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531.
Environmental Control and Limnological Impacts of a Large Recurrent Spring Bloom in Lake Washington,USA 总被引:3,自引:1,他引:2
A series of statistical analyses were used to identify temporal and spatial patterns in the phytoplankton and nutrient dynamics
of Lake Washington, an mesotrophic lake in Washington State (USA). These analyses were based on fortnightly or monthly samples
of water temperature, Secchi transparency, ammonium (NH4), nitrate (NO3), inorganic phosphorus (IP), total nitrogen (TN), total phosphorus (TP), dissolved oxygen (DO), pH and chlorophyll a (chl a) collected during 1995–2000 from 12 stations. Lake Washington has a very consistent and pronounced annual spring diatom bloom
which occurs from March to May. During this bloom, epilimnetic chl a concentrations peak on average at 10 μg/L, which is 3 times higher than chl a concentrations typically seen during summer stratified conditions. The spring bloom on average comprised 62% diatoms, 21%
chlorophytes and 8% cyanobacteria. During summer stratification, diatoms comprised 26% of the phytoplankton community, chlorophytes
37% and cyanobacteria 25%. Cryptophytes comprised approximately 8% of the community throughout the year. Overall, 6 phytoplankton
genera (i.e., Aulacoseira, Fragilaria, Cryptomonas, Asterionella, Stephanodiscus, and Ankistrodesmus) cumulatively accounted for over 50% of the community. These analyses also suggest that the phytoplankton community strongly
influences the seasonality of NO3, IP, DO, pH and water clarity. According to a MANOVA, seasonal fluctuations explained 40% of the total variability for the
major parameters, spatial heterogeneity explained 10% of variability, and the seasonal-spatial interaction explained 10% of
variability. Distinctive patterns were identified between offshore and inshore sampling stations. The results of our analyses
also suggest that spatial variability was substantial, but much smaller than temporal variability. 相似文献
532.
In situ trampling occurred under experimental conditions to quantify the differences in the responses to anthropogenic trampling
in four dominant species of Hawaiian corals, Porites compressa, Porites lobata, Montipora capitata, and Pocillopora meandrina. Trampling was simulated daily for a period of nine days at which time further breakage was minimal. Forty treatment colonies
produced 559 fragments. Trampling was followed by an 11-month recovery period.
Coral colony and fragment mortality was low. All four species were highly tolerant of inflicted damage, suggesting that some
species of corals can withstand limited pulse events that allow time for recovery.
Growth rates following trampling were significantly lower in the treatment groups for three of the four species. This study
demonstrated that very few trampling events can produce significant changes in growth even after a long recovery period.
Survivorship of fragments is clearly size- and species-dependent in M. capitata and P. compressa. Smaller fragments (<5 cm) had higher mortality than larger fragments (>5 cm). High breakage rates for M. capitata and P. compressa are consistent with the nearshore, low-energy regions they inhabit—the same environment frequented by skin divers and waders.
Mechanical tests were conducted to determine tensile and compressive strengths. Pocillopora meandrina exhibited the strongest skeletal strength, followed in decreasing order by Porites lobata, Porites compressa, and Montipora capitata. The skeletal strength obtained from the experiments correlate with the wave energy present in the environments in the regions
they inhabit, suggesting that structural strength of corals is an adaptive response to hydraulic stress. 相似文献
533.
The importance of the surrounding landscape to aquatic ecosystems has been well established. Most research linking aquatic
ecosystems to landscapes has focused on the one-way effect of land on water. However, to understand fully the complex interactions
between aquatic and terrestrial ecosystems, aquatic ecosystems must be seen not only as receptors of human modification of
the landscape, but also as potential drivers of these modifications. We hypothesized that the presence of aquatic ecosystems
influences the spatial distribution of human land use/cover of the nearby landscape (≤1 km) and that this influence has changed
through time from the 1930s to the 1990s. To test this hypothesis, we compared the distribution of residential, agricultural,
and forested land use/cover around aquatic ecosystems (lakes, wetlands, and streams) to the overall regional land use/cover
proportion in an area in southeast Michigan, USA; we also compared the distribution of land use/cover around county roads/highway
and towns (known determinants of many land use/cover patterns) to the regional proportion. We found that lakes, wetlands,
and streams were strongly associated with the distribution of land use/cover, that each ecosystem type showed different patterns,
and that the magnitude of the association was at least as strong as the association with human features. We also found that
the area closest to aquatic ecosystems (<500 m) was more strongly associated with land use/cover distribution than areas further
away. Finally, we found that the strength of the association between aquatic ecosystems and land use/cover increased from
1938 to 1995, although the overall patterns were similar through time. Our results show that a more complete understanding
is needed of the role of aquatic ecosystems on the distribution of land use/cover. 相似文献
534.
