全文获取类型
收费全文 | 6606篇 |
免费 | 512篇 |
国内免费 | 2167篇 |
专业分类
安全科学 | 484篇 |
废物处理 | 163篇 |
环保管理 | 1220篇 |
综合类 | 4565篇 |
基础理论 | 705篇 |
环境理论 | 2篇 |
污染及防治 | 1160篇 |
评价与监测 | 634篇 |
社会与环境 | 300篇 |
灾害及防治 | 52篇 |
出版年
2024年 | 9篇 |
2023年 | 92篇 |
2022年 | 176篇 |
2021年 | 249篇 |
2020年 | 275篇 |
2019年 | 262篇 |
2018年 | 214篇 |
2017年 | 273篇 |
2016年 | 363篇 |
2015年 | 387篇 |
2014年 | 442篇 |
2013年 | 528篇 |
2012年 | 545篇 |
2011年 | 633篇 |
2010年 | 388篇 |
2009年 | 575篇 |
2008年 | 412篇 |
2007年 | 555篇 |
2006年 | 466篇 |
2005年 | 339篇 |
2004年 | 277篇 |
2003年 | 307篇 |
2002年 | 224篇 |
2001年 | 190篇 |
2000年 | 188篇 |
1999年 | 165篇 |
1998年 | 125篇 |
1997年 | 102篇 |
1996年 | 67篇 |
1995年 | 86篇 |
1994年 | 87篇 |
1993年 | 60篇 |
1992年 | 43篇 |
1991年 | 26篇 |
1990年 | 13篇 |
1989年 | 11篇 |
1988年 | 15篇 |
1987年 | 10篇 |
1986年 | 16篇 |
1985年 | 11篇 |
1984年 | 6篇 |
1982年 | 9篇 |
1981年 | 6篇 |
1980年 | 9篇 |
1979年 | 10篇 |
1978年 | 7篇 |
1977年 | 5篇 |
1974年 | 4篇 |
1973年 | 5篇 |
1971年 | 4篇 |
排序方式: 共有9285条查询结果,搜索用时 15 毫秒
991.
992.
Characteristics of large cooking oil pool fires and their extinguishment by water mist 总被引:1,自引:0,他引:1
Z. Liu D. Carpenter A.K. Kim 《Journal of Loss Prevention in the Process Industries》2006,19(6):516-526
Large cooking oil pool fires, occurring in industrial oil cookers, present a severe hazard to food processing plants due to their size and the large amount of hot oil involved. This paper reports a series of full-scale fire experiments conducted in a large industrial oil cooker mock-up. The characteristics of large cooking oil pool fires and the effect of oil depth and hood position in the oil cooker on fire growth were studied. The use of water mist for extinguishing large oil pool fires and their extinguishing performance under different discharge pressure and with different types of water mist systems were investigated. Experimental results showed that the cooking oil underwent a substantial expansion in volume during heating. The fires developed quickly once the oil auto-ignited. The fire growth rate was affected by the oil depth in the pan and the hood position in the oil cooker. The water mist fire suppression systems effectively extinguished large cooking oil fires and prevented them from re-igniting. Their extinguishing performance was determined by the type of water mist system, discharge pressure and hood position in the oil cooker. 相似文献
993.
This paper deals with the estimation of the shadow prices of pollutants with a nonparametric directional distance function approach, where the inefficiency involved in the production process is taken into account unlike the previous studies. The directional vector, which is critical to the estimation and subject to the criterion for an appropriate efficiency rule proposed here, is calculated by using the annual plans of power plants in terms of production and environment. In the empirical study for Korea's electric power industry during the period of 1990-1995, we find that the average shadow prices of sulfur oxides (SOx), nitrogen oxides (NOx), and total suspended particulates (TSP) are approximately 10% lower than those calculated under the assumption of full efficiency. The methodology we propose and the findings obtained in the empirical study allow us to undertake better decision-making over a broad range of environmental policy issues. 相似文献
994.
995.
