全文获取类型
收费全文 | 187篇 |
免费 | 28篇 |
国内免费 | 18篇 |
专业分类
安全科学 | 70篇 |
废物处理 | 9篇 |
环保管理 | 18篇 |
综合类 | 93篇 |
基础理论 | 8篇 |
污染及防治 | 16篇 |
评价与监测 | 6篇 |
社会与环境 | 2篇 |
灾害及防治 | 11篇 |
出版年
2024年 | 1篇 |
2023年 | 3篇 |
2022年 | 9篇 |
2021年 | 8篇 |
2020年 | 9篇 |
2019年 | 6篇 |
2018年 | 2篇 |
2017年 | 8篇 |
2016年 | 9篇 |
2015年 | 4篇 |
2014年 | 9篇 |
2013年 | 14篇 |
2012年 | 28篇 |
2011年 | 12篇 |
2010年 | 8篇 |
2009年 | 12篇 |
2008年 | 2篇 |
2007年 | 4篇 |
2006年 | 8篇 |
2005年 | 10篇 |
2004年 | 6篇 |
2003年 | 9篇 |
2002年 | 7篇 |
2001年 | 4篇 |
2000年 | 6篇 |
1999年 | 10篇 |
1998年 | 5篇 |
1997年 | 1篇 |
1996年 | 7篇 |
1995年 | 2篇 |
1994年 | 2篇 |
1993年 | 2篇 |
1992年 | 3篇 |
1989年 | 1篇 |
1987年 | 1篇 |
1969年 | 1篇 |
排序方式: 共有233条查询结果,搜索用时 15 毫秒
181.
This study was performed to investigate the utility of bio-oil, produced via a fast pyrolysis process, as an antifungal agent against wood-rot fungi. Bio-oil solutions (25-100 wt.%) were prepared by diluting the bio-oil with EtOH. Wood block samples (yellow poplar and pitch pine) were treated with diluted bio-oil solutions and then subjected to a leaching process under hot water (70 °C) for 72 h. After the wood block samples were thoroughly dried, they were subjected to a soil block test using Tyromyces palustris and Trametes versicolor. The antifungal effect of the 75% and 100% bio-oil solutions was the highest for both wood blocks. Scanning electron microscopy analysis indicated that some chemical components in the bio-oil solution could agglomerate together to form clusters in the inner part of the wood during the drying process, which could act as a wood preservative against fungal growth. According to GC/MS analysis, the components of the agglomerate were mainly phenolic compounds derived from lignin polymers. 相似文献
182.
183.
James R. Leech Steven R. Abt Christopher I. Thornton Phil G. Combs 《Journal of the American Water Resources Association》1999,35(4):877-885
ABSTRACT: There is a need to provide flood protection while maintaining stable bed and bank conditions in the riverine system, to stabilize earth embankment dams and spiliways, and to stabilize highway or railway embankments and levee systems. One approach to providing erosion protection and stabilization of channel banks, embankments and spill conveyances is with articulated concrete block systems. Numerous articulated concrete block systems are available for bank stabilization. However, prior to field installations few means are available to evaluate how well these block systems perform. To assist the designer in predicting site specific suitability, a series of hydraulic testing protocols have been developed to analyze block system performance. Two articulated block system testing protocols are presented to indicate how block hydraulic characteristics may be determined and provide performance assurance to both the designer and the owner. 相似文献
184.
185.
Ronald C. Griffin 《Journal of the American Water Resources Association》2001,37(5):1335-1347
ABSTRACT: When the goal of water pricing is elevated from mere cost recovery to deriving the greatest value from scarce water and associated nonwater resources, conventional rate regimes are found to be deficient. To address the challenge of creating rates that are both efficient and budget-balancing, several theoretical and practical aspects of rate-making are considered. Purposeful selection of rate parameters for a specific billing system is demonstrated to serve efficiency and cost recovery objectives. Attention to non-accounting opportunity costs is an important system element, but these costs are often not fully borne by the utility or its customers. In situations where this issue is serious, state or federal pricing policy may be necessary. 相似文献
186.
