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261.
Gerardo Herrera Rosa María Mateos Juan Carlos García-Davalillo Gilles Grandjean Eleftheria Poyiadji Raluca Maftei Tatiana-Constantina Filipciuc Mateja Jemec Auflič Jernej Jež Laszlo Podolszki Alessandro Trigila Carla Iadanza Hugo Raetzo Arben Kociu Maria Przyłucka Marcin Kułak Michael Sheehy Xavier M. Pellicer Charise McKeown Graham Ryan Veronika Kopačková Michaela Frei Dirk Kuhn Reginald L. Hermanns Niki Koulermou Colby A. Smith Mats Engdahl Pere Buxó Marta Gonzalez Claire Dashwood Helen Reeves Francesca Cigna Pavel Liščák Peter Pauditš Vidas Mikulėnas Vedad Demir Margus Raha Lídia Quental Cvjetko Sandić Balazs Fusi Odd Are Jensen 《Landslides》2018,15(2):359-379
Landslides are one of the most widespread geohazards in Europe, producing significant social and economic impacts. Rapid population growth in urban areas throughout many countries in Europe and extreme climatic scenarios can considerably increase landslide risk in the near future. Variability exists between European countries in both the statutory treatment of landslide risk and the use of official assessment guidelines. This suggests that a European Landslides Directive that provides a common legal framework for dealing with landslides is necessary. With this long-term goal in mind, this work analyzes the landslide databases from the Geological Surveys of Europe focusing on their interoperability and completeness. The same landslide classification could be used for the 849,543 landslide records from the Geological Surveys, from which 36% are slides, 10% are falls, 20% are flows, 11% are complex slides, and 24% either remain unclassified or correspond to another typology. Most of them are mapped with the same symbol at a scale of 1:25,000 or greater, providing the necessary information to elaborate European-scale susceptibility maps for each landslide type. A landslide density map was produced for the available records from the Geological Surveys (LANDEN map) showing, for the first time, 210,544 km2 landslide-prone areas and 23,681 administrative areas where the Geological Surveys from Europe have recorded landslides. The comparison of this map with the European landslide susceptibility map (ELSUS 1000 v1) is successful for most of the territory (69.7%) showing certain variability between countries. This comparison also permitted the identification of 0.98 Mkm2 (28.9%) of landslide-susceptible areas without records from the Geological Surveys, which have been used to evaluate the landslide database completeness. The estimated completeness of the landslide databases (LDBs) from the Geological Surveys is 17%, varying between 1 and 55%. This variability is due to the different landslide strategies adopted by each country. In some of them, landslide mapping is systematic; others only record damaging landslides, whereas in others, landslide maps are only available for certain regions or local areas. Moreover, in most of the countries, LDBs from the Geological Surveys co-exist with others owned by a variety of public institutions producing LDBs at variable scales and formats. Hence, a greater coordination effort should be made by all the institutions working in landslide mapping to increase data integration and harmonization. 相似文献
262.
Stefano Branca Maria Grazia Branciforti Antonio Fernando Chiavetta Rosa Anna Corsaro 《Geoarchaeology》2016,31(1):3-16
The amphitheater of Catania is one of the main architectural structures built during Roman domination of the town. It was constructed in two successive phases between the 1st and 2nd centuries A.D. and fell into disuse from the second half of the 4th century. Detailed geological and petrographic investigations allow better geomorphological reconstruction of the area where the monument was built. In particular, the western and eastern portions of the amphitheater are built on prehistoric lava flows, named Barriera del Bosco and Larmisi, respectively. We infer that the choice of site to build the monument was highly influenced by the morphological setting of the area. In fact, the location at the contact between two lava flow fields facilitated excavation and removal of rocks due to the incoherence of the scoriaceous lateral border of the lava flows. Integrating both archaeological and geological data has revealed that a large number of Neolithic, Greek, and Roman sites are located in the lava fields of Barriera del Bosco and Larmisi within the present urban district of Catania, indicating that during its long history the city was directly impacted by only one lava flow, namely in A.D. 1669. 相似文献
263.