Bipasha Baruah 《Natural resources forum》2007,31(3):226-237
The Self‐Employed Women's Association (SEWA) is a trade union founded in 1972 to organize women in the informal sector in the western Indian state of Gujarat for better working conditions and social security provisions. The Gujarat Mahila Housing SEWA Trust (MHT) and the SEWA Bank are independently registered SEWA sister organizations that facilitate self‐employed women's access to housing and financial services, respectively. This paper seeks to document and critically analyze the experiences of MHT and SEWA Bank in partnering with the state, the private sector, funding agencies, urban local bodies and other NGOs in developing and delivering housing, water and sanitation programs for low‐income urban families living in slums. Using MHT as a case study, this paper will shed light upon challenges and opportunities NGOs may face while collaborating with partners with different core philosophies, motivations, working styles, strengths and constraints. The paper also makes recommendations that would enable different actors to play an optimal role in partnerships designed to improve the living and working conditions of the poor. 相似文献
996.
Hydrological Connectivity Between Headwater Streams and Downstream Waters: How Science Can Inform Policy1 总被引:1,自引:0,他引:1
Tracie‐Lynn Nadeau Mark Cable Rains 《Journal of the American Water Resources Association》2007,43(1):118-133
Abstract: In January 2001, the U.S. Supreme Court ruled that the U.S. Army Corps of Engineers exceeded its statutory authority by asserting Clean Water Act (CWA) jurisdiction over non‐navigable, isolated, intrastate waters based solely on their use by migratory birds. The Supreme Court’s majority opinion addressed broader issues of CWA jurisdiction by implying that the CWA intended some “connection” to navigability and that isolated waters need a “significant nexus” to navigable waters to be jurisdictional. Subsequent to this decision (SWANCC), there have been many lawsuits challenging CWA jurisdiction, many of which are focused on headwater, intermittent, and ephemeral streams. To inform the legal and policy debate surrounding this issue, we present information on the geographic distribution of headwater streams and intermittent and ephemeral streams throughout the U.S., summarize major findings from the scientific literature in considering hydrological connectivity between headwater streams and downstream waters, and relate the scientific information presented to policy issues surrounding the scope of waters protected under the CWA. Headwater streams comprise approximately 53% (2,900,000 km) of the total stream length in the U.S., excluding Alaska, and intermittent and ephemeral streams comprise approximately 59% (3,200,000 km) of the total stream length and approximately 50% (1,460,000 km) of the headwater stream length in the U.S., excluding Alaska. Hillslopes, headwater streams, and downstream waters are best described as individual elements of integrated hydrological systems. Hydrological connectivity allows for the exchange of mass, momentum, energy, and organisms longitudinally, laterally, vertically, and temporally between headwater streams and downstream waters. Via hydrological connectivity, headwater, intermittent and ephemeral streams cumulatively contribute to the functional integrity of downstream waters; hydrologically and ecologically, they are a part of the tributary system. As this debate continues, scientific input from multiple fields will be important for policymaking at the federal, state, and local levels and to inform water resource management regardless of the level at which those decisions are being made. Strengthening the interface between science, policy, and public participation is critical if we are going to achieve effective water resource management. 相似文献
997.
998.
999.
Suburbanization and drought: A mixed methods vulnerability assessment in rainy Massachusetts 总被引:1,自引:0,他引:1
This paper presents evidence that water restrictions in suburbanizing eastern Massachusetts towns are becoming more common, controlling for climate. We then assess the relationship between these suburban droughts and residential development. Focusing on the suburbs of Boston, seven towns independent of the Boston water supply system were selected to represent differing levels of sprawl-style growth. Water restrictions are becoming more frequent in all of the towns studied, and models demonstrate that restrictions are increasing in duration, independent of climate. Interviews suggest that residential development is playing a central role in this increasing sensitivity to suburban drought, though other factors are also important. Long-term planning and integration of land-use planning and water management emerged as two key paths for attenuating the impacts of development. 相似文献
1000.