全文获取类型
收费全文 | 442篇 |
免费 | 19篇 |
国内免费 | 8篇 |
专业分类
安全科学 | 23篇 |
废物处理 | 36篇 |
环保管理 | 134篇 |
综合类 | 27篇 |
基础理论 | 63篇 |
污染及防治 | 120篇 |
评价与监测 | 37篇 |
社会与环境 | 23篇 |
灾害及防治 | 6篇 |
出版年
2023年 | 2篇 |
2022年 | 5篇 |
2021年 | 6篇 |
2020年 | 2篇 |
2019年 | 4篇 |
2018年 | 4篇 |
2017年 | 10篇 |
2016年 | 17篇 |
2015年 | 8篇 |
2014年 | 18篇 |
2013年 | 32篇 |
2012年 | 20篇 |
2011年 | 37篇 |
2010年 | 18篇 |
2009年 | 19篇 |
2008年 | 37篇 |
2007年 | 26篇 |
2006年 | 24篇 |
2005年 | 46篇 |
2004年 | 25篇 |
2003年 | 18篇 |
2002年 | 11篇 |
2001年 | 7篇 |
2000年 | 9篇 |
1999年 | 7篇 |
1998年 | 8篇 |
1997年 | 2篇 |
1996年 | 7篇 |
1995年 | 2篇 |
1994年 | 4篇 |
1993年 | 1篇 |
1992年 | 5篇 |
1991年 | 3篇 |
1990年 | 2篇 |
1989年 | 2篇 |
1988年 | 3篇 |
1987年 | 1篇 |
1986年 | 4篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1982年 | 2篇 |
1981年 | 1篇 |
1980年 | 3篇 |
1979年 | 4篇 |
排序方式: 共有469条查询结果,搜索用时 15 毫秒
101.
Alejandro Jim��nez Fern��ndez de Palencia Agust�� P��rez-Foguet 《Sustainability Science》2011,6(1):37-49
This paper examines the challenge of achieving a balance between the implementation of centrally designed pro-poor policies
and the decentralization of responsibilities to local governments in many African countries. It analyzes the implementation
of the Rural Water Supply and Sanitation Program in Tanzania. Key mechanisms for planning and allocating resources are analyzed
at ministry, district, and village levels. Results show that a mixture of policy incoherencies, technical shortcomings and
political influence determine that only a small proportion of funds reaches the underserved areas. We argue that a greater
connection between the bottom-up and top-down planning mechanisms, and a sharp increase of downwards accountability are needed
before decentralized decision-making result in better resources allocation. Meanwhile a bigger intervention from central government
is needed. 相似文献
102.
103.
In most OECD countries, emergency response to accidents and natural disasters is very dependent on a trained workforce of emergency services volunteers: fire, rescue, medical, care and relief. With its large area, sparsely settled population, and frequent periods of low rainfall, Australia is particularly vulnerable to the threat posed by wildfires. There are an estimated 220,000 rural fire volunteers (in a population of 20 million) in eight state and territory volunteer rural fire services. These fire services have experienced significant decreases in volunteer numbers over the past decade, a trend which is true also of North American volunteer fire services. An investigation suggests that the decrease is driven by two related sets of factors: economic and demographic. Globalisation and deregulation of the economy, and technological innovation, have resulted in structural changes in the nature of work: privatisation, casualisation, self-employment, and demands for increased productivity. These factors make it more difficult for members of communities to volunteer, regardless of their motivation to do so. Further, like many other OECD countries, Australia's birth rate has fallen over the last three decades, resulting in a decline in the proportion of the population aged between 25 and 45 years—a trend that is unlikely to be reversed in the foreseeable future. These economic and demographic changes make it difficult for Australian volunteer rural fire agencies to meet their community protection responsibilities. Responding to these challenges may require radical changes in the way that these fire services are organised and supported. 相似文献
104.
105.
Uranium is a redox active contaminant of concern to both human health and ecological preservation. In anaerobic soils and sediments, the more mobile, oxidized form of uranium (UO(2)(2+) and associated species) may be reduced by dissimilatory metal-reducing bacteria. Despite rapid reduction in controlled, experimental systems, various factors within soils or sediments may limit biological reduction of U(VI), inclusive of competing electron acceptors and alterations in uranyl speciation. Here we elucidate the impact of U(VI) speciation on the extent and rate of reduction, and we examine the impact of Fe(III) (hydr)oxides (ferrihydrite, goethite, and hematite) varying in free energies of formation. Observed pseudo first-order rate coefficients for U(VI) reduction vary from 12 +/- 0.60 x 10(-3) h(-1) (0 mM Ca in the presence of goethite) to 2.0 +/- 0.10 x 10(-3) h(-1) (0.8 mM Ca in the presence of hematite). Nevertheless, dissolved Ca (at concentrations from 0.2 to 0.8 mM) decreases the extent of U(VI) reduction by approximately 25% after 528 h relative to rates without Ca present. Imparting an important criterion on uranium reduction, goethite and hematite decrease the dissolved concentration of calcium through adsorption and thus tend to diminish the effect of calcium on uranium reduction. Ferrihydrite, in contrast, acts as a competitive electron acceptor and thus, like Ca, decreases uranium reduction. However, while ferrihydrite decreases U(VI) in solutions without Ca, with increasing Ca concentrations U(VI) reduction is enhanced in the presence of ferrihydrite (relative to its absence)-U(VI) reduction, in fact, becomes almost independent of Ca concentration. The quantitative framework described herein helps to predict the fate and transport of uranium within anaerobic environments. 相似文献
106.
