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961.
962.
Stephen J. Eaton David M. Hodgson Natasha L. M. Barlow Estelle E. J. Mortimer Claire L. Mellett 《第四纪科学杂志》2020,35(6):760-775
Offshore stratigraphic records from the North Sea contain information to reconstruct palaeo-ice-sheet extent and understand sedimentary processes and landscape response to Pleistocene glacial–interglacial cycles. We document three major Middle to Late Pleistocene stratigraphic packages over a 401-km2 area (Norfolk Vanguard/Boreas Offshore Wind Farm), offshore East Anglia, UK, through the integration of 2D seismic, borehole and cone penetration test data. The lowermost unit is predominantly fluviatile [Yarmouth Roads Formation, Marine Isotope Stage (MIS) 19–13], including three northward-draining valleys. The middle unit (Swarte Bank Formation) records the southernmost extent of tunnel valley-fills in this area of the North Sea, providing evidence for subglacial conditions most likely during the Anglian stage (MIS 12) glaciation. The Yarmouth Roads and Swarte Bank deposits are truncated and overlain by low-energy estuarine silts and clays (Brown Bank Formation; MIS 5d–4). Smaller scale features, including dune-scale bedforms, and abrupt changes in cone penetration test parameters, provide evidence for episodic changes in relative sea level within MIS 5. The landscape evolution recorded in deposits of ~MIS 19–5 are strongly related to glacial–interglacial cycles, although a distinctive aspect of this low-relief ice-marginal setting are opposing sediment transport directions under contrasting sedimentary process regimes. 相似文献
963.
Pieter Hoekstra Raye Lahti Jim Hild C. Richard Bates David Phillips 《Ground Water Monitoring & Remediation》1992,12(4):110-117
Time domain electromagnetic (TDEM) soundings were utilized in site assessment studies for the purpose of accomplishing two objectives: (1) measuring the migration of brines from oil and gas field evaporation pits, and (2) mapping the continuity of clay strata. Both case histories are representative of common objectives in site assessment. The data for both examples were analyzed by one-dimensional ridge regression inversions.
Both case histories illustrate that TDEM is an effective method for determining the lateral and vertical resistivity distribution (geoelectric section) of the subsurface in the depth range from about 5 m to 100 m, and it is known from other investigations that depths of investigations up to 2500 m can be achieved with TDEM.
Frequently, the lateral extent of contaminant plumes emanating from localized sources are of limited areal extent. The case history involving the use of TDEM to map a brine plume shows that a TDEM measurement has a relatively small zone of influence, so that meaningful information about the lateral and vertical extent of the plume can be obtained. Both case histories demonstrate the ability of TDEM to determine geoelectric sections below layers of low resistivity. 相似文献
Both case histories illustrate that TDEM is an effective method for determining the lateral and vertical resistivity distribution (geoelectric section) of the subsurface in the depth range from about 5 m to 100 m, and it is known from other investigations that depths of investigations up to 2500 m can be achieved with TDEM.
Frequently, the lateral extent of contaminant plumes emanating from localized sources are of limited areal extent. The case history involving the use of TDEM to map a brine plume shows that a TDEM measurement has a relatively small zone of influence, so that meaningful information about the lateral and vertical extent of the plume can be obtained. Both case histories demonstrate the ability of TDEM to determine geoelectric sections below layers of low resistivity. 相似文献
964.
David E. Atkinson 《Geo-Marine Letters》2005,25(2-3):98-109
Storm event statistics for the open-water season (June–October) were extracted from the terrestrial-based observational record throughout the circumpolar coastal regime over the period 1950–2000. The Barents/Norwegian and Kara regions exhibited an active spring/quiet summer signature typical of the mid-latitudes. The Kara and Laptev Sea regions had a strong June peak possibly associated with early sea ice breakup. The Chukchi sector exhibited large storm power values (defined as speed2*duration). Storm counts declined from 1950 to 1970, shifted rapidly from 1970 to 1974 to a level of greater mean activity and greater inter-annual variability, and declined after 1988. 相似文献
965.
966.
