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   354篇
  免费   26篇
  国内免费   45篇
安全科学   14篇
废物处理   9篇
环保管理   75篇
综合类   151篇
基础理论   97篇
污染及防治   41篇
评价与监测   11篇
社会与环境   11篇
灾害及防治   16篇
  2023年   7篇
  2022年   3篇
  2021年   8篇
  2020年   11篇
  2019年   5篇
  2018年   7篇
  2017年   9篇
  2016年   13篇
  2015年   13篇
  2014年   20篇
  2013年   40篇
  2012年   29篇
  2011年   29篇
  2010年   14篇
  2009年   25篇
  2008年   19篇
  2007年   19篇
  2006年   20篇
  2005年   23篇
  2004年   11篇
  2003年   12篇
  2002年   6篇
  2001年   8篇
  2000年   9篇
  1999年   11篇
  1998年   4篇
  1997年   5篇
  1996年   5篇
  1995年   4篇
  1994年   2篇
  1993年   5篇
  1992年   2篇
  1991年   2篇
  1990年   2篇
  1989年   1篇
  1988年   2篇
  1987年   1篇
  1986年   1篇
  1985年   4篇
  1984年   3篇
  1983年   1篇
  1982年   3篇
  1980年   1篇
  1979年   3篇
  1974年   1篇
  1969年   2篇
排序方式: 共有425条查询结果,搜索用时 15 毫秒
251.
Weather, climate, and flood predictions are incorporated into human decisions in a wide variety of situations, including decisions related to hazardous hydrometeorological events. This article examines ethical aspects of such predictions and decisions, focusing on the case of the 1997 Red River flood in Grand Forks, North Dakota and East Grand Forks, Minnesota (US). The analysis employs a formal ethical framework and analytical method derived from medical and business ethics. The results of the analysis highlight issues related to forecast generation, communication of forecast meaning and uncertainty, responsibility for the use of forecasts in decision making, and trade-offs between the desire for forecast certainty and the risk of missed events. Implications of the analysis for the broader arenas of weather, climate, and flood prediction and disaster management are also discussed.  相似文献   
252.
《Environmental Hazards》2013,12(4):87-104
Abstract

The focus of this study is public participation in the water resource and associated hazards management decision-making processes. It explores the importance, feasibility, and effectiveness of public participation in the flood management, decision-making process, with particular attention to the case of the Red River Basin of Manitoba, Canada. The nature and efficacy of public participation in the hearings conducted by the International Joint Commission (IJC) in the aftermath of the 1997 Red River flood are critically reviewed. The results of the analysis suggest that the IJC has been more sensitive to the views of the public and concerned stakeholders than the Red River Basin Task Force. The IJC incorporated a substantial portion of the opinions, suggestions, and concerns expressed by the public into the final recommendations produced by the commission for the Canadian and American federal governments. Public participation was an integral component of the IJC hearings, and was expected to contribute to flood preparedness in the future. The reasons for such accommodation of public and the stakeholders' views in decision-makingare primarily attributed to making the proposed projects and programs socio-economically and politically feasible. Because of their general characteristics, the lessons from the case of the Red River Basin could be used as an effective tool in other resource and environmental hazard management areas.  相似文献   
253.
Kinetics and isotherms of Neutral Red adsorption on peanut husk   总被引:2,自引:0,他引:2  
Adsorption of Neutral Red (NR) onto peanut husk in aqueous solutions was investigated at 295 K. Experiments were carried out as function of pH, adsorbent dosage, contact time, and initial concentration. The equilibrium adsorption data were analyzed by Langmuir, Freundlich, Temkin, Dubinin-Radushkevich, and Toth isotherm models. The results indicated that the Toth and Langmuir models provided the best correlation of the experimental data. The adsorption capacity of peanut husk for the removal of NR was deter...  相似文献   
254.
Isotopes of uranium in the sea-water sediments collected from two different areas (El Hamraween harbour and Ras El Behar) on the Egyptian coast of the red sea have been studied using radiochemical separation procedures and alpha-particle spectrometry. Activity concentrations of 238U, 235U, 234U were calculated. The activities observed indicated enhanced radioactivity levels in sea-water sediments of El Hamraween harbour area due to the activities of phosphate shipment operation. Secular equilibrium between 234U and 238U was found in the analyzed samples. The average activity ratio of 235U/238U was close to the value 0.046 for uranium in nature.  相似文献   
255.
Abstract

Population, resources and environment constitute the basis for economic and social advances. Their coordinative development is the key factor for the continuous, stable and harmonious development of economy and society. China is a developing country which needs to mobilize the whole society to coordinate among population, resources and environment and to keep publicity and research in pace so as to deepen people's understanding and improve the methods of achieving this coordination.  相似文献   
256.
Abstract

