全文获取类型
收费全文 | 488篇 |
免费 | 19篇 |
国内免费 | 9篇 |
专业分类
测绘学 | 35篇 |
大气科学 | 78篇 |
地球物理 | 81篇 |
地质学 | 170篇 |
海洋学 | 47篇 |
天文学 | 69篇 |
综合类 | 1篇 |
自然地理 | 35篇 |
出版年
2024年 | 1篇 |
2023年 | 3篇 |
2022年 | 4篇 |
2021年 | 9篇 |
2020年 | 6篇 |
2019年 | 10篇 |
2018年 | 10篇 |
2017年 | 6篇 |
2016年 | 28篇 |
2015年 | 19篇 |
2014年 | 16篇 |
2013年 | 27篇 |
2012年 | 26篇 |
2011年 | 36篇 |
2010年 | 30篇 |
2009年 | 39篇 |
2008年 | 15篇 |
2007年 | 20篇 |
2006年 | 19篇 |
2005年 | 24篇 |
2004年 | 16篇 |
2003年 | 11篇 |
2002年 | 13篇 |
2001年 | 16篇 |
2000年 | 8篇 |
1999年 | 8篇 |
1998年 | 3篇 |
1997年 | 3篇 |
1996年 | 4篇 |
1995年 | 8篇 |
1994年 | 8篇 |
1993年 | 10篇 |
1992年 | 6篇 |
1991年 | 10篇 |
1990年 | 4篇 |
1989年 | 3篇 |
1988年 | 6篇 |
1987年 | 1篇 |
1986年 | 5篇 |
1985年 | 3篇 |
1984年 | 5篇 |
1983年 | 2篇 |
1982年 | 1篇 |
1981年 | 5篇 |
1980年 | 1篇 |
1979年 | 2篇 |
1978年 | 1篇 |
1976年 | 2篇 |
1975年 | 2篇 |
1974年 | 1篇 |
排序方式: 共有516条查询结果,搜索用时 15 毫秒
51.
Variation in surface turbulence and the gas transfer velocity over a tidal cycle in a macro-tidal estuary 总被引:2,自引:0,他引:2
Christopher?J.?ZappaEmail author Peter?A.?Raymond Eugene?A.?Terray Wade?R.?McGillis 《Estuaries and Coasts》2003,26(6):1401-1415
The gradient flux technique, which measures the gas transfer velocity (k), and new observational techniques that probe turbulence in the aqueous surface boundary layers were conducted over a tidal
cycle in the Plum Island Sound, Massachusetts. Efforts were aimed at testing new methods in an estuarine system and to determine
if turbulence created by tidal velocity can be responsible for the short-term variability ink. Measurements were made during a low wind day, at a site with tidal excursions of 2.7 m and a range in tidal velocity of
nearly 1 m s−1. Estimates ofk using the gradient flux technique were made simultaneously with the Controlled Flux Technique (CFT), infrared imagery, and
high-resolution turbulence measurements, which measure the surface renewal rate, turbulent scales, and the turbulent dissipation
rate, respectively. All measurements were conducted from a small mobile catamaran that minimizes air- and water-side flow
distortions. Infrared imagery showed considerable variability in the turbulent scales that affect air-water gas exchange.
These measurements were consistent with variation in the surface renewal rate (range 0.02 to 2 s−1), the turbulent dissipation rate (range 10−7 to 10−5 W kg−1), andk (range 2.2 to 12.0 cm hr−1). During this low wind day, all variables were shown to correlate with tidal speed. Taken collectively our results indicate
the promise of these methods for determining short-term variability in gas transfer and near surface turbulence in estuaries
and demonstrate that turbulent transport associated with tidal velocity is a potentially important factor with respect to
gas exchange in coastal systems. 相似文献
52.
