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   248篇
  免费   3篇
安全科学   9篇
废物处理   2篇
环保管理   29篇
综合类   115篇
基础理论   31篇
污染及防治   40篇
评价与监测   14篇
社会与环境   10篇
灾害及防治   1篇
  2021年   3篇
  2018年   3篇
  2017年   5篇
  2016年   6篇
  2015年   5篇
  2014年   3篇
  2013年   12篇
  2012年   7篇
  2011年   7篇
  2010年   6篇
  2009年   9篇
  2008年   8篇
  2007年   6篇
  2006年   6篇
  2005年   8篇
  2004年   3篇
  2003年   5篇
  2002年   3篇
  2001年   4篇
  2000年   8篇
  1999年   4篇
  1994年   3篇
  1993年   7篇
  1992年   4篇
  1991年   5篇
  1990年   3篇
  1985年   3篇
  1983年   3篇
  1976年   7篇
  1975年   3篇
  1967年   4篇
  1966年   3篇
  1964年   4篇
  1963年   4篇
  1960年   3篇
  1957年   2篇
  1956年   3篇
  1955年   2篇
  1952年   3篇
  1951年   2篇
  1950年   5篇
  1940年   2篇
  1938年   2篇
  1932年   3篇
  1931年   2篇
  1930年   4篇
  1929年   2篇
  1927年   2篇
  1926年   2篇
  1925年   2篇
排序方式: 共有251条查询结果,搜索用时 140 毫秒
21.
Overuse of nitrogen (N) fertilizers in agriculture activities has caused severe water pollution in China. The lack of data at producer level hampers decision makers in the development and implementation of efficient policies to curb excessive N-fertilizer use. In a survey of 300 farm households in the Liangzihu Lake basin, we identified factors associated with farmers’ decisions on N-fertilizer use and application rate. Household survey and multiple linear regression models indicate that the average application rate in the study region is 229 kg N ha?1, which exceeds the recommended rate for maximum profit for cereal crops (maize, wheat, and rice) in China of 150–180 kg N ha?1. High N-application rates are associated with low farmland productivity (coefficient = ?15.66, p = 0.02), a high share of off-farm income (coefficient = 27.14, p = 0.003), and a low education level of the household head (coefficient = ?10.83, p = 0.039). Neither physical infrastructure nor access to input markets appears to be related to N-application rates. It may be concluded that excessive use of N in agriculture of Central China is mainly a problem of insufficient awareness and high share of off-farm income.  相似文献   
22.
In 1995, common tern (Sterna hirundo) eggs from the big German rivers, the Rhine, Weser and Elbe were collected to study the contamination with organochlorines and mercury. We found distinct differences between the rivers: common tern eggs from the Rhine had higher concentrations of PCBs and HCHs, while eggs from the Elbe had higher residues of DDT, HCB and mercury. Also toxic PCB congeners had higher residue levels in the Rhine. Considering all organochlorines, samples from the Rhine also had the highest concentrations, while those from the Elbe were the lowest. With 5.7 μg×g?1 fresh weight, the ΖCBs had a level endangering breeding success. Fish eating birds should be used as indicators of the contamination of the rivers with environmental chemicals and should be included in monitoring programmes.  相似文献   
23.
Substantial conflict exists over water management and allocation in the Platte River Basin of Nebraska. An interdisciplinary computer simulation model, representing the water quantity, water quality, environmental, and economic dimensions of the conflict, was developed in order to analyze the tradeoffs among allocation scenarios. Most importantly, decisionmakers and interest groups were involved in model development. Simulation results for a base case and two scenarios are presented. One scenario favors protection of instream flow for wildlife; the other favors water diversions for agriculture. Impacts of the instream flow scenario, as measured by the amount of land irrigated, groundwater levels, the amount of wildlife habitat for cranes and catfish, and net agricultural benefits did not differ greatly from those of the base case. However, impacts of the diversion scenario were substantial. On the negative side, instream flows and wildlife habitat declined an average of 39 percent; while, on the positive side, groundwater levels and net agricultural benefits each increased 6 percent. The modeling process was successful insofar as it promoted an understanding among the highly diverse interest groups of the systems nature of the Basin. One agreement on a water diversion schedule among three of the parties has been reached, partly as a result of this process. More comprehensive compromises have not yet been forged. Our experience, however, indicates that modeling success at the policymaking level depends more on the extent to which the policymakers understand the model than it does on model sophistication.  相似文献   
24.
25.
26.
ABSTRACT This paper describes the development and use of a mixed integer programming model for the planning of land disposal wastewater treatment facilities. Consideration is given to relevant construction and operating costs for land sites, transmission arteries, land acquisition costs, tangible benefits from land use, controls on aquifers, and various other engineering and technical constraints The model is used to determine which land disposal sites should serve which treatment plants, when initial construction should be initiated and completed, and when capacity expansion should occur. The model's application to the St. Louis Standard Metropolitan Statistical Area is illustrated and discussed.  相似文献   
27.
This study proposes and tests a meso‐level model of deep acting in work teams that draws on emotional contagion theory to explain how shared means of complying with display rules can arise in work teams. We argue that the presence of influential deep actors can lead to greater convergence (lower dispersion) on individual deep acting in the team. That is, team members behave more similarly. When a team has greater convergence, deep acting by individual members should be related to lower emotional exhaustion and higher job satisfaction and in‐role performance. In a sample of mature work teams, these hypotheses received general support. Our findings suggested that team‐level deep acting effects can foster benefits for team members (lower emotional exhaustion and higher satisfaction) and organizations (higher job performance). Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   
28.
This study examines people's immediate responses to earthquakes in Christchurch, New Zealand, and Hitachi, Japan. Data collected from 257 respondents in Christchurch and 332 respondents in Hitachi revealed notable similarities between the two cities in people's emotional reactions, risk perceptions, and immediate protective actions during the events. Respondents' physical, household, and social contexts were quite similar, but Hitachi residents reported somewhat higher levels of emotional reaction and risk perception than did Christchurch residents. Contrary to the recommendations of emergency officials, the most frequent response of residents in both cities was to freeze. Christchurch residents were more likely than Hitachi residents to drop to the ground and take cover, whereas Hitachi residents were more likely than Christchurch residents to evacuate immediately the building in which they were situated. There were relatively small correlations between immediate behavioural responses and demographic characteristics, earthquake experience, and physical, social, or household context.  相似文献   
29.
30.
There are now numerous sustainable development evaluation methods to evaluate sustainable development progress. Which one to use will depend on the resources, the goals and the stakeholders. Ideally the method selected and its indicators would themselves indicate how to achieve sustainable development. Such a choice can be difficult without a framework to help ensure the representation of the essential elements of sustainable development.

This paper presents such a framework by drawing on ecological terminology to define aspects of sustainable development as manifested in the natural world. Examples of how these can be measured are provided along with an explanation of how the components of the framework contribute to achieving sustainable development in social systems.  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