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731.
Samuel S. Harrison 《Ground Water Monitoring & Remediation》1986,6(2):73-76
An upsurge in oil- and gas-well drilling in northwestern Pennsylvania and western New York has been accompanied by several incidents of contamination of ground water by methane. Determining which well is causing the contamination is extremely difficult if more than one gas or oil well is present in the area.
The fact that the solubility of methane decreases as the pressure on ground water decreases provides a quantitative basis for monitoring changes in the amount of methane in the ground water. Quantitative measurements of the volume of methane given off by ground water pumped from a well as the water enters atmospheric pressure permit detection of temporal changes in the gas content which are too subtle to be detected visually. These gas volume changes may, in some cases, be correlated with variations in the pressure of methane in the annulus of nearby individual gas/oil wells and thus may provide a means of pinpointing the gas/oil well that is causing the methane contamination.
The basic principle of the gas-volume monitoring apparatus (GVMA) described in this paper is that as a measured amount of ground water enters atmospheric pressure the gas which comes out of solution is trapped and measured. The GVMA can be constructed of materials costing less than $100 and requires no special skills to assemble or operate. In a recent study conducted in a western New York village, four homeowners were able to collect quantitative gas-volume data from their household water wells daily in about one-half hour. Unlike laboratory analyses for dissolved methane, there is no cost involved in monitoring with the GVMA beyond the initial instrument cost and operator time. Another advantage is that the data are available immediately. 相似文献
The fact that the solubility of methane decreases as the pressure on ground water decreases provides a quantitative basis for monitoring changes in the amount of methane in the ground water. Quantitative measurements of the volume of methane given off by ground water pumped from a well as the water enters atmospheric pressure permit detection of temporal changes in the gas content which are too subtle to be detected visually. These gas volume changes may, in some cases, be correlated with variations in the pressure of methane in the annulus of nearby individual gas/oil wells and thus may provide a means of pinpointing the gas/oil well that is causing the methane contamination.
The basic principle of the gas-volume monitoring apparatus (GVMA) described in this paper is that as a measured amount of ground water enters atmospheric pressure the gas which comes out of solution is trapped and measured. The GVMA can be constructed of materials costing less than $100 and requires no special skills to assemble or operate. In a recent study conducted in a western New York village, four homeowners were able to collect quantitative gas-volume data from their household water wells daily in about one-half hour. Unlike laboratory analyses for dissolved methane, there is no cost involved in monitoring with the GVMA beyond the initial instrument cost and operator time. Another advantage is that the data are available immediately. 相似文献
732.
Keith W. Gates Brian E. Perkins Jackie G. EuDaly Amanda S. Harrison Wayne A. Bough 《Estuaries and Coasts》1985,8(2):244-251
A study to determine the impact of seafood packing and processing effluents discharged to southeastern estuarine waters was conducted in July and August of 1979. The environmental impact of current seafood processing wastes on Georgia’s estuaries appears to be minimal when compared with the natural organic load. One large estuary demonstrated a high residual capacity to receive processing effluents without significant change. The BOD load from shrimp thawing, peeling, sorting, and cleaning operations at a large seafood processing plant was shown to be equivalent to the organic material generated by a 302 m2 plot (57 ft×57 ft) of salt marsh. NH4?N levels were greater than, but the same order of magnitude as, natural runoff from marsh land. 相似文献
733.
John D. Payzant Thomas W. Mojelsky Terry D. Cyr Douglas S. Montgomery Otto P. Strausz 《Organic Geochemistry》1985,8(2):177-180
Homologous series of 9-n-alkyl fluorene-9-ols and their nuclear methylated derivatives have been detected in the Alberta oil sands and their structure identified by infrared, field ionization and capillary gas chromatography-mass spectrometry and by comparison with synthetic standards. 相似文献
734.
735.
Howard W. Harder Eric C. Christensen Janis R. Matthews Terry F. Bidleman 《Estuaries and Coasts》1980,3(2):142-147
Toxaphene concentrations in rainfall over a South Carolina salt marsh were monitored from 1976–1978. This insecticide is toxic to some organisms in the low μg/kg range and causes sublethal effects in the very low ng/kg range. Rainfall was sampled by both continuously exposed collectors and by collectors which were exposed only during actual precipitation. Toxaphene concentrations in individual rainstorms showed a high day-to-day variation, and in general were 10–100 times higher than PCB and DDT levels. Washout ratios for toxaphene were higher than those reported for other chlorinated hydrocarbons, but lower than those of trace metals. During and immediately following the summer use season, toxaphene levels in rain exceeded by several times those concentrations reported to produce bone damage to young fish in laboratory experiments. The estimated aerial input of toxaphene to the 26 km2 estuary was 1.2 kg over a 4-month period. Most of this input appeared to be due to rainfall rather than dry deposition. *** DIRECT SUPPORT *** A01BY010 00007 相似文献
736.
