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   599篇
  免费   11篇
  国内免费   7篇
安全科学   31篇
废物处理   32篇
环保管理   165篇
综合类   54篇
基础理论   138篇
污染及防治   144篇
评价与监测   37篇
社会与环境   13篇
灾害及防治   3篇
  2023年   2篇
  2021年   5篇
  2020年   2篇
  2019年   8篇
  2018年   6篇
  2017年   10篇
  2016年   16篇
  2015年   10篇
  2014年   8篇
  2013年   72篇
  2012年   16篇
  2011年   25篇
  2010年   29篇
  2009年   28篇
  2008年   23篇
  2007年   27篇
  2006年   34篇
  2005年   17篇
  2004年   20篇
  2003年   25篇
  2002年   20篇
  2001年   13篇
  2000年   12篇
  1999年   15篇
  1998年   16篇
  1997年   6篇
  1996年   16篇
  1995年   11篇
  1994年   16篇
  1993年   9篇
  1992年   4篇
  1991年   6篇
  1990年   7篇
  1989年   6篇
  1988年   6篇
  1987年   3篇
  1986年   4篇
  1985年   4篇
  1984年   8篇
  1983年   5篇
  1982年   8篇
  1981年   6篇
  1980年   8篇
  1979年   7篇
  1978年   4篇
  1977年   3篇
  1976年   2篇
  1975年   3篇
  1974年   2篇
  1973年   2篇
排序方式: 共有617条查询结果,搜索用时 921 毫秒
151.
ABSTRACT: A significant fraction of rhodamine WT dye was lost during a short term multitracer injection experiment in a mountain stream environment. The conservative anion chloride and the sorbing cation lithium were concurrently injected. In-stream rhodamine WT concentrations were as low as 45 percent of that expected, based on chloride data. Concentration data were available from shallow‘wells’dug near the stream course and from a seep of suspected return flow. Both rhodamine WT dye and lithium were nonconservative with respect to the conservative chloride, with rhodamine WT dye closely following the behavior of the sorbing lithium. Nonsorption and sorption mechanisms for rhodamine WT loss in a mountain stream were evaluated in laboratory experiments. Experiments evaluating nonsorption losses indicated minimal losses by such mechanisms. Laboratory experiments using sand and gravel size streambed sediments show an appreciable capacity for rhodamine WT sorption. The detection of tracers in the shallow wells and seep indicates interaction between the stream and the flow in the surrounding subsurface, intergravel water, system. The injected tracers had ample opportunity for intimate contact with materials shown in the laboratory experiments to be potentially sorptive. It is suggested that in the study stream system, interaction with streambed gravel was a significant mechanism for the attenuation of rhodamine WT dye (relative to chloride).  相似文献   
152.
ABSTRACT: The water-based activity involvement of participants at state and federal and local and private facilities identified by using participation rate groups is examined. No differences between participant groups within activities based on socio-economic characteristics were found. However, groups of highly active individuals were identified at both types of properties. It is suggested that social action system variables be added to traditional social aggregate variables to assist the understanding of leisure involvement.  相似文献   
153.
Falling incidents among the hospitalized elderly were investigated using a case/control methodology to identify high-risk individuals. The medical records of all patients who had a reported fall (N = 173) in 1978 in one geriatric facility were compared with the records of a random sample of patients without a reported fall (N = 339). The significant risk factors were male sex, urinary incontinence within 48 hours prior to the fall, and psychoactive medication 12 hours prior to the fall. It was concluded that some patients may have a greater tendency to fall than others and suggestions for exploring future means of prevention are presented.  相似文献   
154.
In one study funded by the United States Department of Agriculture, people from North Dakota were interviewed to discover which moral principles they use in evaluating the morality of transgenic organisms and their introduction into markets. It was found that although the moral codes the human subjects employed were very similar, their views on transgenics were vastly different. In this paper, the codes that were used by the respondents are developed, compared to that of the academically composed Belmont Report, and then modified to create the more practical Common Moral Code. At the end, it is shown that the Common Moral Code has inherent inconsistency flaws that might be resolvable, but would require extensive work on the definition of terms and principles. However, the effort is worthwhile, especially if it results in a common moral code that all those involved in the debate are willing to use in negotiating a resolution to their differences.  相似文献   
155.
