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61.
Lucia S. Herbeck Miriam Sollich Daniela Unger Marianne Holmer Tim C. Jennerjahn 《Marine pollution bulletin》2014
The impact of pond aquaculture effluents on the distribution and performance of seagrasses was examined in NE Hainan, tropical China. Samples were taken along transects in three back-reef areas with different extent of aquaculture production in their hinterland. High δ15N in seagrass leaves and epiphytes (6–9‰) similar to values in pond effluents documented aquaculture as dominant nitrogen source in the back-reefs with decreasing impact with distance from shore. Seagrass species abundance, shoot density and biomass were lower and concentrations of nutrients, chlorophyll and suspended matter were higher at nearshore sites with high and moderate pond abundance than at the control site. High epiphyte loads and low δ34S in seagrass leaves suggest temporal shading and sulphide poisoning of the nearshore seagrasses. Observed gradients in environmental parameters and seagrass performance indicate that the distance from the pond outlets and size of the adjacent pond agglomeration are major determinants of seagrass degradation. 相似文献
62.
In this work an overview of the potential rock fall source areas and propagation assessment in the Province of Potenza territory has been presented. The rock fall process is characterized by two steps: the detachment of blocks and subsequently their propagation along the slope. The adopted methodology, used for the first time in the study area, and the software Histofit and FlowR have been very useful tools for the preliminary assessment of rock fall susceptibility at a regional scale, in particular because they have required low data of the study area. Only the DEM may be sufficient together with an appropriate choice of the input parameters and algorithms, that is to say: calculation method, directions algorithm, inertial algorithm and friction loss function. The output of the model is a map of the rock fall source areas, the propagation probabilities and the propagation kinetic energy. The results show that the adopted methodology is successful for the identification of rock fall source areas at a regional scale and the propagation probability obtaining an interesting rock fall susceptibility map. 相似文献
63.
Greig A. Paterson Andrew P. Roberts Conall Mac Niocaill Adrian R. Muxworthy Lucia Gurioli José G. Viramonté Carlos Navarro Shoshana Weider 《Bulletin of Volcanology》2010,72(3):309-330
Paleomagnetic data from lithic clasts collected from Mt. St. Helens, USA, Volcán Láscar, Chile, Volcán de Colima, Mexico and
Vesuvius, Italy have been used to determine the emplacement temperature of pyroclastic deposits at these localities and to
highlight the usefulness of the paleomagnetic method for determining emplacement temperatures. At Mt. St. Helens, the temperature
of the deposits (T
dep
) at three sites from the June 12, 1980 eruption was found to be ≥532°C, ≥509°C, and 510–570°C, respectively. One site emplaced
on July 22, 1980 was emplaced at ≥577°C. These new paleomagnetic temperatures are in good agreement with previously published
direct temperature measurements and paleomagnetic estimates. Lithic clasts from pyroclastic deposits from the 1993 eruption
of Láscar were fully remagnetized above the respective Curie temperatures, which yielded a minimum T
dep
of 397°C. Samples were also collected from deposits thought to be pyroclastics from the 1913, 2004 and 2005 eruptions of
Colima. At Colima, the sampled clasts were emplaced cold. This is consistent with the sampled clasts being from lahar deposits,
which are common in the area, and illustrates the usefulness of the paleomagnetic method for distinguishing different types
of deposit. T
dep
of the lower section of the lithic rich pyroclastic flow (LRPF) from the 472 A.D. deposits of Vesuvius was ~280–340°C. This
is in agreement with other, recently published paleomagnetic measurements. In contrast, the upper section of the LRPF was
emplaced at higher temperatures, with T
dep
~520°C. This temperature difference is inferred to be the result of different sources of lithic clasts between the upper
and lower sections, with the upper section containing a greater proportion of vent-derived material that was initially hot.
Our studies of four historical pyroclastic deposits demonstrates the usefulness of paleomagnetism for emplacement temperature
estimation. 相似文献
64.
Marco Massa Francesca Pacor Lucia Luzi Dino Bindi Giuliano Milana Fabio Sabetta Antonella Gorini Sandro Marcucci 《Bulletin of Earthquake Engineering》2010,8(5):1175-1187
The Italian strong-motion database was created during a joint project between Istituto Nazionale di Geofisica e Vulcanologia
(INGV, Italian Institute for Geophysics and Vulcanology) and Dipartimento della Protezione Civile (DPC, Italian Civil Protection). The aim of the project was the collection, homogenization and distribution of strong motion data acquired in Italy in the
period 1972–2004 by different institutions, namely Ente Nazionale per l’Energia Elettrica (ENEL, Italian electricity company), Ente per le Nuove tecnologie, l’Energia e l’Ambiente (ENEA, Italian energy and environment organization) and DPC. Recently the strong-motion data relative to the 23th December 2009, Parma (Mw = 5.4 and Mw = 4.9) and to the April
2009 L’Aquila sequences (13 earthquakes with 4.1 ≤ Mw ≤ 6.3) were included in the Italian Accelerometric Archive (ITACA) database
(beta release). The database contains 7,038 waveforms from analog and digital instruments, generated by 1.019 earthquakes
with magnitude up to 6.9 and can be accessed on-line at the web site . The strong motion data are provided in the unprocessed and processed versions. This article describes the steps followed
to process the acceleration time series recorded by analogue and digital instruments. The procedures implemented involve:
baseline removal, instrumental correction, band pass filtering with acausal filters, integration of the corrected acceleration
in order to obtain velocity and displacement waveforms, computation of acceleration response spectra and strong motion parameters.
This procedure is applied to each accelerogram and it is realised to preserve the low frequency content of the records. 相似文献
65.
