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   611篇
  免费   96篇
  国内免费   62篇
安全科学   261篇
废物处理   9篇
环保管理   132篇
综合类   197篇
基础理论   103篇
环境理论   2篇
污染及防治   18篇
评价与监测   18篇
社会与环境   15篇
灾害及防治   14篇
  2024年   4篇
  2023年   47篇
  2022年   42篇
  2021年   35篇
  2020年   35篇
  2019年   42篇
  2018年   27篇
  2017年   28篇
  2016年   32篇
  2015年   40篇
  2014年   31篇
  2013年   49篇
  2012年   33篇
  2011年   37篇
  2010年   37篇
  2009年   41篇
  2008年   25篇
  2007年   20篇
  2006年   37篇
  2005年   22篇
  2004年   9篇
  2003年   14篇
  2002年   17篇
  2001年   10篇
  2000年   13篇
  1999年   16篇
  1998年   9篇
  1997年   2篇
  1996年   5篇
  1995年   4篇
  1994年   1篇
  1993年   1篇
  1991年   3篇
  1973年   1篇
排序方式: 共有769条查询结果,搜索用时 15 毫秒
301.
对被淘汰的老型选煤浮选机作为气浮法处理含油污水设备进行了可行性分析,并作了含油污水处理的实验模拟,实验结果表明,可以用煤炭浮选机作为气浮法污水处理设备,且处理含油污水效果较好,废物的再开发利用程度高,具有较好的环境效益和经济效益。  相似文献   
302.
In natural resource management facilitation literature, little attention is paid to sensitive issues in multi-stakeholder interaction and learning. This article aims to fill this gap. It discusses the variety of discursive strategies used by stakeholders to address sensitive issues with regard to fishery management in Benin, in three different settings: individual interviews, homogeneous groups' discussions, and a heterogeneous group meeting. Issues that proved sensitive were discussed openly in the interviews or homogeneous groups' discussions, but not at all, or only indirectly, in the heterogeneous group meeting. With indirect discursive strategies, two out of the seven sensitive issues were put on the discussions' agenda. We conclude that the other issues were too sensitive among others because of historically grown interdependency between interventionists and fishers. We suggest that dealing with sensitive issues is an important dimension of the facilitation of interactive learning processes and provide methodological guidelines to detect and address such issues.  相似文献   
303.
Abstract

Machine tool, which is the basis energy consumed device in manufacturing system, its energy consumption model and energy efficiency evaluation are the prerequisites for energy saving in manufacturing. Considering the multi-energy-sources features,analysed the mathematical model of a CNC continuous generating grinding machine tool from the view of energy constitute. The energy sources of a CNC continuous generating grinding machine tool are classified into gear grinding system, grinding wheel dressing system and auxiliary system. Based on the power balance equations of energy flow, the energy flow system of a CNC continuous generating grinding machine tool is established. And then the energy consumption mathematical model of a CNC continuous generating grinding machine tool is set up by combining the power balance equations with the operating features of three kinds of energy sources. The case study shows that the proposed energy consumption model can provide fundamental support for energy consumption forecasting, energy efficiency analysis and energy-saving optimisation during the machine tool operation process.  相似文献   
304.
Environmental changes are increasing the need to understand complex cross-scale feedbacks in social–ecological systems. However, consistent conceptualisation of learning associated with environmental governance is lacking, and research mainly centres on individual variables. This paper identifies a typology of such learning, and theorises about configurations of variables. Focusing on experimentation as an intervention geared towards learning, it proposes a definition of policy experiment. A theoretical framework is presented, summarising a typology of experiments based on learning-related variables embedded in design choices, and reflected in institutional rule aggregations. The framework facilitates systematic analysis of real-world cases and testing of hypotheses on the effects of different types of experiment on learning. A case study demonstrates application of the framework. Results suggest future research paths that include attention to additional relevant variables. The findings have relevance for scholars interested in experimentation and learning, and environmental policy-makers considering experimentation to assess policy innovations.  相似文献   
305.
Planning researchers traditionally conceptualize learning as cognitive changes in individuals. In this tradition, scholars assess learning with pre- and post-measures of understandings or beliefs. While valuable for documenting individual change, such methods leave unexamined the social processes in which planners think, act, and learn in groups, which often involve the use of technical tools. The present interdisciplinary research program used Learning Sciences research methods, including conversation analysis, interaction analysis, and visualization of discourse codes, to understand how tools like agent-based models and geographic information systems mediate learning in planning groups. The objective was to understand how the use of these tools in participatory planning can help stakeholders learn about complex environmental problems, to make more informed judgments about the future. The paper provides three cases that illustrate the capacity of such research methods to provide insights into planning groups’ learning processes, and the mediating roles of planning tools.  相似文献   
306.
