tsunami hazard assessment as the input to a pilot study of the vulnerability of residential and commercial buildings in Seaside, OR, USA. We map building
exposure, apply the Papathoma Tsunami Vulnerability Assessment Model to calculate building vulnerability and estimate probable maximum loss (PML) associated with a 1:500 year tsunami flood. Almost US$0.5 billion worth of buildings would be inundated, 95% of single
story residential and 23% of commercial buildings would be destroyed with PML’s exceeding US$0.5 billion worth of buildings would be inundated, 95% of single
story residential and 23% of commercial buildings would be destroyed with PML’s exceeding US116 million. These figures only
represent a tiny fraction of the total values of exposed assets and loss that would be associated with a Cascadia tsunami
impacting the NW Pacific coast. Not withstanding the various issues associated with our approach, this study represents the
first time that PML’s have ever been calculated for a Cascadia type tsunami, and these results have serious implications for
tsunami disaster risk management in the region. This method has the potential to be rolled out across the United States and
elsewhere for estimating building vulnerability and loss to tsunami. 相似文献
262.
Marangoni Gazineu Marinho Pinto Paula Martins Campos Ricardo Gallo Marcos Nicolas Parente Ribeiro Carlos Eduardo 《Ocean Dynamics》2023,73(6):303-315
Ocean Dynamics - Accurate simulations of significant wave height (Hs) are extremely important for the safety of navigation, port operations, and oil and gas exploration. Thus, accurate forecasts of... 相似文献
263.
Marcelo C.L. Cohen Beatriz L. Figueiredo Nedra N. Oliveira Neuza A. Fontes Marlon Carlos França Luiz C.R. Pessenda Adriana V. de Souza Kita Macario Paulo C.F. Giannini José A. Bendassolli Paula Lima 《地球表面变化过程与地形》2020,45(2):375-392
Projections of the impacts of modern Relative Sea Level (RSL) rise on estuarine mangroves should be supported by coastal topographic data and records of mangrove dynamics under past RSL change. This work identified inland and seaward mangrove migrations along the Jucuruçu River (Bahia, Northeastern Brazil), during the Holocene based on sedimentary features, palynological and geochemical (δ13C, δ15N, C/N) data integrated with digital elevation models. During the Middle Holocene, in response to RSL rise, the estuary saw mangrove forest establish up to ~37 km inland. RSL stood between -1.4 (+0.36/-2.2 m) and +1 (2.19/0.2 m) around 7400 cal yr BP, and rose to a highest position of +3.25 (4.22/2.45 m) reached around 5350 cal yr BP. That marine incursion caused the inland replacement of freshwater vegetation by mangroves on tidal flats. Since then, the estuary experienced RSL fall, reducing inland tidal water salinity towards the Late Holocene, making that the mangroves were replaced by freshwater floodplain vegetation. Today, in the seaward part of the estuary near its mouth, mangroves occupy an area of ~10 km2 along tidal channels. Considering a RSL rise of 98 cm up to the end of the 21st century, at a rate significantly higher than that of Middle Holocene RSL rise (1.5 mm/yr) and fall (0.6 mm/yr), the current mangrove substrates are expected to drown and/or eroded near the coast, while new mangroves may establish inland, at topographically higher tidal flats in nowadays freshwater-tidal zones. Mangrove area could expand over 13 km2 of coastal and flood plain. Following the same interaction between RSL/climate changes and Holocene mangrove dynamics, such upstream mangrove migration may be attenuated or intensified by changes in fluvial discharge. © 2019 John Wiley & Sons, Ltd. 相似文献
264.
Rúbia Martins Bernardes Ramos Ana Paula Biz Deolinda Alvarez Tavares Mnica Beatriz Kolicheski Tirzh Lins Porto Dantas 《洁净——土壤、空气、水》2020,48(7-8)
Given the issue of lipids in effluent treatment systems and their negative impact on the environment, this study aimed to examine lipid degradation by homogenous catalytic ozonation with the aid of iron and manganese ions. This technology presents the possibility of completely mineralizing pollutants using hydroxyl radicals. Milk is chosen as the lipid source because of the high concentration of triglycerides in its matrix, this kind of lipid being the one found most frequently in food and, consequently, in effluent treatment systems. The milk pH value is controlled, and acidic, neutral, and basic conditions are evaluated. The rates of pseudo‐first‐order reactions and the effective value are estimated. It is shown that under acidic conditions low catalyst dosages are enough to cause the complete degradation of lipids. Under neutral conditions, a similar behavior is observed. Under basic conditions, higher catalyst dosages give higher reaction rates. The order of effectiveness of the catalysts under acidic and basic conditions is Fe2+ > Mn2+, with Mn2+ > Fe2+ under neutral conditions. Homogeneous catalytic ozonation is therefore efficient at lipid degradation. This technique is viable economically, since the lipid removal occurred at low ozone levels. In addition, the ions used as catalysts are naturally abundant. 相似文献
265.
