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   14189篇
  免费   185篇
  国内免费   1737篇
安全科学   314篇
废物处理   1034篇
环保管理   1551篇
综合类   3338篇
基础理论   3829篇
污染及防治   3608篇
评价与监测   1160篇
社会与环境   1071篇
灾害及防治   206篇
  2024年   3篇
  2023年   80篇
  2022年   232篇
  2021年   172篇
  2020年   120篇
  2019年   121篇
  2018年   1634篇
  2017年   1541篇
  2016年   1435篇
  2015年   421篇
  2014年   388篇
  2013年   501篇
  2012年   831篇
  2011年   1756篇
  2010年   985篇
  2009年   879篇
  2008年   1178篇
  2007年   1464篇
  2006年   263篇
  2005年   206篇
  2004年   180篇
  2003年   215篇
  2002年   256篇
  2001年   161篇
  2000年   165篇
  1999年   143篇
  1998年   161篇
  1997年   114篇
  1996年   106篇
  1995年   81篇
  1994年   65篇
  1993年   58篇
  1992年   53篇
  1991年   26篇
  1990年   35篇
  1989年   12篇
  1988年   8篇
  1987年   12篇
  1986年   7篇
  1985年   4篇
  1984年   13篇
  1983年   13篇
  1982年   3篇
  1981年   3篇
  1979年   2篇
  1978年   2篇
  1977年   1篇
  1935年   2篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
71.
探幽海螺沟     
武玉霞 《防灾博览》2009,(2):97-105
走过的地方不多,看过的地方不少,就自然风光而言,位于四川省甘孜藏族自治州泸定县境内的海螺沟冰川森林公园,是我见到过的最美的景致之一。然而,在全球升温和温室气体减排加剧的大背景下,海螺沟冰川雪线上升、冰川后退,形成了冰溜面、冰斗、冰川磨光面和冰川擦痕等特殊的冰蚀地貌,许多动植物资源正面临生死存亡的境地,一幕幕现实的场景呼唤着人类在享受现代化文明的同时,也要爱护和关心人类赖以生存的地球家园。  相似文献   
72.
Green development emphasizes co-development between economic and environmental dimensions, and is a people-centered sustainable development approach. Western China demands green development, and international experience could provide necessary, unique and important help and support for Western China to achieve its green development goals. This paper has made a comprehensive overall review and analysis of international experience in green development policy and its implementation, in particular, OECD countries’ (mostly Australia and Canada) experience have been analyzed following the major policy foci defined by the Task Force on Strategy and Policies on Environment and Development in Western China initiated by China Council for International Cooperation on Environment and Development (CCICED). Data and information were gathered from the field surveys and investigations, expert meetings, as well as literature review. The main sessions include policy framework and road map establishment, implementation and performance assessment, co-development between economic development and environmental protection, as well as green employment and poverty alleviation. The paper has addressed five policy considerations for the future promotion of green development in Western China.  相似文献   
73.
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   
74.
This paper reports environmental analysis results of food and tannery Tunisian companies to identify the features of environmental management system (EMS) that is implemented recently. EMS via ISO 14001 has become one of the principal tools used by companies to handle environmental aspects and impacts through their various complex activities interacted with environment. While several companies have implemented and maintained a formal EMS, it has related mainly to their benefits in short term without responding to the sustainable development recommendations and practices. This study focuses on the strong linkage between the EMS effectiveness of food–tannery Tunisian companies and sustainability. A proactive environmental management approach is proposed and adopts a qualitative and quantitative assessment for factor analysis. It provides a strategic EMS framework and principles for sustainability to evolve the future enterprises’ benefits that has a clear influence on environmental performance in long term.  相似文献   
75.
Brazil is considered one of the world’s leading producers of biofuels given the predominance of ethanol fuel in its energy matrix. However, despite the prominence of Brazil in ethanol production, the vast majority of biodiesel production plants in Brazil use methanol instead of ethanol as the alcohol for transesterification reaction, as is generally the case in the rest of the world. The aim of this paper is therefore to examine the transesterification process in the Brazilian biodiesel production in terms of sustainability. In this regard, it was necessary to evaluate the way in which the industrial process is currently carried out, the role of government incentives or subsidies for the use of ethanol to produce biodiesel, and the investments of companies in technology development for the same purpose. This study presents indications that the development of the biodiesel market in Brazil is still oriented toward a production model which is inconsistent with the environmental and social aspects of sustainability.  相似文献   
76.
