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   8182篇
  免费   577篇
  国内免费   271篇
安全科学   1631篇
废物处理   138篇
环保管理   3093篇
综合类   2149篇
基础理论   820篇
环境理论   10篇
污染及防治   207篇
评价与监测   334篇
社会与环境   363篇
灾害及防治   285篇
  2023年   90篇
  2022年   115篇
  2021年   182篇
  2020年   246篇
  2019年   193篇
  2018年   169篇
  2017年   225篇
  2016年   312篇
  2015年   258篇
  2014年   321篇
  2013年   460篇
  2012年   456篇
  2011年   579篇
  2010年   390篇
  2009年   505篇
  2008年   360篇
  2007年   479篇
  2006年   474篇
  2005年   363篇
  2004年   394篇
  2003年   301篇
  2002年   279篇
  2001年   272篇
  2000年   271篇
  1999年   205篇
  1998年   131篇
  1997年   135篇
  1996年   108篇
  1995年   105篇
  1994年   49篇
  1993年   62篇
  1992年   57篇
  1991年   48篇
  1990年   33篇
  1989年   27篇
  1988年   35篇
  1987年   33篇
  1986年   27篇
  1985年   24篇
  1984年   27篇
  1983年   17篇
  1982年   22篇
  1981年   18篇
  1980年   24篇
  1979年   33篇
  1978年   22篇
  1975年   14篇
  1973年   14篇
  1972年   16篇
  1971年   14篇
排序方式: 共有9030条查询结果,搜索用时 484 毫秒
471.
This paper presents results of the assessment on benefit sharing and payment mechanisms tested by six non-governmental organizations (NGOs)-piloted Reducing Emissions from Deforestation and Forest Degradation (REDD+) initiatives in Tanzania. Results from the assessment indicate that models applied by most of the REDD+ pilot projects have provided most of decisions for the distribution of benefits to the communities through village general assemblies. Based on requirements of the tested models, national benefit-sharing mechanism models are proposed. Major attributes to be considered in the development of national benefit-sharing models should include: (i) ensuring that the existing government structure is not excluded to ensure sustainability; (ii) village general assembly is involved in determining the distribution of the benefits accrued; and (iii) transparency in handling the carbon finance is ensured. Models that are proposed for the national REDD+ benefit sharing apply to two forest management systems, namely Joint Forest Management (JFM) and Community Based Forest Management (CBFM). The paper recommends testing of the two proposed models to determine whether they could be useful in sharing benefits resulting from REDD+ in Tanzania.  相似文献   
472.
由于产业发展正处于转型阶段,我国畜禽养殖污染治理中的管理问题比技术问题更加突出,选择适宜的组织管理模式尤其重要。融合了效果分析、效率评价和适应性分析,尝试构建一个养殖废弃物资源化利用管理模式综合评价框架,并选择太湖流域4个不同类型的典型案例进行方法例证。研究表明,传统的养殖企业主导型管理模式应用于小型、分散养殖废弃物资源化利用时面临着经济效率低、适应性差难题;农村废弃物处理中心、种植企业和有机肥企业的参与可以改善小型、分散养殖废弃物资源化利用的经济效率;综合考虑效果、效率与适应性,种植企业、有机肥企业主导型模式的适宜推广范围更广。应根据不同地区种植-养殖产业关系、污染治理需求、经济发展水平与政府投入能力等,灵活组合应用不同管理模式。  相似文献   
473.
国外流域管理的成功经验对雅砻江流域管理的启示   总被引:2,自引:0,他引:2  
世界各国对流域管理的不断探索,大大丰富了流域管理的理论和实践,流域管理已成为国家和地区水资源管理的一种行之有效的模式。我国的流域管理尚处于最初的探索阶段,如何借鉴国外流域管理的成功经验,形成有效的流域管理模式已成为我国水资源管理的主要任务之一。为了给国内流域管理实践提供一些有益的借鉴,分析总结了具有代表性的美国田纳西河流域管理模式、澳大利亚墨累 达令河流域管理模式和英国泰晤士河流域管理模式的成功经验和存在的问题。以雅砻江流域水电开发为实例,在对该流域的实际情况进行全面分析的基础上,将该流域与上述三条流域进行比较,充分借鉴三条流域管理模式成功经验,提出了雅砻江流域管理的相关对策和建议。  相似文献   
474.
