首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   244篇
  免费   8篇
  国内免费   2篇
安全科学   22篇
废物处理   11篇
环保管理   48篇
综合类   23篇
基础理论   71篇
污染及防治   51篇
评价与监测   10篇
社会与环境   8篇
灾害及防治   10篇
  2021年   2篇
  2020年   2篇
  2019年   4篇
  2018年   6篇
  2017年   7篇
  2016年   7篇
  2015年   11篇
  2014年   5篇
  2013年   19篇
  2012年   9篇
  2011年   19篇
  2010年   8篇
  2009年   6篇
  2008年   10篇
  2007年   8篇
  2006年   7篇
  2005年   8篇
  2004年   9篇
  2003年   6篇
  2002年   11篇
  2001年   3篇
  2000年   7篇
  1999年   6篇
  1998年   2篇
  1997年   3篇
  1996年   2篇
  1995年   3篇
  1994年   4篇
  1993年   4篇
  1992年   3篇
  1991年   3篇
  1988年   1篇
  1987年   2篇
  1985年   6篇
  1984年   6篇
  1982年   2篇
  1981年   3篇
  1980年   4篇
  1979年   4篇
  1978年   1篇
  1977年   5篇
  1976年   2篇
  1975年   3篇
  1974年   3篇
  1972年   2篇
  1971年   1篇
  1970年   3篇
  1969年   1篇
  1960年   1篇
排序方式: 共有254条查询结果,搜索用时 15 毫秒
141.
This paper reports results from two studies that test a refinement of the equity sensitivity construct first in an experimental setting and second in a field setting. Results from Study 1 show that benevolents express tolerance for both overreward and underreward relative to entitleds and equity sensitives and that benevolents report relatively high levels of satisfaction regardless of reward condition. Study 1 results also show that manipulation of outcomes produce a more dramatic effect on satisfaction than does manipulation of inputs. Results from Study 2 reveal significantly different exchange ideologies for benevolents and entitleds and show that entitleds place more importance on pay whereas benevolents place more importance on the work itself. For both benevolents and entitleds, there is a positive correlation between assessments of distributive justice and job satisfaction. Implication of the findings both for equity theory research and the practice of management are discussed.  相似文献   
142.
143.
Air emissions and residual ash samples were collected and analyzed during experiments of open, uncontrolled combustion of electronic waste (e-waste), simulating practices associated with rudimentary e-waste recycling operations. Circuit boards and insulated wires were handled separately to simulate processes associated with metal recovery. The average emissions of polychlorinated dibenzodioxins and dibenzofurans (PCDD/PCDFs) were 92 ng toxic equivalency (TEQ)/kg [n = 2, relative standard deviation (RSD) = 98%] and 11 900 ng TEQ/kg (n = 3, RSD = 50%) of the initial mass of the circuit boards and insulated wire, respectively. The value for the insulated wire is about 100 times higher than that for backyard barrel burning of domestic waste. The emission concentrations of polybrominated dibenzodioxins and dibenzofurans (PBDD/PBDFs) from the combustion of circuit boards were 100 times higher than for their polychlorinated counterparts. Particulate matter (PM) sampling of the fly ash emissions indicated PM emission factors of approximately 15 and 17 g/kg of the initial mass for the circuit boards and insulated wire, respectively. Fly ash samples from both types of e-waste contained considerable amounts of several metallic elements and halogens; lead concentrations were more than 200 times the United States regulatory limits for municipal waste combustors and 20 times those for secondary lead smelters. Leaching tests of the residual bottom ash showed that lead concentrations exceeded U.S. Environmental Protection Agency landfill limits, designating this ash as a hazardous waste.  相似文献   
144.
A case study of urban heat islands in the Carolinas   总被引:3,自引:0,他引:3  
Urbanization tends to aggravate the negative effects of climate. The objective of this research is to aid in the understanding of the spatial variation of urban heat islands within selected cities in North and South Carolina. This understanding will help guide efforts to cool cities in order to increase human comfort, conserve energy and resources, and reduce air pollution in both of these states.  相似文献   
145.
Sheets of mantle tissue from above the mantle line of Mercenaria mercenaria were incubated for 2, 6 and 20 h at 20°C in 50 Ci 3H-glycine in 50 ml artificial seawater. Incorporation of tritium into soluble proteins excreted by the mantle and into tissue proteins was followed. The excretion of soluble protein continued throughout the experiment; the proportion of incorporated label excreted reached 17% by 20 h. The initiation of excretion of labelled protein seemed to lag 60 to 70 min behind the initiation of protein synthesis. Protein synthesis by the mantle contributed to proteins of the extrapallium and mantle chambers and, thus, may be involved in synthesis and regulation of proteins involved in the shell-formation process.  相似文献   
146.
