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991.
Nathan E. Bramall Richard Quinn Andrew Mattioda Kathryn Bryson Julie D. Chittenden Amanda Cook Cindy Taylor Giovanni Minelli Pascale Ehrenfreund Antonio J. Ricco David Squires Orlando Santos Charles Friedericks David Landis Nykola C. Jones Farid Salama Louis J. Allamandola Søren V. Hoffmann 《Planetary and Space Science》2012,60(1):121-130
The Space Environment Viability of Organics (SEVO) experiment is one of two scientific payloads aboard the triple-cube satellite Organism/ORganic Exposure to Orbital Stresses (O/OREOS). O/OREOS is the first technology demonstration mission of the NASA Astrobiology Small Payloads Program. The 1-kg, 1000-cm3 SEVO cube is investigating the chemical evolution of organic materials in interstellar space and planetary environments by exposing organic molecules under controlled conditions directly to the low-Earth orbit (LEO) particle and electromagnetic radiation environment. O/OREOS was launched on November 19, 2010 into a 650-km, 72°-inclination orbit and has a nominal operational lifetime of six months. Four classes of organic compounds, namely an amino acid, a quinone, a polycyclic aromatic hydrocarbon (PAH), and a metallo-porphyrin are being studied. Initial reaction conditions were established by hermetically sealing the thin-film organic samples in self-contained micro-environments. Chemical changes in the samples caused by direct exposure to LEO radiation and by interactions with the irradiated microenvironments are monitored in situ by ultraviolet/visible/near-infrared (UV/VIS/NIR) absorption spectroscopy using a novel compact fixed-grating CCD spectrometer with the Sun as its light source. The goals of the O/OREOS mission include: (1) demonstrating key small satellite technologies that can enable future low-cost astrobiology experiments, (2) deploying a miniature UV/VIS/NIR spectrometer suitable for in-situ astrobiology and other scientific investigations, (3) testing the capability to establish a variety of experimental reaction conditions to enable the study of astrobiological processes on small satellites, and (4) measuring the chemical evolution of organic molecules in LEO under conditions that can be extrapolated to interstellar and planetary environments. In this paper, the science and technology development of the SEVO instrument payload and its measurements are described. 相似文献
992.
993.
Oliver Wetter Christian Pfister Johannes P. Werner Eduardo Zorita Sebastian Wagner Sonia I. Seneviratne Jürgen Herget Uwe Grünewald Jürg Luterbacher Maria-Joao Alcoforado Mariano Barriendos Ursula Bieber Rudolf Brázdil Karl H. Burmeister Chantal Camenisch Antonio Contino Petr Dobrovolný Rüdiger Glaser Iso Himmelsbach Andrea Kiss Oldřich Kotyza Thomas Labbé Danuta Limanówka Laurent Litzenburger Øyvind Nordli Kathleen Pribyl Dag Retsö Dirk Riemann Christian Rohr Werner Siegfried Johan Söderberg Jean-Laurent Spring 《Climatic change》2014,125(3-4):365-367
994.
Observations using a three-dimensional scanning coherent Doppler lidar in an urban area revealed the characteristics of streaky structures above a rough, inhomogeneous surface for a high-Reynolds-number flow. The study focused on two points: (1) the frequency of occurrence and conditions required for the presence of streaky structures, and (2) the universal scaling of the spacing of streaky structures (\(\lambda )\). The horizontal snapshots of the radial velocity were visually classified into six groups: Streak, Mixed, Fishnet, No streak, Front, and Others. The Streak category accounted for more than 50% of all possible flows and occurred when the horizontal wind speed was large and the atmospheric stratification was near-neutral. The spacing (\(\lambda )\) was estimated from the power spectral density of the streamwise velocity fluctuations along the spanwise direction. The spacing \(\lambda \) decreased with an increase in the local velocity gradient. Furthermore, it was revealed that the local velocity gradient normalized by the friction velocity and the boundary-layer height (\(z_i )\) comprehensively predicts \(\lambda /z_i \) under various experimental and environmental conditions, in terms of the scale of motion (i.e., indoor and outdoor scales), thermal stratification (i.e., from weakly unstable to stable stratification), and surface roughness (i.e., from flat to very rough surfaces). 相似文献
995.