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   
77.
In the present paper, the optimum design of a PV system used to operate a water pumping system was determined for Oman. The system design focused on the environmental conditions of Sohar city. The implementation and measurement of the designed system are presented to prove the effectiveness of the proposed system. The results show that the system can provide the required power at peak hours, leading to a substantial reduction in the sizing of the PV system. Consequently, the investment capital costs 2400 USD, and the cost of energy is equal to 0.309 USD/kWh. Furthermore, the results indicate that the system annual yield factor is 2024.66 kWh/kWp and that the capacity factor is 23.05 %, which is encouraging since the latter is typically 21 %. The system capital cost and the cost of energy are worth comparing to a diesel generator. A comparison is made between the proposed system and several others in the literature. The comparison indicated that the system cost of energy is promising.  相似文献   
78.
In 2014, there was virtually no summer in northern and central-southern Italy. Storm after storm battered the peninsula, triggering floods and landslides from Veneto to Puglia. We studied the coverage of “the year without a summer” in Italy by analyzing the content of 171 news articles from two influential online newspapers. Our software-based analysis enabled us to observe that the two newspapers hardly ever mentioned climate change in their coverage of the weather anomaly that affected Italy in the summer of 2014. This type of coverage is in line with climate science, according to which there is no evidence of a climate change-related influence on summer precipitation patterns in Southern Europe—whereas such influence has been documented for northern Europe. We compared our results with a recent paper, which documented that the same online dailies chose to represent the particularly hot summer of 2012 in Italy as a direct consequence of climate change. We corroborated this comparison also on the basis of a preliminary analysis we performed on the media coverage of the exceptionally hot and arid summer of 2015 in Italy.  相似文献   
79.
This study aimed at investigating the retention of Pb and Cd in soils and the geochemical factors influencing the adsorption of these pollutants. Soil samples were air-dried and ground to pass through a 2-mm sieve, and different soil extracts were prepared for chemical analysis (organic matter, cation exchange capacity and pH). Total Pb and Cd were extracted with diacid using digestion method and determined by atomic adsorption spectrophotometer (AAS) after filtration. Results revealed that the heavy metals retention ratio (RR) of the Rhodic ferralsol, Xanthic ferralsol and Mollic gleysol (2) were very high for Cd (>80 %) and was relatively low (generally < 60 %) for Pb. In contrast, RRs for the Plinthic gleysol and the Mollic gleysol (1) were relatively low (<60 %), regardless of the heavy metal concerned. Multiple regression equations indicated for Pb and Cd concentrations different linear relationships over simple linear regression, when pH, organic matter, clay percentage and cation exchange capacity (CEC) were used as independent variables. Results indicate that organic matter exerts major influences on the retention of Pb and Cd in soils, while CEC, clay content and pH have a minor influence in this process in the Ntem watershed. From these observations, the application of soil organic matter could be a solution in protecting shallow aquifers from heavy metal pollution and thus insuring that they are not a hazard to public health.  相似文献   
80.
Increasing environmental issues, economic and cultural differences, the regulatory framework and the great attention to social responsibility, have forced companies to face the challenge of sustainability. Thus, the adaption of a proper marketing strategy in order to achieve a sustainable competitive advantage in the market (specially export markets) has become an important principle in accepting companies. In this regard, this study is a systematic literature review, which investigated 102 published articles in international journals between 1964 and 2015. In the literature review, the main focus was on key issues such as sustainability, marketing strategies, financial and market export performance. In this article, at first, the concept of sustainability from different aspects was collected and described. Then, external factors, such as competitive intensity, public concern, regulations, technology, cultural/social, and economic, as well as internal factors, such as managers, employees, stakeholders, affecting sustainability, were studied. Finally, adaption of export marketing strategies in order to achieve sustainability export performance is discussed.  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