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   416篇
  免费   4篇
  国内免费   2篇
安全科学   30篇
废物处理   14篇
环保管理   119篇
综合类   40篇
基础理论   80篇
环境理论   2篇
污染及防治   85篇
评价与监测   37篇
社会与环境   13篇
灾害及防治   2篇
  2022年   5篇
  2021年   6篇
  2020年   2篇
  2019年   3篇
  2018年   9篇
  2017年   7篇
  2016年   12篇
  2015年   5篇
  2014年   9篇
  2013年   39篇
  2012年   11篇
  2011年   17篇
  2010年   7篇
  2009年   9篇
  2008年   19篇
  2007年   19篇
  2006年   8篇
  2005年   17篇
  2004年   6篇
  2003年   14篇
  2002年   17篇
  2001年   6篇
  2000年   10篇
  1999年   6篇
  1998年   2篇
  1997年   7篇
  1996年   6篇
  1995年   7篇
  1994年   12篇
  1993年   7篇
  1992年   5篇
  1991年   4篇
  1990年   8篇
  1989年   3篇
  1988年   5篇
  1987年   6篇
  1986年   6篇
  1985年   8篇
  1984年   9篇
  1983年   7篇
  1982年   8篇
  1981年   14篇
  1980年   8篇
  1979年   2篇
  1978年   4篇
  1977年   3篇
  1975年   3篇
  1974年   2篇
  1957年   1篇
  1947年   1篇
排序方式: 共有422条查询结果,搜索用时 31 毫秒
291.
292.
ABSTRACT: To provide a basis for regional hydroclimatic forecasting, New England (NE) precipitation and streamflow are compared with indices for the El Niño/Southern Oscillation, the Pacific North American (PNA) pattern, and the North Atlantic Oscillation (NAO). Significant positive correlations are found between the NAO index and monthly streamflow at western inland locations, with the strongest seasonal correlations occurring in winter. Smoothed records for the winter NAO and winter streamflow are highly correlated at some sites, suggesting that interrelationships are most significant in the low frequency spectrum. However, correlations between the NAO and precipitation are not significant, so further examination of other factors is needed to explain the relationship between the NAO and streamflow. NAO related regional air temperature, sea surface temperature (SST), storm tracking, and snowfall variability are possible mechanisms for the observed teleconnection. Exceptionally cool regional air temperatures, and SSTs, and unique regional storm track patterns characterized NE's climate during the famous 1960s drought, suggesting that concurrent (persistent) negative NAO conditions may have contributed to the severity of that event. Monthly and winter averaged regional streamflow variability are also significantly correlated with the PNA index. This, along with results from previous studies, suggests that tropospheric wave character and associated North Pacific SST anomalies are also related to NE regional drought conditions.  相似文献   
293.
Potential health risks and cleanup costs are primary factors for measuring the effectiveness of a remediation project concerning a site contaminated with residual radioactive materials. Demanding cleanup of a contaminated site to its original condition, while eliminating any health risks after cleanup, can require prohibitive costs. However, by setting practical remediation objectives and by performing realistic but conservative risk assessments, health risks can be acceptable and cleanup costs can be reasonable. This article uses the South-Middle and Southeast Vaults Decontamination and Demolition Project at Argonne National Laboratory to demonstrate how negligible health risks can result after cleanup with minimal cleanup costs. Substantial cost savings of approximately $2 million was realized by implementing in-place decontamination and demolition (D&D) on the basis of acceptable risk, instead of requiring cleanup of the site to its original condition. By using the RESRAD computer program as a modeling tool, we show the maximum projected radiation dose (0.1 mrem per year) and the potential lifetime cancer risk (on the order of 106) to an individual from exposure to the residual radioactivities are negligibly small. In addition to aiding in the selection of a preferred remediation alternative, results of the RESRAD modeling were also used to guide the implementation of the selected alternative to reduce exposures from the dominant pathway and to ensure that exposures from all pathways would be as low as reasonably achievable.  相似文献   
294.