Tributyltin (TBT) was detected in all 24 surface sediment (top 2 cm) samples collected from Coddington Cove, Newport, RI. TBT surface sediment concentrations ranged from 32 to 372 ng Sn/g with a mean concentration of 146 ng Sn/g. Analyses of selected core sections detected TBT in at least the top 18 cm at all 7 stations where cores were collected. No consistent TBT concentration trends with depth for these cores suggest mixing is an important process in the sediment column. In one core (station 28), TBT was found in the 76-86 cm section at a concentration of 141 ng Sn/g; thus sediments are a significant sink for TBT. However, sediment mixing processes can enhance releases of bioavailable TBT. Mussels, clams and fish from Coddington Cove contain TBT at concentrations ranging from 9.2 to 977 ng Sn/g. TBT concentrations in lobsters were below the detection limit (<6 ng Sn/g). Based on available screening criteria, TBT concentrations in Coddington Cove sediment is likely to be having an adverse effect on the biota at some locations.  相似文献   
147.
In those states that have not included CWM as hazardous materials in their RCRA programs, the RCRA requirements for management of hazardous waste would not strictly apply to any of the CWM. The Army has historically implemented procedures requiring that chemical warfare agents be managed as RCRA hazardous waste regardless of the concentration, physical form, or configuration of the agent. Such application of strict hazardous waste requirements to management of potentially nonhazardous CWM can result in remedial costs well out of proportion to potential human health and environmental benefits. Recent development of chronic toxicity values for the CWM has opened the door for development of cleanup and waste management standards for waste streams or media containing small residual amounts of CWM. Implementation of this health-based approach to management of CWM remediation wastes may, in part, help to reduce potentially unnecessary hazardous waste management costs for the nonhazardous CWM.  相似文献   
148.
Fresh TiO2 was found to possess a strong germicidal activity even without UV irradiation. Live Yeast (Saccharomyces cerevisiae) cells in contact with fresh TiO2 were found deformed and dead after 15 min contact. The cause of germicidal activity was discussed from the observed cell deformation, lysis and increased absorption at 1680 cm-1 in FT-IR spectra of the affected cells, which proved the oxidizing effect of fresh TiO2 to cells. The deformation caused by the stretching of cell wall and pressure built-up inside the cell, led to cell burst and release of intracellular materials. The degree of cell deformation was found positively related with the wetting property of TiO2. Cells are negatively charged, for Gram-negative cell (thinner cell wall), a higher germicidal effect was observed than Gram-positive cells. The germicidal effect of TiO2 gradually decreases after exposure to air at room temperature, as the wetting property decreases. This kind of germicidal activity was more effective compared to other germicidal process such as UVA/TiO2 or Ag+. This shed light on designing new germicidal material either maintained by visible light irradiation, or by oxidation effect generated by reactive oxygen species.  相似文献   
149.
Pressure on consumer goods manufacturers to develop new products with significantly less environmental impact is growing, through increased consumer awareness of environmental issues and governments setting ambitious emissions reductions targets. A strategic response to this pressure is to prepare a portfolio of innovative product ideas to meet a range of future emissions reductions targets. However, although extensive work exists on ideation (the generation of novel product ideas) and eco-design (design for reduced environmental impact), eco-ideation (generation of ideas that particularly aim to reduce environmental impacts) has had little attention. The challenge of eco-ideation is to release the creativity of a broad range of employees, only few of whom may be familiar with the drivers of environmental impact.This paper proposes a novel tool to facilitate the generation of radical product and process ideas giving step-change reductions in greenhouse gas emissions. The features of products and processes that drive greenhouse gas emissions across the product life cycle were characterized with a set of indicators. A simple visual tool was created to show these indicators on a sliding scale between best and worst imaginable performance. A leading question associated with each slider was designed to stimulate lower impact ideas. The tool was iteratively refined and simplified through structured testing with individuals from across a range of roles and differing knowledge of environmental impacts. The final eco-ideation tool used 14 scales, with leading questions for each scale developed to stimulate idea generation.The tool’s effectiveness was evaluated through use in a series of 15 individual workshops and compared with the outcomes of an equal number of conventional 12-person group-brainstorming sessions. The comparison suggests that using the simple tool generally leads to a wider range of more radical ideas than emerge from group brainstorming.  相似文献   
150.
Headwater streams are the most numerous in terms of both number and length in the conterminous United States and play important roles as spawning and rearing grounds for numerous species of anadromous fish. Stream temperature is a controlling variable for many physical, chemical, and biological processes and plays a critical role in the overall health and integrity of a stream. We investigated the controls on stream temperature in salmon‐bearing headwater streams in two common hydrogeologic settings on the Kenai Peninsula, Alaska: (1) drainage‐ways, which are low‐gradient streams that flow through broad valleys; and (2) discharge‐slopes, which are high gradient streams that flow through narrow valleys. We hypothesize local geomorphology strongly influences surface‐water and groundwater interactions, which control streamflow at the network scale and stream temperatures at the reach scale. The results of this study showed significant differences in stream temperatures between the two hydrogeologic settings. Observed stream temperatures were higher in drainage‐way sites than in discharge‐slope sites, and showed strong correlations as a continuous function with the calculated topographic metric flow‐weighted slope. Additionally, modeling results indicated the potential for groundwater discharge to moderate stream temperature is not equal between the two hydrogeologic settings, with groundwater having a greater moderating effect on stream temperature at the drainage‐way sites.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号