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   282篇
  免费   30篇
  国内免费   45篇
安全科学   14篇
环保管理   104篇
综合类   98篇
基础理论   63篇
环境理论   1篇
污染及防治   29篇
评价与监测   10篇
社会与环境   33篇
灾害及防治   5篇
  2023年   7篇
  2022年   5篇
  2021年   7篇
  2020年   8篇
  2019年   9篇
  2018年   9篇
  2017年   18篇
  2016年   10篇
  2015年   13篇
  2014年   16篇
  2013年   31篇
  2012年   10篇
  2011年   16篇
  2010年   16篇
  2009年   10篇
  2008年   15篇
  2007年   32篇
  2006年   12篇
  2005年   7篇
  2004年   11篇
  2003年   5篇
  2002年   4篇
  2001年   8篇
  2000年   6篇
  1999年   6篇
  1998年   4篇
  1997年   2篇
  1996年   10篇
  1995年   5篇
  1994年   10篇
  1993年   2篇
  1992年   3篇
  1991年   1篇
  1990年   3篇
  1989年   5篇
  1988年   2篇
  1987年   1篇
  1986年   3篇
  1984年   2篇
  1983年   1篇
  1982年   2篇
  1980年   1篇
  1979年   2篇
  1976年   1篇
  1975年   1篇
  1974年   1篇
  1973年   2篇
  1971年   1篇
  1969年   1篇
排序方式: 共有357条查询结果,搜索用时 15 毫秒
281.
生态系统价值核算指标体系研究   总被引:2,自引:1,他引:1       下载免费PDF全文
生态系统价值核算是开展生态系统保护成效评估的重要手段,也是支撑生态文明制度体系建设的关键技术之一.指标体系的设定是开展生态系统价值核算的重要前提和基础,但当前生态系统价值还缺少统一的核算指标,因此,在一定程度上制约了生态系统价值在生态系统管理与决策中的应用.在总结归纳当前生态系统价值相关指标体系的基础上,以服务于生态系统管理和相关绩效考核为目标,提出了包括生物生产性、人类收益性、保护成效性、实际发生性、实物度量性、数据可获性、持续更新性、非危害性在内的8项生态系统价值核算原则,筛选形成了包括7个功能类别、15个一级科目和26个二级科目的生态系统价值核算指标体系,并针对实物量达到一定数值才能形成服务的指标设定了核算基准.以厦门市为例探讨了这一指标体系的应用能力,其不仅包括了厦门市主要生态系统服务,而且体现了厦门市作为沿海旅游城市的区域特色.在此基础上,探索了开展生态系统价值统计核算的可能途径,主要包括建立生态系统价值统计核算公式,编制技术导则,开展培训、制定定期发布制度等,旨在为实现生态系统价值的业务核算及其应用提供技术支撑.   相似文献   
282.
The vegan ideal is entailed by arguments for ethical veganism based on traditional moral theory (rights and/or utilitarianism) extended to animals. The most ideal lifestyle would abjure the use of animals or their products for food since animals suffer and have rights not to be killed. The ideal is discriminatory because the arguments presuppose a male physiological norm that gives a privileged position to adult, middle-class males living in industrialized countries. Women, children, the aged, and others have substantially different nutritional requirements and would bear a greater burden on vegetarian and vegan diets with respect to health and economic risks, than do these males. The poor and many persons in Third World nations live in circumstances that make the obligatory adoption of such diets, where they are not already a matter of sheer necessity, even more risky.Traditional moral theorists (such as Evelyn Pluhar and Gary Varner whose essays appear in this issue) argue that those who are at risk would beexcused from a duty to attain the virtue associated with ethical vegan lifestyles. The routine excuse of nearly everyone in the world besides adult, middle-class males in industrialized countries suggests bias in the perspective from which traditional arguments for animal rights and (utilitarian) animal welfare are formulated.  相似文献   
283.
