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   3863篇
  免费   69篇
  国内免费   38篇
安全科学   233篇
废物处理   131篇
环保管理   1024篇
综合类   349篇
基础理论   925篇
环境理论   7篇
污染及防治   854篇
评价与监测   264篇
社会与环境   147篇
灾害及防治   36篇
  2023年   16篇
  2022年   25篇
  2021年   31篇
  2020年   28篇
  2019年   40篇
  2018年   55篇
  2017年   70篇
  2016年   105篇
  2015年   84篇
  2014年   84篇
  2013年   470篇
  2012年   141篇
  2011年   189篇
  2010年   134篇
  2009年   151篇
  2008年   175篇
  2007年   218篇
  2006年   150篇
  2005年   132篇
  2004年   150篇
  2003年   151篇
  2002年   117篇
  2001年   72篇
  2000年   81篇
  1999年   51篇
  1998年   60篇
  1997年   47篇
  1996年   63篇
  1995年   63篇
  1994年   66篇
  1993年   53篇
  1992年   48篇
  1991年   42篇
  1990年   42篇
  1989年   34篇
  1988年   44篇
  1987年   30篇
  1986年   36篇
  1985年   34篇
  1984年   31篇
  1983年   38篇
  1982年   49篇
  1981年   48篇
  1980年   25篇
  1979年   28篇
  1978年   25篇
  1977年   31篇
  1976年   13篇
  1974年   10篇
  1972年   11篇
排序方式: 共有3970条查询结果,搜索用时 15 毫秒
121.
ABSTRACT: A small lake in the Chicago Metropolitan Area was from 91 to 95 percent efficient in removing suspended sediment and from 76 to 94 percent efficient in removing copper, iron, lead, and zinc from urban runoff. Sediments accumulated in the lake in the form of an organic-rich mud at an average rate of 20 millimeters per year; this reduced lake storage and covered potential habitat for aquatic organisms. Copper, lead, and zinc concentrations were closely associated with suspended-sediment concentrations and with silt- and clay-sized fractions of lake sediment. Although concentrations of mercury and cadmium were near detection limits in runoff, measurable concentrations of these metals accumulated in the lake sediments.  相似文献   
122.
Four broad classes of dependent variables (psychological strain, physical illness symptoms, health-related behaviour and social participation) were associated with eleven categories of stressors and stress moderators from work and family life, using multiple logistic regression analysis for a random sample of 8700 full-time male and female members of T.C.O., a major Swedish white-collar labour federation (covering 25 per cent of the Swedish labour force). Our goal was to find broad patterns of associations by comparing relative magnitudes of effects for (a) stressors and stress moderators; (b) work and family activities, and (c) males and females. Fifty per cent of the associations between environmental factors and dependent variables were significant in the predicted direction at the 5 per cent level. However, only 5 per cent of the associations are as strong, for example, as average smoking/heart disease associations. Our primary conclusion is that job factors are the next strongest set of predictors of health and behaviour after age. Job factors are stronger than family factors for both men and women; proportionally increasing the explained variance by over 60 per cent versus roughly 20 per cent for family factors (over the 25 per cent of explanation due to demographic factors). The overall pattern of stressor/outcome associations is quite similar for men and women, although both job/outcome and family burden/outcome associations are stronger for women than for men. We failed to find a clear linkage between particular stressors and particular physical illnesses. Among the job factors, control and work load have the strongest associations; with the former predicting behaviour patterns and job satisfaction (along with social support), and the latter predicting mental strain symptoms. Family problems are associated with increased health risks (stronger for men) and family responsibilities and constraints affect health behaviour (stronger for women). Job satisfaction is the most successfully predicted outcome in the study, and is similarly affected for men and women.  相似文献   
123.
The study shows that, for a sample of 818 industrial workers, work role centrality (WRC) is positively related to task autonomy and to organizational conditions of sector of ownership, unit-type of production system, and production stability; it is also weakly related to the orientations of production managers concerning the sharing of information, general supervision and granting autonomy. The task autonomy - work role centrality relationship is maintained beyond other organizational conditions, but the effects of managerial orientations are attenuated by task autonomy and by organizational conditions. Situational conditions such as production system and stability, managerial orientations and task autonomy add to the variance of WRC explained by personal attributes of gender, education and job training, and by the outcome of job satisfaction, and a combined model of both types of variables is the most efficient. Generally, work role centrality is found to be a fairly sensitive response to the work situation, but it is suggested that perceptual and attitudinal data be added to the explanatory model.  相似文献   
124.