Paula S. Haynes Deirdre Brophy David McGrath Roisin O'Callaghan Stephen Comerford Paul Casburn 《Journal of Sea Research》2010,64(4):494-504
Turbot (Psetta maxima Linnaeus) is a high value commercially exploited marine flatfish which occurs in European waters, from the Northeast Atlantic to the Arctic Circle, the Baltic and Mediterranean Sea. In Ireland, turbot are the most valuable commercial non-quota species. Very little is known about their population dynamics in the wild, in particular during the sandy beach nursery phase of the life history. In 2000, a survey was established to assess flatfish species on nursery grounds on the west coast of Ireland. Eleven sandy beaches were assessed for 0+ turbot by beach seining, over an eight year period (2000–2007) during the months of August and September. The objective of the study was to estimate juvenile turbot abundance and size structure to determine if any spatial and annual trends existed. Large scale variability in the recruitment of fish to nursery grounds may be indicative of fluctuations in the adult stock. Turbot were found to recruit to five beaches consistently over the eight year period. Temporal and spatial variability in the relative abundance and length of turbot was discerned, with no apparent overall trend. However, certain nursery grounds were shown in most of the years examined to support higher abundances of turbot in comparison to other areas over the eight year period. Turbot abundances on nursery grounds were significantly correlated with mean spring sea temperatures during the pelagic stage. The condition of turbot did not significantly differ on an annual or spatial scale. Mean densities of 0+ turbot along the Irish coast were found to be similar and at times higher than other areas in Europe, ranging from 0.1 (± 0.3) individuals 1000 m− 2 to 18.5 (± 6.9) individuals 1000 m− 2. Mean turbot total length on beaches ranged from 3.8 cm (± 0.6) to 6.6 cm (± 4.3). The observed spatial and temporal variability in abundance and length highlights the need for long-term studies when assessing juvenile flatfish populations. Results from the present study have provided much needed baseline data on wild juvenile turbot populations which is severely lacking for this species both on an Irish and on a European scale. 相似文献
266.
Valter Amaral Henrique N. Cabral Stuart Jenkins Stephen Hawkins José Paula 《Estuarine, Coastal and Shelf Science》2009
Estuarine and nearshore marine areas are vital habitats for several fish and benthic invertebrates. The shore crab Carcinus maenas (Crustacea: Brachyura: Portunidae) inhabits a variety of coastal, estuarine and lagoon habitats. At low tide, habitat structural complexity may be most important for crabs in the intertidal, providing refuge from predation and desiccation. The quality of different vegetated and nonvegetated estuarine and rocky shore habitats in SW Portugal and SW England was evaluated for intertidal C. maenas populations. We estimated population density, size–structure, and potential growth (RNA/DNA ratios) to investigate habitat quality. Vegetated estuarine habitats supported higher crab densities, than nonvegetated estuarine and rocky shore habitats. Investigation of population size–structure revealed that all habitats seem important recruitment and nursery areas although estuarine habitats in SW Portugal appeared to support higher densities of new recruits than equivalent habitats in SW England. Significant variation was found in RNA/DNA ratios among habitats. Ratios were highest in the rocky shore suggesting a high quality habitat where growth potential is high. We speculate that competition from other top-predators (Pachygrapsus spp.) rather than low habitat quality may limit the occurrence of C. maenas in intertidal rocky shore habitats in SW Portugal. In estuarine environments RNA/DNA ratios were significantly higher in the vegetated than in the nonvegetated estuarine habitats in SW Portugal but not in SW England, suggesting geographic differences in the extent to which highly structure habitats represent high quality. Our results challenge the current paradigm that structured habitats are necessarily those of higher quality for C. maenas. 相似文献
267.
