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   996篇
  免费   12篇
  国内免费   5篇
安全科学   24篇
废物处理   57篇
环保管理   69篇
综合类   192篇
基础理论   184篇
污染及防治   314篇
评价与监测   101篇
社会与环境   57篇
灾害及防治   15篇
  2023年   11篇
  2022年   29篇
  2021年   39篇
  2020年   17篇
  2019年   19篇
  2018年   50篇
  2017年   31篇
  2016年   59篇
  2015年   47篇
  2014年   51篇
  2013年   77篇
  2012年   43篇
  2011年   68篇
  2010年   54篇
  2009年   46篇
  2008年   66篇
  2007年   59篇
  2006年   45篇
  2005年   29篇
  2004年   24篇
  2003年   33篇
  2002年   23篇
  2001年   19篇
  2000年   15篇
  1999年   4篇
  1998年   4篇
  1997年   2篇
  1996年   4篇
  1995年   6篇
  1994年   8篇
  1993年   6篇
  1992年   5篇
  1990年   3篇
  1988年   1篇
  1986年   2篇
  1985年   1篇
  1984年   2篇
  1983年   1篇
  1982年   2篇
  1981年   2篇
  1979年   1篇
  1978年   1篇
  1975年   1篇
  1964年   1篇
  1962年   1篇
  1956年   1篇
排序方式: 共有1013条查询结果,搜索用时 31 毫秒
891.
892.
893.
Regional Environmental Change - Research on hydropower development has shown that a diversity of social and environmental impacts of dams is distributed unevenly among various state and corporate...  相似文献   
894.
Consideration of gender in the disaster sphere has centred almost exclusively on the vulnerability and capacities of women. This trend stems from a polarised Western understanding of gender as a binary concept of man—woman. Such an approach also mirrors the dominant framing of disasters and disaster risk reduction (DRR), emphasising Western standards and practices to the detriment of local, non‐Western identities and experiences. This paper argues that the man—woman dichotomy is an insufficient construct with which to address the gendered dimensions of a disaster as it fails to capture the realities of diverse gender minorities in non‐Western contexts. The paper presents case studies from the Philippines, Indonesia, and Samoa, where gender minorities display specific patterns of vulnerability associated with their marginal positions in society, yet, importantly, also possess a wide array of endogenous capacities. Recognition of these differences, needs, skills, and unique resources is essential to moving towards inclusive and gender‐sensitive DRR.  相似文献   
895.
Natural rubber grafted with poly(vinyl acetate) copolymer (NR-g-PVAc) was synthesized by emulsion polymerization. Three graft copolymers were prepared with different PVAc contents: 1 % (G1), 5 % (G5) and 12 % (G12). Poly(lactic acid) (PLA) was melt blended with natural rubber (NR) and/or NR-g-PVAc in a twin screw extruder. The blends contained 10–20 wt% rubber. The notched Izod impact strength and tensile properties were determined from the compression molded specimens. The effect of NR mastication on the mechanical properties of the PLA/NR/NR-g-PVAc blend was evaluated. Characterization by DMTA and DSC showed an enhancement in miscibility of the PLA/NR-g-PVAc blend. The temperature of the maximum tan δ of the PLA decreased with increasing PVAc content in the graft copolymer, i.e., from 71 °C (pure PLA) to 63 °C (the blend containing 10 % G12). The increase in miscibility brought about a reduction in the rubber particle diameter. These changes were attributed to the enhancement of toughness and ductility of PLA after blending with NR-g-PVAc. Therefore, NR-g-PVAc could be used as a toughening agent of PLA and as a compatibilizer of the PLA/NR blend. NR mastication was an efficient method for increasing the toughness and ductility of the blends which depended on the blend composition and the number of mastications.  相似文献   
896.
The main objectives of this study were to investigate the compostability of wastewater treatment sludge (WTS) containing different bulking agents (BAs) and to determine the most efficient BA. Four different compost trials consisting of mixtures of wheat straw (WS), plane leaf (PL), corncob (CC) and sunflower stalk (SS) with WTS were performed in laboratory reactors. In all experiments, a mixture of 60% WTS and 40% BA (wet basis) was used. The temperature, dry matter (DM), organic matter (OM), pH, electrical conductivity (EC) and C/N ratio were monitored during the composting process. Evaluation of the operational parameters showed that the highest organic matter degradation (i.e. 37.6%), loss of dry matter (i.e. 29.6%) and temperature (i.e. 64 °C) were achieved for the WTS-CC mixtures. Results also showed that the WTS-SS mixture was also successful in terms of these operational parameters. Use of bulking agents for the treatment of wastewater treatment sludge in composting process is an important issue with regards to process efficiency, economy and disposal of agricultural waste. Corncob and sunflower stalk that were previously not used for the composting of WTS from food industry were shown to be highly successful BA materials in this study.

