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   118篇
  免费   29篇
  国内免费   48篇
安全科学   19篇
废物处理   7篇
环保管理   33篇
综合类   86篇
基础理论   22篇
污染及防治   15篇
评价与监测   5篇
社会与环境   5篇
灾害及防治   3篇
  2023年   5篇
  2022年   5篇
  2021年   4篇
  2020年   6篇
  2019年   7篇
  2018年   9篇
  2017年   8篇
  2016年   7篇
  2015年   6篇
  2014年   11篇
  2013年   18篇
  2012年   6篇
  2011年   9篇
  2010年   11篇
  2009年   11篇
  2008年   7篇
  2007年   16篇
  2006年   12篇
  2005年   2篇
  2004年   9篇
  2003年   1篇
  2002年   2篇
  2001年   5篇
  2000年   2篇
  1999年   2篇
  1998年   1篇
  1997年   3篇
  1994年   1篇
  1993年   1篇
  1989年   1篇
  1986年   1篇
  1985年   1篇
  1984年   1篇
  1981年   1篇
  1977年   1篇
  1971年   1篇
  1969年   1篇
排序方式: 共有195条查询结果,搜索用时 15 毫秒
61.
采用批平衡试验法,研究了新型螯合型表面活性剂N-十二酰基乙二胺三乙酸钠(N-LED3A)增溶菲的性能,并探讨了其增溶热力学和动力学特征.结果表明:N-LED3A可有效增溶菲,菲的表观溶解度S*w及其在表面活性剂单体和胶束相的分配系数Kmn和Kmc均随温度升高而增大;N-LED3A的临界胶束浓度(CMC)随温度的升高(15、25、35、45℃)呈现先减小后增大的趋势;菲在N-LED3A单体/水、胶束/水的表观摩尔分配焓变ΔH*mm、ΔH*mc分别为18.30、13.12 kJ·mol-1,菲在水、N-LED3A单体和胶束中的表观摩尔溶解热分别为18.87、37.17和31.99 kJ·mol-1,均为吸热过程,故温度升高有利于菲在N-LED3A单体和胶束中的分配作用,菲在水、N-LED3A单体和胶束中的溶解量随温度升高而增大。动力学方程拟合结果表明,一级动力学方程最适合描述N-LED3A对菲的增溶过程.  相似文献   
62.
An experiment on urban effects of warm season rainfall of a moderately sized city and its downwind towns found no evidence of global enhancement. However, there are grounds for believing that the intra urban distribution of precipitation is influenced by urban variables among which air pollution and urban roughness are considered primary. The presence of an urban heat island did not appear to improve rainfall. On the contrary, it appears to be a factor in the relative aridity of the downtown sector of the city.  相似文献   
63.
In this article, we focus on documented and possible effects of fish stocking in terms of ecosystem services. The increasing use of fish stocking between 1970 and 2000 in the semiurban setting of Stockholm archipelago, Sweden, is used as case study. The objective is to analyze this management practice from an ecosystem perspective, accounting for both the ecological and social context of releasing fish. The results show that enhancements of four native species (Salmo S. trutta, Salmo salar, Stizostedion lucioperca, and Anguilla anguilla) have dominated over new introductions of one nonnative species. (Oncorhynchus mykiss). The major objective has been to increase fish catches for local resource users. Involved stakeholders include three management agencies, one hydropower company, and several local sport fishing associations. Documented effects focus on recapture and production rates. However, our analysis suggests that additional positive or negative effects on biodiversity, food web dynamics, mobile links, or ecological information may also result, with possible consequences for the long-term provision of food, game, and aesthetic values. We conclude that a more adaptive and cooperative management approach could benefit from a deeper analysis of where, when, and what species is released, by whom, which stakeholders that use the fish and those ecosystem services the fish generate, and of the role of formal and informal institutions for monitoring and evaluating the success of releasing fish.  相似文献   
64.
The Town Scheme approach to urban conservation is being used increasingly as a major method of repairing historic buildings in conservation areas. A Town Scheme involves a long‐term financial and administrative partnership between the various levels of government. An annual budget made up of equal contributions from central government and the participating local authority is used to finance a multi‐year programme of repairs. Owners can apply for grants which are usually for 40 per cent of approved costs, and repair work must relate to the original structure and architectural details of an approved list of historic buildings. Town Schemes by themselves cannot totally transform the environmental quality of conservation areas, and the most successful schemes are part of wide‐ranging renewal and enhancement projects.  相似文献   
65.
