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951.
The Chisone Valley is located in the internal NW Alps, in the Pinerolese District, an area characterized by present low to medium seismicity. Fine-grained sediments (sand, silt and clay with interbedded gravel) crop out in the lower Chisone Valley: they were first interpreted as glaciolacustrine deposits, and then as a lacustrine infilling of the valley floor probably due to differential uplifting of the valley mouth. Review of this data, together with new field and palynological observations, lead us to refer the lacustrine deposits to approximately the Lower Pleistocene (Villafranchian). In many outcrops, the lacustrine deposits show strong soft-sediment deformation such as convolute laminations, water-escape structures and disrupted beds, some of them associated with folds and faults (cm to dm in size); only two sites show metric to decametric folds and faults trending E-W and N-S. Detailed structural analysis conducted along a recently exposed section (Rio Gran Dubbione site) shows several soft-sediment deformation features on the limbs of mesoscale folds. Because of their intimate structural association, the origin of these minor structures seems to be connected to synsedimentary activity on reverse and normal faults (m to dm in size) affecting the lacustrine deposits in the same locality. Soft-sediment deformation features can be interpreted as possible paleoseismites. If so, the present seismicity of the Pinerolese District, which is the major area of such activity in NW Italy, cannot be considered an isolated episode in the geological evolution of the region; even if there is no supporting evidence for continuous seismicity, the deformations in the lacustrine sediments of the Chisone Valley testify to Early Pleistocene seismic activity, probably related to the recent tectonic evolution of the internal side of the NW Alps. 相似文献
952.
953.
Marco Landolfi 《Solar physics》1987,109(2):287-306
We present a diagnostic method for detecting magnetic field gradients and velocity gradients in sunspots through the analysis of Stokes parameters profiles in magnetoactive lines. On one hand, the method is based on the concept of response functions for the Stokes profiles introduced by Landi Degl'Innocenti and Landi Degl'Innocenti (1977); on the other hand, it takes advantage of the diagnostic content of the residuals between observed Stokes profiles and best-fit Unno-profiles. The analysis of synthesis profiles obtained for the line 6302.502 FeI forming in the Sunspot Sunspot Model (Avrett, 1981) suggests that the method could actually be promising, at least if the dependence of the magnetic field vector on optical depth is sufficiently simple. 相似文献
954.
Near-infrared, adaptive optics observations of AGN achieve a spatial resolution comparable to that of the Hubble Space Telescope
at visible and ultraviolet wavelengths. Using the ESO adaptive optics system, we have mapped the nuclear region of NGC 1068
in the near-infrared at 2.2, 3.5 and 4.8 μm. These data show the presence of strong near-infrared emission within the central
100 pc around the nucleus. At the K, L and M bands, the dominant emission peak is unresolved at resolutions of 35 pc (K),
15 pc (L) and 23 pc (M). We find that the emission peaks at 2.2, 3.5 and 4.8 μm are offset by 0.3±0.1" south of the HST optical
continuum peak. The infrared peaks are coincident with the HST imaging polarimetry center thought to mark the hidden nucleus.
We conclude that the infrared emission peaks are also directly related with the hidden nucleus and that they outline the dusty
torus around the central engine, as expected from current AGN models. From our first estimate of the fluxes in L and M, we
derive a dust temperature of 750 K for the unresolved component.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
955.
Daniele Nizzoli Giuseppe Castaldelli Marco Bartoli David Thomas Welsh Patricia Arriaga Gomez Anna Elisa Fano Pierluigi Viaroli 《Marine Ecology》2002,23(S1):297-306
Abstract. Dark respiration rates, dissolved inorganic nitrogen (DIN) fluxes and nitrification rates were measured at two sites in the microtidal Sacca di Goro lagoon in September 2000. DIN fluxes correlated with the biomass of the dominant macrofauna species (the amphipod Corophium spp. at station Giralda and the polychaete Neanthes spp. at station Faro). Respiration (> 6 mmol O2 m−2 h−1 ) and ammonium fluxes (> 80μmol N m−2 h−1 ) were higher at station Giralda despite the lower organic matter content (4.5 %) and lower macrofauna biomass (4 g AFDW m−2 ). At both sites ammonium fluxes were significantly correlated with the biomass of the benthic infauna, but Corophium stimulated ammonium NH4 + fluxes 3-fold compared to Neanthes. The amphipod also enhanced nitrification rates (> 300 μmol N m−2 h−1 ) due to the high density of its burrows, the higher NH4 + regeneration rates and the enhanced oxygen supply to the bacteria. 相似文献
956.
