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211.
We examined genetic diversity in 464 individuals of the monotypic lily Harperocallis flava in its two habitats (seepage bogs and a roadside right-of-way) and five populations of a co-occurring related lily, Tofieldia racemosa. The endangered H. flava, endemic to the Apalachicola lowlands of the Florida panhandle, was monomorphic for the 22 loci scored. In contrast, T. racemosa had a high proportion of polymorphic loci ( Ps = 68.2%; Pp = 47.7%) with moderate genetic diversity (   Hes = 0.134; Hep = 0.114). Estimated gene flow was moderately high ( Nm = 2.07) for T. racemosa, with most (93%) of the total genetic diversity found within populations. Despite the low level of genetic divergence, some isolation by distance was detected among T. racemosa populations. Harperocallis flava and other species without discernable genetic variation pose special problems for conservation biologists because genetic criteria are not available for the development of ex situ and in situ conservation and management strategies.  相似文献   
212.
This paper extends earlier work on the standards and prices approach to pollution control by considering simultaneously spatial considerations, interactive pollutants, and joint abatement costs. The form of environmental constraints appropriate to water pollution problems is discussed in detail and the implications for the standards and prices approach to water pollution control are assessed. The presence of interactive pollutants and joint abatement costs is shown to have important implications for both the theoretical properties and the implementation of the standards and prices approach.  相似文献   
213.
A compound detected in extracts of blubber of harbor seals, , found dead in Puget Sound in the north-western United States over the period 1972–1982 was identified as (chlorophenyl)methanol from its mass spectral characteristics and by synthesis. Concentrations in harbor seal blubber ranged from 23 to 750 ng/g of the lipid weight and showed no evident changes over the time interval of the study. Concentrations were highly correlated with those of most of the other organochlorines detected in the harbor seal extracts, indicating a similar pattern of uptake and accumulation. The compound is used in the manufacture of optically active polymers, which appear to be a plausible source.  相似文献   
214.
A semi-natural field study was carried out to assess the likelihood of a potentiation of toxicity between the ergosterol biosynthesis inhibiting (EBI) fungicide, prochloraz, and the organophosphorus (OP) insecticide, malathion, in the red-legged partridge (Alectoris rufa). Groups of partridges kept in four large grassland enclosures were exposed to either prochloraz-treated or control wheat for 7 days after which two of the enclosures were sprayed with malathion whilst the remaining two were sham-sprayed. Cytochrome P-450, aldrin epoxidase and 7-ethoxyresorufin-O-deethylase (EROD) activities were found to be significantly higher in the group exposed to prochloraz alone compared to controls, suggesting that induction of the hepatic microsomal monooxygenase system had occurred by ingestion of prochloraz-treated wheat. However, the level of induction produced was not sufficient to cause a potentiation of malathion toxicity. There was evidence for induction of several forms of P-450 recognised by antibodies raised against 1A1, 2C6 and 4A1 in the prochloraz-exposed partridges.  相似文献   
215.
Urinary gonadotropin peptide (UGP; β-core fragment), a major metabolite of human chorionic gonadotropin (hCG), was shown recently to be markedly elevated in Down syndrome pregnancy between 19 and 22 weeks of gestation. To confirm and extend this finding, we obtained maternal urine and matching maternal serum samples from 14 cases of Down syndrome and six other aneuploidies between 17 and 21 weeks of gestation. UGP was measured in all these samples and in 91 singleton control urines. Results were corrected for urinary creatinine level and expressed as multiples of the control median (MOM). hCG levels were assayed in all serum samples from the cases and compared with previously established reference values. The median UGP level in Down syndrome cases was 5.34 MOM (range 2.71–12.57); 88 per cent of the values were above the 95th centile of control levels after modelling. The median maternal serum hCG level for the same cases was 2.20 MOM (range 0.84–3.40); 36 per cent of the values were above the 95th centile. The level of UGP in every case including all other aneuploidies was higher than the comparable maternal serum hCG level. Elevated UGP measurements are strongly associated with fetal Down syndrome during the second trimester and could contribute to improved Down syndrome screening protocols that are more accessible and less expensive than are currently available.  相似文献   
216.