Susana Mendes Ma Jos Fernndez-Gmez Paula Resende Mrio Jorge Pereira Ma Purificacin Galindo-Villardn Ulisses Miranda Azeiteiro 《Estuarine, Coastal and Shelf Science》2009,84(4):637-644
This study examines the spatio-temporal structure of diatom assemblages in a temperate estuary (Ria de Aveiro, Western Portugal). Eighteen monthly surveys were conducted, from January 2002 to June 2003, at three sampling sites (at both high and low tide) along the estuarine salinity gradient. The relationship of diatom assemblages and environmental variables was analysed using the STATICO method, which has been designed for the simultaneous analysis of paired ecological tables. This method allowed examination of the stable part of the environment-diatom relationship, and also the variations of this relationship through time. The interstructure factor map showed that the relationship between the 11 environmental variables and the abundance of the 231 diatom species considered was strongest in the months May and September 2002 and January, February and May 2003. The stable part of the species–environment relationships mainly consisted of a combined phosphate, chlorophyll a and salinity gradient linked to a freshwater-marine species gradient. A more pronounced gradient was observed in January, February and May 2003. Diatom assemblages showed clear longitudinal patterns due to the presence of both marine and freshwater components. May and September 2002 had the least structured gradients with marine-estuarine species appearing in the freshwater side of the gradient. The most complete gradient in February 2003 could be considered, in terms of bio-ecological categories, as the most structured period of the year, with a combination of strong marine influence in the lower zone and freshwater influence in the upper. The best-structured gradients were during periods of a diatom bloom. Stable diatom assemblages (with a strong structure and a good fit between the diatoms and environment) are described and characterized. This study shows the efficiency of the STATICO analysis. The inclusion of space-time data analysis tools in ecological studies may therefore improve the knowledge of the dynamics of species–environmental assemblages. 相似文献
268.
Paulo Torres Gil Penha-Lopes Luís Narciso Adriano Macia José Paula 《Estuarine, Coastal and Shelf Science》2008
Variations in egg volume and fatty acid (FA) content through embryogenesis were evaluated in Uca species from Inhaca island, Mozambique. Egg volume increased 96.1%, 93.3%, 84.2%, 92.9%, 96.3%, respectively, in Uca annulipes, Uca inversa, Uca urvillei, Uca chlorophthalmus and Uca vocans (p < 0.05). Fatty acid content decreased through embryogenesis, showing its importance as fuel during embryonic development. Major fatty acids were 16:0, 18:0, 16:1n-7, 18:1n-9, 18:1n-7, 18:2n-6, 20:5n-3 and 20:4n-3. Unsaturated fatty acids (UFA) and saturated fatty acids (SFA) were used up at a similar rate for U. annulipes and U. inversa contrarily to the other three species. Within the UFA, MUFA were more consumed than PUFA for all species except U. chlorophthalmus. The high values detected for fatty acid trophic markers (essential C18 and C20 PUFAs) and odd-numbered fatty acid suggest that Uca species occupy medium trophic level, primarily omnivores and scavengers/detritivores consuming algae common in the intertidal habitats. The fatty acid consumption pattern during embryonic development was essentially similar between species with some variation as expected, as FA content varies within species mainly due to female feeding ecology, nutritional and physiological conditions, differential demands on resource allocation and geographic and seasonal variations in embryonic development. 相似文献
269.
We have developed a new approach to the problem of the chemical fingerprinting of artifacts manufactured from volcanic rocks of basaltic and andesitic composition. The method is an adaptation of standard energy-dispersive X-ray fluorescence spectrometry and is based on the observation that for irregularly-shaped rock fragments, the ratios of the intensities of the characteristic X-rays of certain trace elements are proportional to the ratios of the concentrations of those elements. This observation has allowed us to obtain geochemical data about the artifacts in a way that is rapid, inexpensive, and nondestructive, making it particularly suited to archaeological applications. We have used our approach to compare a suite of artifacts from an archaeological site in Martis Valley, near Truckee, California, with a group of lava flows from the surrounding area. Using a numerical measure of the geochemical difference between samples, we have been able to group the artifacts on the basis of their geochemistry, to determine which artifacts were manufactured from material found in Martis Valley and, in at least one case, to identify the lava flow that was the actual source of the lithic material for several of the artifacts. 相似文献