Both the Aalborg Commitments and the guidance on integrated urban environmental management and sustainable urban transport plans proposed by the EU Thematic Strategy on the Urban Environment foresee a baseline review as the first step in developing integrated urban management plans and systems. A baseline review of urban sustainability undertaken in Riga reveals significant discrepencies between the sustainability criteria of the Aalborg Commitments and the: responsibilities and competencies of the municipal government and administration as defined by statutes; policy goals and measures defined in municipal planning documents; policy goals and measures defined in the Riga Development Plan. To better orient the mandate of the municipality towards sustainable development, municipal statutes should be supplemented to more fully reflect the issues defined by the Aalborg Commitments and should include sustainability as a goal. In order to strengthen the implementation of sustainable development specific policy goals, measures and targets should be formulated for all the Aalborg Commitments issues when revising existing municipal planning documents or developing a municipal sustainable development management plan. An analysis of the European Common Indicators and the State of the Environment in Riga 2001 indicators indicates that they can only partially fulfill a monitoring function for the implementation of the Aalborg Commitments. This highlights a need to better coordinate sustainable development initiatives at the European level. The methodology used for the baseline review in Riga is useful for assessing the status of urban sustainability when preparing integrated urban management plans or systems, but requires testing elsewhere. Readers should send their comments on this paper to BhaskarNath@aol.com within 3 months of publication of this issue.  相似文献   
475.
A susceptibility indexing method was developed based on vulnerability and quality indices. The contamination susceptibility index (SI) at a given location was calculated by taking the product of the vulnerability index (VI) and the quality index (QI): SI = VI × QI. This method incorporates both hydrogeological and hydrochemical data for a comprehensive index mapping. The DRASTIC index methodology was used for the hydrogeological data evaluations. The quality index calculation procedure based on a water quality classification scheme was introduced to evaluate hydrochemical data. The suggested susceptibility indexing method was applied to the Küçük Menderes river basin located in western Turkey. The susceptibility index map shows both hydrogeological and hydrochemical data related to the contamination problem including areas that should be taken into consideration during water management planning. The index map indicates that the most susceptible groundwater is located along the river channel between Kiraz and Tire towns, in the Selçuk area and along the Fertek stream channel to the north of Torbal? town. The results indicate that the incorporation of both hydrogeological and hydrochemical datasets enables more realistic evaluations than those of an individual dataset to estimate the groundwater contamination susceptibility of an aquifer. The numerical procedure applied could be extended further by including other parameters such as retardation, potential contaminant sources, etc. that affect the water quality in a given basin.  相似文献   
476.
Existing and projected water shortages and related factors have helped focus attention on the need for water reuse. With recent technological advances in wastewater treatment, it is now possible to produce reclaimed water of any quality. Thus, the use of reclaimed water will depend on the reuse opportunities and the cost of the required infrastructure. Historically, centralized wastewater treatment facilities have served the needs of organized societies since the mid 1800s. However, as there are limited options for expansion of most existing centralized facilities, the use of satellite and decentralized wastewater management systems offers significant advantages including being close both to the source of wastewater generation and to potential water reuse applications. The comparative advantages of satellite and decentralized wastewater management systems for a number of water reuse applications are presented and discussed in this paper. Selected case studies are presented to demonstrate the utility of satellite and decentralized wastewater management. Specific issues associated with the application of such systems in existing and in new developments are examined and discussed.  相似文献   
477.
This paper reviews the effects of six post-modern management concepts as applied to Turkish forestry. Up to now, Turkish forestry has been constrained, both in terms of its operations and internal organization, by a highly bureaucratic system. The application of new thinking in forestry management, however, has recently resulted in new organizational and production concepts that promise to address problems specific to this Turkish industry and bring about positive changes. This paper will elucidate these specific issues and demonstrate how post-modern management thinking is influencing the administration and operational capacity of Turkish forestry within its current structure.  相似文献   
478.
