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961.
Tracer kinetic analysis of radioisotope incorporation into dissolved organic compounds reveals two distinct patterns of photosynthate release by macroalgae. In experiments employing Sargassum lacerifolium, dissolved organic carbon was produced at a constant rate during light incubations. Steady state rates of production were never achieved in experiments employing either Ecklonia radiata (Turn.) J. Agardh. or Ulva lactuca L. Analysis of the time-varying radioactivity curves obtained in experiments using these algae always resulted in models consistent with dissolved organic carbon production being an autocatalytic process. Preincubation of U. lactuca in the dark resulted in a diminished (ca. 40%) rate of dissolved organic carbon production during the subsequent light incubations. In no case did the radioisotope content of the dissolved organic carbon approach a limiting value, indicating that in contrast to phytoplankton, uptake rates of photosynthate by macroalgae are always less than the rates of production. 相似文献
962.
Genetic variation was studied at two polymorphic loci for 3 yr (November 1978–February 1982) in juvenile sand flounder (Rhombosolea plebeia) in Wellington Harbour, New Zealand. The Gpi-1 locus showed a heterogeneity in genotype frequencies, but this was not clearly related to season or to fish length. At the Gpi-2 locus, genotype frequencies were dependent upon length and showed a significant excess of homozygotes in juveniles but not in adults. This latter phenomenon has been reported previously in several species of marine molluscs, and so may be common to marine organisms producing large numbers of pelagic larvae. Reasons for the excess of homozygotes are discussed, and it is suggested that assortative mating is the most likely explanation and that this is an area of marine population genetic research which has been over-looked. 相似文献
963.
Lori E. Apodaca Jeffrey B. Bails C. Michelle Smith 《Journal of the American Water Resources Association》2002,38(1):133-149
ABSTRACT: Shallow ground water in areas of increasing urban development within the Upper Colorado River Basin was sampled for inorganic and organic constituents to characterize water‐quality conditions and to identify potential anthropogenic effects resulting from development. In 1997, 25 shallow monitoring wells were installed and sampled in five areas of urban development in Eagle, Grand, Gunnison, and Summit Counties, Colorado. The results of this study indicate that the shallow ground water in the study area is suitable for most uses. Nonparametric statistical methods showed that constituents and parameters measured in the shallow wells were often significantly different between the five developing urban areas. Radon concentrations exceeded the proposed USEPA maximum contaminant level at all sites. The presence of nutrients, pesticides, and volatile organic compounds indicate anthropogenic activities are affecting the shallow ground‐water quality in the study area. Nitrate as N concentrations greater than 2.0 mg/L were observed in ground water recharged between the 1980s and 1990s. Low concentrations of methylene blue active substances were detected at a few sites. Total coliform bacteria were detected at ten sites; however, E. coli was not detected. Continued monitoring is needed to assess the effects of increasing urban development on the shallow ground‐water quality in the study area. 相似文献
964.
France Lamy John Bolte Mary Santelmann Courtland Smith 《Journal of the American Water Resources Association》2002,38(2):517-529
ABSTRACT: Making decisions for environmental management is a complex task due to the multiplicity and diversity of technological choices. Furthermore, the exploitation of natural resources and the preservation of the natural environment imply objectives that are often in conflict within a sustainable development paradigm. Managers and other decision makers require techniques to assist them in understanding strategic decision making. This paper illustrates the use of a multiple‐objective decision‐making methodology and an integrative geographical information system‐based decision‐making tool developed to help watershed councils prioritize and evaluate restoration activities at the watershed level. Both were developed through a multidisciplinary approach. The decision‐making tool is being applied in two watersheds of Oregon's Willamette River Basin. The results suggest that multiple‐objective methods can provide a valuable tool in analyzing complex watershed management issues. 相似文献
965.
Scott A. Smith 《环境质量管理》1997,6(3):43-47
Companies today are continuously improving their efforts to incorporate an environmental management system (EMS) in their everyday operations and work practices, with an emphasis on identifying and reducing risks. Risks may include the cost of enforcement penalties, potential workplace dangers to employees, or cleanup liabilities due to past or present practices. Environmental auditing is an effective tool commonly used to enhance an EMS. Typically, there are two levels of auditing: (1) a review of management systems and (2) a review of compliance with regulatory requirements. There is yet another intermediate level of auditing that is more focused than management systems or compliance audits—compliance delivery systems (CDS) audits. This article examines the elements making up these systems for improving compliance performance and provides a ?ready to use”? checklist of items for managers to begin implementation. 相似文献
966.
The Millville Remediation Program recently received the 1995 Honor Award for national excellence in environmental engineering from the prestigious American Academy of Environmental Engineers (AAEE). This article discusses various aspects employed to investigate and remediate multimedia contamination at the site and the unique applications of technologies which were responsible for receiving the AAEE honor award. Unique aspects of the project included utilization of variable speed drives to set individual pumping rates for each groundwater recovery well, development of sophisticated remote monitoring and operation capabilities which minimized O&M labor costs, and development of a groundwater treatment system which has consistently achieved nondetect effluent discharges. The remote monitoring and operation capabilities enables O&M staff to monitor and change setpoints for the groundwater recovery, treatment, and recharge systems. 相似文献
967.
