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   165篇
  免费   3篇
安全科学   18篇
废物处理   19篇
环保管理   23篇
综合类   28篇
基础理论   37篇
污染及防治   23篇
评价与监测   16篇
社会与环境   2篇
灾害及防治   2篇
  2022年   2篇
  2021年   3篇
  2020年   4篇
  2019年   4篇
  2017年   2篇
  2016年   6篇
  2015年   6篇
  2014年   7篇
  2013年   12篇
  2012年   9篇
  2011年   8篇
  2010年   7篇
  2009年   9篇
  2008年   9篇
  2007年   7篇
  2006年   7篇
  2005年   7篇
  2004年   4篇
  2003年   12篇
  2002年   11篇
  2001年   9篇
  1999年   2篇
  1998年   2篇
  1997年   1篇
  1996年   1篇
  1995年   3篇
  1994年   6篇
  1993年   2篇
  1992年   1篇
  1990年   1篇
  1986年   1篇
  1984年   1篇
  1979年   1篇
  1976年   1篇
排序方式: 共有168条查询结果,搜索用时 31 毫秒
21.
Editor's note: Companies embracing TQEM must evaluate and change their manufacturing processes to stay globally competitive in the nineties. This article shows how an environmentally conscious manufacturing program incorporating new approaches to waste reduction will help companies achieve their corporatewide TQEM and strategic goals.  相似文献   
22.
23.
A eutrophication assessment method was developed as part of the National Estuarine Eutrophication Assessment (NEEA) Program. The program is designed to improve monitoring and assessment of eutrophication in the estuaries and coastal bays of the United States with the intent to guide management plans and develop analytical and research models and tools for managers. These tools will help guide and improve management success for estuaries and coastal resources. The assessment method, a Pressure-State-Response approach, uses a simple model to determine Pressure and statistical criteria for indicator variables (where applicable) to determine State. The Response determination is mostly heuristic, although research models are being developed to improve that component. The three components are determined individually and then combined into a single rating. Application to several systems in the European Union (E.U.), specifically in Portugal, shows that the method is transferable, and thus is useful for development of management measures in both the Unites States and E.U. This approach identifies and quantifies the key anthropogenic nutrient input sources to estuaries so that management measures can target inputs for maximum effect. Because nitrogen is often the limiting nutrient in estuarine systems, examples of source identification and quantification for nitrogen have been developed for 11 coastal watersheds on the U.S. east coast using the WATERSN model. In general, estuaries in the Northeastern United States receive most of their nitrogen from human sewage, followed by atmospheric deposition. This is in contrast to some watersheds in the Mid-Atlantic (Chesapeake Bay) and South Atlantic (Pamlico Sound), which receive most of their nitrogen from agricultural runoff. Source identification is important for implementing effective management measures that should be monitored for success using assessment methods, as described herein. For instance, these results suggest that Northeastern estuaries would likely benefit most from improved sewage treatment, where as the Mid and South Atlantic systems would benefit most from agricultural runoff reductions.  相似文献   
24.
25.
26.
Keeling LJ 《Ambio》2005,34(4-5):316-319
Good animal welfare is necessary if an agricultural system is to be sustainable. Although we have been concerned about the welfare of our animals since we first domesticated them and became dependent on their health and reproduction, this article focuses mainly on the development of the animal welfare debate since the 1960s. It presents animal welfare as a science that arose from society's concern about the way animals are kept. These moral and ethical concerns lead to it having a value framework that must also be taken into consideration. Different definitions of animal welfare, as well as examples of research, are presented and discussed in the light of developments in this area. For example, in recent years there has been an increased interest among consumers for animal-friendly products, as there has been for environment friendly products, and this has stimulated the move from experimental studies of animal welfare to its application in practice and to monitoring animal welfare on farms. Traditionally such measurements have been resource based, e.g. specifying the minimum amount of feeding space or the maximum stocking density, but now the trend is toward animal-based measures, such as the numberof lame animals, body condition, etc.  相似文献   
27.
The extent of within field variability in the degradation rate of the pesticides isoproturon, azoxystrobin and diflufenican, and the role of intrinsic soil factors and technical errors in contributing to the variability, was investigated in sites on sandy-loam and clay-loam. At each site, 40 topsoil samples were taken from a 160 x 60 m area, and pesticides applied in the laboratory. Time to 25% dissipation (DT25) ranged between 13 and 61 weeks for diflufenican, 5.6 and 17.2 weeks for azoxystrobin, and 0.3 and 12.5 weeks for isoproturon. Variability in DT25 was higher in the sandy-loam in which there was also greatest variability in soil chemical and microbial properties. Technical error associated with pesticide extraction, analysis and lack of model fit during derivation of DT25 accounted for between 5.3 and 25.8% of the variability for isoproturon and azoxystrobin, but could account for almost all the variability for diflufenican. Azoxystrobin DT25, sorption and pH were significantly correlated.  相似文献   
28.
29.
The effect of queen pheromones on worker honey bee ovary development   总被引:11,自引:4,他引:11  
We report results that address a long-standing controversy in honey bee biology, the identity of the queen-produced compounds that inhibit worker honey bee ovary development. As the honey bee is the only organism for which identities have been proposed for any pheromone that regulates reproduction, the resolution of its identity is of broad significance. We examined the effects of synthetic honey bee queen mandibular pheromone (QMP), four newly identified queen retinue pheromone components, and whole-queen extracts on the ovary development of caged worker bees. The newly identified compounds did not inhibit worker ovary development alone, nor did they improve the efficacy of QMP when applied in combination. QMP was as effective as queen extracts at ovary regulation. Caged workers in the QMP and queen extract treatments had better developed ovaries than did workers remaining in queenright colonies. We conclude that QMP is responsible for the ovary-regulating pheromonal capability of queens from European-derived Apis mellifera subspecies.  相似文献   
30.
Reductions in North American sulfur dioxide (SO2) emissions promoted expectations that aquatic ecosystems in southeastern Canada would soon recover from acidification. Only lakes located near smelters that have dramatically reduced emissions approach this expectation. Lakes in the Atlantic provinces, Quebec and Ontario affected only by long-range sources show a general decline in sulfate (SO4(2-)) concentrations, but with a relatively smaller compensating increase in pH or alkalinity. Several factors may contribute to the constrained (or most likely delayed) acidity response: declining base cation concentrations, drought-induced mobilization of SO4(2-), damaged internal alkalinity generation mechanisms, and perhaps increasing nitrate or organic anion levels. Monitoring to detect biological recovery in southeastern Canada is extremely limited, but where it occurs, there is little evidence of recovery outside of the Sudbury/Killarney area. Both the occurrence of Atlantic salmon in Nova Scotia rivers and the breeding success of Common Loons in Ontario lakes are in fact declining although factors beyond acidification also play a role. Chemical and biological models predict that much greater SO2 emission reductions than those presently required by legislation will be needed to promote widespread chemical and latterly, biological recovery. It may be unrealistic to expect that pre-industrial chemical and biological conditions can ever be reestablished in many lakes of southeastern Canada.  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