全文获取类型
收费全文 | 177篇 |
免费 | 1篇 |
国内免费 | 1篇 |
专业分类
测绘学 | 4篇 |
大气科学 | 6篇 |
地球物理 | 37篇 |
地质学 | 80篇 |
海洋学 | 13篇 |
天文学 | 15篇 |
综合类 | 2篇 |
自然地理 | 22篇 |
出版年
2021年 | 1篇 |
2019年 | 3篇 |
2018年 | 1篇 |
2017年 | 4篇 |
2015年 | 3篇 |
2014年 | 5篇 |
2013年 | 8篇 |
2012年 | 2篇 |
2011年 | 6篇 |
2010年 | 6篇 |
2009年 | 10篇 |
2008年 | 9篇 |
2007年 | 8篇 |
2006年 | 11篇 |
2005年 | 14篇 |
2004年 | 17篇 |
2003年 | 5篇 |
2002年 | 6篇 |
2001年 | 4篇 |
2000年 | 1篇 |
1999年 | 5篇 |
1998年 | 6篇 |
1997年 | 1篇 |
1996年 | 1篇 |
1995年 | 2篇 |
1994年 | 4篇 |
1993年 | 5篇 |
1992年 | 2篇 |
1990年 | 4篇 |
1989年 | 2篇 |
1988年 | 5篇 |
1987年 | 2篇 |
1986年 | 2篇 |
1985年 | 1篇 |
1984年 | 5篇 |
1983年 | 2篇 |
1981年 | 1篇 |
1980年 | 4篇 |
1966年 | 1篇 |
排序方式: 共有179条查询结果,搜索用时 31 毫秒
61.
Stéphane Gaffet Giovanna Cultrera Michel Dietrich Françoise Courboulex Fabrizio Marra Michel Bouchon Arrigo Caserta Cécile Cornou Anne Deschamps Jean-Paul Glot Robert Guiguet 《Journal of Seismology》2000,4(4):525-541
Strong site effects were observed during the two M
W 5.7 and M
W 6.0 main shocks of the Colfiorito seismic crisis which occured on September 26, 1997 in Umbria-Marche (Central Italy).The most obvious indications of these effects are the dramatic differences in damage shown by buildings of similar construction in neighboring villages.Such observations were specifically made in the Verchiano valley in the fault area, 15 km south of Colfiorito where the Verchiano village and the Colle and Camino hamlets were heavily damaged (MCS intensity IX-X) since the first main shock of 1997/09/26,while in contrast, the Curasci village located 2 km eastwards remains almost intact.In order to study the anomalous ground motion amplifications in this area, an array of 11, 3-components seismo- and accelero-meters was set up during the 1997/10/20-24 period, extending from the western side of the valley, up to the top of Mount San Salvatore, going accross the Colle and Curasci hamlets.During the experiment, 67 aftershocks enlightened the valley from the Colfiorito (10 km north) and the Sellano (6 km south) active swarms.Seismic refraction experiments were conducted at the same time in the 500 m wide, 1500 m long Verchiano valley in order to determine the thickness and main characteristics of the alluvial infilling.The main results are: (i) compared to the valley side ground motion, and for all the events, recordings in the central part of the valley (piana di Verchiano) show relative amplification of 10 with a clear lengthening of the seismogram duration by a factor of 2 – (ii) broad band relative amplification of 6–8 is also clearly identified at the top of the Mount San Salvatore overhanging the valley – (iii) any of the site effect measurements done explains by itself the strongly contrasted damage observed at Colle and Curasci: i.e. the modification of the near-field radiation pattern by interaction with the free heterogeneous surface may have induced local shadow zones that saved Curasci. 相似文献
62.
63.
Willy Baeyens Jean-Paul Mommaerts Leo Goeyens Frank Dehairs Hugues Dedeurwaerder Ghislain Decadt 《Estuarine, Coastal and Shelf Science》1984,18(5):499-510
Spatial and temporal variations of dissolved inorganic nitrogen (DIN) have been assessed in onshore and offshore areas of the Southern Bight on the basis of several years' measurements. They indicate that both the residual flow lines and DIN isoconcentration lines run parallel with the coast except in the vicinity of important freshwater discharge points such as the Scheldt estuary. Evidence was found that the seasonal DIN oscillations are not created through fluctuations in input conditions at the lateral boundaries, despite considerable fluctuations in these inputs which include the English Channel (from 500 tons(t) N day?1 in June up to approximately 2000 t N day?1 in February) and also rivers such as the Scheldt estuary (up to 50 t N day?1 in January but less than 5 t N day?1 in June–July). In both the onshore and offshore areas the sum of daylight phytoplanktonic nitrogen intake and sediment release of nitrogen corresponds to the observed DIN variations during most of the year. Pelagic N-mineralization from natural or grazing mortality of phytoplankton (220 mg N m?2 day?1 onshore at its maximum) can account for the differences (200 mg N m?2 day?1 onshore at its maximum), especially at the end of the phytoplankton spring bloom. Although the causes of DIN oscillations onshore and offshore are the same, the results differ because offshore (1) the vegetative season lasts longer, and (2) DIN is exhausted at the end of the phytoplankton spring bloom. 相似文献
64.
