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461.
462.
Frederick J. Wells 《Resources Policy》1975,1(6):313-325
An analysis of the long-term demands, supplies and costs for phosphorus is employed as an example of ‘worst case’ research. Worst case research attempts to bound the problems posed in The Limits to Growth relating to running out of minerals and other raw materials by studying the costs of obtaining such materials from some vast source such as common rock. Since the costs of extracting minerals from these near infinite sources are as high as they would go for thousands of years, they represent the upper limit or worst case outlook, especially since the estimated costs are based on current technology. Recycling, conservation and other possibilities are also examined. At least in certain cases it may be possible from such research to make clearer judgements about the questions of exhaustion posed by the ’limits to growth’ literature. 相似文献
463.
464.
The Aquatic Macrophyte Community Index (AMCI) is a multipurpose tool developed to assess the biological quality of aquatic
plant communities in lakes. It can be used to specifically analyze aquatic plant communities or as part of a multimetric system
to assess overall lake quality for regulatory, planning, management, educational, or research purposes. The components of
the index are maximum depth of plant growth; percentage of the littoral zone vegetated; Simpson's diversity index; the relative
frequencies of submersed, sensitive, and exotic species; and taxa number. Each parameter was scaled based on data distributions
from a statewide database, and scaled values were totaled for the AMCI value. AMCI values were grouped and tested by ecoregion
and lake type (natural lakes and impoundments) to define quality on a regional basis. This analysis suggested that aquatic
plant communities are divided into four groups: (1) Northern Lakes and Forests lakes and impoundments, (2) North-Central Hardwood
Forests lakes and impoundments, (3) Southeastern Wisconsin Till Plains lakes, and (4) Southeastern Wisconsin Till Plains impoundments,
Driftless Area Lakes, and Mississippi River Backwater lakes. AMCI values decline from group 1 to group 4 and reflect general
water quality and human use trends in Wisconsin. The upper quartile of AMCI values in any region are the highest quality or
benchmark plant communities. The interquartile range consists of normally impacted communities for the region and the lower
quartile contains severely impacted or degraded plant communities. When AMCI values were applied to case studies, the values
reflected known impacts to the lakes. However, quality criteria cannot be used uncritically, especially in lakes that initially
have low nutrient levels. 相似文献
465.
Bisphenol A: emissions from point sources 总被引:14,自引:0,他引:14
Bisphenol A is widely used for the production of epoxy resins and polycarbonate plastics. Special in vitro test systems and animal experiments showed a weak estrogenic activity for Bisphenol A. Based on in vitro receptor interaction studies, the activity was estimated to be 2 x 10(-3) lower than that of estradiol. Especially aquatic wildlife could be endangered by waste water discharges. To manage possible risks arising from Bisphenol A contamination, the major fluxes need to be obtained and the contributors to the contamination of municipal treatment plants need to be determined. In this study, industrial emitters and communal waste waters were monitored simultaneously. Mixed samples were taken over periods of one week at nine sample sites. The results showed that the concentrations and fluxes were variable. The paper industry was the major Bisphenol A contributor to the influent of the waste water treatment plant. All the other fluxes measured, including two household areas, were considerably low. About 90% of the total load was removed during the waste water treatment. 相似文献
466.
Genesis T. Yengoh Augustin Tchuinte Frederick Ato Armah Justice O. Odoi 《Mitigation and Adaptation Strategies for Global Change》2010,15(8):825-841
This study set out to examine why agricultural production in differing agro-ecological zones of the same country responds
differently to a common environmental event (an extension of the rainy season). We find that the heavy reliance of farmers
in the drier agro-ecological zones on seasonal cycles make them more vulnerable to an extension of the rainy season than those
in regions where rainfall is less relied on. Effects in these vulnerable regions include significant damage to crops as well
as a shortage in local markets, which raises prices of basic food commodities. The difference between prices in low and high
food producing periods is low for crops that can easily be preserved during rains (such as cassava at 58% from an average
of 20% in previous years and yams at 82% from 65%). Crops that depend on sunshine for preservation experience greater differences
between low and high periods (maize at 92% from an average of 31% in previous years, sorghum at 180% from 53%, and beans at
68% from 42%). In zones with a history of unreliable dry seasons, farmers are more adapted to coping with an extension of
the rainy season and possess technology and skills which can be made available to others in vulnerable zones through inter-regional
knowledge transfer of knowledge and skills. This study further reinforces the understanding that isolated climate shocks could
be important in understanding and managing vulnerability. Also, vulnerability is quite variable even among communities in
the same country, in which people practice the same economic activity and are exposed to the same shock. 相似文献
467.