Jean-Claude Andr Jean-Yves Caneill Michel Dqu Philippe Rogel Laurent Terray Yves Tourre 《Comptes Rendus Geoscience》2002,334(16):1115
The atmosphere and the ocean are subject to many dynamical instabilities, which limit the time during which their behaviour can be deterministically forecasted. At longer timescales, the atmosphere can be predicted at best using statistical methods, as a response to external forcing linked to sea- and land-surface anomalies. Climate being defined as the mean of atmospheric states, it appears that it can be predicted up to a few months in advance, which is the characteristic time of the so-called slow components of the climate system. Forecasting can sometimes be extended to longer time ranges, especially when the coupled ocean–atmosphere system exhibits internal variability modes, with characteristic times of a few years. Seasonal climate forecasting is most often based upon Monte-Carlo simulations, where the various realisations correspond to slightly different initial conditions. The present sate-of-the-art in Europe (ECMWF) and/or in the USA (IRI) allows to forecast such major phenomena, as El Niño, up to six months in advance. Finally, some parameters may exhibit predictability at still longer time-ranges (inter-annual to decadal), but only for certain regions. The example of electricity production is used to underline the potentially large economical benefit of seasonal climate forecasting. To cite this article: J.-C. André et al., C. R. Geoscience 334 (2002) 1115–1127.
Résumé
L'atmosphère et l'océan sont le siège d'instabilités dynamiques, qui limitent la durée pendant laquelle il est possible d'en prévoir l'évolution de façon déterministe. Au-delà, l'atmosphère n'est plus prévisible, au mieux, que de façon statistique, en fonction du forçage externe qu'exerce(nt) sur elle l'océan et/ou la surface des continents. Le climat (au sens d'une moyenne des états atmosphériques) se révèle ainsi prévisible jusqu'à des échéances temporelles de quelques mois, échelle de temps caractéristique des composantes dites « lentes » du système climatique. La prévision peut s'étendre à des échéances parfois plus longues, dans le cas où le système couplé océan–atmosphère posséderait des modes de variabilité temporelle de périodes caractéristiques de quelques années. La prévision climatique saisonnière est très souvent construite à partir de simulations de type Monte-Carlo, avec des ensembles de réalisations utilisant des conditions initiales légèrement différentes. Dans l'état actuel de ces prévisions, qu'elles soient réalisées en Europe (CEPMMT) ou aux États-Unis (IRI), il est possible de prévoir environ six mois à l'avance un certain nombre de phénomènes climatiques, en particulier ceux liés aux épisodes dits « El Niño », pour lesquels l'amplitude des variations est suffisamment importante. Il existe, par ailleurs, une prévisibilité à encore plus longue échéance (inter-annuelle à décennale), mais seulement pour certains paramètres et certaines régions. L'exemple de la production d'électricité montre l'importance économique potentielle très grande de la prévision climatique saisonnière. Pour citer cet article : J.-C. André et al., C. R. Geoscience 334 (2002) 1115–1127. 相似文献53.
Morten Smelror John Dehls Jrg Ebbing Eiliv Larsen Erik R. Lundin
ystein Nordgulen Per Terje Osmundsen Odleiv Olesen Dag Ottesen Christophe Pascal Thomas F. Redfield Leif Rise 《Global and Planetary Change》2007,58(1-4):382
The present-day topography/bathymetry of the Norwegian mainland and passive margin is a product of complex interactions between large-scale tectonomagmatic and climatic processes that can be traced back in time to the Late Silurian Caledonian Orogeny. The isostatic balance of the crust and lithosphere was clearly influenced by orogenic thickening during the Caledonian Orogeny, but was soon affected by post-orogenic collapse including overprinting of the mountain root, and was subsequently affected by a number of discrete extensional events eventually leading to continental break-up in Early Eocene time. In the mid-Jurassic the land areas experienced deep erosion in the warm and humid climate, forming a regional paleic surface. Rift episodes in the Late Jurassic and Early Cretaceous, with differential uplift along major fault zones, led to more pronounced topographic contrasts during the Cretaceous, and thick sequences of clastic sediments accumulated in the subsiding basins on the shelf. Following renewed extension in the Late Cretaceous, a new paleic surface developed in the Paleocene. Following break-up the margin has largely subsided thermally, but several Cenozoic shortening events have generated positive contraction structures. On the western side of the on-shore drainage divide, deeper erosion took place along pre-existing weakness zones, creating the template of the present day valleys and fjords. In the Neogene the mainland and large portions of the Barents Sea were uplifted. It appears that this uplift permitted ice caps to nucleate and accumulate during the Late Pliocene northern hemisphere climatic deterioration. The Late Pliocene to Pleistocene glacial erosion caused huge sediment aprons to be shed on to the Norwegian Sea and Barents Sea margins. Upon removal of the ice load the landmass adjusted isostatically, and this still continues today. 相似文献
54.