In this paper, we review the available data for polybrominated diphenylethers (PBDEs) and other flame retardants in wildlife, with the exception of fishes from Europe and North America which are covered in more detail elsewhere. More data are available for PBDEs than for other compounds, and these show that some of these compounds have become widely distributed in the environment, being found in samples from Europe, Australia, Azerbaijan, North America and the Arctic. Most available data relate to birds and their eggs and marine mammals, but the results of two food web studies are also included. The detection of PBDEs in pelagic marine mammals which feed in deep offshore waters, including baleen whales, indicate that these compounds have found their way into deep-water, oceanic food webs as well as the coastal/shallow sea examples described in detail. In the North Sea study, the most marked increase in lipid-normalised concentrations of six BDE congeners occurred during transfer from predatory fish to marine mammals. In the St. Lawrence Estuary study, marked differences in the ratios observed between species suggested that some fish species may be able to metabolise BDE99.A number of time trend studies have also been conducted, notably in guillemot eggs from Sweden (1969-2000), beluga whales from the Canadian Arctic (1982-1997 and 1989-2001) and from the St. Lawrence Estuary (1988-1999), and ringed seals from the Canadian Arctic (1981-2000). In the temperate latitudes, from these and other studies (e.g. in dated sediment cores), PBDE concentrations began to rise earlier than in those from high latitudes, in line with data for production and use. These trends have now slowed in many cases. Declines could be expected in Europe for many congeners following the cessation of manufacture and use of the penta-mix formulation in the EU, though these are not yet apparent in environmental samples. In Arctic biota, however, the rapidly rising concentrations seen currently in Canada could be expected to continue for some time, reflecting continued production and use of the penta-mix formulation in North America (>95% of the world total) and the impact of long-range atmospheric transport.  相似文献   
156.
An assessment of Disaster Risk and its Management in Thailand   总被引:16,自引:0,他引:16  
Gary Shook 《Disasters》1997,21(1):77-88
Historically, Thailand has been a disaster-free country, suffering only minor losses from natural hazards through the years. Emerging as a newly industrialised nation, the kingdom now faces an increased risk of economic and public damage from man-made disasters associated with rapid development. A risk assessment was carried out on the level of disaster management. That assessment was preceded by an analysis of the traditional definitions of disaster risk, resulting in a redefinition to fit the needs of this study. This holds that the risk of disaster is the product of hazards, vulnerability and the level of management exercised over both the hazard and the vulnerable elements.
The results of the risk assessment, conducted through analysis of those three components, are discussed along with impediments which may hinder good disaster or accident management. Floods, in both natural and man-made manifestations, were identified as the highest risk factor, followed by major accidents and explosions, both man-made hazards. Major recommendations arising from the study included the consolidation of disaster management responsibilities currently held by several agencies into a central co-ordinating committee, the review and restructure of related law and regulations, the conduct of provincial and country-wide hazard assessments and the creation of a 'culture of safety' in Thailand  相似文献   
157.
158.
A measure of family social support for workers was developed, and initial investigations of its psychometric characteristics were conducted. Data from several samples endorse the internal consistency of the support dimensions of emotional sustenance and instrumental assistance, and confirmatory factor analysis findings reinforce the bidimensional structure of the instrument. Lack of a relationship with social desirability, correlations with life and job satisfactions, and gender differences in perceived instrumental assistance afford preliminary validity evidence. Exploratory multiple regression analyses revealed significant three-way interactions suggesting that the level of emotional sustenance from family members may be important to job satisfaction for employed women. Furthermore, empirical evidence was generated to assess the viability of the instrument relative to other existing measures of social support. Results supported convergent, discriminant, and nomological validity.  相似文献   
159.
ABSTRACT: The evolution of ground-water law in eight states in the Midwest (Illinois, Indiana, Iowa, Michigan, Minnesota, Missouri, Ohio, and Wisconsin) is examined, and a review of transitions in ground-water doctrines is presented. Two underlying themes in changing ground-water management are communicated. First, ground-water law is evolving from private property rules of capture based on the absolute ownership doctrines to rules requiring conservation and sharing of ground water as a public resource. Second, in both courts and state legislatures, a proactive role of ground-water management is emerging, again, with an emphasis on sharing. Both of these trends are apparent in the Midwest. In the last decade midwestern states have (1) seen significant shifts in court decisions on ground-water use with greater recognition of the reciprocal or mutually dependent nature of ground-water rights, and (2) seen increased legislative development of comprehensive ground-water management statutes that emphasize the reciprocal liabilities of ground-water use. These trends are examined and ground-water management programs discussed for eight states in the Midwest.  相似文献   
160.
ABSTRACT: Regression models are presented that can be used to estimate mean loads for chemical oxygen demand, suspended solids, dissolved solids, total nitrogen, total ammonia plus nitrogen, total phosphorous, dissolved phosphorous, total copper, total lead, and total zinc at unmonitored sites in urban areas. Explanatory variables include drainage area, imperviousness of drainage basin to infiltration, mean annual rainfall, a land-use indicator variable, and mean minimum January temperature. Model parameters are estimated by a generalized-least-squares regression method that accounts for cross correlation and differences in reliability of sample estimates between sites. The regression models account for 20 to 65 percent of the total variation in observed loads.  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