David F. Bradford Lynda A. Smith Deborah S. Drezner J. David Shoemaker 《Environmental management》1991,15(6):785-795
In much of the San Joaquin Valley, California, USA, inadequate drainage of applied irrigation water and accumulating salts
in the soil have necessitated the installation of subsurface tile drainage systems to preserve crop productivity. At present,
these subsurface drainage waters are disposed of by means of evaporation ponds or discharges into the San Joaquin River. Unfortunately,
most of these agricultural drainage waters contain high concentrations of salts and naturally occurring trace elements, such
as selenium, and recent evidence indicates that substantial numbers of waterbirds are exposed to contamination by selenium
in the evaporation ponds. In order to avoid, minimize, or mitigate the adverse impacts on wildlife using the ponds, alternative
pond management methods must be identified and evaluated for implementation. A number of methods have the potential to be
cost-effective in significantly reducing the contamination hazard to birds using agricultural evaporation ponds. Twenty general
methods were evaluated in this study, and four methods are recommended for implementation: remove levee vegetation, remove
windbreaks, deepen the ponds, and haze birds. A number of other methods are recommended for further consideration because
they appear to have good prospects for reducing the contamination hazard: steepen interior levee slopes, apply herbicides
and insecticides, place netting on pond shorelines, and provide freshwater habitat adjacent to evaporation ponds. It may be
necessary to use a combination of methods to effectively control selenium contamination of aquatic birds because it is unlikely
that a single affordable pond management method will be able to entirely eliminate the contamination hazard. 相似文献
968.
Ann C. Smith 《环境质量管理》1991,1(2):121-129
Environmental auditing evolved as a means of providing assurance to top management that its health, safety, and environmental responsibilities were being adequately discharged and that no significant noncompliances existed. The author takes an in-depth look at the HSE audit program developed at Allied-Signal to permit continuous improvement of environmental management systems. 相似文献
969.
R. Thomas. James Kim O'Dell Val H. Smith 《Journal of the American Water Resources Association》1994,30(3):531-546
ABSTRACT: Water quality in eutrophic Lake Tohopekaliga, Florida, improved markedly from 1982 to 1992 as a result of reductions in phosphorus and nitrogen loading to the lake. Annual budgets of water, chloride, phosphorus and nitrogen were constructed for the lake, and indicate it is a sink for phosphorus and a source for nitrogen. Water column concentrations of total phosphorus, soluble reactive phosphorus, total nitrogen, dissolved inorganic nitrogen, and chlorophyll a all declined as external inputs of nutrients decreased. Water column nitrogen: phosphorus ratios have increased, suggesting a probable shift from nitrogen- to phosphorus-limitation. This apparent shift in nutrient limitation status also is supported by comparisons of the mean Trophic State Indices for phosphorus, nitrogen, and chlorophyll a. These improvements in water quality are attributed to the diversion of wastewater treatment plant effluent from the lake, and the increased use of wet retention ponds for stormwater runoff. 相似文献
970.
Incidence of adverse biological effects within ranges of chemical concentrations in marine and estuarine sediments 总被引:118,自引:0,他引:118
Edward R. Long Donald D. Macdonald Sherri L. Smith Fred D. Calder 《Environmental management》1995,19(1):81-97
Matching biological and chemical data were compiled from numerous modeling, laboratory, and field studies performed in marine
and estuarine sediments. Using these data, two guideline values (an effects range-low and an effects range-median) were determined
for nine trace metals, total PCBs, two pesticides, 13 polynuclear aromatic hydrocarbons (PAHs), and three classes of PAHs.
The two values defined concentration ranges that were: (1) rarely, (2) occasionally, or (3) frequently associated with adverse
effects. The values generally agreed within a factor of 3 or less with those developed with the same methods applied to other
data and to those developed with other effects-based methods. The incidence of adverse effects was quantified within each
of the three concentration ranges as the number of cases in which effects were observed divided by the total number of observations.
The incidence of effects increased markedly with increasing concentrations of all of the individual PAHs, the three classes
of PAHs, and most of the trace metals. Relatively poor relationships were observed between the incidence of effects and the
concentrations of mercury, nickel, total PCB, total DDT and p,p′-DDE. Based upon this evaluation, the approach provided reliable
guidelines for use in sediment quality assessments. This method is being used as a basis for developing National sediment
quality guidelines for Canada and informal, sediment quality guidelines for Florida.
The methods and guidelines presented in this report do not necessarily represent the policy of the National Oceanic and Atmospheric
Administration, Environment Canada, or Florida Department of Environmental Protection. 相似文献