Terrascope is a freshman learning community at the Massachusetts Institute of Technology (MIT) in which teams of students work to find solutions to large ‘unsolvable’ problems and to communicate about those problems with a wide variety of audiences in multiple formats. The program strongly promotes students’ autonomy in focusing and structuring their work, and student projects culminate in public presentations, both to general audiences and to panels of technical specialists. Students who have completed the program tend to show strong engagement with environmental and sustainability issues, as well as the skills and experience to work intensively on such issues within multidisciplinary teams. Here, we present the program as a case study, with some discussion of the factors that are key to its operation.
Ari W. EpsteinEmail:
  相似文献   
307.
Considerable attention is now being given to the role and importance of education and learning implications of participatory resource and environmental governance. The contention is that such learning has the potential to transform behaviour, and in the case of resource management, may help change current patterns in resource use towards a more sustainable social-ecological system. Our purpose is to establish the opportunities for learning afforded to those participating in local level resource management committees in two Cambodian fishing communities and consider the learning outcomes from such opportunities. Our approach was qualitative and used a case study design. The findings establish a wide range of committee resource management activities that resulted in both instrumental (e.g., learning about administrative procedures) and communicative (e.g., insights into the need to conserve mangroves) learning. It was revealed that such learning can lead to changes in behaviour at the community level (e.g., managing local waste). Our findings also indicated a number of motivators and enablers of learning such as opportunities for dialogue, leadership and the presence of declining resources.  相似文献   
308.
陈静  陈敏  王宇  王静 《环境技术》2009,27(6):36-39
本项目结合湖北省科技计划自然科学基金项目“混凝土结构使役环境的智能模拟”,在WTST-150试验机硬件平台基础上,以LabVIEW8.5为开发平台,设计了一套混凝土结构使役环境中温度智能模拟LabVIEW软件,主要包括能初始化程序、温度采集与显示子程序、温度PID控制子程序、温度存储和查询子程序。经投入实验验证,该软件能实现实时曲线显示、温度控制、试验状态和保存试验数据、数据查询、手动加热、分配温度通道、PID控制参数整定、制冷、读入温度曲线等功能。具有实时在线循环检测、采集数据、响应快速等优点,并具有良好的故障诊断能力和可维护性以及超强的纠错能力。本软件完善了WTST-150试验机的温度控制系统,使其更加符合实际工况。  相似文献   
309.
One hypothesis for the function of song repertoires is that males learn multiple song types so that they may share songs with neighbors, allowing them to match during territorial interactions. In at least one song sparrow population, in Washington, territorial males share a high proportion of song types with their neighbors and use these shared songs in matching. We recorded song sparrows in Pennsylvania and quantified sharing of whole songs and song segments. We found that song sharing is an order of magnitude less common in the Pennsylvania population. We found sharing of song segments to be significantly more common than the sharing of whole songs in three of the five fields we examined, while we found no significant differences between whole and partial song sharing in the remaining two fields. Finally, we found no evidence that sharing is greater between birds in the same field compared to birds in different fields. Taken with the data from Washington song sparrows, these results provide evidence for intraspecific geographic variation in the organization of song repertoires, and suggest that song sharing has not been a strong selective force in the evolution of song repertoires in song sparrows as a species. Furthermore, Washington and Pennsylvania song sparrows differ in how they learn song, in that Washington birds copy whole songs, while Pennsylvania birds appear to copy and recombine song segments, as has been found in laboratory studies of song learning. Thus both song learning and the function of song repertoires differ between populations of song sparrows. Such intraspecific geographic variation offers a unique opportunity to explore the ecological and historical factors which have influenced the evolution of song. Received: 30 June 1997 / Accepted after revision: 8 March 1998  相似文献   
310.
为提升含腐蚀缺陷管道失效压力预测精度,准确把控管道状态,建立基于DE-BPNN的含腐蚀缺陷管道失效压力预测模型,有效避免BPNN模型陷入局部最优问题,提升预测精度.基于61组管道爆破实验数据,分别用DE-BPNN与BPNN模型进行仿真计算.结果表明:DE-BPNN预测结果平均相对误差为3.26%,R2为0.98585,...  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