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   281篇
  免费   6篇
安全科学   13篇
废物处理   16篇
环保管理   59篇
综合类   37篇
基础理论   72篇
污染及防治   51篇
评价与监测   27篇
社会与环境   8篇
灾害及防治   4篇
  2023年   3篇
  2022年   7篇
  2021年   2篇
  2020年   3篇
  2019年   3篇
  2018年   4篇
  2017年   8篇
  2016年   8篇
  2015年   10篇
  2014年   14篇
  2013年   20篇
  2012年   10篇
  2011年   22篇
  2010年   6篇
  2009年   10篇
  2008年   17篇
  2007年   13篇
  2006年   9篇
  2005年   10篇
  2004年   4篇
  2003年   8篇
  2002年   11篇
  2001年   5篇
  2000年   6篇
  1999年   8篇
  1997年   5篇
  1996年   4篇
  1995年   4篇
  1994年   4篇
  1993年   4篇
  1992年   4篇
  1990年   2篇
  1989年   2篇
  1988年   1篇
  1987年   1篇
  1986年   3篇
  1985年   6篇
  1984年   4篇
  1983年   3篇
  1982年   6篇
  1981年   3篇
  1980年   4篇
  1979年   1篇
  1978年   1篇
  1977年   1篇
  1975年   1篇
  1970年   1篇
  1959年   1篇
排序方式: 共有287条查询结果,搜索用时 171 毫秒
251.
As the number of manual handling injuries in carers and nurses continues to be very high, the problem of how to prevent injury has not been solved. Despite the obvious need for optimum working environments, the literature does not really support that an ergonomics or systems approach solves the injury problem. Similarly, the evidence for training as a preventive strategy is equivocal, although clearly people handling requires trained handlers for both their own and the patient's safety. This research aimed to evaluate the outcomes of training in a method of manual handling of people, Dotte's Manutention method, which claims to decrease back strain and effort in carers. The study evaluated handling techniques and injury outcomes of a group of nurses in a nursing home trained in this method, using two other homes as comparisons. The study hypothesized that training in the Manutention method would decrease back strain and resultant back injuries in nurses working in geriatric care. The results showed a clear pattern of declining incidence of nurses' back pain for the nurses trained in Manutention and increasing incidence in the other two homes. These findings approached significance with a probability of < 0.1. Of those respondents who indicated a decrease in pain during the twelve month research period, all attributed it to their training. Ninety four percent of respondents who received training agreed it made their manual handling job easier. The observation method used was not sensitive enough to evaluate the multiple movements involved in a patient transfer. A supplementary controlled study was performed using videotaping and the Ovako Working Assessment System (OWAS). Manutention lifts were rated significantly better than non-Manutention on the critical variable of working posture (p < 0.01) and observed effort (p < 0.05). Accident statistics on patient handling did not show decreased injury rates at twelve months. The difficulties of controlling variables in the workplace and of the measurement of complex handling tasks were limitations of this study.  相似文献   
252.
253.
This paper reviews the regulatory history for nitrogen oxides (NOx) pollutant emissions from stationary sources, primarily in coal-fired power plants. Nitrogen dioxide (NO2) is one of the six criteria pollutants regulated by the 1970 Clean Air Act where National Ambient Air Quality Standards were established to protect public health and welfare. We use patent data to show that in the cases of Japan, Germany, and the United States, innovations in NOx control technologies did not occur until stringent government regulations were in place, thus "forcing" innovation. We also demonstrate that reductions in the capital and operation and maintenance (O&M) costs of new generations of high-efficiency NOx control technologies, selective catalytic reduction (SCR), are consistently associated with the increasing adoption of the control technology: the so-called learning-by-doing phenomena. The results show that as cumulative world coal-fired SCR capacity doubles, capital costs decline to approximately 86% and O&M costs to 58% of their original values. The observed changes in SCR technology reflect the impact of technological advance as well as other factors, such as market competition and economies of scale.  相似文献   
254.
Polybrominated diphenyl ethers (PBDEs) are flame retardants which have been found to be increasing in the environment. Because of structural similarities to the polychlorinated biphenyls and concerns that PBDEs may be widespread, we have investigated their presence in a food source, namely chickens. A GC-MS method was developed to analyze mono- through deca-BDEs in chicken fat samples. The method utilized GC pressure programming and selected ion monitoring to quantitate PBDEs at the low part per billion level. Four 13C-labeled surrogates were used to determine recoveries; recoveries averaged from 76% to 114%. Thirteen chickens from the Southern US and a composite sample of chickens from North Dakota were analyzed by this method. The total concentrations of PBDEs on a whole weight basis ranged from 1.7 ppb in North Dakota chickens to 39.4 ppb in a chicken from Arkansas. On a lipid weight basis, these levels were lower than those generally found in fish and fish-eating mammals. The PBDE pattern was also different from other samples reported; penta-BDEs rather than tetra-BDEs were the most prominent congeners.  相似文献   
255.
256.
