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91.
Frederick?S.?ScharfEmail author John?P.?Manderson Mary?C.?Fabrizio Jeffrey?P.?Pessutti John?E.?Rosendale Robert?J.?Chant Allen?J.?Bejda 《Estuaries and Coasts》2004,27(3):426-436
Seasonal and interannual patterns in the spatial distribution of bluefish (Pomatomus saltatrix) within a Middle Atlantic Bight estuary were examined using multipanel gillnets fished biweekly at 14 fixeds stations in
the Sandy Hook Bay-N avesink River estuary during May–November of 1998 and 1999. To characterize habitats along the estuarine
gradient, we measured several abiotic and biotic variables concurrently with gillnet sampling. Juvenile (age-0 and age-1+)
bluefish were captured regularly during both years along with large numbers of Atlantic menhaden (Brevoortia tyrannus), which were confirmed by diet analyses to be bluefish’s primary forage species. The date of initial appearance of age-0
bluefish and menhaden in the estuary varied between years and may have been related to interannual differences in seawater
temperatures on the continental shelf during spring. Delayed estuarine arrival of prey fishes may have contributed to variability
in bluefish diets between years. Within the estuary, bluefish spatial distribution were consistent across seasons and years:
bluefish were most common in areas associated with high concentrations of suspended materials and the presence of menhaden.
Community analyses also indicated habitat overlap between bluefish and menhaden. Spatial distribution patterns revealed the
consistent occurrence of piscivorous bluefish in shallow estuarine habitats that retained suspended materials and aggregated
prey fishes. Foraging success of bluefish and other estuarine piscivores may be closely linked with the availability of these
productive habitat, highlighting the need for future study of biological interactions and the governing physical processes. 相似文献
92.
93.
Twenty years of paleoseismology in Italy 总被引:1,自引:0,他引:1
Italy has one of the most complete and historically extensive seismic catalogues in the World due to a unique and uninterrupted flow of written sources that have narrated its seismic history since about the end of the Iron Age. Seismic hazard studies have therefore always been mainly based upon this huge mass of data. Nevertheless, the Italian catalogue probably “lacks” many M ≥ 6.5 events, the seismogenetic structures responsible for which are characterized by recurrence times that are longer than the time span covered by our historical sources. For these reasons, and as in other countries, earthquake data that in Italy have been derived from paleoseismological studies should finally become a necessary ingredient in seismic risk assessment. Indeed, over the past 20 years, some hundred trenches have been excavated, supplying reliable and conclusive data on the recent activities of many faults. Through to many robust datings of surface fault events, these studies have provided the ages of several unknown or poorly known M ≥ 6.5 earthquakes. Here, we summarize the state of the art of paleoseismology in Italy, and present a first catalogue of 56 paleoearthquakes (PCI) that occurred mainly in the past 6 kyr. The PCI integrates the historical/instrumental seismic catalogue, and extends it beyond the recurrence time of the seismogenetic faults (2000 ± 1000 yr). We feel confident that the use of the PCI will enhance future probabilistic seismic hazard assessment, and thus contribute to more reliable seismic risk mitigation programs. 相似文献
94.
Mario Tribaudino Fabrizio Nestola Marco Bruno Tiziana Boffa Ballaran Christian Liebske 《Physics and Chemistry of Minerals》2008,35(5):241-248
The high temperature volume and axial parameters for six C2/c clinopyroxenes along the NaAlSi2O6–NaFe3+Si2O6 and NaAlSi2O6–CaFe2+Si2O6 joins were determined from room T up to 800°C, using integrated diffraction profiles from in situ high temperature single crystal data collections. The thermal
expansion coefficient was determined by fitting the experimental data according to the relation: ln(V/V
0) = α(T − T
0). The thermal expansion coefficient increases by about 15% along the jadeite–hedenbergite join, whereas it is almost constant
between jadeite and aegirine. The increase is related to the Ca for Na substitution into the M2 site; the same behaviour was
observed along the jadeite–diopside solid solution, which presents the same substitution at the M2 site. Strain tensor analysis
shows that the major deformation with temperature occurs in all samples along the b axis; on the (010) plane the higher deformation occurs in jadeite and aegirine at a direction almost normal to the tetrahedral–octahedral
planes, and in hedenbergite along the projection of the longer M2–O bonds. The orientation of the strain ellipsoid with temperature
in hedenbergite is close to that observed with pressure in pyroxenes. Along the jadeite–aegirine join instead the high-temperature
and high-pressure strain are differently oriented. 相似文献
95.