Amelia Gómez‐Villar Javier Santos‐González Rosa Blanca González‐Gutiérrez José María Redondo‐Vega 《Geografiska Annaler: Series A, Physical Geography》2015,97(4):633-651
A total of 156 glacial cirques located on two different areas in the Cantabrian Mountains (NW Spain) were identified and measured in order to continue and expand the study of these large‐scale erosional forms in European mountains. Environmental variables that may explain cirque distribution (altitude, aspect and lithology), and their most important morphometric features (area, length (L), width (W), headwall height (H), and L/W, L/H and W/H indices), are analysed. Statistical analysis has been applied as indicators of contrast (ANOVA) and association (correlation and regression). Conglomerate analysis (CLUSTER) has been used to discriminate cirque groups based on their morphometric variables. Results show that cirques occur at lower altitudes in the Upper Sil River basin area than in the Montaña Central area due to a lower former equilibrium line altitude (ELA) position. In the Upper Sil River basin, environmental variables appear to have had a strong influence on the location and size of cirques: the largest cirques are located in quartzite rocks at elevations above 2000 m and face N or NE. In Montaña Central, the influence of these factors was more limited as a consequence of higher geological structure control. Cirque sizes generally are modest compared with cirques present in other mountain ranges globally, most likely due to shorter glacial occupancy in the Cantabrian Mountains. 相似文献
264.
Occurrence of selected estrogens in mangrove sediments 总被引:1,自引:0,他引:1
Froehner S Machado KS Stefan E Bleninger T da Rosa EC Martins Cde C 《Marine pollution bulletin》2012,64(1):75-79
This paper presents results related to the occurrence and distribution of estrogens along the Brazilian coast. Three mangrove areas were chosen to evaluate the presence of estrogens in surface sediments of mangrove forests. The presence of estrogens was observed in all studied sites. 17-α-Ethinylestradiol (EE2), a synthetic estrogen, was the most common and has been found in higher concentration (0.45-129.78 ng/g) compared to 17-β-estradiol (E1) and estrone (E2) (both being natural estrogens). The concentrations of E1 and E2 ranged from 0.02 to 49.27 ng/g and 0.03 to 39.77 ng/g, respectively. Theoretically, under anaerobic conditions EE2 can be reduced to E1 even in environments such as sediments of mangrove forests, which are essentially anaerobic. Even if the concentrations of estrogens seem to be insignificant in some samples, the effects remain uncertain. 相似文献
265.
A. Castro C. Fernández H. El-Hmidi M. El-Biad M. Díaz J. de la Rosa F. Stuart 《International Journal of Earth Sciences》1999,88(1):26-37
The Aracena metamorphic belt (AMB), southwest Iberian peninsula, is characterized by the following geological elements: (a)
a high-temperature/low-pressure (HT/LP) metamorphic belt a few kilometres wide and more than 200 km long; (b) a linear belt
of oceanic amphibolites with a low-pressure inverted metamorphic gradient; (c) crustal-scale ductile shear zones; and (d)
mafic, noritic intrusions of high-Mg andesite (boninite) composition. The relationships between these elements led to the
proposal of a model of ridge subduction for this sector of the Hercynian belt of Europe. This interpretation is supported
by the age relationships displayed between the main rock units considered representative of the main tectonic and petrological
processes responsible for the geological elements mentioned previously. The results of a geochronological study (Ar–Ar, Rb–Sr
and Sm–Nd) clearly support a Late Paleozoic tectonic evolution at an active continental margin. The time evolution of the
metamorphism in the oceanic domain, ranging from 342.6±0.6 Ma in the west to 328.4±1.2 Ma in the east, over a distance of
70 km along the metamorphic belt, support a tectonic model of triple-junction migration responsible for the creation at depth
of a slab-free window with decisive consequences for the thermal evolution of the region. The origin of the linear metamorphic
belt of HT/LP regime may be explained by the migration along a continental margin of a punctual thermal anomaly induced by
the creation of a triple-junction at the continental margin.
Received: 9 March 1998 / Accepted: 9 December 1998 相似文献
266.
267.
