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   4600篇
  免费   134篇
  国内免费   107篇
安全科学   193篇
废物处理   41篇
环保管理   1116篇
综合类   2000篇
基础理论   308篇
环境理论   19篇
污染及防治   322篇
评价与监测   628篇
社会与环境   193篇
灾害及防治   21篇
  2024年   1篇
  2023年   27篇
  2022年   40篇
  2021年   60篇
  2020年   167篇
  2019年   61篇
  2018年   58篇
  2017年   112篇
  2016年   145篇
  2015年   106篇
  2014年   183篇
  2013年   228篇
  2012年   163篇
  2011年   322篇
  2010年   157篇
  2009年   286篇
  2008年   227篇
  2007年   227篇
  2006年   231篇
  2005年   114篇
  2004年   139篇
  2003年   196篇
  2002年   183篇
  2001年   184篇
  2000年   207篇
  1999年   178篇
  1998年   156篇
  1997年   150篇
  1996年   92篇
  1995年   65篇
  1994年   82篇
  1993年   78篇
  1992年   51篇
  1991年   32篇
  1990年   14篇
  1989年   18篇
  1988年   10篇
  1987年   8篇
  1986年   16篇
  1985年   14篇
  1984年   15篇
  1983年   4篇
  1982年   7篇
  1981年   6篇
  1980年   4篇
  1978年   11篇
  1977年   5篇
  1974年   1篇
排序方式: 共有4841条查询结果,搜索用时 656 毫秒
311.
根据我国水泥工业的现状及存在的主要问题,分析了水泥行业清洁生产的内容、指标,提出了推行水泥行业的清洁生产,不仅可以加快产业结构调整和新型干法水泥的发展,同时也是保护环境的重要途径。  相似文献   
312.
313.
Sense of place can be conceived as a multidimensional construct representing beliefs, emotions and behavioural commitments concerning a particular geographic setting. This view, grounded in attitude theory, can better reveal complex relationships between the experience of a place and attributes of that place than approaches that do not differentiate cognitive, affective and conative domains. Shoreline property owners (N=290) in northern Wisconsin were surveyed about their sense of place for their lakeshore properties. A predictive model comprising owners' age, length of ownership, participation in recreational activities, days spent on the property, extent of property development, and perceptions of environmental features, was employed to explain the variation in dimensions of sense of place. In general, the results supported a multidimensional approach to sense of place in a context where there were moderate to high correlations among the three place dimensions. Perceptions of environmental features were the biggest predictors of place dimensions, with owners' perceptions of lake importance varying in explanatory power across place dimensions.  相似文献   
314.
This study uses knowledge discovery concepts to analyze large amounts of data step by step for the purpose of assisting in the formulation of environmental policy. We performed data cleansing and extracting from existing nation-wide databases, and used regression and classification techniques to analyze the data. The current water hardness in Kaohsiung, Taiwan contributes to the prevention of cardiovascular disease (CVD) but exacerbates the development of renal stones (RS). However, to focus on water hardness alone to control RS would not be cost effective at all, because the existing database parameters do not adequately allow for a clear understanding of RS. Analysis of huge amounts of data can most often turn up the most reliable and convincing results and the use of existing databases can be cost-effective.  相似文献   
315.
The regional-scale importance of an aquatic stressor depends both on its regional extent (i.e., how widespread it is) and on the severity of its effects in ecosystems where it is found. Sample surveys, such as those developed by the U.S. Environmental Protection Agency’s Environmental Monitoring and Assessment Program (EMAP), are designed to estimate and compare the extents, throughout a large region, of elevated conditions for various aquatic stressors. In this article, we propose relative risk as a complementary measure of the severity of each stressor’s effect on a response variable that characterizes aquatic ecological condition. Specifically, relative risk measures the strength of association between stressor and response variables that can be classified as either “good” (i.e., reference) or “poor” (i.e., different from reference). We present formulae for estimating relative risk and its confidence interval, adapted for the unequal sample inclusion probabilities employed in EMAP surveys. For a recent EMAP survey of streams in five Mid-Atlantic states, we estimated the relative extents of eight stressors as well as their relative risks to aquatic macroinvertebrate assemblages, with assemblage condition measured by an index of biotic integrity (IBI). For example, a measure of excess sedimentation had a relative risk of 1.60 for macroinvertebrate IBI, with the meaning that poor IBI conditions were 1.6 times more likely to be found in streams having poor conditions of sedimentation than in streams having good sedimentation conditions. We show how stressor extent and relative risk estimates, viewed together, offer a compact and comprehensive assessment of the relative importances of multiple stressors.  相似文献   
316.