Remodeling the clock: coactivators and signal transduction in the circadian clockworks 总被引:1,自引:0,他引:1
Frank Weber 《Die Naturwissenschaften》2009,96(3):321-337
468.
Andrea Cattaneo Ruben Lubowski Jonah Busch Anna Creed Bernardo Strassburg Frederick Boltz Ralph Ashton 《Environmental Science & Policy》2010,13(8):742-753
Reducing emissions from deforestation and forest degradation (REDD) can be an effective and efficient means of mitigating climate change. However, the perceived equity in the distribution of financial incentives for REDD could also emerge as a critical issue in international negotiations. The design of reference levels, which provide the benchmark for crediting emissions reductions, affects the economic incentives for national participation in a REDD mechanism and thus the overall willingness to reach an agreement on REDD. This paper compares the equity impacts of five proposed reference level designs using a partial-equilibrium model. Tradeoffs among equity, environmental effectiveness and cost-efficiency indicate the proposals trigger similar aggregate emissions reductions but lead to different outcomes in efficiency and alternative measures of equity. If equity across countries is measured as the financial incentive provided relative to a country's forest carbon stock, then a REDD mechanism compensating a uniform share of at-risk carbon stocks is the most equitable. On the other hand, if equity is evaluated as the financial incentive relative to the opportunity costs of participating in REDD, then the most equitable approach would be compensating emissions reductions but withholding a part of the payments to compensate for carbon stocks, which also encourages broader country participation under our model. 相似文献
469.
Frederick A. Armah Justice O. Odoi Genesis T. Yengoh Samuel Obiri David O. Yawson Ernest K. A. Afrifa 《Mitigation and Adaptation Strategies for Global Change》2011,16(3):291-306
Desertification, climate variability and food security are closely linked through drought, land cover changes, and climate
and biological feedbacks. In Ghana, only few studies have documented these linkages. To establish this link the study provides
historical and predicted climatic changes for two drought sensitive agro-ecological zones in Ghana and further determines
how these changes have influenced crop production within the two zones. This objective was attained via Markov chain and Fuzzy
modelling. Results from the Markov chain model point to the fact that the Guinea savanna agro-ecological zone has experienced
delayed rains from 1960 to 2008 while the Sudan savanna agro-ecological zone had slightly earlier rains for the same period.
Results of Fuzzy Modelling indicate that very suitable and moderately suitable croplands for millet and sorghum production
are evenly distributed within the two agro-ecological zones. For Ghana to adapt to climate change and thereby achieve food
security, it is important to pursue strategies such as expansion of irrigated agricultural areas, improvement of crop water
productivity in rain-fed agriculture, crop improvement and specialisation, and improvement in indigenous technology. It is
also important to encourage farmers in the Sudan and Guinea Savanna zones to focus on the production of cereals and legumes
(e.g. sorghum, millet and soybeans) as the edaphic and climatic factors favour these crops and will give the farmers a competitive
advantage. It may be necessary to consider the development of the study area as the main production and supply source of selected
cereals and legumes for the entire country in order to free lands in other regions for the production of crops highly suitable
for those regions on the basis of their edaphic and climatic conditions. 相似文献
470.
Ivonne Bedei Tascha Gehrke Karl-Philipp Gloning Matthias Meyer-Wittkopf Daria Willner Martin Krapp Alexander Scharf Jan Degenhardt Kai-Sven Heling Peter Kozlowski Kathrin Trautmann Kai M. Jahns Annegret Geipel Jan-Erik Baumüller Lucas Wilhelm Ingo Gottschalk Andreas Schröer Alexander Graf Aline Wolter Johanna Schenk Axel Weber Ignatia B. Van den Veyver Roland Axt-Fliedner 《黑龙江环境通报》2023,43(2):192-206