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791.
792.
Robert S. Kandel 《Environment international》1979,2(4-6)
In this survey the earth is viewed from the astrophysical perspective, i.e. using global mean values of environmental parameters. The role of carbon dioxide is described in the processes of energy transfer from the earth's surface to space, which determine “global climate” as measured by the mean surface temperature. Analogies and differences between the problems of the terrestrial atmosphere and those of the solar and stellar atmospheres are examines, both in the computation of model atmosphere and in remote sensing of atmospheric temperature and composition. Subsequently, the temporal astrophysical perspective, with a review of the evolution of CO2 abundance and climate on astrophysical or geological time scales, on earth as on Venus (the runaway greenhouse) and on Mars is introduced. Variation of CO2 may have been critical to the maintenance of an environment in which life could originate and evolve, and may itself have been affected by life. On human time scales, the recent and continuing increase in atmospheric CO2 raises new problems, which are briefly surveyed. It is argued, that the differential greenhouse effect of increased CO2 in the earth's atmosphere is essentially identical to the “blanketing effect” of spectral lines on the temperature structure of stellar atmospheres. The methods used by astrophysicists in such studies are reviewed and compared with those used to evaluate the differential greenhouse effect of CO2 in radiative-convective models of the earth's atmosphere. The latter methods remain relatively crude, but recent results by different authors are in reasonably good agreement; however, the astrophysical perspective, i.e. the use of one-dimensional global mean models, remains a gross simplification of the real complexity of the earth's climate system, which is also true in stellar atmospheres. 相似文献
793.
James H. Stewart 《Journal of Environmental Planning and Management》1983,26(2):83-88
A review of the use of planning and design briefs by local authorities in the United Kingdom was carried out in 1982–83 to test whether the role of the brief as an instrument of local policy and as a promotional tool in the development process was being fully exploited. The paper provides a state of the art review, presents a summary of the findings and offers some comments on the results. It concludes that most authorities now use briefs as part of their normal planning procedures, but that there is potential which is not yet being exploited. 相似文献
794.
The main goals of this paper are to (1) highlight the need for sustainable development as a means to conserve natural resources and the environment, which often represent the basis for tourism development, (2) illustrate the importance of assessing tourists' preferences when designing programs and policies central to the sustainable development of a tourism area, and (3) study tourists' interests in sustainable development. With these goals in mind, 180 tourists from Europe, Latin America, and North America were interviewed as they were leaving the resort region of Punta Cana in the Dominican Republic. The main factors that they considered when deciding where to go on a beach vacation were evaluated, as well as their preferences regarding four programs designed to improve recreational and environmental management of the area. Preferences by tourists were elicited both in monetary and non-monetary terms. This paper reports the non-monetary analysis of the data. The results indicate that clean ocean water and beaches, quality of services, and price are the most important factors considered by the respondents before deciding to come to Punta Cana. It was not possible to obtain reliable responses on how tourists perceived the four programs contributing to the sustainable development of Punta Cana. Nevertheless, they expressed high interest and willingness to pay for two of these programs: the outdoor aquarium and the Water Management Program. The results reported in this paper show how important it is to elicit tourists' preferences of programs central to the sustainable development of tourism areas since these preferences can drive managers' development decisions in more sustainable directions. 相似文献
795.
796.
Robert Mendelsohn 《Journal of Environmental Economics and Management》1984,11(3):202-207
A model of environmental regulation under uncertainty is developed to compare the effect of price versus quantity rules upon technical change. Quantity rules tend to encourage more efficient levels of technical change. 相似文献
797.
John C. Mycock Rodney A. Gibson Joyce M. Foster James H. Turner 《Environment international》1981,6(1-6)
As a follow-up to a pilot study, a full scale investigation of applying high velocity fabric filtration to coal-fired boiler fly ash control was conducted. Two filter systems were separately applied to two 60,000 lb/h coal-fired boilers. Performance evaluations conducted over the course of a year included total mass removal efficiency and fractional efficiencies. One filtration system employed Teflon felt as the filter media while the second system employed Gore-Tex, a Polytetrofluorethylene (PTFE) laminate on PTFE woven backing. During the course of the year, a limited number of glass felt and woven glass bags were introduced into the house containing Gore-Tex. As a separate option, the second system was outfitted entirely with woven glass bags. Preliminary results indicate acceptable performance at air-to-cloth ratio of 6 to 1. Future plans call for utilizing one of the baghouse systems for SO2 removal. 相似文献
798.
Douglas A. Wolfe K. John Scott John R. Clayton Jr. John Lunz James R. Payne Timothy A. Thompson 《Chemistry and Ecology》1995,10(1):137-156
Standardized tests were applied to aromatic and polar fractions of sediment extracts to determine whether polar constituents or oxidative degradation products contributed significantly to the toxicity of sediments oiled by the Exxon Valdez spill. Intertidal sediment and pore-water samples were collected in September 1990 from two heavily oiled sites and an unoiled site in Prince William Sound (PWS). Methylene chloride extracts from these samples were fractionated by liquid chromatography into aliphatic, aromatic and polar fractions, and the aromatic and polar fractions were tested for toxicity using the MicrotoxR test, bivalve larval mortality and development (Mytilus); several measures of genotoxicity in Mytilus, including SOS ChromotestR, anaphase aberrations and sister chromatid exchange; and survival, anaphase aberrations and teratogenicity in coho salmon (Onchorhynchus kisutch). MicrotoxR and SOS ChromotestR protocols were applied in a screening mode to all samples, whereas other tests were applied only to selected fractions from two sites. Samples from Bay of Isles (oiled) were consistently more toxic (usually only 2 to 5-fold) than the Mooselips Bay (unoiled) samples, which gave very low responses in all tests. for both sites, however, responses to polar and aromatic fractions were about the same in most tests, suggesting that while the overall toxicity of the oil was low in these samples, at least part of that toxicity was derived from polar constituents. Compared to the parent hydrocarbons, polar oxidation products partition preferentially into pore-water and are more rapidly diluted and dispersed in the water column. These results suggest that polar oxidation products of petroleum hydrocarbons pose little risk to marine organisms, except possibly for infauna continuously exposed to pore-water in heavily oiled sediments. Independent surveys showed that sediment toxicity in PWS declined during 1989-1991 to near background levels, in accord with previous understanding of oil weathering and toxicity. 相似文献
800.
This paper examines the optimal tax to achieve maximum economic yield (MEY) exploitation in a rational expectations model of a competitive open-access fishery. To analyze the dynamic evolution of resource use a structural model which explains the relationship between the firm and the industry is presented. The unregulated equilibrium is contrasted with the potential MEY. Conditions under which the unregulated equilibrium will be MEY are explored. In addition, a tax is devised which will cause non-MEY competitive exploitation to become MEY when the tax is implemented. 相似文献