全文获取类型
收费全文 | 10968篇 |
免费 | 1786篇 |
国内免费 | 6080篇 |
专业分类
安全科学 | 1911篇 |
废物处理 | 355篇 |
环保管理 | 913篇 |
综合类 | 9788篇 |
基础理论 | 3095篇 |
环境理论 | 2篇 |
污染及防治 | 1655篇 |
评价与监测 | 515篇 |
社会与环境 | 350篇 |
灾害及防治 | 250篇 |
出版年
2024年 | 60篇 |
2023年 | 423篇 |
2022年 | 625篇 |
2021年 | 709篇 |
2020年 | 691篇 |
2019年 | 701篇 |
2018年 | 665篇 |
2017年 | 668篇 |
2016年 | 748篇 |
2015年 | 857篇 |
2014年 | 768篇 |
2013年 | 1220篇 |
2012年 | 1238篇 |
2011年 | 1255篇 |
2010年 | 929篇 |
2009年 | 1004篇 |
2008年 | 822篇 |
2007年 | 915篇 |
2006年 | 889篇 |
2005年 | 649篇 |
2004年 | 533篇 |
2003年 | 434篇 |
2002年 | 336篇 |
2001年 | 292篇 |
2000年 | 252篇 |
1999年 | 203篇 |
1998年 | 145篇 |
1997年 | 150篇 |
1996年 | 109篇 |
1995年 | 115篇 |
1994年 | 80篇 |
1993年 | 76篇 |
1992年 | 54篇 |
1991年 | 23篇 |
1990年 | 28篇 |
1989年 | 22篇 |
1988年 | 16篇 |
1987年 | 5篇 |
1986年 | 13篇 |
1985年 | 7篇 |
1984年 | 7篇 |
1983年 | 12篇 |
1982年 | 13篇 |
1981年 | 9篇 |
1980年 | 7篇 |
1979年 | 4篇 |
1978年 | 4篇 |
1973年 | 5篇 |
1972年 | 5篇 |
1971年 | 33篇 |
排序方式: 共有10000条查询结果,搜索用时 375 毫秒
311.
Gregory M. Glenn Artur K. Klamczynski Bor-Sen Chiou Delilah Wood William J. Orts Syed H. Imam 《Journal of Polymers and the Environment》2004,12(3):189-196
Starch aquagel-based lightweight concrete has properties similar to those of other lightweight concrete products. However, starch aquagels are unstable in the strongly alkaline conditions typical of Portland Cement-based concrete and may interfere with the setting process. The effect of alkali treatments on the physical, mechanical, and functional properties of starch aquagels and aquagels from starch/polymer blends was investigated. Starch was blended at 100–115°C in a twin-screw extruder with five different polymers to determine whether the blends improved alkaline resistance. Polymer blends containing 5%, 15%, and 30% of the polymer hydrated and formed aquagels when equilibrated in water for 24 h. However, equilibrium moisture content was lower for the blends compared to the starch control. Aquagels equilibrated in 0.15 N NaOH swelled, lost compressive strength and had greater than 90% moisture. The blend of starch and 30% PVOH absorbed less moisture and was more resistant to alkaline dissolution in 1 N NaOH than the other blends tested making it a more suitable material for aquagel-based concrete. The moisture content of starch-based aquagels and mixing time were critical factors in determining setting times. The size of aquagel blends had a minor effect on density and compressive strength. 相似文献
312.
313.
UV/O3复合降解水中2,4-二氯酚的试验研究 总被引:2,自引:1,他引:2
以紫外光源为主要依托,变换反应器中的不同工艺条件,分别对紫外光、臭氧和紫外/臭氧三种不同于工艺条件对水中污染物2,4-二氯酚(2 ,4-DCP)的降解规律进行研究.结果表明,UV/O3复合对2,4-DCP的降解较UV、O3单独作用效果好;溶液的酸碱度影响UV/O3对2 ,4-DCP的降解;此外,溶液中含有细菌时,E. coli的杀灭效果仍表现为UV/O3>O3>UV.细菌的杀灭和2,4-DCP的降解均消耗羟基自由基,形成竞争反应,从而影响到2,4-DCP的降解效果. 相似文献
314.
315.
系统评价天然蛭石吸附氨氮的效果 总被引:7,自引:1,他引:7
采用在人工配置含氨氮的污水中投加蛭石的方法,系统研究了天然蛭石吸附污水中氨氮的饱和吸附容量以及蛭石吸附氨氮的等温吸附曲线,探讨了污水的pH值、温度、浓度对氨氮去除率的影响及各影响因子的大小,结果表明,蛭石的饱和吸附量为20 8mg/g;蛭石吸附量在pH2 0~6 0范围内随着pH的增大而增大,最佳pH为4 0~6 0;温度在15~35℃范围内,吸附量随温度的升高减小,氨氮的去除率随着蛭石用量的增加而增加,影响因素的大小顺序为:pH>蛭石的用量>吸附时间>温度。这为蛭石作为一种新型氨氮吸附材料提供了基础参数。 相似文献
316.