107.
During summer, a grizzly bear (Ursus arctos horribilis) in the Greater Yellowstone Ecosystem (GYE) (USA) can excavate and consume millions of army cutworm moths (Euxoa auxiliaris) (ACMs) that aggregate in high elevation talus. Grizzly bears in the GYE were listed as threatened by the US Fish and Wildlife Service in 1975 and were proposed for delisting in 2005. However, questions remain about key bear foods. For example, ACMs are agricultural pests and concern exists about whether they contain pesticides that could be toxic to bears. Consequently, we investigated whether ACMs contain and transport pesticides to bear foraging sites and, if so, whether these levels could be toxic to bears. In 1999 we collected and analyzed ACMs from six bear foraging sites. ACMs were screened for 32 pesticides with gas chromatography with electron capture detection (GC-ECD). Because gas chromatography with tandem mass spectrometry (GC-MS/MS) can be more sensitive than GC-ECD for certain pesticides, we revisited one site in 2001 and analyzed these ACMs with GC-MS/MS. ACMs contained trace or undetectable levels of pesticides in 1999 and 2001, respectively. Based on chemical levels in ACMs and numbers of ACMs a bear can consume, we calculated the potential of chemicals to reach physiological toxicity. These calculations indicate bears do not consume physiologically toxic levels of pesticides and allay concerns they are at risk from pesticides transported by ACMs. If chemical control of ACMs changes in the future, screening new ACM samples taken from bear foraging sites may be warranted. 相似文献
108.
Toxicity of copper to acetoclastic and hydrogenotrophic activities of methanogens and sulfate reducers in anaerobic sludge 总被引:1,自引:0,他引:1
Heavy metals could potentially negatively impact microorganisms in anaerobic sulfate reducing bioreactors. The objective of this is study was to evaluate the inhibitory effect of copper to acetoclastic and hydrogenotrophic activities of methanogens and sulfate reducers in sludge obtained from a full-scale sulfate reducing bioreactor. The 50% inhibiting concentration (50%IC) of Cu(2+) to acetoclastic and hydrogenotrophic methanogens was 20.7 and 8.9 mg l(-1), respectively. The 50%IC of Cu(2+) to acetoclastic sulfate reduction was 32.3 mg l(-1). The hydrogenotrophic sulfate reducers were only inhibited by 27% at the highest concentration of Cu(2+) tested, 200 mg l(-1), indicating a high level of tolerance. The soluble Cu(2+) was observed to decrease rapidly in both the methanogenic and sulfate reducing assays. The highest level of decrease was observed in the hydrogenotrophic sulfate reducing assay which was over 99% in 5h. The results of this study indicate that sulfate reducing biotechnologies would be robust at relatively high inlet concentrations of Cu(2+). 相似文献
109.
The commonly used plasticizers di-ethylhexyl phthalate (DEHP) and di-ethylhexyl adipate (DEHA) are known to partially degrade in the presence of soil microorganisms, such as Rhodococcus rhodochrous, releasing persistent and toxic metabolites. The metabolites adipic acid and 2-ethylhexanol were both shown to inhibit growth of the degrading microbe. 2-Ethylhexanol enhanced the activity of ethanol dehydrogenase - an enzyme involved in its metabolism - but the activity of this enzyme was inhibited by adipic acid. The metabolite usually seen in the highest concentrations - 2-ethylhexanoic acid - did not exhibit any evidence of inhibition. It was shown that the high concentration of this metabolite was due to the inability of R. rhodochrous to degrade it. Comparisons with other small carboxylic acids supported the argument that the ethyl branch was the reason for the resistance of 2-ethylhexanoic acid to degradation. The hydrophobicity of the cell surface was shown to be a factor in plasticizer degradation. The primary carbon source could be either water-soluble or hydrophobic and a hydrophobic substrate led to a cell surface that attracted the plasticizer and facilitated degradation. The most hydrophobic of the plasticizers, DEHP, was particularly sensitive to this effect. 相似文献
110.
Jiménez-Ramos MC García-Tenorio R Vioque I Manjón G García-León M 《Environmental pollution (Barking, Essex : 1987)》2006,142(3):487-492
More than 30 years after the occurrence of an aircraft accident which involved the detonation of two nuclear weapons in the surrounding area of the village of Palomares (Spain), the affected terrestrial area has been investigated for remaining transuranic contamination. Evidence from the presence of this contamination was initially found through the analysis of the 241Am inventories in superficial soil samples collected in the region, and was confirmed through the analysis of the (239+240)Pu inventories and their associated 238Pu/(239+240)Pu activity ratios in the same samples. However, it was also observed that a considerable fraction of the remaining contamination in the area was present in particulate form, i.e. as "hot particles". The work performed in our laboratory for identification, isolation and characterisation of these "hot particles" as well as some conclusions obtained from these analyses are outlined in this paper. 相似文献