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21.
Kristen E.Sukalac 《生态毒理学报》2000,22(2):63-64
国际农业食品网络(IAFN)是1996年联合国粮农组织世界粮食高峰会议时为协调农业发展领域中与国际组织有关的活动而成立的.该网络只是一个讨论论坛,其中与会者可以确认他们的共同关注和分享各种思路的经验. 相似文献
22.
Kristen M. Waring Danielle M. Reboletti Lauren A. Mork Ching-Hsun Huang Richard W. Hofstetter Amanda M. Garcia Peter Z. Fulé T. Seth Davis 《Environmental management》2009,44(4):824-835
Predicted climate warming is expected to have profound effects on bark beetle population dynamics in the southwestern United
States. Temperature-mediated effects may include increases in developmental rates, generations per year, and changes in habitat
suitability. As a result, the impacts of Dendroctonus frontalis and Dendroctonus mexicanus on forest resources are likely subject to amplification. To assess the implications of such change, we evaluated the generations
per year of these species under three climate scenarios using a degree-day development model. We also assessed economic impacts
of increased beetle outbreaks in terms of the costs of application of preventative silvicultural treatments and potential
economic revenues forgone. Across the southwestern USA, the potential number of beetle generations per year ranged from 1–3+ under
historical climate, an increase of 2–4+ under the minimal warming scenario and 3–5+ under the greatest warming scenario. Economic
benefits of applying basal area reduction treatments to reduce forest susceptibility to beetle outbreaks ranged from 7.75/ha (NM) to7.75/ha
(NM) to 95.69/ha (AZ) under historical conditions, and 47.96/ha (NM) to47.96/ha (NM) to 174.58/ha (AZ) under simulated severe drought conditions.
Basal area reduction treatments that reduce forest susceptibility to beetle outbreak result in higher net present values than
no action scenarios. Coupled with other deleterious consequences associated with beetle outbreaks, such as increased wildfires,
the results suggest that forest thinning treatments play a useful role in a period of climate warming. 相似文献
23.
24.
Leaf structural diversity is related to hydraulic capacity in tropical rain forest trees 总被引:1,自引:0,他引:1
The hydraulic resistance of the leaf (R1) is a major bottleneck in the whole plant water transport pathway and may thus be linked with the enormous variation in leaf structure and function among tropical rain forest trees. A previous study found that R1 varied by an order of magnitude across 10 tree species of Panamanian tropical lowland rain forest. Here, correlations were tested between R1 and 24 traits relating to leaf venation and mesophyll structure, and to gross leaf form. Across species, R1 was related to both venation architecture and mesophyll structure. R1 was positively related to the theoretical axial resistivity of the midrib, determined from xylem conduit numbers and dimensions, and R1 was negatively related to venation density in nine of 10 species. R1 was also negatively related to both palisade mesophyll thickness and to the ratio of palisade to spongy mesophyll. By contrast, numerous leaf traits were independent of R1, including area, shape, thickness, and density, demonstrating that leaves can be diverse in gross structure without intrinsic trade-offs in hydraulic capacity. Variation in both R1-linked and R1-independent traits related strongly to regeneration irradiance, indicating the potential importance of both types of traits in establishment ecology. 相似文献
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27.
Kristen Ounanian Jan P.M. van Tatenhove Paulina Ramírez-Monsalve 《Journal of Environmental Policy & Planning》2020,22(2):211-225
ABSTRACTIn the North Sea, many oil and gas fields will reach the end of their productivity and their associated structures will be decommissioned. OSPAR decision 98/3 prescribes removal of all disused offshore structures as the only acceptable decommissioning option. This policy is the legacy of the 1995 Brent Spar incident, which resulted in the current dominant discourse of ‘Hands off the Oceans,’ ruling out the conversion of oil and gas rigs into artificial reefs (Rigs-to-Reefs (RtR)). The shift from a conservation to a restoration paradigm could open up the RtR debate. In this paper, a discourse analysis is carried out to discern whether and how ideas about RtR and ecosystem restoration are articulated to challenge the dominant ‘Hands off the Oceans’ discourse and thereby bring about change in North Sea decommissioning policy. A discourse analytic framework is applied to elucidate whether an ‘RtR as Restoration’ discourse can be distinguished and how competing claims are presented in the various storylines. Our analysis shows an ‘RtR as Restoration’ discourse, consisting of four different storylines. Given the fragmented nature of this discourse, the ‘RtR as Restoration’ discourse will not overcome the dominant ‘Hands off the Oceans’ discourse. 相似文献
28.
Peter M. Schwarz Craig A. Depken II Alex Hanning Kristen Peterson 《Journal of environmental management》2009,90(12):3730
This study uses California data to compare redevelopment for properties subject to mandatory and voluntary cleanup. CalSites are subject to the CERCLA liability approach, while properties in the Voluntary Cleanup Program (VCP) are subject to a risk-based approach (RBA) that allows some contamination to remain for non-residential redevelopment. The expectation is that VCPs will show a greater proportion of industrial redevelopment, which has the least stringent standard, and a smaller proportion of residential redevelopment. The results show an overall trend toward more residential redevelopment of contaminated properties, but consistent with expectations, the trend is weaker for VCP properties than CalSites. 相似文献
29.
INTRODUCTION: Some research suggests that conducting safety observations of another's safety performance may serve as an effective tool in increasing the safety performance of the observer. The primary purpose of the present study was to assess the effects of conducting safety observations on the postural safety performance of observers engaging in an assembly task for short time periods. The secondary objectives of the study were: (a) to measure productivity, and (b) to measure the accuracy of participant safety observations. METHOD: An ABC (A: baseline, B: information, C: observation) multiple-baseline design counterbalanced across postural behaviors (back, shoulder, and feet position) was implemented with six participants. RESULTS AND DISCUSSION: Substantial improvements in postural safety occurred after participants conducted safety observations, and these improvements did not appear to negatively affect productivity. Results also suggest that there is no relation between the accuracy of an observer's safety observation and their subsequent safety performance. IMPACT ON INDUSTRY: This research provides evidence that a safety observation process can function to increase safe postural behavior of observers. Thus, the implementation of such a process may contribute to the prevention of musculoskeletal disorders and related costs in the workplace. 相似文献
30.
Aneja VP Blunden J James K Schlesinger WH Knighton R Gilliam W Jennings G Niyogi D Cole S 《Journal of environmental quality》2008,37(2):515-520
Recent studies suggest that human activities accelerate the production of reactive nitrogen on a global scale. Increased nitrogen emissions may lead to environmental impacts including photochemical air pollution, reduced visibility, changes in biodiversity, and stratospheric ozone depletion. In the last 50 yr, emissions of ammonia (NH3), which is the most abundant form of reduced reactive nitrogen in the atmosphere, have significantly increased as a result of intensive agricultural management and greater livestock production in many developed countries. These agricultural production practices are increasingly subject to governmental regulations intended to protect air resources. It is therefore important that an accurate and robust agricultural emission factors database exist to provide valid scientific support of these regulations. This paper highlights some of the recent work that was presented at the 2006 Workshop on Agricultural Air Quality in Washington, D.C. regarding NH3 emissions estimates and emission factors from agricultural sources in the U.S. and Europe. In addition, several best management practices are explored as the scientific community attempts to maximize the beneficial use of reactive nitrogen while simultaneously minimizing negative environmental impacts. 相似文献