ABSTRACT: Lactose-negative Escherichia coil from cattle feces appeared as yellow, atypical colonies on m-FC medium plates with water samples from rangeland streams. The lactose-negative E. coil may impact stream water quality analyses if infrequent samples are collected; are less antibiotic resistant than the lactose-positive E. coili isolated from rangeland streams; and are colicinogenic toward all the laboratory strains of E. coil examined and toward 61 percent of the lactose-positive E. coil rangeland-stream isolates that were tested. This latter result could explain the potentially low degree of antibiotic resistance transfer from lactose-positive to lactose-negative E. coil. In addition, the colicinogenicity of the lactose-negative E. coil may interfere with microbiological water quality analyses that depend upon lactose fernientations with mixed populations of coliforms.  相似文献   
125.
Fishermen were aggregated into high-, mid-, and low-consumptive groups according to the importance they placed on catching fish. Analysis of variance indicated that each consumptive group was unique in the importance it placed on other fish-related variables. Low-consumptive fishermen rated most other aspects of the fishing experience, such as interacting with nature, relaxation, and escaping the daily routine, more important than did high-consumptive fishermen. Low-consumptive fishermen also fished more frequently and were generally more satisfied with their most recent fishing trip than were high-consumptive-oriented fishermen. The three groups can be viewed as different fishing constituencies. By understanding their characteristics, we can gain additional insights into the impacts of management decisions on recreational fishermen and their experiences.  相似文献   
126.
This study analyses the behaviour of high technology and new firms in the Newbury District of Berkshire in terms of employment, location, genealogy, and local economic impact. It finds that encouraged by good communications networks and a ‘resident electronics establishment’, the direct, as opposed to the indirect, employment consequences are generally encouraging, but not widely replicable. Moreover, the general picture of employment growth masks important differences in labour demand across occupations, particularly with respect to ‘traditional male’ skilled manual workers.  相似文献   
127.
As part of the planning process, maps of natural factors are often superimposed in order to identify areas which are suitable or unsuitable for a particular type of resource management. Overlay maps may also be used to identify analysis areas for predictive modeling of resource productivity and ecological response to management. Current interest in applying computer-assisted mapping technology to making overlay maps is drawing attention to geographic information systems for this purpose. The resultant maps, however, may be so inaccurate or unable to capture significant units of productivity and ecological response that they could lead to imperfect or false conclusions. Recommendations are made on how to proceed in light of these problems.  相似文献   
128.
129.
The objective of the project was to identify all hazardous waste sites in Burlington County, New Jersey that could be detected on existing, medium-scale aerial photographs of the county. The complete set of over 1000 black- and-white stereopairs at a scale of 1:12,000 was carefully examined for initial identification of possible sites. All suspicious sites were examined again on color transparencies of the county at the same 1:12,000 scale. Out of the 1094 black- and-white photos, 250 required further checking on color transparencies using a zoom stereoscope. This examination resulted in a final identification of 67 sites, the locations of which were delineated on 1:24,000 USGS maps. The use of air photo interpretation techniques provided an effective procedure for identifying waste sites quickly as well as providing a useful demonstration program for county and state officials.  相似文献   
130.
ABSTRACT: The relative abundance of small mammals in five forest land cover types on the upper Coastal Plain of north Mississippi was determined. Burrowing mammals accounted for one-half of the total captures; one shrew species that accounted for over one-fourth of the total captures had a strong affinity for well-stocked pine plantations. The opportunity for detention and retention of rainfall was enhanced by burrowing activity. Reductions of stormflow volumes 12 to 15 years after replacing poor quality, upland hardwoods with loblolly pine were only partially explained by increased interception of rainfall; much of the residual reductions are postulated to be due to small mammal burrows. Small mammal activity deserves further study as an important aspect of forest land hydrology.  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