目前生态影响评价研究中的评价对象、内容和方法缺乏统一的模式,本文以攀枝花高耗能园区的开发为例,尝试建立一套系统的工业园区开发生态影响评价方法,该方法以层次分析法为基础,将生态系统分解为经济发展、社会进步、环境保护、景观生态保护四个目标子系统,并在此基础上细化评价因子,通过专家打分和矩阵运算确定其权重,再根据适当的评价标准,运用指数法得出评价结果。结果表明该工业园区在建成前后,其生态综合指数由0.552提高到0.794.其级别由三级提高到二级,说明该园区生态系统总的状态得到改善,该工业园区项目开发可行。 相似文献
317.
Exploiting Abstract Possibilities: A Critique of the Concept and Practice of Product Patenting 总被引:2,自引:0,他引:2
Hans Radder 《Journal of Agricultural and Environmental Ethics》2004,17(3):275-291
Developments in biotechnology and genomics have moved the issue of patenting scientific and technological inventions toward the center of interest. In particular, the patentability of genes of plants, animals, or humans and of genetically modified (parts of) living organisms has been discussed, and questioned, from various normative perspectives. This paper aims to contribute to this debate. For this purpose, it first explains a number of relevant aspects of the theory and practice of patenting. The focus is on a special and increasingly significant type of patents, namely product patents. The paper provides three general arguments against the concept and practice of product patenting. The first argument briefly considers the claim that patents are legitimate because they promote socially useful innovation. Against this claim, it is argued that product patents may hamper rather than promote such innovation. The second and main argument concludes that product patents are not adequately based on actual technological inventions, as they should be according to the usual criteria of patentability. The principal moral issue is that product patents tend to reward patentees for inventions they have not really made available. The final argument proposes a method for patenting the heat of the sun. Assuming that granting this patent will be generally considered absurd, the argument exposes a further, fundamental problem of the concept and practice of product patenting. 相似文献
318.
Hao-Jan Hsing Fang-Kuo Wang Pen-Chi Chiang Wan-Fa Yang 《Resources, Conservation and Recycling》2004,40(4):42
More than 50,000 tons of hazardous waste are imported and exported worldwide each year. Over 50% of hazardous waste is exported to Southeast Asia, of which leather waste is the major component. The exportation quantities of hazardous waste to Organization of Economic Cooperation and Development (OECD) countries are decreasing while they are on the increase to non-OECD countries. Some of these wastes are intended for recycling purposes but the usage of some others is not stipulated. The hazardous waste importation quantity kept fairly steady from 1997 to 2000, of which ash or residues containing copper or copper compounds were the major component. Under existing regulations and measures, the transboundary movement of hazardous waste cannot be effectively controlled and monitored. In order to ensure environmentally sound hazardous waste management, EPA-Taiwan revised the Waste Disposal Act in 2001 and cooperated with the Industrial Development Bureau (IDB) to promote industrial waste reduction and recycling projects. Strategies were proposed based on evaluation according to the 3Es Principles and the site investigation in this study. 相似文献
319.
Magdalena Svanstrm Morgan Frling Michael Modell William A. Peters Jefferson Tester 《Resources, Conservation and Recycling》2004,41(4):573
Environmental aspects of using supercritical water oxidation (SCWO) to treat sewage sludge were studied using a life cycle assessment (LCA) methodology. The system studied is the first commercial scale SCWO plant for sewage sludge in the world, treating sludge from the municipal wastewater treatment facility in Harlingen, TX, USA. The environmental impacts were evaluated using three specific environmental attributes: global warming potential (GWP), photo-oxidant creation potential (POCP) and resource depletion; as well as two single point indicators: EPS2000 and EcoIndicator99. The LCA results show that for the described process, gas-fired preheating of the sludge is the major contributor to environmental impacts, and emissions from generating electricity for pumping and for oxygen production are also important. Overall, SCWO processing of undigested sewage sludge is an environmentally attractive technology, particularly when heat is recovered from the process. Energy-conserving measures and recovery of excess oxygen from the SCWO process should be considered for improving the sustainability potential. 相似文献
320.
Brent J. Dalzell Prasanna H. Gowda David J. Mulla 《Journal of the American Water Resources Association》2004,40(2):533-543
ABSTRACT: This paper studies the effectiveness of alternative farm management strategies at improving water quality to meet Total Maximum Daily Loads (TMDLs) in agricultural watersheds. A spatial process model was calibrated using monthly flow, sediment, and phosphorus (P) losses (1994 to 1996) from Sand Creek watershed in south‐central Minnesota. Statistical evaluation of predicted and observed data gave r2 coefficients of 0.75, 0.69, and 0.49 for flow (average 4.1 m3/s), sediment load (average 0.44 ton/ha), and phosphorus load (average 0.97 kg/ha), respectively. The calibrated model was used to evaluate the effects of conservation tillage, conversion of crop land to pasture, and changes in phosphorus fertilizer application rate on pollutant loads. TMDLs were developed for sediment and P losses based on existing water quality standards and guidelines. Observed annual sediment and P losses exceeded these TMDLs by 59 percent and 83 percent, respectively. A combination of increased conservation tillage, reduced application rates of phosphorus fertilizer, and conversion of crop land to pasture could reduce sediment and phosphorus loads by 23 percent and 20 percent of existing loads, respectively. These reductions are much less than needed to meet TMDLs, suggesting that control of sediment using buffer strips and control of point sources of phosphorus are needed for the remaining reductions. 相似文献