Health benefits assessment is an analytic tool used extensively by the U.S. Environmental Protection Agency (EPA) in characterizing the costs and benefits of air quality regulations. In a 2002 review of EPA methods, the U.S. National Research Council (NRC) called on EPA to more fully account for and communicate uncertainties in estimates of the health benefits of air pollution regulations. In particular, the NRC recommended that EPA use expert judgment to quantify uncertainties in cases where empirical estimates are lacking. In response, EPA developed and carried out an expert elicitation (EE) study to quantify uncertainties in the effects of fine particulate matter (PM2.5) on mortality in the U.S. This work has yielded new estimates of the uncertainty distribution of a key relationship – the concentration–response (C–R) function – used around the world in benefits analyses for air quality regulations. This paper discusses the ways in which the EE results have informed and influenced recent regulatory impact analyses (RIAs) carried out by EPA to characterize and communicate the health benefits of regulations affecting ambient PM2.5 concentrations. Given the growing importance of PM benefits analysis across the globe, recent developments pioneered by EPA could have widespread relevance.  相似文献   
217.
Recent perspectives on public responses to environmental and risk communication have emphasised the interpretation, judgement and 'sense-making' that takes place when lay audiences receive information and advice. In this paper we consider the public reception given to air-quality information in the UK as one example of a government information and communication initiative. Drawing on elements of a wider research project undertaken in the city of Birmingham in the UK, involving a survey and in-depth interviews with members of the public, it examines the extent of awareness and use of information services, attitudes towards information and the role of information in behaviour change. The objective of the paper is to assess in practical terms the impact of air-quality information available through the media and other sources, as well as to provide empirical evidence with which to reflect on debates over the practice of environmental communication and the stimulation of pro-environmental behaviour. Conclusions are drawn which point to both problems with air quality information provision and the possibilities of more effective and appropriate interventions through local-level initiatives.  相似文献   
218.
Although vast literature exists on the drivers of tropical deforestation and its ecological consequences, less is known about how patterns of forest fragmentation emerge in the first place. The purpose of this paper is to address this issue for the Brazilian portion of the Amazon basin by analyzing the social processes generative of five specific patterns, including rectangular, fishbone, radial, dendritic, and what we refer to as ‘the stem of the rose.’ We argue that forest fragmentation patterns in the Brazilian Amazon are largely determined by the types and arrival times of the agents who engage in land clearing. We also argue that the patterns manifest in the landscape by virtue of road construction and agricultural property formation, which often occur in tandem. We conclude by placing our discussion within legal and institutional contexts, and observe that fragmentation stemming from formal colonization projects is more consistent with biodiversity conservation than that associated with a laissez-faire occupation. However, erosive impacts may be greater in topographically sensitive areas.  相似文献   
219.
Participation by small and medium enterprise (SME) in corporate social responsibility issues has been found to be lacking. This is a critical issue, as individually SMEs may have little impact on the environment but their collective footprint is significant. The management style and ethical stance of the owner-manager affects business decision making and therefore has a direct impact on the environmental actions of the business. Although adoption of environmental practices to create competitive advantage has been advocated, many businesses see implementation as a cost which cannot be transferred to their customers. After a brief review of pertinent literature this paper reports on an exploratory investigation into the issue. Results show that whereas owner-managers of small enterprises express concern regarding the environment, this does not then translate into better waste management practices.  相似文献   
220.
Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous in the global environment and are subsequently transported into aquatic sediments. As PAHs are formed by various processes, source identification using diagnostic ratios can provide insight to PAH emission sources to distinguish between pyrogenic and petrogenic PAH sources. PAH diagnostic ratios were applied as a forensic source apportionment technique to assess aggregate historical sediment data from 31 small craft harbors (SCHs) across Nova Scotia, Canada. Multiple diagnostic ratios suggest that PAHs present in Nova Scotia SCH sediments are pyrogenic (combustion) in origin, while consistently suggesting that coal‐related PAH sources are potential dominant specific sources. National Institute of Standards and Technology Standard Reference Materials (SRMs) were used as reference for coal tar, urban dust, and diesel exhaust particulates in ratio applications. The SRM for coal tar was most similar to Nova Scotia SCH sediments in multiple ratio applications. Diagnostic ratio results were corroborated by comparing the PAH profile of sediments to source profiles from the literature. Results indicate that Nova Scotia SCH sediments follow global trends by exhibiting a dominant pyrogenic PAH signature, and the specific coal‐related PAH signature of Nova Scotia SCH sediments may be influenced by contamination inputs related to historical industrial coal mining and combustion activities in the province.  相似文献   
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