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   276篇
  免费   0篇
  国内免费   6篇
安全科学   8篇
废物处理   18篇
环保管理   31篇
综合类   32篇
基础理论   59篇
环境理论   1篇
污染及防治   95篇
评价与监测   21篇
社会与环境   16篇
灾害及防治   1篇
  2022年   2篇
  2021年   2篇
  2020年   2篇
  2019年   2篇
  2018年   1篇
  2017年   3篇
  2016年   6篇
  2015年   13篇
  2014年   6篇
  2013年   27篇
  2012年   8篇
  2011年   20篇
  2010年   10篇
  2009年   12篇
  2008年   17篇
  2007年   24篇
  2006年   18篇
  2005年   22篇
  2004年   16篇
  2003年   23篇
  2002年   4篇
  2001年   9篇
  2000年   4篇
  1999年   3篇
  1998年   3篇
  1997年   1篇
  1996年   2篇
  1995年   6篇
  1994年   4篇
  1992年   2篇
  1991年   2篇
  1990年   1篇
  1986年   1篇
  1985年   1篇
  1981年   2篇
  1975年   1篇
  1941年   1篇
  1936年   1篇
排序方式: 共有282条查询结果,搜索用时 15 毫秒
161.
Summary In 1986, the Danish Environmental Protection Agency established a new regulatory system aimed at small-scale polluting activities. Contrary to the dominant regulatory system based on individual standards for each polluting activity, the new regulatory system established uniform and fixed environmental standards for all activities within a trade. The fixed standards concern location, design and daily operation. Thus far, the new regulatory system has been implemented in the trades of fur farms and auto-repair shops.This study shows that fixed environmental standards reduce the total administrative costs, intensify local monitoring and enforcement of the standards, and improve the environmental state. It is proposed that the following criteria should be considered if the regulatory system is to be implemented in other trades. The trade should consist of many units and be characterised by a moderate pace of technological development, it should posses well-defined and well-known environmental problems, and have a cooperative trade association. In Denmark several trades have been identified as obvious objects for future regulation by fixed environmental standards.Bente Kjærgård is a Research Associate in the Department of Environment, Technology and Social Studies at Roskilde University. Correspondence should be addressed to this author. The other authors are Associate Professors in the same Department. Each author possesses a research degree as follows: Per Homann Jespersen in Chemical Engineering, Henning Schroll in Biology, Jesper Holm in Technological Planning, and Bente Kjærgård in Environmental Planning.  相似文献   
162.
Bite forces and evolutionary adaptations to feeding ecology in carnivores   总被引:2,自引:0,他引:2  
Christiansen P  Wroe S 《Ecology》2007,88(2):347-358
The Carnivora spans the largest ecological and body size diversity of any mammalian order, making it an ideal basis for studies of evolutionary ecology and functional morphology. For animals with different feeding ecologies, it may be expected that bite force represents an important evolutionary adaptation, but studies have been constrained by a lack of bite force data. In this study we present predictions of bite forces for 151 species of extant carnivores, comprising representatives from all eight families and the entire size and ecological spectrum within the order. We show that, when normalized for body size, bite forces differ significantly between the various feeding categories. At opposing extremes and independent of genealogy, consumers of tough fibrous plant material and carnivores preying on large prey both have high bite forces for their size, while bite force adjusted for body mass is low among specialized insectivores. Omnivores and carnivores preying on small prey have more moderate bite forces for their size. These findings indicate that differences in bite force represent important adaptations to and indicators of differing feeding ecologies throughout carnivoran evolution. Our results suggest that the incorporation of bite force data may assist in the construction of more robust evolutionary and palaeontological analyses of feeding ecology.  相似文献   
163.
164.
Lichens are a bottleneck resource for circumpolar populations of reindeer, and as such, for reindeer husbandry as an indigenous Sami land-use tradition in northern Sweden. This study uses ground lichen data and forest information collected within the Swedish National Forest Inventory since 1953, on the scale of northern Sweden. We found a 71 % decline in the area of lichen-abundant forests over the last 60 years. A decline was observed in all regions and age classes and especially coincided with a decrease of >60 year old, open pine forests, which was the primary explanatory factor in our model. The effects of reindeer numbers were inconclusive in explaining the decrease in lichen-abundant forest. The role that forestry has played in causing this decline can be debated, but forestry can have a significant role in reversing the trend and improving ground lichen conditions.