Understanding how setting attributes influence the nature of the visitor experience is crucial to effective recreation management. Highly influential attributes are useful indicators to monitor within a planning framework, such as Limits of Acceptable Change. This study sought to identify the setting attributes perceived to have the most profound effect on the ability to have “a real wilderness experience” and to assess the degree to which attribute importance varied with situational context and visitor characteristics. To this end, exiting hikers were surveyed at moderate and very high use trailheads in Alpine Lakes Wilderness, WA (USA), and Three Sisters Wilderness, OR (USA). They were asked about the degree to which encountering varying levels of different setting attributes would add to or detract from their experience. Attributes with the largest range of effect on experience, based on evaluations of different levels, were considered most important. The most influential attributes were litter and several types of campsite interaction—people walking through camp and number of other groups camping close by. The perceived importance of setting attributes did not vary much between wilderness locations with substantially different use levels, suggesting that conclusions are robust and generalizable across wilderness areas. There also was little difference in the perceptions of day and overnight visitors. In contrast, we found substantial variation in the perceived importance of setting attributes with variation in wilderness experience, knowledge, attachment, and motivation. Our results validate the emphasis of many wilderness management plans on indicators of social interaction, such as number of encounters.  相似文献   
479.
Pervious concrete typically has an infiltration rate far exceeding any expectation of precipitation rate. The limiting factor of a retention based pervious concrete system is often defined by how quickly the underlying soil subgrade will infiltrate the water temporarily stored within the concrete and/or aggregate base. This issue is of particular importance when placing a pervious concrete system on compacted fine textured soils. This research describes the exfiltration from twelve pervious concrete plots constructed on a compacted clay soil in eastern Tennessee, USA. Several types of treatments were applied to the clay soil prior to placement of the stone aggregate base and pervious concrete in an attempt to increase the exfiltration rate, including: 1) control – no treatment; 2) trenched – soil trenched and backfilled with stone aggregate; 3) ripped – soil ripped with a subsoiler; and 4) boreholes – placement of shallow boreholes backfilled with sand. The average exfiltration rates were 0.8 cm d−1 (control), 4.6 cm d−1 (borehole), 10.0 cm d−1 (ripped), and 25.8 cm d−1 (trenched). The trenched treatment exfiltrated fastest, followed by the ripped and then the borehole treatments, although the ripped and borehole treatments were not different from one another at the 5% level of significance. The internal temperature of the pervious concrete and aggregate base was monitored throughout the winter of 2006–2007. Although the temperature of the pervious concrete dropped below freezing 24 times, freezing concrete temperatures never coincided with free water being present in the large pervious concrete pores. The coldest recorded air temperature was −9.9 °C, and the corresponding coldest recorded pervious concrete temperature was −7.1 °C. The temperature of the pervious concrete lagged diurnal air temperature changes and was generally buffered in amplitude, particularly when free water was present since the addition of water increases the thermal capacity of the pervious concrete greatly. The temperature of the aggregate base was further buffered to diurnal changes, and no freezing temperatures were recorded.  相似文献   
480.
In many European countries, accommodating water has become the dominant paradigm in river management. In the Netherlands, extensive river restoration projects are being implemented, many of which draw serious opposition from the public. To investigate the causes of such opposition, a comprehensive study of public attitudes towards river restoration was conducted in three floodplains, both before and after river restoration. The study combined quantitative questionnaires (N = 562) with open interviews (N = 29). This paper describes how local residents perceive the effects of river restoration on landscape quality and how residents and protest groups use landscape quality in combination with other arguments to strategically frame river management policies. Results show that measurement of the perceived outcomes of nature restoration needs to be complemented by a more dynamic type of research, focusing on the social processes of the framing of restoration plans. Theoretically, the paper aims to contribute to the development of a rigorous research strategy to study framing processes in environmental management, using a mixed-methods approach.  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