ABSTRACT: Country level electoral data were used to analyze the voting patterns of eight water related constitutional amendment elections. Both water quality enhancement amendments (1971, 1976), and three of six water development amendments (1957, 1962, 1966) have been ratified, thus establishing a statewide policy of reservoir development, a funding mechanism to implement such a policy, and the creation of a water management agency. Begining with the 1969 election, a West Texas-East Texas regionalized voting pattern has emerged, resulting in the defeat of three amendments (1969, 1976, 1981) intended to provide additional funding for water development. This regionalization reflects different climatic, physiographic, economic, and locational factors, and represents a potential obstacle to coordinated water management in Texas.  相似文献   
66.
The ranking of air quality control measures according to a number of evaluation criteria and with the participation of a large number of interested publics is demonstrated. A pilot study for the South Coast Air Quality Management District of California serves as the reference point. Several methodological considerations are addressed, such as: (a) the enhancement of criterion priorities to account for the variability among the performance of the control measures when incommensurable impact levels are applied: (b) the derivation of alternative rankings according to the priorities of potential coalitions; (c) the assessment of the potential acceptability of a collective ranking given the degree of solidarity among participants with similar interest affiliations; and (b) the assessment of the extent to which the performance of specific control measures may override priority differences and lead to insignificant ranking differences.  相似文献   
67.
Numerous evaluation tools for the built environment have been developed in recent decades only some however integrate the outdoor environment. In EcoEffect, a Swedish assessment system, the outdoor environment is one of five areas covered. The purpose of this article is to describe and discuss various issues that evolved during the testing and developing phase of the EcoEffect Outdoor tool. The tool is designed to cover all important health risks to people in an outdoor environment, to show the relationship between circumstances in the outdoor environment and the levels specified in Swedish legislation and to enable a speedy and accurate assessment of the outdoor environment on a property. The work has been carried out in cooperation with experts, residents and representatives of the construction and property sectors. The tool has been tested on existing properties, discussed in focus groups, and has been subject to theoretical development. The results have provided a basis for changing both the EcoEffect Outdoors tool and the framework of the EcoEffect system. Important conclusions here include the notion that a clear account should be given of the fundamental values of the tool, that environmental impact should be reported in the same way throughout the whole assessment process and that the tool has to adhere to both scientific and practical validity to be useful for the building sector.  相似文献   
68.
对排烟温度低于160 ℃的锅炉尾部烟道内直接喷水调质技术进行了探讨,从实际应用情况来看,此项技术改造规模小,不影响除灰系统正常运行,并且能提高1%~2.5%的除尘效率.  相似文献   
69.
甘肃省冬春季人工增雨雪作业指挥系统   总被引:1,自引:0,他引:1  
为了提高甘肃省人工增雨雪的水平和效果,准确、及时地把握作业气象条件,使人工增雨雪在抗旱减灾中取得更好的社会、经济效益,研制建立了“甘肃省冬春季人工增雨雪作业指挥系统”。该系统包括作业信息系统、作业指挥系统和效果检查系统共3个分系统。详细介绍了各分系统的组成和功能。  相似文献   
70.
Stream restoration and enhancement projects: is anyone monitoring?   总被引:3,自引:2,他引:1  
Declines in salmon stocks and general watershed health in Washington State, USA, have led to an increase in stream restoration and enhancement projects initiated throughout the state. The increasing number of projects has also raised questions regarding the monitoring of these efforts. Project managers receiving hydraulic project approvals (HPAs) were surveyed to determine whether monitoring was taking place on their projects. About half the project managers surveyed reported the collection of baseline data and the use of biological, physical, chemical, or other water quality measures for their projects. Of those who reported collection of monitoring data, only 18% indicated that monitoring was required. Respondents were also asked to rank the importance of various project goals on a Likert scale. Project managers with projects focusing on “engineering” goals (e.g., roadbed stabilization) were less likely than other project managers to collect baseline monitoring data. Project managers with projects focusing on “restoration/ecological” or “fisheries” goals were more likely than other project managers to collect monitoring measures. Although monitoring appears to be taking place in slightly more than half of the projects surveyed, the nature of the data collected varies widely across projects, and in most cases the monitoring effort is voluntary. This suggests that project sponsors, funders, and managers must consider the issues involved in requiring appropriate monitoring, establishing standardized monitoring guidelines, the time frames in which to monitor, providing other incentives for conducting monitoring, and ensuring adequate funding for monitoring efforts.  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