José Luis Arce Rodolfo Macías Armando García Palomo Lucia Capra José Luis Macías Paul Layer Hernando Rueda 《Journal of Volcanology and Geothermal Research》2008
Zempoala is an extinct Pleistocene (∼ 0.7–0.8 Ma) stratovolcano that together with La Corona volcano (∼ 0.9 Ma) forms the southern end of the Sierra de las Cruces volcanic range, Central Mexico. The volcano consists of andesitic and dacitic lava flows and domes, as well as pyroclastic and epiclastic sequences, and has had a complex history with several flank collapses. One of these collapses occurred during the late Pleistocene on the S–SE flank of the volcano and produced the Zempoala debris avalanche deposit. This collapse could have been triggered by the reactivation of two normal fault systems (E–W and NE–SW), although magmatic activity cannot be absolutely excluded. The debris avalanche traveled 60 km to the south, covers an area of 600 km2 and has a total volume of 6 km3, with a calculated Heim coefficient (H/L) of 0.03. Based on the textural characteristics of the deposit we recognized three zones: proximal, axial, and lateral distal zone. The proximal zone consists of debris avalanche blocks that develop a hummocky topography; the axial zone corresponds with the main debris avalanche deposit made of large clasts set in a sandy matrix, which transformed to a debris flow in the lateral distal portion. The deposit is heterolithologic in composition, with dacitic and andesitic fragments from the old edifice that decrease in volume as bulking of exotic clasts from the substratum increase. Several cities (Cuernavaca, Jojutla de Juárez, Alpuyeca) with associated industrial, agricultural, and tourism activities have been built on the deposit, which pose in evidence the possible impact in case of a new event with such characteristics, since the area is still tectonically active. 相似文献
66.
Rigoberto Rosas‐Luis María de Lourdes Jimnez Badillo Lucia Montoliu‐Elena Piedad S. Morillo‐Velarde 《Marine Ecology》2019,40(1)
Octopuses are active predators that feed on a wide range of prey including crustaceans, fishes, and mollusks. They are important components of coral reef systems and support local and artisanal fisheries in the Gulf of México. Octopus insularis has been found to be one of the most relevant components in catches from the coral reef system of Veracruz in the southwestern Gulf of Mexico, and its role in the ecosystem requires assessment. To corroborate the morphological identification of O. insularis, six octopuses were identified by genetic methods. And to understand the trophic relationships between this octopus species and its prey, 394 octopuses caught during 2016 and 2017 by an artisanal fleet were sampled and their stomach contents analyzed. Results showed that crustaceans are the most frequently consumed group, with the genera Mithraculus and Etisus being the most important in the diet. Fishes, bivalves, and gastropods were identified as uncommon prey items in the diet. Their presence in the stomachs could be related to the movement of this octopus outside of the coral reef. Considering that our samples were of medium‐ and large‐sized individuals, cannibalism could be discarded for O. insularis in this size range in the Veracruz reef system. These findings suggest a generalist and opportunistic predation of O. insularis on the most abundant and available prey in the study area, namely the crustaceans. These represents an effective transfer of biomass from the low trophic levels to top predators in the coral reef system. 相似文献
67.
Anssi Pekkarinen Lucia Reithmaier Peter Strobl 《ISPRS Journal of Photogrammetry and Remote Sensing》2009,64(2):171-183
This paper describes a simple and adaptive methodology for large area forest/non-forest mapping using Landsat ETM+ imagery and CORINE Land Cover 2000. The methodology is based on scene-by-scene analysis and supervised classification. The fully automated processing chain consists of several phases, including image segmentation, clustering, adaptive spectral representativity analysis, training data extraction and nearest-neighbour classification. This method was used to produce a European forest/non-forest map through the processing of 415 Landsat ETM+ scenes. The resulting forest/non-forest map was validated with three independent data sets. The results show that the map’s overall point-level agreement with our validation data generally exceeds 80%, and approaches 90% in central European conditions. Comparison with country-level forest area statistics shows that in most cases the difference between the forest proportion of the derived map and that computed from the published forest area statistics is below 5%. 相似文献
68.
The Large Marine Ecosystem (LME) concept is widely established as a large-scale approach to coastal and marine management. LME-oriented activities have focused mainly on natural sciences. Socioeconomic and governance aspects have only recently been receiving increased attention. The 64 LMEs that have been defined appeared to exhibit considerable diversity in characteristics that would be expected to affect governability. This paper explores two questions: (1) Do the LMEs vary widely enough in geopolitical complexity that different approaches to governance may be required for different LMEs? (2) Are there groups of LMEs within which one might take similar approaches to governance? The analysis demonstrates that there is considerable heterogeneity among LMEs with regard to characteristics that would be expected to affect governability. It concludes that a diversity of governance approaches will be required to cope with this heterogeneity. It also appears that LMEs can be grouped according to these characteristics. This suggests that different approaches could be considered for clusters rather than for individual LMEs and that there can be sharing of experience and learning within clusters. The types of relationships between features of LMEs and the ‘best’ approaches to marine governance are discussed in the context of emerging governance ideas. 相似文献
69.
70.
Two groups of rocks are distinguished in the Assab volcanic range (Afar) on the basis of their petrology. The first one is a typical alkaline suite with high Li, Ba, Rb, Sr, Th and U concentrations. A second subalkaline group may be related to a parental basalt characterized by low trace-element concentrations and intermediate in character between alkali and tholeiitic basalt.U and Th concentrations of the analyzed Assab basalts, as well the reported values for the alkali and transitional basalts of the East African Rift and the Afar depression, are higher than values reported for similar basalts from oceanic and continental environments. 相似文献