65.
Clusters of galaxies are the most recently assembled, massive, bound structures in the Universe. As predicted by General Relativity,
given their masses, clusters strongly deform space-time in their vicinity. Clusters act as some of the most powerful gravitational
lenses in the Universe. Light rays traversing through clusters from distant sources are hence deflected, and the resulting
images of these distant objects therefore appear distorted and magnified. Lensing by clusters occurs in two regimes, each
with unique observational signatures. The strong lensing regime is characterized by effects readily seen by eye, namely, the production of giant arcs, multiple images, and arclets.
The weak lensing regime is characterized by small deformations in the shapes of background galaxies only detectable statistically. Cluster
lenses have been exploited successfully to address several important current questions in cosmology: (i) the study of the lens(es)—understanding cluster mass distributions and issues pertaining to cluster formation and evolution, as well as constraining
the nature of dark matter; (ii) the study of the lensed objects—probing the properties of the background lensed galaxy population—which is statistically at higher redshifts and of lower
intrinsic luminosity thus enabling the probing of galaxy formation at the earliest times right up to the Dark Ages; and (iii)
the study of the geometry of the Universe—as the strength of lensing depends on the ratios of angular diameter distances between the lens, source and observer, lens
deflections are sensitive to the value of cosmological parameters and offer a powerful geometric tool to probe Dark Energy.
In this review, we present the basics of cluster lensing and provide a current status report of the field. 相似文献
66.
Jean-Paul Liégeois Mohamed G. Abdelsalam Nasser Ennih Aziouz Ouabadi 《Gondwana Research》2013,23(1):220-237
In this paper, we show with examples that cratons involved in intercontinental collisions in a lower plate position are often affected by orogenic events, leading to the transformation of their margins. In some cases, craton interiors can also be shaped by intense collisional processes, leading to the generation of intracratonic orogenic belts. We propose to call these events “metacratonization” and the resulting lithospheric tract “metacraton”. Metacratons can appear similar to typical orogenic belts (i.e. active margin transformed by collisional processes) but are actually sharply different. Their main distinctive characteristics (not all are present in each metacraton) are: (1) absence of pre-collisional events; (2) absence of lithospheric thickening, high-pressure metamorphism being generated by subduction, leading to high gradient in strain and metamorphic intensity; (3) preservation of allochthonous pre-collisional oceanic terranes; (4) abundant post-collisional magmatism associated with shear zones but not with lithospheric thickening; (5) presence of high-temperature–low-pressure metamorphism associated with post-collisional magmatism; (6) intracontinental orogenic belts unrelated to subduction and oceanic basin closures. Reactivation of the rigid but fractured metacratonic lithosphere will cause doming, asthenospheric volcanism emplacement, and mineralizations due to repetitive mineral enrichments. This paper provides several geological cases exemplifying these different metacratonic features in Scandinavia, Sahara, Central Africa and elsewhere. A special focus is given to the Saharan Metacraton because it is where the term “metacraton” originated and it is a vastly expanded tract of continental crust (5,000,000 km2). Metacratonization is a common process in the Earth's history. Considering the metacraton concept in geological studies is crucial for understanding the behavior of cratons and their partial destruction. 相似文献
67.
Limited information has been available about the influence of loading density on the performances of Scophthalmus maximus, especially in recirculating aquaculture systems (RAS). In this study, turbot (13.84±2.74 g; average weight±SD) were reared at four different initial densities (low 0.66, medium 1.26, sub-high 2.56, high 4.00 kg/m2) for 10 weeks in RAS at 23±1°C. Final densities were 4.67, 7.25, 14.16, and 17.47 kg/m2, respectively, which translate to 82, 108, 214, and 282 percent coverage of the tank bottom. Density had both negative and independent impacts on growth. The final mean weight, specific growth rate (SGR), and voluntary feed intake significantly decreased and the coefficient of variation (CV) of final body weight increased with increase in stocking density. The medium and sub-high density groups did not differ significantly in SGR, mean weight, CV, food conversion rate (FCR), feed intake, blood parameters, and digestive enzymes. The protease activities of the digestive tract at pH 7, 8.5, 9, and 10 were significantly higher for the highest density group, but tended to be lower (not significantly) at pH 4 and 8.5 for the lowest density group. The intensity of protease activity was inversely related to feed intake at the different densities. Catalase activity was higher (but not significantly) at the highest density, perhaps because high density started to induce an oxidative effect in turbot. In conclusion, turbot can be cultured in RAS at a density of less than 17.47 kg/m2. With good water quality and no feed limitation, initial density between 1.26 and 2.56 kg/m2 (final: 7.25 and 14.16 kg/m2) would not negatively affect the turbot cultured in RAS. For culture at higher density, multi-level feeding devices are suggested to ease feeding competition. 相似文献
68.