Electronic supplementary material

The online version of this article (doi:10.1007/s13280-015-0759-0) contains supplementary material, which is available to authorized users.  相似文献   
165.
The radiation doses to humans resulting from a potential release of radionuclides from a geological repository for long-lived waste are assessed over tens or even hundreds of thousands of years. Ingestion is expected to be the major exposure pathway, and the group with the highest exposures will be those that consume the most contaminated food. In this paper, we characterize the group of individuals with the highest exposures by considering the physical and biological characteristics of the contaminated area and human requirements for energy and nutrients. We then calculate intake rates based on land-use scenarios drawn from self-sustained communities spanning prehistoric times to an industrial-age agrarian culture. The approach is illustrated by simulating groundwater release of four radionuclides to an expected discharge area. We argue that the derived intake rates may serve as credible bounding cases when projected doses are evaluated for compliance with regulatory criteria.  相似文献   
166.
改善生产方法,和恰当使用投入与技术,可以以有益于环境的方式提高生产率,过去食品生产上的成功导致人均食品可得性显著增加,但它们部分地以牺牲自然资源为代价来实现.迅速提高的生产率减少了农业向新土地的扩张,从而对生物多样性、野生生物和土壤产生积极影响,负面影响包括引进大量化学农药,以及水和土壤退化.今后的关键问题并非自然资源是否足以供养未来各代人,而是是否要引进必要的政策和技术.  相似文献   
167.
As policy makers and funders have become more concerned with allocating scarce resources effectively, attention to the sustainability of health intervention programs has increased. However, the empirical knowledge base about factors facilitating or working against sustainability remains at an early stage. The aim of this study was to contribute to improved understanding of the conditions under which community-based injury prevention programs are most likely to attain sustainability. Ten Swedish community-based injury prevention programs were analysed with respect to factors that contribute to or detract from program sustainability. All the programs are integrated within existing municipality structures. Data were collected by means of semi-structured telephone interviews with key informants.The results suggested that different factors are interrelated, with no one factor being either primary or by itself sufficient for program sustainability. Financial, human, and relational resources lay the groundwork for the long-term operation of a program. The “integrated” program model appears to facilitate sustainability, but program intensity is vulnerable to changes in the financial status of the municipality and the priority-setting by municipality political decision makers. Sustainability may be compromised if a program becomes too dependent on a few key individuals. In contrast to financial, human, and relational resources, structural resources (e.g., injury surveillance and goals) appeared to have limited influence on sustainability. The programs were sustained with little evidence of effectiveness, resulting in limited feedback about how to improve a program in order to achieve and maintain long-term effectiveness.  相似文献   
168.
The emission of di-(2-ethylhexyl)phthalate (DEHP) from one type of vinyl flooring with ~15% (w/w) DEHP as plasticizer was measured at 22 °C in five FLECs + one blank FLEC (Field and Laboratory Emission Cell). Initially, the flow through all FLECs was 450 ml min?1. After 689 days the flows were changed to 1000 ml min?1, 1600 ml min?1, 2300 ml min?1, and 3000 ml min?1, respectively, in four FLECs, and kept at 450 ml min?1 in one FLEC. Air samples were collected from the effluent air at regular intervals. After 1190 days the experiments were terminated and the interior surfaces of all six FLECs were rinsed with methanol to estimate the internal surface concentrations of DEHP. The DEHP air concentration and specific emission rate (SER) at steady state was estimated for the five different flow rates. The steady-state concentrations decreased slightly with increasing air flow with only the two highest flow rates resulting in significantly lower concentrations. In contrast, the SERs increased significantly. Despite large variation, the internal surface concentrations appeared to decrease slightly with increasing FLEC flow. Computational fluid dynamic (CFD) simulations suggest that the interior gas and surface concentrations were roughly uniform for the low flow case (450 ml min?1), under which, the partitioning between the FLEC internal surface and chamber air was examined. Although paired t-tests showed no difference between CFD and experimental results for DEHP air concentrations and SERs at steady-state conditions, CFD indicated that the experimental DEHP surface concentrations in the FLECs were underestimated. In conclusion, the experiments showed that the emission of DEHP from vinyl flooring is subject to “external” control and that the SER is strongly and positively dependent on the air exchange rate. However, the increased SER almost compensates for the decrease in gas-phase concentration caused by the increased air exchange.  相似文献   
169.
Forest landscapes provide benefits from a wide range of goods, function and intangible values. But what are different forest owner categories’ profiles of economic use and non-use values? This study focuses on the complex forest ownership pattern of the River Helge å catchment including the Kristianstad Vattenrike Biosphere Reserve in southern Sweden. We made 89 telephone interviews with informants representing the four main forest owner categories. Our mapping included consumptive and non-consumptive direct use values, indirect use values, and non-use values such as natural and cultural heritage. While the value profiles of non-industrial forest land owners and municipalities included all value categories, the forest companies focused on wood production, and the Swedish Environmental Protection Agency on nature protection. We discuss the challenges of communicating different forest owners’ economic value profiles among stakeholders, the need for a broader suite of forest management systems, and fora for collaborative planning.

Electronic supplementary material

The online version of this article (doi:10.1007/s13280-012-0374-2) contains supplementary material, which is available to authorized users.  相似文献   
170.
Summary A partially migratory population of European blackbirds Turdus merula was studied in central Europe during the non-breeding season. Body weight and the amount of subcutaneous fat deposits showed seasonal variations typical for each age and sex category. Juveniles were fattest in autumn and spring and both juveniles and females lost fat and body weight in mid-winter. Adults and males reached their maximum body weight in mid-winter. These findings together with data from Schwabl (1983) suggest that juveniles and females constitute the main fraction of those birds migrating from the area in autumn. In winter mainly adults and males have access to food resources. These patterns may be regulated by dominance behaviour, since adults and males are usually dominant over juveniles and females throughout the non-breeding season. Subordinate birds that stay in the area probably suffer from a higher winter mortality but have the advantage of early breeding.  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