R. De Rosa 《Bulletin of Volcanology》1999,61(3):162-173
This paper illustrates some problems involved in the quantitative compositional study of pyroclastic deposits and proposes
criteria for selecting the main petrographic and textural classes for modal analysis. The relative proportions of the different
classes are obtained using a point-counting procedure applied to medium-coarse ash samples that reduces the dependence of
the modal composition on grain size and avoids tedious counting of different grain-size fractions. The major purposes of a
quantified measure of component distributions are to: (a) document the nature of the fragmenting magma; (b) define the eruptive
dynamics of the eruptions on a detailed scale; and (c) ensure accuracy in classifying pyroclastic deposits. Compositional
modes of the ash fraction of pyroclastic deposits vary systematically, and their graphical representation defines the compositional
and textural characteristics of pyroclastic fragments associated with different eruptive styles. Textural features of the
glass component can be very helpful for inferring aspects of eruptive dynamics. Four major parameters can be used to represent
the component composition of pyroclastic ash deposits: (a) juvenile index (JI); (b) crystallinity index (CrI); (c) juvenile
vesicularity index (JVI); and (d) free crystal index (FCrI). The FCrI is defined as the ratio between single and total crystal
fragments in the juvenile component (single crystals+crystals in juvenile glass). This parameter may provide an effective
estimate of the mechanical energy of eruptions. Variations in FCrI vs JVI discriminate among pyroclastic deposits of different
origin and define compositional fields that represent ash derived from different fragmentation styles.
Received: 15 January 1998 / Accepted: 8 February 1999 相似文献
268.
Widespread syn-eruptive volcaniclastic deposits in the Pleistocenic basins of South-Western Calabria
Since late Tortonian, depositional sequences developed along the Southern Calabrian forearc, inside the half-graben depressions of the Mesima-Gioia Tauro and Reggio Calabria basins. In these basins volcaniclastic sedimentation took place during lower to middle Pleistocene. Volcaniclastic deposits consist of isolated pumice swarms, ash layers and thick successions of lapilli and ash. 相似文献
269.
Flow dynamics within a peatland are governed by hydraulic parameters such as hydraulic conductivity, dispersivity and specific yield, as well as by anisotropy and heterogeneity. The aim of this study is to investigate hydraulic parameters variability in peat through the use of different field and laboratory methods. An experimental site located in the Lanoraie peatland complex (southern Quebec, Canada) was used to test the different approaches. Slug and bail tests were performed in piezometer standpipes to investigate catotelm hydraulic conductivity. Combined Darcy tests and tracer experiments were conducted on cubic samples using the modified cube method (MCM) to assess catotelm hydraulic conductivity, anisotropy and dispersivity. A new laboratory method is proposed for assessing acrotelm hydraulic conductivity and gravity drainage using a laboratory experimental tank. Most of slug tests' recovery curves were characteristic of compressible media, and important variability was observed depending on the initial head difference. The Darcy experiments on cubic samples provided reproducible results, and anisotropy (Kh > Kv) was observed for most of samples. All tracer experiments displayed asymmetrical breakthrough curves, suggesting the presence of retardation and/or dual porosity. Hydraulic conductivity estimates performed using the experimental tank showed K variations over a factor of 44 within the upper 40 cm of the acrotelm. The results demonstrate that the intrinsic variability associated with the different field and laboratory methods is small compared with the spatial variability of hydraulic parameters. It is suggested that a comprehensive assessment of peat hydrological properties can be obtained through the combined use of complementary field and laboratory investigations. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
270.
Maria Isabel Arce Daniel von Schiller Rosa Gómez 《Aquatic Sciences - Research Across Boundaries》2014,76(2):295-311
Streams are significant locations for nitrate (NO3 ?) processing within landscapes. This is especially important in dry climates given the limited water availability for biological processes elsewhere. In arid and semiarid regions, many streams are naturally saline. Elevated salinity can constrain the structure and function of aquatic organisms, which is expected to increase worldwide being associated to global warming. We investigated whole-reach NO3 ? uptake and denitrification in nine semiarid streams of variable water salinity (i.e. from freshwater to hyposaline) to test if NO3 ? processing would decrease with increasing salinity. We used pulse additions and Tracer Addition for Spiraling Curve Characterization (TASCC) to measure whole-reach uptake of added NO3 ?, and the acetylene block technique to measure sediment denitrification. TASCC results showed that only five of nine streams were able to retain added NO3 ?. Of these five retentive streams, four were saline; however, salinity did not control significantly the variation in whole-reach NO3 ? uptake observed across streams. Other measured environmental variables such as streambed NH4 + and organic carbon availability were better at explaining this variation. Denitrification was detected in all streams except one and its variation across streams was also independent of salinity. Although denitrification rates tended to be high, their contribution to whole-reach NO3 ? uptake was insignificant (≤2.16 %). Alternative pathways, heterotrophic assimilation and/or dissimilatory NO3 ? reduction to NH4 +, were probably responsible for most whole-reach NO3 ? uptake. Together, our results highlight that the function of streams in controlling external NO3 ? inputs is highly variable and salinity does not apparently constrain this role. 相似文献