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41.
42.
Macroalgal survival in ballast water tanks 总被引:1,自引:0,他引:1
Despite a large amount of research into invasive species and their introductions, there have been no studies focused on macroalgal transport in ballast water. To address this, we collected replicate samples of ballast water from 12 ships in two Mediterranean harbours (Naples and Salerno). Filtered samples were kept in culture for a month at Mediterranean mean conditions (18 degrees C, 12:12h LD, 60micromol photons m(-2)s(-1)). Fifteen macroalgal taxa were cultured and differed according to the geographic origin of the ballast water. Most of the cultured algae were widely distributed species (e.g. Ulva spp. and Acinetospora-phase). However, Ulva ohnoi Hiraoka and Shimada, described from Japan, was hitherto unknown in the Mediterranean Sea. We show for the first time that ballast water can be an important vector for the transport of microscopic stages of macroalgae and that this can be a vector for the introduction of alien species. 相似文献
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44.
Cristina Iuga C. Ignacio Sainz-Díaz Annik Vivier-Bunge 《Geochimica et cosmochimica acta》2010,74(12):3587-12246
Clay particles are present in large quantities in mineral dust of atmospheric aerosols, and their interaction with organic species may influence atmospheric reactions and the prediction of environmental risks. However, the kinetics and mechanisms of adsorption and reaction of atmospheric volatile organic compounds on aerosol surfaces are not well understood.In this work, quantum chemical methods are used to study the adsorption of C2-C5 aliphatic aldehydes on silicate clusters active sites, and their subsequent reaction with OH radicals. It is shown that adsorption may occur in two different ways, and that the adsorption complex structure determines the subsequent path of its reaction with OH. The initial step in the OH reaction with acetaldehyde occurs according to the same mechanism as in the gas phase, i.e., the aldehydic hydrogen abstraction. Starting from propanal, another abstraction channel becomes increasingly important, involving mainly the abstraction of a β-hydrogen of the aliphatic chain. In the presence of a silica monomer model surface, the reaction rate of aldehydes with OH free-radicals is smaller than in the gas phase. Furthermore silicates are good sinks for trapping these aldehydes. Thus, our results may have implications in the study of tropospheric chemistry and cosmochemistry. 相似文献
45.
Pietro Marescotti Eva Azzali Diego Servida Cristina Carbone Giovanni Grieco Luisa De Capitani Gabriella Lucchetti 《Environmental Earth Sciences》2010,61(1):187-199
In this work, we investigated a 3 ha sulphide-bearing waste-rock dump (Libiola Mine, Italy) using mineralogical, geochemical,
and geostatistical analyses. The dumped materials were highly heterogeneous in grain size and lithology and varied both laterally
and vertically. Other than the host rock of the ore, basalts and serpentinites, the dumped materials contained high amounts
of low-grade chalcopyrite- and pyrite-rich mineralisations. Due to these characteristics and to the absence of minerals able
to neutralise acidity, this waste-rock dump can be classified as an acid mine drainage (AMD) producer. The study confirms
that AMD is still active and, in the best scenario, can persist for up to 6.17 × 103 years. The consequences of this process are of serious environmental concern as it involves strong acidification of the circulating
waters, the release of potentially toxic metals into the soil, streams and rivers and the precipitation of huge quantities
of secondary Fe-oxides and Fe-oxyhydroxides. 相似文献
46.
