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   159篇
  免费   3篇
安全科学   6篇
废物处理   2篇
环保管理   35篇
综合类   41篇
基础理论   34篇
污染及防治   26篇
评价与监测   9篇
社会与环境   8篇
灾害及防治   1篇
  2023年   1篇
  2022年   1篇
  2021年   1篇
  2020年   3篇
  2019年   2篇
  2018年   3篇
  2017年   3篇
  2016年   8篇
  2015年   6篇
  2014年   8篇
  2013年   14篇
  2012年   10篇
  2011年   3篇
  2010年   6篇
  2009年   8篇
  2008年   9篇
  2007年   5篇
  2006年   6篇
  2005年   2篇
  2004年   5篇
  2003年   5篇
  2002年   2篇
  2001年   3篇
  2000年   3篇
  1999年   3篇
  1998年   2篇
  1996年   3篇
  1994年   1篇
  1993年   1篇
  1992年   2篇
  1991年   1篇
  1989年   1篇
  1986年   1篇
  1985年   2篇
  1984年   5篇
  1982年   3篇
  1981年   1篇
  1976年   3篇
  1975年   2篇
  1972年   1篇
  1971年   2篇
  1969年   4篇
  1965年   1篇
  1962年   1篇
  1961年   1篇
  1960年   1篇
  1959年   1篇
  1955年   1篇
  1940年   1篇
排序方式: 共有162条查询结果,搜索用时 31 毫秒
31.
Climate Change Projections for the United States Midwest   总被引:1,自引:0,他引:1  
Environmental and societal factors such asair quality, water quality andavailability, land use changes andexpanding urbanization are alreadyaffecting human health and welfare,agriculture, and natural ecosystems in theMidwestern United States. Over thiscentury, these existing stresses willlikely be exacerbated by climate changesresulting from human activities. It isessential that policy decisions aimed atpreserving the well-being of a region beinformed by a good understanding of theregion's climate, how climate might change,and the uncertainties inherent in futureprojections. Recent updates in climatemodeling expertise and an expanded view ofpossible non-intervention emissionscenarios have narrowed the range of changethat can be expected over the Midwestthroughout the next century in some ways,while broadening it in others. In contrastto previous studies, which generallyconsider a mid-range scenario for futureemissions, this study presents the range ofchange that would result from low to highscenarios for climate change. In this waywe account for uncertainties inanthropogenic forcing on climate change inthe region and quantify the potentialeffects of human actions on future climate.This analysis also combines the latestclimate model projections with historicalrecords of observed climate over the pastcentury, effectively placing potentialchanges in extreme event frequencies suchas heavy rainfall events and temperaturethreshold exceedances within the context ofobserved variability over the past century.The purpose of this study is to provide anupdated picture of the potential impacts ofclimate change on the Midwest to inform theimpact assessment and policy developmentcommunity. From the magnitude of thechanges projected by this study, it isclear that these must be included in futurepolicy decisions in order to ensure thesuccessful adaptation and survival ofexisting human and natural systems in theMidwest.  相似文献   
32.
We have determined the congener compositions of nine commercial Aroclor products of polychlorinated biphenyls (PCBs) to the sub-part-per-million level using high-resolution gas chromatography combined with high-resolution mass spectrometry according to US Environmental Protection Agency (EPA) Method 1668A. These Aroclor composition data should allow improved characterization and risk assessment of PCB contamination at hazardous waste sites, particularly for dioxin-like PCB congeners. By combining the data on the concentrations of each dioxin-like congener with its World Health Organization toxicity equivalency factor, we have established dioxin toxic equivalent concentrations for each pure Aroclor product.  相似文献   
33.
34.
The prenatal diagnosis of achondrogenesis in association with cystic hygroma is described. Ultrasound findings of severe short-limbed dwarfism, decreased vertebral ossification, and normal ossification of the calvarium were all consistent with achondrogenesis type II. Although the unusual finding of associated cystic hygroma raised the suspicion of a concurrent chromosome abnormality, the karyotype of both fetal lymphocytes and fetal fibroblasts was normal. Autopsy confirmed dilated lymphatic channels in the basal endothelial layer of the skin, cystic hygroma, and coarctation of the aorta. Although previously unreported, we suggest that the features of this case of achondrogenesis indicate an association with lymphatic stasis and jugular lymphatic obstruction sequence in this syndrome.  相似文献   
35.