Role of Adaptive Management for Watershed Councils 总被引:1,自引:0,他引:1
Habron G 《Environmental management》2003,31(1):0029-0041
Recent findings in the Umpqua River Basin in southwestern Oregon illustrate a tension in the rise of both community-based
and watershed-based approaches to aquatic resource management. While community-based institutions such as watershed councils
offer relief from the government control landowners dislike, community-based approaches impinge on landowners' strong belief
in independence and private property rights. Watershed councils do offer the local control landowners advocate; however, institutional
success hinges on watershed councils' ability to reduce bureaucracy, foster productive discussion and understanding among
stakeholders, and provide financial, technical, and coordination support. Yet, to accomplish these tasks current watershed
councils rely on the fiscal and technical capital of the very governmental entities that landowners distrust. Adaptive management
provides a basis for addressing the apparent tension by incorporating landowners' belief in environmental resilience and acceptance
of experimentation that rejects “one size fits all solutions.” Therefore community-based adaptive watershed management provides
watershed councils a framework that balances landowners' independence and fear of government intrusion, acknowledges the benefits
of community cooperation through watershed councils, and enables ecological assessment of landowner-preferred practices. Community-based
adaptive management integrates social and ecological suitability to achieve conservation outcomes by providing landowners
the flexibility to use a diverse set of conservation practices to achieve desired ecological outcomes, instead of imposing
regulations or specific practices. 相似文献
535.
The US Clean Water Act and habitat replacement: evaluation of mitigation sites in Orange County,California, USA 总被引:2,自引:2,他引:0
Both permit requirements and ecological assessments have been used to evaluate mitigation success. This analysis combines
these two approaches to evaluate mitigation required under Section 404 of the United States Clean Water Act (CWA) and Section
10 of the Rivers and Harbors Act, which allow developers to provide compensatory mitigation for unavoidable impacts to wetlands.
This study reviewed permit files and conducted field assessments of mitigation sites to evaluate the effectiveness of mitigation
required by the US Army Corps of Engineers for all permits issued in Orange County, California from 1979 through 1993. The
535 permit actions approved during this period allowed 157 ha of impacts. Mitigation was required on 70 of these actions,
with 152 ha of enhanced, restored, and created habitat required for 136 ha of impacts. In 15 permit actions, no mitigation
project was constructed, but in only two cases was the originally permitted project built; the two cases resulted in an unmitigated
loss of 1.6 ha. Of the remaining 55 sites, 55% were successful at meeting the permit conditions while 11% failed to do so.
Based on a qualitative assessment of habitat quality, only 16% of the sites could be considered successful and 26% were considered
failures. Thus, of the 126 ha of habitat lost due to the 55 projects, only 26 ha of mitigation was considered successful.
The low success rate was not due to poor enforcement, although nearly half of the projects did not comply with all permit
conditions. Mitigation success could best be improved by requiring mitigation plans to have performance standards based on
habitat functions. 相似文献
536.
The separate collection of waste, and especially of recyclables with specific collection systems, would not be possible without
the involvement of the users. Apart from the physical installations such as collection containers, collection points, etc.,
the motivation of the users is an essential component. Motivation can be reinforced through public relations work. In addition
to the underlying technical considerations, this paper describes the difference between communication in general and public
relations and specifically examines public involvement in recycling. Through the use of examples, we look at the targeted
users and typical media employed. Furthermore, we analyzes the development of public involvement. The examples show that public
relations for recycling strategies relies to a great extent on attitudes, habits, and access to the target group. Thus, standardized
procedures cannot be developed. For these reasons, public relation activities must be planned carefully and professionally
and include an analysis of the target group, choice of media, and verification of success. 相似文献
537.