96.
Distribution and population structure of deep‐dwelling red coral in the Northwest Mediterranean
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Michela Angiolillo Andrea Gori Simonepietro Canese Marzia Bo Cristina Priori Giorgio Bavestrello Eva Salvati Fabrizio Erra Michael Greenacre Giovanni Santangelo 《Marine Ecology》2016,37(2):294-310
Commercially harvested since ancient times, the highly valuable red coral Corallium rubrum (Linnaeus, 1758) is an octocoral endemic to the Mediterranean Sea and adjacent Eastern Atlantic Ocean, where it occurs on rocky bottoms over a wide bathymetric range. Current knowledge is restricted to its shallow populations (15–50 m depth), with comparably little attention given to the deeper populations (50–200 m) that are nowadays the main target of exploitation. In this study, red coral distribution and population structure were assessed in three historically exploited areas (Amalfi, Ischia Island and Elba Island) in the Tyrrhenian Sea (Western Mediterranean Sea) between 50 and 130 m depth by means of ROV during a cruise carried out in the summer of 2010. Red coral populations showed a maximum patch frequency of 0.20 ± 0.04 SD patches·m?1 and a density ranging between 28 and 204 colonies·m?2, with a fairly continuous bathymetric distribution. The highest red coral densities in the investigated areas were found on cliffs and boulders mainly exposed to the east, at the greatest depth, and characterized by medium percentage sediment cover. The study populations contained a high percentage (46% on average) of harvestable colonies (>7 mm basal diameter). Moreover, some colonies with fifth‐order branches were also observed, highlighting the probable older age of some components of these populations. The Ischia population showed the highest colony occupancy, density and size, suggesting a better conservation status than the populations at the other study locations. These results indicate that deep dwelling red coral populations in non‐stressed or less‐harvested areas may diverge from the inverse size‐density relationship previously observed in red coral populations with increasing depth. 相似文献
97.
98.
Evaluation of the influence of experimental conditions on H/V results from ambient noise recordings 总被引:5,自引:2,他引:3
Jean-Luc Chatelain Bertrand Guillier Fabrizio Cara Anne-Marie Duval Kuvvet Atakan Pierre-Yves Bard 《Bulletin of Earthquake Engineering》2008,6(1):33-74
The H/V-noise technique is now widely used to estimate site effect parameters (fundamental frequency and sometimes the associated soil amplification), and many surveys using this technique have provided convincing results. However, a general agreement on a methodology for data acquisition, data processing and result interpretation has yet to be found. H/V measurements from ambient noise recordings imply both reliability of the results and rapidity of data collection. It is therefore important to understand which experimental conditions (1) influence data quality and reliability, and (2) can help speeding up the recording process. Within the framework of the SESAME European project, a specific task was defined to investigate the reliability of the H/V spectral ratio technique in assessing the site effects. The aim of WP02, one specific Work Package of the SESAME project, is to study the effects of experimental conditions on both stability and reproducibility of H/V results. This study has been conducted in a purely experimental way, by testing the possible influence of various experimental conditions on H/V results both on the frequency peak value and on its amplitude. WP02 results help setting up the experimental conditions under which ambient noise recordings have to be performed in order to provide reproducible, reliable and meaningful H/V results. In this paper we present the results of the WP02 SESAME project concerning the evaluation of the influence of experimental conditions of ambient noise recording on H/V results. 相似文献
99.
Miriam Colombi Barbara Borzi Helen Crowley Mauro Onida Fabrizio Meroni Rui Pinho 《Bulletin of Earthquake Engineering》2008,6(3):485-504
The concerted effort to collect earthquake damage data in Italy over the past 30 years has led to the development of an extensive
database from which vulnerability predictions for the Italian building stock can be derived. A methodology to derive empirical
vulnerability curves with the aforementioned data is presented herein and the resulting curves have been directly compared
with mechanics-based vulnerability curves. However, it has been found that a valid comparison between the empirical and analytical
vulnerability curves is not possible mainly due to a number of shortcomings in the database of surveyed buildings. A detailed
discussion of the difficulties in deriving vulnerability curves from the current observed damage database is thus also presented. 相似文献