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71.
Giulio Bigazzi Zehra Yegingil Tuncay Ercan Massimo Oddone Mehmet Özdogan 《Bulletin of Volcanology》1993,55(8):588-595
Twenty obsidian samples from Central and North Anatolia were dated by the fission track method. Split samples analyzed in two different laboratories give consistent results. Data presented refer to three volcanic fields and are summarized as follows: Orta-Sakaeli (Northern Anatolia) obsidians with ages from 21–23 Ma; Göllü Dagi dome complex near Çiftlik (Central anatolia) has given ages between 1.33–0.98 Ma; Acigöl caldera (Central Anatolia) shows three age groups: (1) Eruptions of precaldera (Bogazköy) obsidians with ages 0.18–0.15 Ma; (2) Formation of the large intracaldera dome Kocadag-Taskesiktepe at about 0.08 Ma (uncorrected apparent age of 0.075 Ma); and (3) Acigöl peripheral obsidian domes with plateau ages of 0.020 and 0.019 Ma, and an additional uncorrected age of 0.018 Ma form a distinct age group. This fission track parameters discriminate between the various obsidian sources of prehistoric obsidian artifacts. 相似文献
72.
Modelling the rainfall-induced mobilization of a large slope movement in northern Calabria 总被引:2,自引:1,他引:1
Giovanna Capparelli Pasquale Iaquinta Giulio G. R. Iovine Oreste G. Terranova Pasquale Versace 《Natural Hazards》2012,61(1):247-256
Two recent phases of mobilization of a large, rainfall-induced debris slide are analysed in terms of relationships between
rains and phases of displacement. The first activation at San Rocco (San Benedetto Ullano, Calabria) occurred on 28 January
2009, after extraordinary rains had stricken the region for a couple of months. Detailed geomorphologic field surveys, combined
with measurements of superficial displacements at datum points, were performed to properly recognize the evolution of the
phenomenon. In addition, a real-time control system of rains and superficial displacements measured at extensometers was implemented,
to better analyse the evolution of the phenomenon. In early May 2009, the activity reduced to very slow displacements, persisting
in the same condition for the following 8 months. On 1 February 2010, premonitory signs of a new phase of activation were
noticed, again following 2 months of extraordinary rainfalls. After few days of further precipitations, the middle sector
of the landslide activated since 11 February, disrupting the road network and threatening the major lifelines and some buildings.
A hydrological analysis aimed at simulating the dates of activation and the main phases of acceleration of the phenomenon
was carried out, by calibrating the empirical model FLaIR against the daily rainfalls and the history of known phases of mobilization since 1970. Calibration allowed to successfully
simulate both the cited phases of activity of the San Rocco landslide, by predicting the beginning of the movements as well
as the following paroxysmal stages, as testified by the measurements at datum points and extensometers. The set of parameters
obtained through calibration reflects the influence of both prolonged antecedent rains, and of high-intensity rainfalls of
shorter duration, which slightly preceded the major displacements. Once calibrated the model, a suitable threshold could be
defined, by analysing the trend of the mobility function against the history of activations of the considered slope movement,
and by excluding false alarms. Accordingly, a reliable tool for predicting the phases of activity of a large slope movement
could therefore be obtained. 相似文献
73.
Asymptotic solution for the two-body problem with constant tangential thrust acceleration 总被引:1,自引:0,他引:1
Claudio Bombardelli Giulio Baù Jesus Peláez 《Celestial Mechanics and Dynamical Astronomy》2011,110(3):239-256
An analytical solution of the two body problem perturbed by a constant tangential acceleration is derived with the aid of
perturbation theory. The solution, which is valid for circular and elliptic orbits with generic eccentricity, describes the
instantaneous time variation of all orbital elements. A comparison with high-accuracy numerical results shows that the analytical
method can be effectively applied to multiple-revolution low-thrust orbit transfer around planets and in interplanetary space
with negligible error. 相似文献
74.
Massimo Cerdonio Fabrizio De Marchi Roberto De Pietri Philippe Jetzer Francesco Marzari Giulio Mazzolo Antonello Ortolan Mauro Sereno 《Celestial Mechanics and Dynamical Astronomy》2010,107(1-2):255-264
The analysis of non-radiative sources of static or time-dependent gravitational fields in the Solar System is crucial to accurately estimate the free-fall orbits of the LISA space mission. In particular, we take into account the gravitational effects of Interplanetary Dust (ID) on the spacecraft trajectories. The perturbing gravitational field has been calculated for some ID density distributions that fit the observed zodiacal light. Then we integrated the Gauss planetary equations to get the deviations from the LISA Keplerian orbits around the Sun. This analysis can be eventually extended to Local Dark Matter (LDM), as gravitational fields are expected to be similar for ID and LDM distributions. Under some strong assumptions on the displacement noise at very low frequency, the Doppler data collected during the whole LISA mission could provide upper limits on ID and LDM densities. 相似文献
75.
Marsh soil properties vary drastically across estuarine salinity gradients, which can affect soil strength and, consequently, marsh edge erodibility. Here, we quantify how marsh erosion differs between saline and brackish marshes of the Mississippi Delta. We analyzed long-term (1932–2015) maps of marsh loss and developed an algorithm to distinguish edge erosion from interior loss. We found that the edge erosion rate remains nearly constant at decadal timescales, whereas interior loss varies by more than 100%. On average, roughly half of marsh loss can be attributed to edge erosion, the other half to interior loss. Based on data from 42 cores, brackish marsh soils had a lower bulk density (0.17 vs. 0.27 g/cm3), a higher organic content (43% vs. 26%), a lower shear strength (2.0 vs. 2.5 kPa), and a lower shear strength in the root layer (13.8 vs. 20.7 kPa) than saline marsh soils. We then modified an existing marsh edge erosion model by including a salinity-dependent erodibility. By calibrating the erodibility with the observed retreat rates, we found that the brackish marsh is two to three times more erodible than the saline marshes. Overall, this model advances the ability to simulate estuarine systems as a whole, thus transcending the salinity boundaries often used in compartmentalized marsh models. 相似文献
76.