拉萨和合肥环境下不同厚度保温材料EPS火蔓延特性研究 总被引:1,自引:0,他引:1
为了揭示保温材料EPS在不同厚度以及不同压力和氧气浓度等条件下火蔓延特性规律,分别在高原地区的拉萨和平原地区的合肥对其进行了火蔓延实验。实验是在小尺寸火蔓延实验台中进行的。通过分析在水平放置时,不同厚度保温材料在两地火蔓延过程中火蔓延速度、平均池火长度、平均最大火焰高度等特性参数的变化规律,定量地揭示了高原和平原环境对不同厚度保温材料EPS火蔓延特性参数的影响。结果表明,保温材料EPS火蔓延速度、平均池火长度、平均最大火焰高度在拉萨和合肥环境条件下,均随着保温材料厚度的增加而增加。同种厚度EPS在两地火蔓延过程中,火蔓延速度、平均池火长度、平均最大火焰高度在合肥地区都高于拉萨地区的特点。 相似文献
187.
赵迎龙 《中国特种设备安全》2014,(5):51-53
依据现行电梯标准中对安全控制的基本要求,从事故现象入手,对一起永磁同步曳引机冲顶事故进行分析,指出了电梯在电气控制回路设计和部件选型中存在的一些常见问题,模拟分析出了可能的事故过程,最后对改进电梯控制系统设计提出了一些建议。希望在电梯控制回路的绝缘保护等问题上能够引起业内人士对电路控制结构安全设计的足够重视。 相似文献
188.
Godinho-Castro AP Testolin RC Janke L Corrêa AX Radetski CM 《Waste management (New York, N.Y.)》2012,32(1):153-157
Civil engineering-related construction and demolition debris is an important source of waste disposed of in municipal solid waste landfills. After clay materials, gypsum waste is the second largest contributor to the residential construction waste stream. As demand for sustainable building practices grows, interest in recovering gypsum waste from construction and demolition debris is increasing, but there is a lack of standardized tests to evaluate the technical and environmental viability of this solid waste recycling process. By recycling gypsum waste, natural deposits of gypsum might be conserved and high amounts of the waste by-product could be reused in the civil construction industry. In this context, this paper investigates a physical property (i.e., resistance to axial compression), the chemical composition and the ecotoxicological potential of ceramic blocks constructed with different proportions of clay, cement and gypsum waste, and assesses the feasibility of using a minimal battery of tests to evaluate the viability of this recycling process. Consideration of the results for the resistance to axial compression tests together with production costs revealed that the best formulation was 35% of plastic clay, 35% of non-plastic clay, 10% of Portland cement and 20% of gypsum waste, which showed a mean resistance of 4.64 MPa. Energy dispersive X-ray spectrometry showed calcium and sulfur to be the main elements, while quartz, gypsum, ettringite and nacrite were the main crystalline compounds found in this formulation. Ecotoxicity tests showed that leachate from this formulation is weakly toxic toward daphnids and bacteria (EC20% = 69.0 and 75.0, respectively), while for algae and fish the leachate samples were not toxic at the EC50% level. Overall, these results show that the addition of 20% of gypsum waste to the ceramic blocks could provide a viable substitute for clay in the ceramics industry and the tests applied in this study proved to be a useful tool for the technical and environmental evaluation of this recycling process, bacterial and daphnid tests being more sensitive than algae and fish tests. 相似文献
189.
为分析街区尺寸对应急救援车辆行程时间的影响,基于小(120 m)、中(264 m)、大(440 m)3种典型街区尺寸,将救援车辆行程时间分为街区内、外2部分,以总行程时间最小为目标,构建基于背景流量水平的救援车辆路径选择仿真模型。设置4种救援场景,分别求解各救援场景在不同街区尺寸下的最短路径时间、冗余度及复杂度。结果表明:街区尺寸对街区内、外部救援时间均有影响,而前者在救援路径距离较短、街区尺寸较大的路网中占据较大比例(可达50%以上);救援路径包含路段的流量较小时,中、大街区尺寸路网表现类似,而高流量下大尺寸具备更优的救援时间;街区尺寸越小,救援路径冗余度与复杂度均越大。 相似文献
190.
依据多年从事环境污染治理的经验,设计出治理锅炉风机噪声的隔声室,并对该隔声室的制造、治理效果进行了评价,得出了该隔声室是控制噪声污染的有效设备。 相似文献