Jean-Franois Lnat Patrick Bachlery Alain Bonneville Pascal Tarits Jean-Louis Chemine Hugues Delorme 《Journal of Volcanology and Geothermal Research》1989,36(1-3)
On December 4, 1983 an eruption started at vents located 1.5 km southwest of the summit of Piton de la Fournaise at the base of the central cone. After 31 months of quiescence this was one of the longest repose period in the last fifty years. The eruption had two phases: December 4 to January 18 and January 18 to February 18. Phase 1 produced about 8 × 106 m3 of lava and Phase II about 9 × 106 m3. The erupted lava is an aphyric basalt whose mineralogical and geochemical composition is close to that of other lavas emitted since 1977.The precursors of the December 4 outbreak were limited to two-week shallow (1.5–3 km) seismic crisis of fewer than 50 events. No long-term increase was noted in the local seismicity which is very quiet during repose periods and no long-term ground inflation preceded the eruption. Outbreaks of Phases I and II were preceded by short (2.5 hours and 1.5 hours) seismic swarms corresponding to the rise of magma toward the surface from a shallow reservoir. Large ground deformation explained by the emplacement of the shallow intrusions, was recorded during the seismic swarms. A summit inflation was observed in early January, before the phase II outbreak, while the phase I eruption was still continuing.Piton de la Fournaise volcanological observatory was installed in 1980. Seismic and ground deformation data now available for a period of 4 years including the 1981 and the 1983–1984 eruptions, allow us to describe the physical behavior of the volcano during this period. These observations lead us to propose that the magma transfer from deep levels to the shallow magma reservoir is not a continuous process but a periodic one and that the shallow magma reservoir was not resupplied before the 1981 and 1983–1984 eruptions. Considerations on the eruptive history and the composition of recent lavas indicate that the reservoir was refilled in 1977. 相似文献
55.
Patrick Berrebi Pascal Rodriguez Jean-Antoine Tomasini Ghislaine Cattaneo-Berrebi Alain J. Crivelli 《Estuarine, Coastal and Shelf Science》2005,65(4):708-716
The presence and the distribution of two cryptic sedentary gobies, Pomatoschistus microps and Pomatoschistus marmoratus, were investigated in several lagoons stretching along the Golfe du Lion, southern France Mediterranean coast, and Corsica. Pomatoschistus microps is the only sedentary Pomatoschistus species in two shallow lagoons with large variations of salinity and temperature. In contrast, P. marmoratus, another sedentary species, can be found preferentially in a deep salty lagoon with small salinity variations. Both species occur sympatrically in the Rhone Delta and hybridise, producing fertile offspring. Using allozymes, competition, linked to fitness, is invoked to explain the distribution pattern of these sibling species. 相似文献
56.
57.