Jean-Paul Boy Jacques Hinderer Caroline de Linage 《Pure and Applied Geophysics》2012,169(8):1373-1390
Since its launch in April 2002, the Gravity Recovery and Climate Experiment (GRACE) mission is recording the Earth’s time-variable gravity field with temporal and spatial resolutions of typically 7–30?days and a few hundreds of kilometers, allowing the monitoring of continental water storage variations from both continental and river-basin scales. We investigate here large scale hydrological variations in Africa using different GRACE spherical harmonic solutions, using different processing strategies (constrained and unconstrained solutions). We compare our GRACE estimates to different global hydrology models, with different land-surface schemes and also precipitation forcing. We validate GRACE observations through two different techniques: first by studying desert areas, providing an estimate of the precision. Then we compare GRACE recovered mass variations of main lakes to volume changes derived from radar altimetry measurements. We also study the differences between different publicly available precipitation datasets from both space measurements and ground rain gauges, and their impact on soil-moisture estimates. 相似文献
69.
Issa Sakho Jean-Paul Dupont Mohamed Talla Cisse Sanae El Janyani Soda Loum 《Environmental Earth Sciences》2017,76(6):253
The understanding of the spatial and temporal dynamic of river systems is essential for developing sustainable water resource management plan. For the Senegal River, this subject is very complex according to the context of (1) transboundary basin, (2) several contrasted climatic zones (Guinea, South Sudanian, North Sudanian and Sahelian) with high rainfall variability and (3) high human pressures (dam construction and water uses). From 1954 to 2000, 80% (mean value) of the Senegal River flows recorded downstream part of the basin are provided by three majors tributaries (Bafing, Bakoye and Faléme) located in the upstream part. Then, in our study, this upper Senegal River basin was chosen in order to investigate the hydrological responses to rainfall variability and dam construction. Two nonparametric statistical methods, Mann–Kendall and Hubert test, were used to detect the long-term changes in the time series of precipitation and water discharge (1954–2000) at the annual and seasonal scales. The continuous wavelet transform (Morlet Wavelet) was employed to characterize the different mode in the water discharge variability. Flow duration curve and cumulative curve methods were used to assess the impact of dams on the hydrological regime of the Senegal River. Results showed that the Senegal River flows have been changing under the influence of both rainfall variation and dam construction. The long-term evolution of water discharge depend on long-term rainfall variability: The wet periods of the 1950s and 1960s correspond to periods of higher river flows, while the droughts of the 1970s and 1980s led to unprecedented river flows deficits. The new period, since 1994, show a high inter-annual variability of rainfall and discharge without clear trend. At seasonal scale, the results showed also a strong relationship between rainfall and runoff (R 2 > 0.8) resulting from alternating wet and dry seasons and rapid hydrological responses according to annual rainfall. Nevertheless, the observed flows during dry seasons highlighted the influence of water storage and restitution of infiltrated waters in soils and surficial formations during wet seasons. In the dry seasons, the water budget of the three upstream tributaries showed a water deficit at the downstream gauging station. This deficit was characterized by water loss to underlying aquifers and highlighted the influence of geological setting on water balance. However, in this context, water restitution during the dry season remained dependent on climatic zone and on the total annual rainfall volume during the previous wet season. The results have highlighted an impact of the Manantali dam previously obscured: The dam has no effect on the regulation of high river flows. That is what explains that since its construction in 1988, flooding of coastal cities, like Saint-louis, by seasonal river floods has not ceased. The flooding risk in coastal cities is not avoided, and the dams caused hyper-salinization of the Senegal lower estuary. The breach created in the coastal barrier of the Langue of Barbary in October 2003 promotes direct export of excess floodwater to the sea and reduces this risk of flooding in the delta area. But, this solution led to considerable loss of potential water resources, and the authors recommend a new water management plan with a global focus. However, this study shows the positives impacts of the two dams. They allow the availability of freshwater in order to support agricultural irrigation in the valley and delta zone, in particular during low flows periods. 相似文献
70.
Influence of interaction between small asperities on various types of slow earthquakes in a 3-D simulation for a subduction plate boundary 总被引:3,自引:1,他引:2
Keisuke Ariyoshi Takane Hori Jean-Paul Ampuero Yoshiyuki Kaneda Toru Matsuzawa Ryota Hino Akira Hasegawa 《Gondwana Research》2009,16(3-4):534-544
Recently, the occurrence of slow earthquakes such as low-frequency earthquakes and very low-frequency earthquakes have been recognized at depths of about 30 km in southwest Japan and Cascadia. These slow earthquakes occur sometimes in isolation and sometimes break into chain-reaction, producing tremor that migrates at a speed of about 5–15 km/day and suggesting a strong interaction among nearby small asperities. In this study, we formulate a 3-D subduction plate boundary model with two types of small asperities chained along the trench at the depth of 30 km. Our simulation succeeds in representing various types of slow earthquakes including low-frequency earthquakes and rapid slip velocity in the same asperity, and indicates that interaction between asperities may cause the very low-frequency earthquakes. Our simulation also shows chain reaction along trench with propagation speed that can be made consistent with observations by adjusting model parameters, which suggests that the interactions also explain the observed migration of slow earthquakes. 相似文献