Objective

Understanding the value, benefits and harms of health interventions is needed to inform best practice and ensure responsible implementation of new approaches to patient care. Such value is demonstrated through the assessment of outcomes; however, which outcomes are assessed is often highly varied across studies and can hinder the ability to draw robust conclusions. The Core Outcome Development for Carrier Screening study aims to understand the outcomes that can meaningfully capture the value of reproductive genetic carrier screening (RGCS).

Method

The authors report an iterative, two-round online Delphi survey of Australian and New Zealand stakeholders to determine the degree of consensus regarding the core outcomes of RGCS. Panellists ranked 83 outcomes according to their perceived importance on a nine-point Likert scale. Using the distribution of rankings, outcomes were grouped into tiers representative of their perceived level of importance and agreement between groups.

Results

The top tier outcomes represent those agreed to be critically important for all future studies of RGCS to assess and were used to define a preliminary core outcome set encompassing the domains (1) primary laboratory outcomes, (2) pregnancy outcomes, (3) resource use and, (4) perceived utility of RGCS.

Conclusion

These findings can guide the selection of meaningful outcomes in studies aiming to demonstrate the value of RGCS. A future international consensus process will expand on these findings and guide the inclusion of diverse perspectives across the range of settings in which RGCS is offered.  相似文献   
36.
37.
38.
39.
Molecular approaches to microbiological monitoring: fecal source detection   总被引:1,自引:0,他引:1  
Molecular methods are useful both to monitor natural communities of bacteria, and to track specific bacterial markers in complex environments. Length-heterogeneity polymerase chain reaction (LH-PCR) and terminal restriction fragment length polymorphism (T-RFLP) of 16S rDNAs discriminate among 16S rRNA genes based on length polymorphisms of their PCR products. With these methods, we developed an alternative indicator that distinguishes the source of fecal pollution in water. We amplify 16S rRNA gene fragments from the fecal anaerobic genus Bacteroides with specific primers. Because Bacteroides normally resides in gut habitats, its presence in water indicates fecal pollution. Molecular detection circumvents the complexities of growing anaerobic bacteria. We identified Bacteroides LH-PCR and T-RFLP ribosomal DNA markers unique to either ruminant or human feces. The same unique fecal markers were recovered from polluted natural waters. We cloned and sequenced the unique markers; marker sequences were used to design specific PCR primers that reliably distinguish human from ruminant sources of fecal contamination. Primers for more species are under development. This approach is more sensitive than fecal coliform assays, is comparable in complexity to standard food safety and public health diagnostic tests, and lends itself to automation and high-throughput. Thus molecular genetic markers for fecal anaerobic bacteria hold promise for monitoring bacterial pollution and water quality.  相似文献   
40.
Survey participants (N=175) were drawn from six branches of a major British supermarket chain. Employees from three branches, who had been selected for transfer to new stores, were surveyed before and after relocation to examine the impact of this transition on individual well‐being. A comparison sample of employees, drawn from similar stores but not involved in relocation, was also surveyed. Cross‐sectional multiple regression analyses found that psychological distress was related to both work demands and personal characteristics (gender, neuroticism, locus of control, and social desirability response). Furthermore, path analysis revealed that after controlling for prior symptom levels, distress during the relocation period was predicted independently by the relocation and by work demands. Although in the present study it was not possible to account for differences in outcomes between new and comparison store employees in terms of changes in measured work characteristics, the negative impact of relocation was found to be buffered by perceptions of control and social support. Additionally, the impact of high work demands was buffered by Type B personal characteristics. Copyright © 1999 John Wiley & Sons, Ltd.  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