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   18691篇
  免费   232篇
  国内免费   303篇
安全科学   551篇
废物处理   784篇
环保管理   2549篇
综合类   2726篇
基础理论   4963篇
环境理论   4篇
污染及防治   5406篇
评价与监测   1206篇
社会与环境   891篇
灾害及防治   146篇
  2022年   178篇
  2021年   186篇
  2020年   143篇
  2019年   176篇
  2018年   270篇
  2017年   280篇
  2016年   459篇
  2015年   373篇
  2014年   565篇
  2013年   1591篇
  2012年   641篇
  2011年   826篇
  2010年   641篇
  2009年   751篇
  2008年   856篇
  2007年   905篇
  2006年   781篇
  2005年   663篇
  2004年   674篇
  2003年   626篇
  2002年   628篇
  2001年   767篇
  2000年   571篇
  1999年   314篇
  1998年   237篇
  1997年   221篇
  1996年   270篇
  1995年   268篇
  1994年   259篇
  1993年   232篇
  1992年   207篇
  1991年   188篇
  1990年   210篇
  1989年   195篇
  1988年   184篇
  1987年   171篇
  1986年   149篇
  1985年   146篇
  1984年   177篇
  1983年   176篇
  1982年   167篇
  1981年   169篇
  1980年   137篇
  1979年   159篇
  1978年   110篇
  1977年   100篇
  1976年   89篇
  1975年   94篇
  1973年   95篇
  1972年   99篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
901.
The aim of this work is to study the colour and chemical modifications of the surfaces in chestnut wood samples as a consequence of irradiating in a controlled environment. The changes were investigated by a new analytical approach by combining traditional techniques such as reflectance spectrophotometry in the visible range and Fourier transform infrared spectroscopy with new hyperspectral imaging, in order to obtain forecast models to describe the phenomenon. The statistical elaboration of the experimental data allowed to validate the measurements and to obtain models enabling to relate the investigated parameters; the elaboration of the hyperspectral images by chemometric methods allowed for studying the changes in the reflectance spectra. A result of great importance is the possibility to correlate the oxidation of wood chemical components with the colour change in a totally non-invasive modality. This result is particularly relevant in the field of cultural heritage and in general in the control processes of wooden materials.  相似文献   
902.
Environmental Science and Pollution Research - Particulate matter with size less than or equal to 2.5 μm (PM2.5) samples were collected from an urban site Pune, India, during April...  相似文献   
903.
Environmental Science and Pollution Research - Little is known about biosecurity measures and toxic effects during pesticide application in the province of Jujuy, Argentina, particularly concerning...  相似文献   
904.

Ingredients in home and personal care products, including UV filters and benzotriazoles, are high production volume chemicals extensively used in our daily life, despite several studies revealed their potential eco-toxicity and endocrine-disrupting capacity. Due to some features, such as high lipophilicity, low degradability, and persistence of many of these compounds, sediments can be considered a sink for them in the aquatic environment. In the present study, nine organic UV filters and three benzotriazoles were investigated for the first time in sediments from four urban rivers in Brazil. The contaminants were analyzed by liquid chromatography-tandem mass spectrometry (LC-MS/MS). The results revealed that octocrylene (OC), etylhexyl-methoxycinnamate (EHMC), benzophenone-3 (oxybenzone, BP3), and benzotriazole (BZT) were the predominant compounds adsorbed on the sediments, with concentrations ranging from 5.6 to 322.2 ng g−1 dry weight. The results reported in this work constitute the first data on the accumulation of polar benzotriazoles and lipophilic organic UV filters in sediments from Brazil.

  相似文献   
905.
Sustainability indicators are well recognized for their potential to assess and monitor sustainable development of agricultural systems. A large number of indicators are proposed in various sustainability assessment frameworks, which raises concerns regarding the validity of approaches, usefulness and trust in such frameworks. Selecting indicators requires transparent and well-defined procedures to ensure the relevance and validity of sustainability assessments. The objective of this study, therefore, was to determine whether experts agree on which criteria are most important in the selection of indicators and indicator sets for robust sustainability assessments. Two groups of experts (Temperate Agriculture Research Network and New Zealand Sustainability Dashboard) were asked to rank the relative importance of eleven criteria for selecting individual indicators and of nine criteria for balancing a collective set of indicators. Both ranking surveys reveal a startling lack of consensus amongst experts about how best to measure agricultural sustainability and call for a radical rethink about how complementary approaches to sustainability assessments are used alongside each other to ensure a plurality of views and maximum collaboration and trust amongst stakeholders. To improve the transparency, relevance and robustness of sustainable assessments, the context of the sustainability assessment, including prioritizations of selection criteria for indicator selection, must be accounted for. A collaborative design process will enhance the acceptance of diverse values and prioritizations embedded in sustainability assessments. The process by which indicators and sustainability frameworks are established may be a much more important determinant of their success than the final shape of the assessment tools. Such an emphasis on process would make assessments more transparent, transformative and enduring.  相似文献   
906.
The assumptions and empirical evidence linking climate change adaptation to development cooperation have led to the emergence of a range of climate change adaptation tools aiming at improving the quality of development cooperation initiatives in times of global change. In order to assess the quality of these tools, we develop an analytic framework to critically assess the social learning and sustainable development outcomes of climate change adaptation tools. The analytic framework defines project objectives, participation typology, participation tools, participation stages, scenarios development, modelling exercises, stakeholder analysis and risk communication strategies that support quality participation outcomes.  相似文献   
907.
Regional Environmental Change - This paper presents empirical data on household perceptions of capability to adapt to climate hazards and associated capacity needs. Households play an important...  相似文献   
908.
Regional Environmental Change - Mountain ecosystems provide key services to a large portion of the population in the tropics. However, they are particularly vulnerable to regional environmental...  相似文献   
909.
Costa Rica is internationally recognized for its abundant biodiversity and being a leader in the promotion of education strategies for biodiversity conservation. We interviewed staff from 16 institutions developing key environmental communication, education, and participation projects for biodiversity conservation in the country. Through content analysis, hierarchical cluster analysis and Chi-square tests, we examined the characteristics of the projects carried out by these institutions and developed a typology of four categories derived from six variables: primary audience, content, project purpose, location, scale, and facility. Then, we designed a conceptual model describing the integration of conservation and economic development in the educational projects. We found two key approaches related to this integration: vision of nature protection which aims to inform audiences of ecological concepts and focuses on schoolchildren and vision of sustainability which engages adult audiences and is management-oriented. Education for community-based environmental management may serve as a good example of educational projects which integrate conservation and economic development, implementing a vision of sustainability.  相似文献   
910.
Currently, energy consumption for cooking in rural households of India is mostly based on fuelwood used in traditional stoves. This paper presents results of a study carried out in a forest fringe area of India on cooking energy use. The concept of calculating levelized cost as cost per unit of useful energy is applied on source–device combinations of cooking and validated in Bargaon Community Development Block of Sundergarh District in Odisha, India. About 92 % of the households in the study area use fuelwood as the only energy source for cooking; the total use of fuelwood for only cooking, in the Block is nearly 1.8 times the total sustainable wood supply showing an urgent need for promoting alternative cooking energy options. This paper also presents an assessment of different cooking options in terms of cost per unit of useful cooking energy. LPG, biogas and gasifier stoves are found to be far too expensive for the local people. Briquette-fired improved stoves appear to be a promising cooking energy option in the study area. Government support and intervention are recommended for promoting this option.  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