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   946篇
  免费   15篇
  国内免费   5篇
安全科学   97篇
废物处理   8篇
环保管理   185篇
综合类   250篇
基础理论   224篇
环境理论   5篇
污染及防治   44篇
评价与监测   90篇
社会与环境   30篇
灾害及防治   33篇
  2023年   4篇
  2022年   8篇
  2021年   18篇
  2020年   15篇
  2019年   17篇
  2018年   14篇
  2017年   23篇
  2016年   40篇
  2015年   22篇
  2014年   43篇
  2013年   41篇
  2012年   23篇
  2011年   55篇
  2010年   30篇
  2009年   73篇
  2008年   66篇
  2007年   72篇
  2006年   58篇
  2005年   43篇
  2004年   34篇
  2003年   26篇
  2002年   28篇
  2001年   18篇
  2000年   24篇
  1999年   32篇
  1998年   27篇
  1997年   14篇
  1996年   19篇
  1995年   14篇
  1994年   18篇
  1993年   11篇
  1992年   9篇
  1991年   6篇
  1990年   3篇
  1987年   1篇
  1986年   6篇
  1985年   1篇
  1984年   3篇
  1983年   2篇
  1980年   1篇
  1979年   2篇
  1977年   1篇
  1973年   1篇
排序方式: 共有966条查询结果,搜索用时 31 毫秒
21.
本文以ABC分类法说明了减轻地震灾害的重要意义,指出了地震灾害绝对损失数额一般会随社会经济发展而逐渐增大这一客观事实。文中提出了表达地震灾害危险性、防抗灾工程投资和社会经济发展关系的一般数学模型,对灾害管理与经济发展的辩证关系进行了讨论。  相似文献   
22.
It is increasingly obvious that social science, while not a sufficient condition for making ecosystem management effective, is a necessary condition. A social science typology of ecosystems is developed, applied, and shown to have substantial and unexpected implications for the practice of ecosystem management. Ecologists and environmental scientists, in particular, will find some conclusions uncomfortable. The application involves a case material from the California northern spotted owl controversy.  相似文献   
23.
Adaptive management: Promises and pitfalls   总被引:3,自引:1,他引:3  
Proponents of the scientific adaptive management approach argue that it increases knowledge acquisition rates, enhances information flow among policy actors, and provides opportunities for creating shared understandings. However, evidence from efforts to implement the approach in New Brunswick, British Columbia, Canada, and the Columbia River Basin indicates that these promises have not been met. The data show that scientific adaptive management relies excessively on the use of linear systems models, discounts nonscientific forms of knowledge, and pays inadequate attention to policy processes that promote the development of shared understandings among diverse stakeholders. To be effective, new adaptive management efforts will need to incorporate knowledge from multiple sources, make use of multiple systems models, and support new forms of cooperation among stakeholders.  相似文献   
24.
人机显示/控制界面适配性综合评价指标和评价方法   总被引:2,自引:2,他引:2  
通过对驾驶舱人机显示 /控制界面适配性指标影响因素、视觉信息流工效的测定与评估方法的研究 ,建立了一套视觉信息流工效综合评估系统研究体系 ;研究的初步结果主要有 ,飞机驾驶员视域中存在最佳、较好、极限工效区 ,并且振动、反射眩光、噪声、显示字符的形状 /颜色特征 /对比度 /显示方式等是影响信息获取工效的主要因素 ;飞机驾驶舱显示布局及显示方式应符合视觉工效学设计原则。  相似文献   
25.
对有过不同程度操舰事故经历的舰艇指挥员和无事故经历的舰艇指挥员的心理素质测评比较研究 ,为舰艇指挥员心理素质的选拔和培训提供依据。根据研究要求选择了 4 2名被试者 ,并对其进行实验测评研究。结果表明 ,实验组在颜色视觉、立体视觉、注意分配能力、简单反应时间、复杂反应时间、速度预期反应等的能力水平都比控制组低 ,同时在结果的图表中 ,还注意到二组被试者在各个反应时指标中的临界值。对比研究的 6个项目指标 ,在一定程度上可以认为是舰艇指挥员心理品质指标中的重要组成部分 ,其临界值可以为更好地选拔合格舰艇指挥员的心理素质提供科学依据。  相似文献   
26.
为了研究实施职业安全健康管理体系(OSHMS)对企业职业安全健康管理状况的影响,对百余家已实施与未实施OSHMS的企业进行了调研,在对调研结果分析研究的基础上,采用双对照分析的方法,对已通过OSHMS认证的企业在建立OSHMS前后的职业安全健康管理状况进行对照比较,以及已建立OSHMS与未建立OSHMS的企业的职业安全健康管理状况进行对照比较,研究结果表明,实施OSHMS有利于提高企业职业安全健康管理的整体水平,改善企业的职业安全健康管理状况,使职业安全健康管理更加科学化和规范化。  相似文献   
27.