We propose a new approach for modeling extreme values that are measured in time and space. First we assume that the observations follow a Generalized Extreme Value (GEV) distribution for which the location, scale or shape parameters define the space–time structure. The temporal component is defined through a Dynamic Linear Model (DLM) or state space representation that allows to estimate the trend or seasonality of the data in time. The spatial element is imposed through the evolution matrix of the DLM where we adopt a process convolution form. We show how to produce temporal and spatial estimates of our model via customized Markov Chain Monte Carlo (MCMC) simulation. We illustrate our methodology with extreme values of ozone levels produced daily in the metropolitan area of Mexico City and with rainfall extremes measured at the Caribbean coast of Venezuela.  相似文献   
284.
十种有机磷农药对扁藻的毒性   总被引:32,自引:1,他引:32  
报告了十种有机磷农药对扁藻生长的半数抑制浓度EC50值,依其毒性大小分:辛硫磷为剧毒;甲基异柳磷、对硫磷、甲基对硫磷为高毒;敌敌畏、氯化乐果、甲胺磷(江苏)、果保灵、甲胺磷(山东)为中等毒性;久效磷、杀灭毙为低毒,并初步探讨了有机磷农药结构和对微藻毒性大小的关系。  相似文献   
285.
An association has been reported between “low” maternal serum alpha-fetoprotein (MSAFP) and fetal chromosome abnormalities, notably Down syndrome. We suggest the predictive value be used for genetic counselling when a “low” MSAFP is found, and present an illustrative risk table. It can also be seen that normal MSAFP in a woman may lower her age-related risks below that previously defined as “high risk”. However, until good estimates of sensitivity and specificity are available from prospective, population based studies, patients should be told that any risk estimates are rough approximations. When good estimates are available, use of age risks alone may become obsolete.  相似文献   
286.
从自然环境资源的自然再生产和社会再生产、以及直接劳动和间接劳动等方面,论证了自然环境资源具有价值,从而为有偿使用提供了理论依据;并进一步揭示了造成自然环境资源危机的重要原因是其价值实现不足。人类在长期发展过程中,以牺牲环境和浪费资源为代价,获取了“虚假利益”;最后提出了自然环境资源实行有偿使用的对策措施。  相似文献   
287.
本文讨论了有关:1)痕量元素地球化学背景值;2)痕量元素地球化学表征;及3)我国某些地区若干痕量元素的背景值。  相似文献   
288.
ABSTRACT: Scarcity combined with differences in values, beliefs, and attitudes can lead to behavior differences and conflicts over water. This paper develops an index for measuring potential conflict using survey information about water attitudes and beliefs of individuals in three groups in a Florida case study. The index helps in assessing the current capability of the institution to reduce conflict. The results suggest that the current institution is effective, but changes may help to streamline the consumptive-use permitting process, to improve educational programs, and to seek improved institutional arrangements to reduce future conflict over economic uses of water.  相似文献   
289.
The fast-degrading land resources of Swaziland requires a multi-faceted approach to their management. One resource of utmost importance to all Swazis is grass. Grass research over the years had focused on pasture grass, while other uses have been neglected. The omission is a serious one and could be attributed to the neglect of indigenous grass knowledge and people's socio-economic values of grasses. Grass as a major resource is used for cattle feed, ecological control measures, medicinal plants and crafts. Within the study area, 46 grass species were identified and described by the local people. The neglect of the people's knowledge and utilitarian values of grass is a waste of resources. Thus, for grass research to be relevant to the people and national development objectives, research scientists should rethink their approach; they need to recognize and incorporate the indigenous knowledge about other uses of grasses.  相似文献   
290.
ABSTRACT: This paper uses the fundamental values of decision makers to guide a long-term wastewater planning process at Seattle Metro, a major utility district. Multiattribute value assessment is used to elicit the objectives of several elected officials and other key decision makers. The results are structured into a fundamental objectives hierarchy and a means-ends objectives network. A set of measures to indicate the performance of planning alternatives in terms of the fundamental objectives is developed. Preliminary value tradeoffs between objectives are elicited from several elected officials. The results of these steps are useful for many aspects of long-term planning: facilitating communication about values and priorities; designing attractive alternatives that are more likely to serve stakeholder interests; identifying information needed to evaluate alternatives; clarifying the relative importance of information about different impacts; providing a basis for quantitative evaluation of the alternatives with multiple objective analysis; and focusing attention on key tradeoffs that will affect the choice of alternatives.  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