Training has been an important component of the environmental audit profession since its outset some 15–20 years ago. Training and education have taken on a variety of forms—from audit texts and articles, to formal courses, to videotapes, to on-the-job training programs. These efforts have helped to advance the sophistication of environmental auditing over the past few years. Now, with the advent of the international ISO 14012 Environmental Auditor Qualification Guidelines,1 the auditing profession in the United States and around the world likely will be transformed in the near future. In fact, many organizations are now reengineering their programs in anticipation of the emerging Guidelines. The expected transformation holds for training and education programs as well. This article suggests some of the ways in which environmental audit training is likely to be reshaped as a result of ISO 14012. Offerors of training courses and seminars would be wise to anticipate the changes and modify their programs accordingly. A quick response could provide a competitive advantage. Moreover, corporate audit program managers should conduct critical evaluations of commercial offerings to assure that the programs' contents are consistent with ISO 14012 “auditor certification” expectations.  相似文献   
295.
296.
Lake Apopka in Florida, USA, is a large (area=124 km2), hypertrophic (mean total phosphorus=0.220 g/m3; mean chlorophylla=60 mg/m3) lake, with a large sedimentary store of available P (1635 × 106 g P). Phosphorus loading from floodplain farms (132 × 106 g P/yr) has been the primary cause of eutrophication. Assuming elimination of farm P loading, the Vollenweider model predicts a decline in equilibrium P concentration from 0.270 to 0.024 g/m3, if the P sedimentation coefficient (σ) remains constant. It is likely, however, that the value for σ will fall with the elimination of farm loading due to unabated internal P loading from the sediments. Under a worst-case scenario (σ=0), the model predicts that exportation of P from the lake via wetland filtration will greatly accelerate the lake's recovery. Recirculation of lake water through a 21-km2, created wetland and elimination of farm P loading is projected to result in a negative P balance for the lake (−23 × 106 g P/yr) leading to depletion of P stores in the lake in about 60 yr. The estimated cost of the project, $20 million, is less than 3% of the estimated cost of dredging. A 3.65-km2 demonstration project is underway to test and refine the wetland filtration technique. We believe the technique could be cost-effective for other hypertrophic lakes.  相似文献   
297.
The predictability of turnover was compared for part-time versus full-time workers. This was accomplished using variables (1) that were hypothesized by Mobley (1977) to precede the turnover decision and (2) that have been shown in previous research to be significantly related to turnover. Measures of these variables were assessed via questionnaires following the second month of employment. Turnover was assessed directly from company records for a period of up to twelve months following employment. None of the hypothesized antecedent variables were significantly related to turnover within the part-time group. However, within the full-time group, all of the hypothesized precursors to turnover were found to be at least marginally related to actual turnover. Further, there was evidence to suggest differential predictability of turnover across full-time and part-time employment status groups, suggesting that the two groups may have a different ‘psychology of work’. These results are discussed in terms of the supportive evidence provided.  相似文献   
298.
A quasi-experiment was used to compare employee behaviors before and after stress management training. Organizational records on employee absenteeism, performance ratings, equipment accidents, and work injuries were obtained for highway maintenance workers who received biofeedback (BIO=21) or muscle relaxation (MR=16) training. Similar data were gathered for a comparison group of employees who did not volunteer for training (n = 80). The pre-training period (time 1) consisted of 2 1/2 years. The post-training period was divided into the year immediately after training (time 2) and the following 1/2 year (time 3). Multiple regression analyses indicated that the MR (but not BIO) group variable explained unique variance in time 2 absenteeism (p < 0.05) but not in performance ratings, equipment accidents, nor work injuries (p > 0.05). Neither group entered predictive models for any measure at time 3 (p > 0.05). The results provide limited support for relaxation training offered as a prevention activity in work settings.  相似文献   
299.
300.
It seems like a simple enough exercise. After the opening meeting, the audit team embarks on an orientation tour to familiarize itself with the layout of the facility. A simple ?walk about”? as the Australians would say. If the site is bigenough, maybe the team climbs into a vehicle for the tour. Although the orientation tour typically represents only one hour, this hour is as important as any other for the audit team. This article discusses ten steps audit teams can take to maximize the effectiveness of the tour. The ten steps came about as a result of observing audit teams during many training audits and seeing persistent problems arise.  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