Integrating information for better environmental decisions   总被引:1,自引:0,他引:1  
As more is learned about the complex nature and extent of environmental impacts from progressive human disturbance, scientists, policy analysts, decision makers, educators, and communicators are increasingly joining forces to develop strategies for preserving and protecting the environment. The Eco-Informa Foundation is an educational scientific organization dedicated to promoting the collaborative development and sharing of scientific information. The Foundation participated in a recent international conference on environmental informatics through a special symposium on integrating information for better environmental decisions. Presentations focused on four general themes: (1) remote sensing and data interpretation, including through new knowledge management tools; (2) risk assessment and communication, including for radioactively contaminated facilities, introduced biological hazards, and food safety; (3) community involvement in cleanup projects; and (4) environmental education. The general context for related issues, methods and applications, and results and recommendations from those discussions are highlighted here.  相似文献   
257.
As a consequence of the accumulation of anthropogenic Pb in upland catchments, there has been much recent concern about the potential mobilisation and transport of Pb from the soils to receiving waters and also the possible harmful effects that this might have on aquatic biota. This paper presents the findings of a two-year study of Pb behaviour in an organic-rich upland catchment at Glensaugh in NE Scotland. Pb inputs to the catchment were characterised by direct measurements of Pb concentration and (206)Pb/(207)Pb ratios in rain water and interception. Pb outputs from the catchment were calculated from measurements on stream water samples taken from the two main streams, the Cairn Burn and Birnie Burn. The relative contribution of Pb from groundwater and throughflow, under different flow conditions (base flow and high flow), to stream waters was investigated via analysis of springs sourced from groundwater and of waters flowing through the various soil horizons (S (surface), A, B, C, and D), respectively. The outcome of intensive sampling and analysis over the two-year time period was that, even with marked reduction in Pb inputs over the past two decades, the catchment was still acting as a net sink for the current atmospheric deposition. Although the Pb isotopic signature for stream water is very similar to that for the contemporaneous rain water ((206)Pb/(207)Pb approximately 1.15-1.16), only a small portion of the rain water is transferred directly to stream water. Instead, the Pb input is transferred to the stream waters mainly via groundwater and it was also confirmed that the latter had a similar Pb isotopic signature. From the Pb isotopic measurements on throughflow waters, however, Pb being removed via the streams contained some previously deposited Pb, i.e. mobilisation of a small portion of soil-derived anthropogenic Pb was occurring. These findings are important not only with respect to the source/sink status of the catchment but also for calculation of the extent of retention of the current atmospheric Pb inputs, which must take account of the release of previously deposited Pb from the catchment soils, a process occurring mainly under high flow conditions.  相似文献   
258.
Summary Behavioral observations over 16 months of two groups of Tana River crested mangabeys (Cercocebus galeritus galeritus) in East Africa provide evidence, contrary to previous reports, for site-specific aggression and territorial exclusion. In addition, movements and vocal responses to neighboring group's long-call vocalizations vary temporally, reflecting seasonal variation in food availability and distribution. Patterns of response to neighboring groups are consistent with the hypothesis that resources should be defended only when it is economic to do so. When fruit resources are rare intergroup interactions are infrequent and groups use separate areas. As fruit availability increases, the distribution of diet species influences the type of interaction; peaceful intergroup interactions generally occur when mangabeys eat uniformly distributed species and aggressive interactions occur when mangabeys eat species with patchy distributions. Differences between male vocal responses and group spatial responses may reflect conflicting objectives of territorial defense by males and females.  相似文献   
259.
Eleven drinking water treatment plants, located downstream of textile plants or pulp and paper mills, have been sampled monthly during a year for the analysis of 17 nonylphenol ethoxylates (NP1-17EO) and two nonylphenoxycarboxylic acids (NP1-2EC). At all but one plant, results in the drinking water, for the sum of these 19 substances, range between below detection levels and 6.7 microg/l. Annual means are between 0.02 and 2.8 microg/l. At the other plant, the yearly average concentration is 10.4 microg/l and the monthly maximum is 43.3 microg/l. In the surface (pre-treatment) water, the annual mean concentrations of the 11 plants range between 0.14 and 17.8 microg/l and the recorded instantaneous maximum is 55.3 microg/l. According to Canadian health authorities, drinking water is a negligible route of human exposure to nonylphenolic compounds, even at the highest concentrations found in this study. After transformation of the data into nonylphenol equivalents, about 20% of the surface water samples exceed the Canadian 1 microg/l nonylphenol water quality guideline for the protection of aquatic life. Some results also exceed Québec's 6 microg/l nonylphenol guideline. The efficiency of the plants in removing nonylphenolic compounds from drinking water is highly variable, ranging from 11% to 99%.  相似文献   
260.
This paper reviews different approaches to using transferable development rights (TDRs) as a way to preserve rural lands in the face of development pressure. One TDR program is examined in detail, that of Calvert County, Maryland, which has had an active TDR market since the mid-1980s. This program uses TDRs as a key policy tool for achieving a total amount of preserved acreage in the county, and for providing incentives for preservation in some areas and development in others. The paper examines both the early difficulties in developing participation in the program, and the events that lead eventually to an active TDR market. It assesses the workings of the market including factors that influence the demand and supply of TDRs, the movement of prices over time, and the location of preserved areas and of additional developed areas. The study found that the program is achieving many of the county's land preservation goals because of the high level of activity in the TDR market. However, most of the additional density is being channeled into rural areas with underlying low-density zoning.  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