Organic peroxides (POs) have been widely used in chemical industries as initiators of polymerization, hardening or bridge formation agents, and they are known for its self-reactive and also mixing hazard characteristics when mixed with other chemicals such as acids and alkalis. It is the purpose of this investigation to propose a simple but useful evaluation flow of mixing hazards of POs with other chemicals using conventional experimental techniques such as a glass test tube test, Dewar vessel test and DSC is proposed. 7 kinds of POs (DEPD, THP, TBEH, TBTC, MEKPO, DTBP, THHP) were mixed with sulfuric acids with various concentration, sodium hydroxide solutions, -iron(III) oxide and acrylonitrile (AN).

Based on the proposed evaluation flow the testing results were classified into 4 ranks due to the hazard criteria. Futhermore DEPD/acrylonitrile mixtures were investigated in more detail and the influences of the mixing ratio and the stirring speed were discussed.  相似文献   

28.
We examined the principal effects of different information network topologies for local adaptive management of natural resources. We used computerized agents with adaptive decision algorithms with the following three fundamental constraints: (1) Complete understanding of the processes maintaining the natural resource can never be achieved, (2) agents can only learn by experimentation and information sharing, and (3) memory is limited. The agents were given the task to manage a system that had two states: one that provided high utility returns (desired) and one that provided low returns (undesired). In addition, the threshold between the states was close to the optimal return of the desired state. We found that networks of low to moderate link densities significantly increased the resilience of the utility returns. Networks of high link densities contributed to highly synchronized behavior among the agents, which caused occasional large-scale ecological crises between periods of stable and high utility returns. A constructed network involving a small set of experimenting agents was capable of combining high utility returns with high resilience, conforming to theories underlying the concept of adaptive comanagement. We conclude that (1) the ability to manage for resilience (i.e., to stay clear of the threshold leading to the undesired state as well as the ability to re-enter the desired state following a collapse) resides in the network structure and (2) in a coupled social–ecological system, the systemwide state transition occurs not because the ecological system flips into the undesired state, but because managers lose their capacity to reorganize back to the desired state. An erratum to this article can be found at .  相似文献   
29.
Theoretical arguments for using a term structure of social discount rates (SDR) that declines with the time horizon have influenced government guidelines in the US and Europe. The certainty equivalent discount rate that often underpins this guidance embodies uncertainty in the primitives of the SDR, such as growth. For distant time horizons the probability distributions of these primitives are ambiguous and the certainty equivalent itself is uncertain. Yet, if a limited set of characteristics of the unknown probability distributions can be agreed upon, ‘sharp’ upper and lower bounds can be defined for the certainty-equivalent SDR. Unfortunately, even with considerable agreement on these features, these bounds are widely spread for horizons beyond 75 years. So while estimates of the present value of intergenerational impacts, including the social cost of carbon, can be bounded in the presence of this ambiguity, they typically remain so imprecise as to provide little practical guidance.  相似文献   
30.
Printed circuit boards (PCBs) from discarded personal computer (PC) and hard disk drive were crushed by explosion in water or mechanical comminution in order to disintegrate the attached parts. More parts were stripped from PCB of PC, composed of epoxy resin; than from PCB of household appliance, composed of phenol resin.In an attempt to raise the copper grade of PCB by removing other components, a carbonization treatment was investigated. The crushed PCB without surface-mounted parts was carbonized under a nitrogen atmosphere at 873–1073 K. After screening, the char was classified by size into oversized pieces, undersized pieces and powder. The copper foil and glass fiber pieces were liberated and collected in undersized fraction. The copper foil was liberated easily from glass fiber by stamping treatment.As one of the mounted parts, the multi-layered ceramic capacitors (MLCCs), which contain nickel, were carbonized at 873 K. The magnetic separation is carried out at a lower magnetic field strength of 0.1 T and then at 0.8 T. In the +0.5 mm size fraction the nickel grade in magnetic product was increased from 0.16% to 6.7% and the nickel recovery is 74%.The other useful mounted parts are tantalum capacitors. The tantalum capacitors were collected from mounted parts. The tantalum-sintered bodies were separated from molded resins by heat treatment at 723–773 K in air atmosphere and screening of 0.5 mm. Silica was removed and 70% of tantalum grade was obtained after more than 823 K heating and separation.Next, the evaluation of Cu recycling in PCB is estimated. Energy consumption of new process increased and the treatment cost becomes 3 times higher comparing the conventional process, while the environmental burden of new process decreased comparing conventional process.The nickel recovery process in fine ground particles increased energy and energy cost comparing those of the conventional process. However, the environmental burden decreased than the conventional one.The process for recovering tantalum used more heat for the treatment and therefore the energy consumption increased by 50%, when comparing with conventional process. However, the market price for tantalum is very large; the profit for tantalum recovery is added. Also the environmental burden decreased by the recycling of tantalum recovery. Therefore, the tantalum recovery is very important step in the PCB recycling. If there is no tantalum, the consumed energy and treatment cost increase in the new process, though the environmental burden decreases.  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