Grasslands were once widespread and species-rich ecosystems. They have drastically decreased throughout the world, largely due to changes in land-uses. Remnant grasslands are often highly degraded and disconnected and require active conservation. In order for grasslands to be maintained worldwide, protected areas need to be created. While adequately creating and managing protected areas has proven difficult, this can be improved by following a three-point guideline: (1) consider many ecological groups (birds, insects, plants); (2) use conservation biology knowledge; (3) seek agreements with concerned parties by comprehending elements of economy, politics and sociology. Based on the example of La Crau, a steppe area in South-eastern France, this review aims at (i) illustrating that this guideline can facilitate creating and managing protected areas and (ii) proposing improvement to the guideline while keeping it simple. In La Crau, the need for conservation was first acknowledged in 1975. Between 1983, when a request for a protection decree was made and 1990, when the first concrete protection measure was taken, 20% of the steppe disappeared. It took another 8 years to reach a concerted management plan in 1998. The review shows how using ecological guidelines would have helped better and faster protection of the steppe. Improvements to the guideline drawn from the La Crau experience include: the protection of some traditional practices; the protection of some degraded habitats that can substitute for habitats that no longer exist; the restoration of degraded habitats that do not qualify for protection; and the flexibility of the management plan.  相似文献   
317.
Chile ratified the Montreal Protocol in 1990 which sets out an agenda for the reduction and then elimination of ozone depleting substances (ODS); however, by 1998 the country had not yet defined a strategy to encourage greater compliance, so that in the same year the National Environmental Commission decided to examine the policy options available. This paper examines the process followed to develop this strategy. As a first step it was necessary to look at how far the implicit policy of "business as usual" could be stretched without jeopardizing Chile's compliance obligations. A second step included quantifying compliance costs and their impact on different policy instruments and so policy choice. Finally, the attitudes of decision-makers or participants were identified, by interviews with officials of the different public agents involved, in order to weigh their views about policy. A strategy was proposed, based on this information, which the Chilean regulator has used, although not in its entirety. The methodology developed could well be useful for developing-country Protocol signatories building their own appropriate compliance strategy.  相似文献   
318.
Hydroelectric dams represent major investments and major sources of environmental and social impacts. Powerful forces surround the decision-making process on public investments in the various options for the generation and conservation of electricity. Brazil’s proposed Belo Monte Dam (formerly Kararaô) and its upstream counterpart, the Altamira Dam (better known by its former name of Babaquara) are at the center of controversies on the decision-making process for major infrastructure projects in Amazonia. The Belo Monte Dam by itself would have a small reservoir area (440 km2) and large installed capacity (11, 181.3 MW), but the Altamira/Babaquara Dam that would regulate the flow of the Xingu River (thereby increasing power generation at Belo Monte) would flood a vast area (6140 km2). The great impact of dams provides a powerful reason for Brazil to reassess its current policies that allocate large amounts of energy in the country’s national grid to subsidized aluminum smelting for export. The case of Belo Monte and the five additional dams planned upstream (including the Altamira/Babaquara Dam) indicate the need for Brazil to reform its environmental assessment and licensing system to include the impacts of multiple interdependent projects.  相似文献   
319.
Sustainable use of water and land resources requires that these scarce resources be appropriately allocated among various competing human activities. Worldwide, there is a realization now that sustainable river basin management should be accorded the highest priority, because it deals not only with technical, but also with ecological and socioeconomic aspects, and thus calls for a multidisciplinary and integrated approach. However, most of the policy and planning documents have either remained silent, or have made only implicit reference to the importance of environmental water demand (EWD) and its quantification. Therefore, in the light of its importance, a methodology has been evolved in this article for quantifying EWD for various forested areas in two distinctly different Indian river basins: Brahmani (humid zone) and Sabarmati (dry zone). The article analyzes and discusses EWD estimates at three different spatial levels: river basins, states, and districts within them, and finally presents a comparative analysis of all these results. Findings of the present study will be immensely useful in understanding various ecological issues connected with water resource projects and proposals in these river basins.  相似文献   
320.
Improving the performance of the state environmental agencies (SEAs) necessitates an effective institutionalization of governmental environmental management functions. There are examples of successful and unsuccessful SEAs in several parts of the world. Analysis and assessment of these cases can deliver useful insights for institution builders. The objective of this article is the assessment of the institutional effectiveness of the SEAs in Turkey through the perceptions of the experts using the Delphi Technique. In this regard, a checklist is developed including 16 criteria and 123 subcriteria to measure the institutional effectiveness of the SEAs. Twenty-eight national and international experts have formed a Delphi panel and evaluated the national and local conditions. Results, based on the perceptions of the experts, indicate that the overall effectiveness of the SEAs is far less than satisfactory. Negative consensus has been reached over the effectiveness of 13 of the16 criteria and 95 of the123 subcriteria; however, no consensus has been achieved over the remainder of the parameters. The survey has also proven that the Delphi Technique can be effectively used for that purpose. Utilization of the checklist method is also useful in diagnosing the problematic components of the SEAs. It is recommended that this approach be used in similar cases elsewhere.  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