957.
Toms Vega Fernndez Marco Milazzo Fabio Badalamenti Giovanni D'Anna 《Estuarine, Coastal and Shelf Science》2005,65(4):645-653
An extensive Posidonia oceanica meadow was partially destroyed by excavation, resulting in areas of seagrass habitat of equal complexity (shoot density) but different heterogeneity (degree of fragmentation). The fish assemblages associated with differently fragmented beds were compared from a landscape perspective. Differences in the fish assemblages were detected, with several species showing different patterns: (1) species that increased their abundance along with the degree of bed fragmentation, (2) species that were more abundant in fragmented beds, but did not show differences between more or less fragmented beds, and (3) species that were mostly abundant in large seagrass patches or in the continuous meadow. The fish assemblages were also affected by depth, but further research is needed to determine properly this effect. Some ecological mechanisms are suggested to operate in the interaction between P. oceanica and the held fish assemblage. 相似文献
958.
Marco Missana 《Astrophysics and Space Science》1979,61(2):277-286
The analysis of the Skylab measurements on the ultraviolet limb spectra confirm the presence of a generalized Compton effect in the solar spectrum which can be explained by Thomson scattering theory. The present measurements on the Orion spectrum and interstellar line towards -Arae give a large generalized Compton effect which could be explained by a resonance scattering theory. These numerical results cannot be due to random errors in the measurements, as follows from the statistical discussion. The need for further measurements is pointed out. 相似文献
959.
OH-bearing planar defects in olivine produced by the breakdown of Ti-rich humite minerals from Dabie Shan (China) 总被引:2,自引:0,他引:2
Jörg Hermann John D. Fitz Gerald Nadia Malaspina Andrew J. Berry Marco Scambelluri 《Contributions to Mineralogy and Petrology》2007,153(4):417-428
The partial breakdown of Ti-chondrodite and Ti-clinohumite during exhumation from ultra-high pressure to amphibolite facies
conditions in garnet-pyroxenites from Dabie Shan (China) produces coronas of olivine coexisting with ilmenite blebs. Fourier
transform infrared (FTIR) spectra of this newly formed olivine exhibit absorption bands in the hydroxyl-stretching region.
Two intense peaks were observed at 3,564 and 3,394 cm−1, identical in energy to peaks in Ti-clinohumite. Transmission electron microscopy (TEM) of the same olivine domains revealed
the presence of a complex (001) planar intergrowth. These interlayers have a 1.35 nm repeat distance, which is characteristic
of clinohumite. Such interlayers are also enriched in Ti with respect to the adjacent olivine as shown by energy dispersive
spectrometry. The combined evidence from FTIR spectroscopy and TEM indicates that OH is incorporated along Ti-clinohumite
planar defects. This study provides evidence that the nominally anhydrous phase olivine may contain OH as a humite-type defect
beyond the breakdown of the hydrous humite minerals and confirms earlier suggestions that Ti plays a key role in OH incorporation
in mantle olivine. We suggest that olivine containing Ti-clinohumite defects is an important phase for water transport in
subduction zones and for the storage of water in cold subcontinental mantle. However, these defects are unlikely to be stable
in hotter parts of the oceanic mantle such as where basaltic magmas are generated. 相似文献
960.
Marco Grasso 《Climatic change》2007,81(3-4):223-246
The article spells out four domains of international distributive justice and the consequent criteria of equity, the purpose
being to identify a pluralistic normative ethical framework for climate mitigation and adaptation strategies. Justice and
equity should play a major role in favouring collective action against climate change, because the more the various dimensions
of such action are just, the more any international climate initiative is feasible in principle. As far as mitigation is concerned,
the definition of a just initial allocation of endowments focuses on the criterion of differentiated equality, taking account
of undeserved inequalities as suggested by Rawls’ theory of justice as fairness. With regard to the subsequent exchange of
endowments, the Pareto principle, supplemented by the envy-freeness one, is a viable option. Possibly a sound reference for
the just financing of adaptation activities is the criterion of differentiated historical responsibility, backed by Rawls’
theory of justice as fairness. As regards the allocation of adaptation resources, the criterion of lack of human security,
as substantiated in Sen’s capability approach, seems promising. 相似文献