Matúš Hyžný Carlos S. Melo Ricardo S. Ramalho Ricardo Cordeiro Patrícia Madeira Lara Baptista A. Cristina Rebelo Cynthia Gómez Alfred Uchman Markes E. Johnson Björn Berning Sérgio P. Ávila 《第四纪科学杂志》2021,36(1):91-109
The presence of decapod crustaceans in the Pliocene and Pleistocene (MIS 5e) fossil record of Santa Maria Island (Azores Archipelago) is herein reviewed. Our study raises the number of fossil decapods from this island from one species to 10 taxa (three for the Pliocene and seven for the Last Interglacial). Four of these 10 taxa are reported for the first time in the fossil record, worldwide. A new species of a mud shrimp is also described (Upogebia azorensis n. sp.). Our study suggests that the Plio–Pleistocene decapod assemblages of the Azores did not differ significantly from modern ones, being dominated by species that are today widespread across the Webbnesia ecoregion, the Mediterranean Sea, and the eastern Atlantic shores, including the Azores. As far as can be judged from the limited fossil record, apparently no tropical crab species with a Cabo Verdean/Senegalese provenance reached the Azores during windows of opportunity associated with Glacial Termination 2 or with the initial setting of the Last Interglacial period. This contribution increases the total number of marine taxa reported for the Pliocene and Pleistocene outcrops of Santa Maria Island to 218 and 155, respectively, highlighting the scientific relevance of its palaeontological heritage. 相似文献
47.
J. P. Phillips L. Cuesta V. Ortega 《Monthly notices of the Royal Astronomical Society》2001,322(4):866-876
The low excitation properties of the planetary nebula (PN) NGC 6720 are known to be unusual, and to imply large ring/core emission ratios. We point out that such characteristics are by no means confined to this source alone, and that high ratios may occur in a large fraction of elliptical and circular PNe. Such trends may arise because of the presence of thin low-excitation emission sheets 'wrapped' within and around the primary outflows. The widths of such shells are required to be exceedingly small, and may (for certain cases) be of order ≪10−2 pc. Such a mechanism appears capable of explaining most of the observed emission properties, and may arise through shock interaction between differing envelopes. Alternative explanations in terms of bipolar or cylindrical outflows are shown to be implausible. 相似文献
48.
Salvatore Erminio Modoni Giuseppe Spagnoli Giovanni Arciero Michela Mascolo Maria Cristina Ochmański Maciej 《Acta Geotechnica》2022,17(11):5073-5087
Acta Geotechnica - Plasticity of clays makes Deep Soil Mixing (DSM) problematic due to the tendency of the material to congest the rotating blades, reduce mixing efficiency and remain... 相似文献
49.
J. C. Morales J.-P. Beaulieu V. Coudé du Foresto M. Ollivier I. Ortega Castello R. Clédassou J. Jaubert P. Van-Troostenberghe R. Varley I. P. Waldmann E. Pascale M. Tessenyi 《Experimental Astronomy》2015,40(2-3):655-670
The Exoplanet Characterization Observatory (EChO) is a concept of a dedicated space telescope optimized for low-resolution transit and occultation spectroscopy to study the exoplanet diversity through the composition of their atmospheres. The scope of this paper is to answer the following question: Can we schedule a nominal EChO mission, with targets known today (in mid 2013), given the science requirements, realistic performances and operational constraints? We examine this issue from the point of view of duration of the mission and the scheduling restrictions with a sample of exoplanet systems known nowadays. We choose different scheduling algorithms taking into account the science and operational constraints and we verified that it is fairly straightforward to schedule a mission scenario over the lifetime of EChO compliant with the science requirements. We identified agility as a critical constraint that reduces significantly the efficiency of the survey. We conclude that even with known targets today the EChO science objectives can be reached in the 4.5 years duration of the mission. We also show that it is possible to use gaps between exoplanet observations, to fit the required calibration observations, data downlinks and station keeping operations or even to observe more exoplanet targets to be discovered in the coming years. 相似文献
50.
Mininni Pablo D. López Fuentes Marcelo Mandrini Cristina H. Gómez Daniel O. 《Solar physics》2004,219(2):367-378
We present a bi-orthogonal decomposition of the temporal and latitudinal distribution of solar magnetic fields from synoptic
magnetograms. Results are compared with a similar decomposition of the distribution of sunspots since 1874. We show that the
butterfly diagrams can be interpreted as the result of approximately constant amplitudes and phases of two oscillations with
periods close to 22 years. A clear periodicity of 7 years can also be identified in the most energetic modes of both spatio-temporal
series. These results can be used to obtain relevant information concerning the physics of the solar dynamo. 相似文献