The partitioning of samarium and thulium between garnets and melts in the systems Mg3Al2-Si3O12-H2O and Ca3Al2Si3O12-H2O has been studied as a function of REE concentration in the garnets at 30 kbar pressure. Synthesis experiments of variable time under constant P, T conditions indicate that garnet initially crystallizes rapidly to produce apparent values of D
Sm (D
Sm=concentration of Sm in garnet/concentration of Sm in liquid) which are too large in the case of pyrope and too small in the case of grossular. As the experiment proceeds, Sm diffuses out of or into the garnet and the equilibrium value of D
Sm is approached. Approximate values of diffusion coefficients for Sm in pyrope garnet obtained by this method are 6 × 10–13 cm2 s–1 at 1,300 ° C and 2 × 10–12 cm2 s–1 at 1,500 ° C, and for grossular, 8.3 × 10–12 cm2 s–1 at 1,200 ° C and 4.6 × 10–11 cm2 s–1 at 1,300 ° C. The equilibrium values of D
Sm have been reversed by experiments with Sm-free pyrope and Sm-bearing glass, and with Sm-bearing grossular and Sm-free glass.Between 12 ppm and 1,000 ppm Sm in pyrope at 1,300 ° C and between 80 ppm and >2 wt.% Tm in pyrope at 1,500 ° C, partition coefficients are constant and independent of REE concentration. Above 100 ppm of Sm in garnet at 1,500 ° C, partition coefficients are independent of Sm concentration. At lower concentrations, however, D
Sm is dependent upon the Sm content of the garnet. The two regions may be interpreted in terms of charge-balanced substitution of Sm3Al5O12 in the garnet at high Sm concentrations and defect equilibria involving cation vacancies at low concentrations. At very low REE concentrations (< 1 ppm Tm in grossular at 1,300 ° C) DREE garnet/liquid again becomes constant with an apparent Henry's Law value greater than that at high concentrations. This may be interpreted in terms of a large abundance of cation vacancies relative to the number of REE ions.The importance of defects in the low concentration region has been confirmed by adding other REE (at 80 ppm level) to the system Mg3Al2Si3O12-H2O at low Sm concentrations. These change D
Sm in the defect region, demonstrating their role in the production of vacancies.Experiments on a natural pyropic garnet indicate that defect equilibria are of importance to REE partitioning within the concentration ranges found in nature. 相似文献
737.
Changes in the depth of Lake Viljandi between 1940 and 1990 were simulated using a lake water and energy-balance model driven by standard monthly weather data. Catchment runoff was simulated using a one-dimensional hydrological model, with a two-layer soil, a single-layer snowpack, a simple representation of vegetation cover and similarly modest input requirements. Outflow was modelled as a function of lake level. The simulated record of lake level and outflow matched observations of lake-level variations (r = 0.78) and streamflow (r = 0.87) well. The ability of the model to capture both intra- and inter-annual variations in the behaviour of a specific lake, despite the relatively simple input requirements, makes it extremely suitable for investigations of the impacts of climate change on lake water balance. 相似文献
738.
739.
740.
T. J. Dempster D. H. W. Hutton T. N. Harrison P. E. Brown G. R. T. Jenkin 《Contributions to Mineralogy and Petrology》1991,107(4):459-471
The development of rapakivi texture in feldspars from the Ketilidian granitoids of south Greenland has been investigated using Sr, O and H isotopes. A low temperature signature is found in the Sr and O data which seemingly contradicts some textural features that point to a magmatic origin of the plagioclase mantles around the K-feldspar ovoids. An origin for these mantles involving exsolution from an original alkali feldspar solid solution is proposed, which involves growth of mantles over a range of conditions determined by the mobility of the exsolving sodic feldspar. This mobility may be enhanced at high temperatures in the presence of melts or increased fluid pressures and at lower temperatures by the processes responsible for the transformation of K-feldspar to microcline. Rapakivi granites with both white and dark green feldspar occur in south Greenland but show no major isotopic differences, although the dark alkali feldspars contain significantly more fluid. Equivalent fluids in the white alkali feldspars may have escaped during plagioclase exsolution. 相似文献