Antonio Augusto Rossotto Ioris Carlos Teodoro Irigaray Pierre Girard 《Climatic change》2014,127(1):139-151
Climatic change is expected to have serious impacts on the Pantanal, a large tropical wetland located in the Upper Paraguay River Basin, in the centre of South America, where a range of institutional responses are being developed to mitigate and adapt to climate change. In order to examine the institutional achievements and challenges for managing the region, a specific typology is initially introduced, which comprises a schematic gradient of institutional responses. An empirical analysis was conducted in Brazil, Bolivia and Paraguay, the three countries that share the Pantanal, which identified the hybrid basis of the policy framework under construction, in the sense that it actually combines elements of various institutional responses included in the proposed typology. Important factors that seem to undermine the efficacy of institutional responses in addressing climate change in the region are the strong influence of the agribusiness sector and the still relatively low importance of the Pantanal for national environmental policy-making. This essay makes a claim that the principles of climate justice should guiding policies and interventions as it they constitute the most appropriate strategy to address the inequality and unfairness related to climate change. 相似文献
996.
Camuffo Dario della Valle Antonio Becherini Francesca 《Theoretical and Applied Climatology》2018,132(3-4):1143-1151
Theoretical and Applied Climatology - Surface wetness is a synergistic factor to determine atmospheric corrosion, monument weathering, mould growth, sick buildings, etc. However, its detection and... 相似文献
997.
The influence of a melt boundary layer on crystal growth is analyzed. The treatment extends the results of Burton, Prim and Slichter (1953) and incorporates composition-dependent growth rates. It is shown that in these general cases the growth rate cannot be arbitrarily fixed but must satisfy a self-consistent equation. Self-consistency problems arise because the growth rate determines the composition profile in the melt and, in turn, the composition profile determines the growth rate. The self-consistent growth rate is shown to vary markedly with the ratio δ/D, where δ is the thickness of the boundary layer and D is the appropriate diffusion coefficient in the melt. This self-consistency can be very important in the analysis of both field and laboratory growth rates as well as in trace element partition kinetic models. 相似文献
998.
Occhipinti Giuseppe Cali Ivo DAltri Antonio Maria Grillanda Nicola de Miranda Stefano Milani Gabriele Spacone Enrico 《Bulletin of Earthquake Engineering》2022,20(4):2219-2244
Bulletin of Earthquake Engineering - This paper reports the results of different finite and discrete element simulations on a well-known benchmark of an unreinforced plane masonry structure.... 相似文献
999.
Paolo Antonio Pirazzoli Stéphane Costa Uwe Dornbusch Alberto Tomasin 《Ocean Dynamics》2006,56(5-6):498-512
This paper is based on statistical analysis of hourly tide measurements for some 285 equivalent full years from the stations
of Weymouth, Bournemouth, Portsmouth, Newhaven, Dover and Sheerness in the UK, and of Cherbourg, Le Havre, Dieppe, Boulogne,
Calais and Dunkirk in France. For each tidal value, surge heights have been determined and correlated with hourly or three-hourly
wind and air pressure data from nearby meteorological stations. Major surges in the area are generally produced by storms
associated with wind from north-west or south-west that tend to push oceanic water into the Channel. Recent medium-term climate
evolution does not seem to increase the flooding risk at French stations, where surge-related winds tend to decrease in frequency
and speed (Cherbourg, Dieppe and Boulogne) or show little change (Le Havre). However, the long-term risk of flooding will
increase through the loss in land elevation due to a continuation of the local relative sea-level rise, especially if this
effect will be enhanced by an acceleration in the global sea-level rise predicted by climatic models. The northern side of
the Channel (Weymouth, Bournemouth and Portsmouth) is mainly exposed to southerly winds that show variable trends. It is also
apparently affected by strong subsidence trends during the last two decades. If lasting, such trends can only increase long-term
flooding risk. The flooding risk has not increased near the eastern end of the Channel. The duration of significant cyclonic
events tends to decrease near Cherbourg but tends to increase near Weymouth, with no conclusive trends in other stations (Portsmouth,
Calais and Dunkirk), where extreme surges may occur also in relatively high-air-pressure situations. In conclusion, medium-term
coastal flooding risk seems to increase especially at Weymouth, Bournemouth and Portsmouth, and also, but less so, at Le Havre
and Sheerness. In addition, few extreme surges occurred during the last decades at the time of spring high tide, which would
seem to be a fortunate coincidence or, in some cases, an effect of tide–surge interaction. The risk of occurrence of less
favourable random events in the near future is therefore of concern, and flood potential would greatly increase if the global
sea-level rise expected in the near future is also considered. 相似文献
1000.