G. Milana R. M. Azzara E. Bertrand P. Bordoni F. Cara R. Cogliano G. Cultrera G. Di Giulio A.M. Duval A. Fodarella S. Marcucci S. Pucillo J. R��gnier G. Riccio 《Bulletin of Earthquake Engineering》2011,9(3):741-759
After the 2009 April 6th Mw 6.3 L??Aquila earthquake (Central Italy) the Italian Civil Defense Department promoted the microzoning study in the ten zones in the epicentral area that suffered major damage. In this paper we present the activities and the results concerning a temporary seismic network installed in the historical L??Aquila city center indicated as ??macroarea 1?? in the microzoning project. Seismic data were collected to investigate the amplification effects in the city and to support the microzoning activities in verifying both geological profiles and 1D numerical modeling of the seismic response of the city. The conventional spectral approaches using both microtremor and earthquake data allowed to determine the fundamental resonance frequencies and the amplification factors within the city respectively. The spatial variability of these quantities can be related to the geological and geomorphologic characteristics of the investigated area. A comparison between the network data and the data recorded by the two strong motion instruments installed in the city was also made. This allows verifying the relative response of the accelerometric stations that recorded in the city the major events of the sequence. 相似文献
77.
Alexandrine Marteel Vania Gaspari Claude F. Boutron Carlo Barbante Paolo Gabrielli Paolo Cescon Giulio Cozzi Christophe P. Ferrari Aurélien Dommergue Kevin Rosman Sungmin Hong Soon Do Hur 《Climatic change》2009,92(1-2):191-211
Cr, Fe, Rb, Ba and U were determined by inductively coupled plasma sector field mass spectrometry (ICP-SFMS) in various sections of the 3,270 m deep ice core recently drilled at Dome C on the high East Antarctic plateau as part of the EPICA program. The sections were dated from 263 kyr bp (depth of 2,368 m) to 672 kyr bp (depth of 3,062 m). When combined with the data previously obtained by Gabrielli and co-workers for the upper 2,193 m of the core, it gives a detailed record for these elements during a 672-kyr period from the Holocene back to Marine Isotopic Stage (MIS) 16.2. Concentrations and fallout fluxes of all elements are found to be highly variable with low values during the successive interglacial periods and much higher values during the coldest periods of the last eight climatic cycles. Crustal enrichment factors indicates that rock and soil dust is the dominant source for Fe, Rb, Ba and U whatever the period and for Cr during the glacial maxima. The relationship between Cr, Fe, Rb, Ba and U concentrations and the deuterium content of the ice appears to be similar before and after the Mid-Brunhes Event (MBE, around 430 kyr bp). Mean concentration values observed during the successive interglacials from the Holocene to MIS 15.5 appear to vary from one interglacial to another at least for part of the elements. Concentrations observed during the successive glacial maxima suggest a decreasing trend from the most recent glacial maxima (MIS 2.2 and 4.2) to the oldest glacial maxima such as MIS 14.2, 14.4 and 16.2, which could be linked with changes in the size distribution of dust particles transported from mid-latitude areas to the East Antarctic ice cap. 相似文献
78.
79.
Regina Freiberger Lutz Hecht Michel Cuney Giulio Morteani 《Contributions to Mineralogy and Petrology》2001,141(4):415-429
Secondary Ca-Al silicates are used to constrain the P-T-x conditions of the very early post-magmatic stage of the intermediate to basic Hercynian plutonic complexes of Charroux-Civray (NW Massif Central, France) and Fichtelgebirge (NE Bavaria, Germany). The secondary Ca-Al silicates hydrogarnet, prehnite, pumpellyite, epidote and laumontite form lenses within unaltered or only slightly chloritized biotite. Hydrogarnet as the first occurring Ca-Al silicate phase crystallizes at temperatures above 340 °C. The common paragenesis prehnite + pumpellyite post-dates hydrogarnet and indicates rather narrow ranges of temperature (200-280 °C) and pressure (2-3 kbar). Laumontite is formed at the end of Ca-Al silicate crystallization (180-260 °C, 1-3 kbar), mostly in small fractures in association with prehnite and adularia. The observed crystallization sequence of the Ca-Al silicates and their stabilities define a retrograde alteration path for the plutonic rocks. The Ca-Al silicate assemblage results from an early pervasive alteration of the plutonic rocks by low XCO2 fluids during post-magmatic cooling. Subsolidus cooling starts at about 4 kbar at solidus temperatures as indicated by magmatic epidote stability, hornblende barometry and fluid inclusion data, and continues under slightly decreasing pressure (uplift) down to 2-3 kbar at 200-280 °C (prehnite-pumpellyite paragenesis). This shows that Ca-Al silicate assemblages may be a unique tool to constrain the P-T conditions of the subsolidus cooling of intermediate to basic plutonic bodies. 相似文献
80.
Prof. Dr. Giulio Pontecorvo 《GeoJournal》1988,16(3):265-272
The recently created exclusive economic zones constitute windfall gains for some coastal states. However, windfall gains, such as the New World's gold for Spain and oil for OPEC, are notoriously difficult to transform into permanent wealth and income streams. These difficulties are discussed in this paper. In addition, a case study of the asset values of fisheries in areas of the NW and W Central Pacific Ocean is presented in detail. For nine countries, the changes in catch, both quantity and value, which resulted from establishment of the EEZ are used as estimators of the windfall gains. 相似文献