Implications: The compostability of wastewater treatment sludge from the food industry with different bulking agents was studied. Wheat straw, plane leaf, corncob, and sunflower stalk were used as bulking agents. The required microbial stabilization and degree of mineralization were achieved with corncobs and sunflower stalks.  相似文献   

897.
A new sensitive technique for the quantification of formaldehyde (HCHO) and total aldehydes has been developed in order to monitor these compounds, which are known to be involved in air quality issues and to have health impacts. Our approach is based on a colorimetric method where aldehydes are initially stripped from the air into a scrubbing solution by means of a turning coil sampler tube and then derivatised with 3-methylbenzothiazolinone-2-hydrazone in acid media (pH?=??0.5). Hence, colourless aldehydes are transformed into blue dyes that are detected by UV–visible spectroscopy at 630 nm. Liquid core waveguide LCW Teflon® AF-2400 tube was used as innovative optical cells providing a HCHO detection limit of 4 pptv for 100 cm optical path with a time resolution of 15 min. This instrument showed good correlation with commonly used techniques for aldehydes analysis such as DNPH derivatisation chromatographic techniques with off-line and on-line samplers, and DOAS techniques (with deviation below 6 %) for both indoor and outdoor conditions. This instrument is associated with simplicity and low cost, which is a prerequisite for indoor monitoring.  相似文献   
898.
To collect a large data set regarding the occurrence of organic substances in sediment, this study presents the examination of 20 micropollutants, as a national survey. The list of target compounds contains two alkylphenols, three polycyclic aromatic hydrocarbons (PAHs) not commonly included in monitoring programmes, six pesticides or metabolites, five pharmaceutical compounds, two hormones, one UV filter and bisphenol A. The selective and sensitive analytical methods, based on quick, easy, cheap, effective, rugged, and safe (QuEChERS) sample preparation followed by liquid chromatography-tandem mass spectrometry (LC-MS/MS) or gas chromatography-time-of-flight mass spectrometry (GC-ToF-MS), allow the quantification at limits comprised between 0.5 and 23 ng/g, depending on the compound. The paper summarizes the analytical results from 154 sampling points. Of the 20 target compounds, 9 were determined at least once, and the sediments contained a maximum of 7 substances. The most frequently detected were PAHs (frequency, 77 %; max., 1,400 ng/g). The pharmaceutical compounds, hormones and pesticides were rarely detected in the samples; the most frequently detected was carbamazepine (frequency, 6 %; max., 31 ng/g). In some cases, the levels of PAHs and bisphenol A exceed the predicted no-effect concentration (PNEC) values.  相似文献   
899.
Grünewald F 《Disasters》2012,36(Z1):S105-S125
Mogadishu, the capital of Somalia, has been central to life, war, and peace in the country for almost two decades. Its urban characteristics, though, have been put to one side for the most part. In recent years, Mogadishu-related issues have been merged mostly into a global agenda for South and Central Somalia, resulting in the technical and coordination approaches employed in the city largely being reproductions of solutions utilised in refugee camps and rural areas. Unfortunately, urban problems require urban solutions. The aid system is just starting to discover how specific aid in cities at war should be, both from an organisational and a technical standpoint. The enhancement of aid practices in an urban setting implies, among other things, a more strategic approach to the specific spatial characteristics of the city, a more fine-tuned analysis of the technical requirements of the urban service delivery systems, and a better understanding of the role of urban institutions.  相似文献   
900.
Technological development has had huge impacts in sports performance throughout the years, fostering the development of specific materials and manufacturing processes for sports-related products. Within this context, a new technology for snowboards was developed taking advantage of the internal coupling effects of Fibre Reinforced Plastics (FRP) using an anisotropic layer design. This work deals with the technical, economic and environmental evaluation of a snowboard made of three alternative materials, namely carbon, glass and flax fibre reinforced plastics. It shows how a life cycle analysis can support the design and development of products by applying a Life Cycle Engineering methodology to the design process of a snowboard using an innovative technology. In this case, both the material choice and the fiber placement angles have a significant impact on the stiffness of the resulting FRP and thus in the three dimensions of analysis - cost, environmental and technical. The natural fiber is the most sustainable option environmentally, the glass fiber is the best one economically and the carbon fibre is the best in terms of technical performance. Therefore, the importance attributed to each dimension of analysis is pondered and traded-off to allow an aggregated analysis of the alternatives and a well-informed decision-making.  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