Ben P. Kirtman Edwin K. Schneider David M. Straus Dughong Min Robert Burgman 《Climate Dynamics》2011,37(11-12):2389-2416
The new interactive ensemble modeling strategy is used to diagnose how noise due to internal atmospheric dynamics impacts the forced climate response during the twentieth century (i.e., 1870?C1999). The interactive ensemble uses multiple realizations of the atmospheric component model coupled to a single realization of the land, ocean and ice component models in order to reduce the noise due to internal atmospheric dynamics in the flux exchange at the interface of the component models. A control ensemble of so-called climate of the twentieth century simulations of the Community Climate Simulation Model version 3 (CCSM3) are compared with a similar simulation with the interactive ensemble version of CCSM3. Despite substantial differences in the overall mean climate, the global mean trends in surface temperature, 500?mb geopotential and precipitation are largely indistinguishable between the control ensemble and the interactive ensemble. Large differences in the forced response; however, are detected particularly in the surface temperature of the North Atlantic. Associated with the forced North Atlantic surface temperature differences are local differences in the forced precipitation and a substantial remote rainfall response in the deep tropical Pacific. We also introduce a simple variance analysis to separately compare the variance due to noise and the forced response. We find that the noise variance is decreased when external forcing is included. In terms of the forced variance, we find that the interactive ensemble increases this variance relative to the control. 相似文献
967.
At the 1992 Rio 'Earth Summit', Australia joined other nations in committing to processes leading to the formulation of 'Local Agenda 21s' (LA21s) by 1996. Subsequently, in the latter year, Whittaker carried out a national survey of local government authorities to evaluate what progress had been made. Whittaker's conclusion was that progress in Australia had been slow, but ten 'leading-edge' Victorian councils were identified through a self-reporting process. In this paper we discuss the concept of LA21, analyse in closer detail the 'progress' that has been made in the ten Victorian councils, and discuss some of the broader forces that, we argue, have made LA21 formulation increasingly difficult, particularly in the state of Victoria in the recent past. 相似文献
968.
Here we have examined interactions of gold nanoparticles differing in primary particle size and coating with the green algae Chlamydomonas reinhardtii as function of the colloidal stability of the particles in the experimental media used for toxicity studies. Interactions of dissolved Au3+ ions with algae were also examined. Included endpoints were photosynthetic yield and algal growth. Morphological and structural effects were examined microscopically and by flow cytometry. The results indicate no significant toxicity of gold nanoparticles to C. reinhardtii. Analysis of published data suggests toxicity of gold nanoparticles on algal growth to relate rather to particular coatings than to the gold core. 相似文献
969.
A Network Model for Dispersion of Communicable Diseases 总被引:3,自引:0,他引:3
The spread of communicable diseases through a population is an intrinsic spatial and temporal process. This paper presents an individual‐based analytical framework for modeling the spatial and temporal heterogeneity in the disease transmission. The framework specifies a network model structure and six associated parameters. These parameters describe the properties of nodes, the properties of links, and the topology of the network. Through this model structure and associated parameters, this framework allows the representation of discrete individuals, individualized interactions, and interaction patterns in a network of human contact. The explicit representation of the spatial distribution and mobility of individuals in particular facilitates the modeling of spatial heterogeneity in the disease transmission. 相似文献
970.
Solid waste samples from a reconnaissance study conducted at ore mining and milling sites were subjected to the U.S. Environmental
Protection Agency extraction procedure (EP) leaching test Sites visited included mines and mills extracting ores of antimony
(Sb), mercury (Hg), vanadium (V), tungsten (W), and nickel (Ni). Samples analyzed included mine wastes, treatment pond solids,
tailings, low grade ore, and other solid wastes generated at these facilities Analysis of the leachate from these tests indicates
that none of the samples generated leachate in which the concentration of any toxic metal parameter exceeded EPA criteria
levels for those metals. By volume, tailings generally constitute the largest amount of solid wastes generated, but these
data indicate that with proper management and monitoring, current EPA criteria can be met for tailings and for most solid
wastes associated with mining and milling of these metal ores. Long-term studies are needed to determine if leachate characteristics
change with time and to assist in development of closure plans and post closure monitoring programs. 相似文献