Monitoring of the ocean environment in southern California, USA, has been conducted by a diverse array of public and private organizations with different motivations, working on a variety of spatial and temporal scales. To create a basis from which to integrate information from these diverse programs, we conducted an inventory of ocean monitoring activities in the Southern California Bight to address the following questions: (1) How much money is being expended annually on marine monitoring programs? (2) Which organizations are conducting the most monitoring? (3) How are resources allocated among the different types of monitoring programs? This inventory focused on programs existing, or those expected to be in existence, for at least 10 years and that were active at any time between 1994 and 1997. For each program identified for inclusion in this study, information was collected on the number of sites, sampling intensity, parameters measured, and methods used. Levels of effort were translated into cost estimates based upon a market survey of local consulting firms. One hundred fourteen marine monitoring programs, conducted by 65 organizations and costing US $31 million annually, were identified. Most of the effort (81 programs, 65% of samples, 70% of costs) was expended by ocean dischargers as part of their compliance with National Pollutant Discharge Elimination System (NPDES) permit requirements. Federal programs (11 programs, 25% of samples, 10% of total expenditures) expended more than state or local government programs. More than one quarter of monitoring expenditures were conducted to measure concentrations and mass of effluent inputs to the ocean. The largest effort expended on receiving water monitoring was for measuring bacteria, followed by sediments, fish/shellfish, water quality, and intertidal habitats. The large level of expenditures by individual agencies has presented opportunities for integrating small, site-specific ocean monitoring programs into regional- and national-scale monitoring and assessment programs. 相似文献
538.
539.
Furimsky E 《Environmental management》2002,30(6):0872-0879
Information on the type and amount of hazardous and toxic waste is required to develop a meaningful strategy and estimate
a realistic cost for clean up of the Sydney Tar Pond site which is located on Cape Breton, in the province of Nova Scotia,
Canada. The site covers the area of the decommissioned Sysco (Sydney Steel Corporation) plant. The materials of concern include
BTEX (benzene, toluene, ethylbenzene, and xylenes), PAH (polycyclic aromatic hydrocarbons), PCB (polychlorinated biphenyl),
and particulates laden with toxic metals, such as arsenic, lead, and others. The originally nontoxic materials such as soil,
blast furnace slag, and vegetation, as well as surface and ground waters, which were subsequently contaminated, must also
be included if they fail tests prescribed by environmental regulations. An extensive sampling program must be undertaken to
obtain data for an accurate estimate of the waste to be cleaned and disposed of. Apparently, 700,000 tons of toxic waste,
which is believed to be present on the site, may represent only a fraction of the actual amount. The clean-up of the site
is only part of the solution. Toxic waste has to be disposed of in accordance with environmental regulations. 相似文献
540.
Land-use planning using geographic information systems (GIS) commonly emphasizes biophysical spatial data; however planning
can be improved by integrating spatial sets of socioeconomic data into the GIS. As an example, we compared a traditional GIS-aided
forestry planning protocol that considered only biophysical suitability, with an integrated GIS-aided approach that incorporated
both biophysical and socioeconomic suitability. The analyses were conducted for the planning of plantation investments in
the Kyaukpadaung Township in the dry zone of central Myanmar. The traditional approach used three biophysical layers for suitability:
land use, slope, and accessibility. In contrast, the integrated GIS approach included biophysical suitability data, perceptions
and preferences of local villagers towards forestry (social suitability), and quantitative socioeconomic data. The results
indicated that the integrated approach provided two principal benefits over the traditional method. First, the integrated
method resulted in a more precise idea of suitable sites for plantation investment that could benefit more rural people and
also lead to greater investment efficiency. Second, incorporating social preference into the GIS takes into account the crucial
element of social capital (viz., social preference), which should lead to higher levels of community acceptance of plantation
projects because those plantations would be established on socially suitable land. A second GIS exercise showed how conservation
investment decisions could be informed using the integrated method. The results of this study support the idea that GIS-aided
planning activities can be enhanced through the incorporation of social data into the analysis. When applicable, spatial data
collection efforts for GIS-based planning exercises should incorporate spatial socioeconomic data. 相似文献