This paper analyses the historical reasons that have resulted in the assumption that natural resources have no valuve. As opposed to this assumption, a conception of resource industry is proposed. The paper expounds the basis of the value of resources and explains the significance of the research of resource value theory. It also attempts to determine the relevant factors, methods and formal expressions of pricing resources.  相似文献   
257.
采用浸渍法制备γ-Al2O3负载磷钨酸(HPW/γ-Al2O3)催化剂.运用红外光谱(FTIR)、X射线衍射(XRD)、热重-差热分析(TG-DTA)、扫描电镜(SEM)对催化剂的微观结构、形貌进行表征.结果表明杂多阴离子保持Keggin结构.将HPW/γ-Al2O3负载型催化剂填充于电化学反应器中,考察催化剂强化电化学法降解酸性大红3R染料的效果.研究表明,HPW/γ-Al2O3催化剂对酸性大红3R溶液显示了良好的催化活性,催化剂负载量为4.6%时,在pH为3、槽电压25.0 V、空气流速0.04 m3.h-1、极板间距3.0 cm反应条件下,60 min后,色度去除率达到97.6%.催化剂重复使用10次后,体系脱色率仍可达到80%左右,但会出现部分活性组分的流失现象.采用可见-紫外光谱对反应中间产物进行定性分析显示,在脱色反应过程中,染料分子中的共轭体系已基本被破坏.  相似文献   
258.
Dissolved inorganic carbon (DIC) is an important source of carbon in aquatic ecosystems, especially under conditions of increased frequency of cyanobacterial bloom. However, the importance of bacteria in direct or indirect utilization of DIC has been widely overlooked in eutrophic freshwater. To identify the functional bacteria that can actively utilize DIC in eutrophic freshwater during cyanobacterial bloom, stable-isotope probing (SIP) experiments were conducted on eutrophic river water with or without inoculation with cyanobacteria (Microcystis aeruginosa). Our 16S rRNA sequencing results revealed the significance of Betaproteobacteria, with similar relative abundance as Alphaproteobacteria, in the active assimilation of H13CO3? into their DNA directly or indirectly, which include autotrophic genera Betaproteobacterial ammonia-oxidizing bacteria. Other bacterial groups containing autotrophic members, e.g. Planctomycetes and Nitrospira, also presented higher abundance among free-living bacteria in water without cyanobacteria. Microcystis aggregates showed a preference for some specific bacterial members that may utilize H13CO3? metabolized by Microcystis as organic matter, e.g. Bacteroidetes (Cytophagales, Sphingobacteriales), and microcystin-degrading bacteria Betaproteobacteria (Paucibacter/Burkholderiaceae). This study provides some valuable information regarding the functional bacteria that can actively utilize DIC in eutrophic freshwater.  相似文献   
259.
Abstract: An essential foundation of any science is a standard lexicon. Any given conservation project can be described in terms of the biodiversity targets, direct threats, contributing factors at the project site, and the conservation actions that the project team is employing to change the situation. These common elements can be linked in a causal chain, which represents a theory of change about how the conservation actions are intended to bring about desired project outcomes. If project teams want to describe and share their work and learn from one another, they need a standard and precise lexicon to specifically describe each node along this chain. To date, there have been several independent efforts to develop standard classifications for the direct threats that affect biodiversity and the conservation actions required to counteract these threats. Recognizing that it is far more effective to have only one accepted global scheme, we merged these separate efforts into unified classifications of threats and actions, which we present here. Each classification is a hierarchical listing of terms and associated definitions. The classifications are comprehensive and exclusive at the upper levels of the hierarchy, expandable at the lower levels, and simple, consistent, and scalable at all levels. We tested these classifications by applying them post hoc to 1191 threatened bird species and 737 conservation projects. Almost all threats and actions could be assigned to the new classification systems, save for some cases lacking detailed information. Furthermore, the new classification systems provided an improved way of analyzing and comparing information across projects when compared with earlier systems. We believe that widespread adoption of these classifications will help practitioners more systematically identify threats and appropriate actions, managers to more efficiently set priorities and allocate resources, and most important, facilitate cross‐project learning and the development of a systematic science of conservation.  相似文献   
260.
Effective planning of resources management is important for facilitating socio-economic development and eco-environmental sustainability. Such a planning effort is complicated with a variety of uncertain, dynamic and nonlinear factors as well as their interactions. In this study, an inexact-stochastic quadratic programming with recourse (ISQP-R) method is developed for reflecting dynamics of system uncertainties based on a complete set of scenarios as well as tackling nonlinearities in the objective function to reflect the effects of marginal utility on system benefits and costs. Moreover, since penalties are exercised with recourse against any infeasibility, the ISQP-R can support the analysis of various policy scenarios that are associated with different levels of economic consequences when the promised targets are violated. The developed method is applied to a case study of planning resources management and developing regional ecological sustainability. The results have been generated and are helpful for decision makers in not only identifying desired resources-allocation strategies but also gaining insight into the tradeoff between economic objective and eco-environment violation risk.  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