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371.
No-take marine protected areas (MPAs), where all fishing is prohibited, have been shown to provide benefits that include greater productivity of fish stocks due to increased densities, average sizes, and reproductive output. A critical component of this success is the effective management of MPAs to ensure that only those activities deemed permissible, are allowed to occur. As of 2008, 161 MPAs had been designated on the Pacific coast of Canada by federal, provincial or municipal authorities. The objective of this study was to discover how many of these MPAs are intended to provide full protection to habitats and species from commercial fishing and whether management measures were put in place to actualize this conservation intent. The comprehensive spatial dataset was built illustrating commercial fisheries closures and this was overlaid with MPA locations in a GIS. The majority of MPAs were designated as IUCN Strict Nature Reserve (Type Ia), Wilderness Area (Type Ib), and National Park (Type II) marine reserves, which are intended to be free from exploitation. It was found that 160 of the 161 MPAs are open to some commercial harvesting within their bounds. One small municipal MPA and portions of three other MPAs are not open to commercial harvesting. The incongruence between management intent and fisheries permitted suggests a management failure between designation of MPAs and implementation of fisheries management regulations. 相似文献
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M. M. Maldoni M. P. Egan R. G. Smith G. Robinson C. M. Wright 《Monthly notices of the Royal Astronomical Society》2003,345(3):912-922
The 2.2–200 μm spectrum of OH32.8–0.3 has been modelled. Mie theory and radiative transfer models of the 3-μm band of H2 O ice are consistent with a strongly crystalline structural phase. This is also confirmed by the presence of a 44/62-μm band complex analogous to that of laboratory crystalline H2 O ice analogues. The highly ordered phase may be the result of direct crystallization upon deposition as has been theorized by Kouchi et al. At the large total optical depths typical of the radiative transfer models for this object (τ9.7 ∼ 40), we find no significant difference between the Mie theory and radiative transfer models of the 3-μm band. On the other hand, large differences are found for the 9.7-μm silicate band. In contrast to Mie theory extinction profiles, those computed via radiative transfer modelling indicate that the 12-μm H2 O ice band (the so-called librational band) is substantially attenuated. This, in addition to the inherent broadness and weakness of the 12-μm ice band, may explain why this band has not been clearly identified in observational spectra of oxygen–rich evolved objects. 相似文献
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R.S. Martin T.A. Mather D.M. Pyle S.F.L. Watt J.A. Day S.J. Collins T.E. Wright A. Aiuppa S. Calabrese 《Journal of Volcanology and Geothermal Research》2009,179(1-2):107-119
Sweet chestnut leaves (Castanea sativa) collected from the flanks of Mt Etna volcano in 2005–2007 were analysed by inductively-coupled plasma mass spectrometry to investigate the spatial and temporal variability of element concentrations. The aim of this work was to determine whether these leaves are a bio-indicator for volcanic gas, aerosol and ash deposition and to gain new insights into the environmental effects of quiescent and eruptive volcanic plumes. Results show a positive correlation between sample variability in the concentration of elements in Castanea sativa and enrichment factors of elements in the plume. The spatial and temporal variability of chalcophilic elements (As, Cd, Cu, Mo, Tl, Zn) is consistent with prevailing winds transporting eruptive plumes to the south-east of the summit, resulting in enhanced plume deposition onto the flanks of the volcano. Similar spatial and temporal variability was found for the halide-forming elements (Cs, K, Rb) and intermediate elements (Al, Co, Mn). The spatial variability of chalcophilic, intermediate and halide-forming elements during quiescent periods was diminished (relative to eruptive periods) and could not be explained by plume deposition. In contrast, the concentrations of lithophilic elements (Ba, Ca, Mg, Sr) did not show any clear spatial variability even during eruptive periods. Comparisons between enrichment factors for elements in Castanea sativa and literature values for enrichment factors of the volcanic plume, groundwater and lichen were made. Whilst Castanea sativa offers insights into the spatial and temporal variability of deposition, the species may not be a bio-indicator for plume composition due to biological fractionation. 相似文献
378.
L. Golub E. DeLuca G. Austin J. Bookbinder D. Caldwell P. Cheimets J. Cirtain M. Cosmo P. Reid A. Sette M. Weber T. Sakao R. Kano K. Shibasaki H. Hara S. Tsuneta K. Kumagai T. Tamura M. Shimojo J. McCracken J. Carpenter H. Haight R. Siler E. Wright J. Tucker H. Rutledge M. Barbera G. Peres S. Varisco 《Solar physics》2007,243(1):63-86
The X-ray Telescope (XRT) of the Hinode mission provides an unprecedented combination of spatial and temporal resolution in solar coronal studies. The high sensitivity
and broad dynamic range of XRT, coupled with the spacecraft’s onboard memory capacity and the planned downlink capability
will permit a broad range of coronal studies over an extended period of time, for targets ranging from quiet Sun to X-flares.
This paper discusses in detail the design, calibration, and measured performance of the XRT instrument up to the focal plane.
The CCD camera and data handling are discussed separately in a companion paper. 相似文献
379.
The Mfolozi Estuary on the KwaZulu-Natal coast of South Africa is the most turbid estuary in Natal due to poor catchment
management, leading to large quantities of suspended particulate matter (SPM) entering the estuary from the Mfolozi River.
This paper quantities some of the solute and sediment dynamics in the Mfolozi Estuary where the main documented environmental
concern is the periodic input of SPM from the Mfolozi Estuary to the St. Lucia system, causing reduction of light penetration
and endangering biological productivity in this important nature reserve. Synoptic water level results have allowed reach
mean bed shear stresses and velocities to be calculated for an observed neap tidal cycle. Results indicate that ebb velocities
dominate the sediment transport processes in the estuary when fluvial input in the Mfolozi River is of the order of 15–20
m3 s–1. Observed and predicted flood tide velocities are too low (<0.35 m s–1) to suspend and transport significant amounts of SPM. Observed results indicate that although the SPM load entering the estuary
is dominantly from the Mfolozi River, the Msunduzi River flow plays a major role in the composition of the estuary's salinity
and velocity fields. It is calculated that the Mfolozi Estuary would fill with sediment in 1.3 years if it was cut off from
the sea. The major fluvial flood events help maintain the estuary by periodically pushing sediment seawards (spit progrades
seawards 5 m yr–1) and scouring and maintaining the main flow channel in the estuary. During low fluvial flow conditions, tidal flow velocities
will become the dominant control on sediment transport in the estuary. Interchange of SPM between the St. Lucia and Mfolozi
estuaries under present conditions is complicated by the strong transverse velocity shear between the two systems at their
combined mouth. This is creating a salinity-maintained axial convergence front that suppresses mixing of solutes and SPM between
the systems for up to 10 h of the tidal cycle during observed conditions.
Received: 22 May 1995 · Accepted: 31 July 1995 相似文献
380.