Jürgen Oberst Valéry Lainey Christophe Le Poncin-Lafitte Veronique Dehant Pascal Rosenblatt Stephan Ulamec Jens Biele J?rn Spurmann Ralph Kahle Volker Klein Ulrich Schreiber Anja Schlicht Nicolas Rambaux Philippe Laurent Beno?t Noyelles Bernard Foulon Alexander Zakharov Leonid Gurvits Denis Uchaev Scott Murchie Cheryl Reed Slava G. Turyshev Jesus Gil Mariella Graziano Konrad Willner Kai Wickhusen Andreas Pasewaldt Marita W?hlisch Harald Hoffmann 《Experimental Astronomy》2012,34(2):243-271
GETEMME (Gravity, Einstein??s Theory, and Exploration of the Martian Moons?? Environment), a mission which is being proposed in ESA??s Cosmic Vision program, shall be launched for Mars on a Soyuz Fregat in 2020. The spacecraft will initially rendezvous with Phobos and Deimos in order to carry out a comprehensive mapping and characterization of the two satellites and to deploy passive Laser retro-reflectors on their surfaces. In the second stage of the mission, the spacecraft will be transferred into a lower 1500-km Mars orbit, to carry out routine Laser range measurements to the reflectors on Phobos and Deimos. Also, asynchronous two-way Laser ranging measurements between the spacecraft and stations of the ILRS (International Laser Ranging Service) on Earth are foreseen. An onboard accelerometer will ensure a high accuracy for the spacecraft orbit determination. The inversion of all range and accelerometer data will allow us to determine or improve dramatically on a host of dynamic parameters of the Martian satellite system. From the complex motion and rotation of Phobos and Deimos we will obtain clues on internal structures and the origins of the satellites. Also, crucial data on the time-varying gravity field of Mars related to climate variation and internal structure will be obtained. Ranging measurements will also be essential to improve on several parameters in fundamental physics, such as the Post-Newtonian parameter ?? as well as time-rate changes of the gravitational constant and the Lense-Thirring effect. Measurements by GETEMME will firmly embed Mars and its satellites into the Solar System reference frame. 相似文献
58.
Gordon R. Osinski Pascal Lee John G. Spray John Parnell Darlene S. S. Lim Theodore E. Bunch Charles S. Cockell Brian Glass 《Meteoritics & planetary science》2005,40(12):1759-1776
Abstract— The Haughton impact structure has been the focus of systematic, multi‐disciplinary field and laboratory research activities over the past several years. Regional geological mapping has refined the sedimentary target stratigraphy and constrained the thickness of the sedimentary sequence at the time of impact to ?1880 m. New 40Ar–39Ar dates place the impact event at ?39 Ma, in the late Eocene. Haughton has an apparent crater diameter of ?23 km, with an estimated rim (final crater) diameter of ?16 km. The structure lacks a central topographic peak or peak ring, which is unusual for craters of this size. Geological mapping and sampling reveals that a series of different impactites are present at Haughton. The volumetrically dominant crater‐fill impact melt breccias contain a calcite‐anhydrite‐silicate glass groundmass, all of which have been shown to represent impact‐generated melt phases. These impactites are, therefore, stratigraphically and genetically equivalent to coherent impact melt rocks present in craters developed in crystalline targets. The crater‐fill impactites provided a heat source that drove a post‐impact hydrothermal system. During this time, Haughton would have represented a transient, warm, wet microbial oasis. A subsequent episode of erosion, during which time substantial amounts of impactites were removed, was followed by the deposition of intra‐crater lacustrine sediments of the Haughton Formation during the Miocene. Present‐day intra‐crater lakes and ponds preserve a detailed paleoenvironmental record dating back to the last glaciation in the High Arctic. Modern modification of the landscape is dominated by seasonal regional glacial and niveal melting, and local periglacial processes. The impact processing of target materials improved the opportunities for colonization and has provided several present‐day habitats suitable for microbial life that otherwise do not exist in the surrounding terrain. 相似文献
59.
60.
Pascal Lazure Valérie Garnier Franck Dumas Christelle Herry Marina Chifflet 《Continental Shelf Research》2009,29(8):985-997
The hydrology of the Bay of Biscay was investigated using the regional ocean model MARS3D (Model for Application at Regional Scale). The simulated hydrology is compared to a set of various data encompassing monthly climatology, remote sensing SST, CTD casts, and coastal salinity measurements. Special focus was put on the validation over the continental shelf. This paper reports that despite some misfits, the climatological hydrology and its seasonal variability are correctly simulated. Various statistics computed over the period from 1999–2004 highlight different aspects of the hydrology. The biases and root mean square errors (RMSE) remain very weak at all depths when comparing salinity (<0.1 and <0.6 psu respectively). The predicted temperature shows a global overestimation of temperature (bias of around 0.8 °C) and the maximum errors are located near the thermocline (rmse of 1 °C at 20–40 m). The model is shown to properly reproduce the annual dynamics of sea surface temperature, as well as the dynamics of large river plumes observed by high frequency time series from coastal salinity gauges. The misfits highlighted by these various comparisons between model and observations are attributed to heat fluxes and mixing parameterisation. 相似文献