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   4303篇
  免费   37篇
  国内免费   27篇
安全科学   88篇
废物处理   268篇
环保管理   366篇
综合类   515篇
基础理论   858篇
环境理论   6篇
污染及防治   1580篇
评价与监测   394篇
社会与环境   277篇
灾害及防治   15篇
  2023年   54篇
  2022年   111篇
  2021年   166篇
  2020年   75篇
  2019年   71篇
  2018年   154篇
  2017年   166篇
  2016年   237篇
  2015年   129篇
  2014年   252篇
  2013年   414篇
  2012年   292篇
  2011年   315篇
  2010年   241篇
  2009年   161篇
  2008年   253篇
  2007年   267篇
  2006年   201篇
  2005年   170篇
  2004年   124篇
  2003年   108篇
  2002年   96篇
  2001年   53篇
  2000年   41篇
  1999年   24篇
  1998年   18篇
  1997年   13篇
  1996年   13篇
  1995年   19篇
  1994年   14篇
  1993年   8篇
  1992年   8篇
  1991年   5篇
  1990年   8篇
  1989年   3篇
  1988年   5篇
  1986年   4篇
  1985年   5篇
  1978年   3篇
  1977年   2篇
  1970年   2篇
  1967年   4篇
  1966年   4篇
  1965年   2篇
  1964年   5篇
  1962年   3篇
  1959年   4篇
  1958年   15篇
  1957年   5篇
  1955年   2篇
排序方式: 共有4367条查询结果,搜索用时 921 毫秒
711.
712.
713.
714.
Environmental Geochemistry and Health - Tree rings may be used as indicators of contamination events providing information on the chronology and the elemental composition of the contamination. In...  相似文献   
715.
The use of microorganisms as biological control agents (BCAs) has become an effective alternative to chemical means of controlling plant pathogens. The antagonistic and inhibitory activity of 71 Bacillus spp. strains, which were isolated from different Mexican sites, were tested against several phytopathogen fungi, Fusarium oxysporum, Fusarium equiseti, Fusarium avenaceum, Bipolaris spp. and Alternaria spp. From the antagonism study, the strain ELI149 showed a marked inhibition of growth against all tested fungi; therefore crude metabolites from this strain were extracted using ethyl acetate and amberlite resin and probed against the same fungi as well as strains of Mucor sp., Penicillium spp. and Paecilomyces spp. The results indicated that amberlite was more suitable for extraction of secondary metabolites with antifungal activity. Finally, observation of cell damage in the tested pathogenic fungi showed marked morphological changes on reproductive structures in all tested fungi indicating that antibiosis was the mechanism of the antagonistic effect. These results suggest that metabolites from the Bacillus strains have a wide spectrum of antibiotic activities, which can be used as biocontrol agents for controlling fungal plant diseases of agricultural importance.  相似文献   
716.
717.
718.
719.
The successful operation of any type of hydrogen-producing bioreactor depends on the performance of the microorganisms present in the system. Both substrate and partial gas pressures are crucial factors affecting dark fermentation metabolic pathways. The main objective of this study was to evaluate the impact of both factors on hydrogen production using anaerobic granular sludge as inoculum and, secondly, to study the metabolic shifts of an anaerobic community subjected to low partial gas pressures. With this goal in mind, seven different wastewater (four synthetic media, two industrial wastewater, and one domestic effluent) and the effect of applying vacuum on the systems were analyzed. The application of vacuum promoted an increase in the diversity of hydrogenproducing bacteria, such as Clostridium, and promoted the dominance of acetoclastic- over hydrogenotrophic methanogens. The application of different media promoted a wide variety of metabolic pathways. Nevertheless, reduction of the hydrogen partial pressure by application of vacuum lead to further oxidation of reaction intermediates irrespective of the medium used, which resulted in higher hydrogen and methane production, and improved the COD removal. Interestingly, vacuum greatly promoted biogenic hydrogen production from a real wastewater, which opens possibilities for future application of dark fermentation systems to enhance biohydrogen yields.  相似文献   
720.
Coral bleaching events are associated with abnormal increases in temperature, such as those produced during El Niño. Recently, a breakdown in the coral–dinoflagellate (genus Symbiodinium) endosymbiosis has been documented in corals exposed to anomalously cold-water temperatures associated with La Niña events. Given the ecological significance of such events, as well as the threat of global climate change, surprisingly little is known about the physiological response of corals to cold stress. This study evaluated some physiological effects of continuous temperature decline in colonies of the eastern Pacific reef-building coral Pocillopora verrucosa. Twenty days of incubation at 18.5–19.0 °C resulted in a substantial decrease in holobiont lipid and Chla content, as well as an increase in Symbiodinium density. These observations suggest a combination of symbiont acclimation due to the temperature decline and reallocation of carbon toward algal growth as opposed to translocation to the host coral. With a decreased availability of symbiont-derived carbon, the coral likely catabolized storage lipids in order to survive the stress event. Despite this stress and some tissue necrosis, no mortality was noted and corals recovered quickly when returned to the ambient temperature. As these results are in marked contrast to similar studies investigating elevated temperature on this coral from this same location, Pocillopora in the Mexican Central Pacific may be more prone to long-term damage and mortality during periods of ocean warming as opposed to ocean cooling.  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