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   692篇
  免费   2篇
  国内免费   6篇
安全科学   5篇
废物处理   3篇
环保管理   24篇
综合类   408篇
基础理论   105篇
污染及防治   113篇
评价与监测   22篇
社会与环境   17篇
灾害及防治   3篇
  2018年   9篇
  2017年   9篇
  2015年   9篇
  2014年   10篇
  2013年   33篇
  2012年   15篇
  2011年   14篇
  2010年   17篇
  2009年   18篇
  2008年   15篇
  2007年   22篇
  2006年   13篇
  2004年   7篇
  2003年   9篇
  2002年   20篇
  2001年   12篇
  2000年   8篇
  1999年   19篇
  1996年   7篇
  1995年   7篇
  1989年   7篇
  1979年   7篇
  1978年   7篇
  1969年   6篇
  1967年   7篇
  1966年   8篇
  1965年   9篇
  1964年   10篇
  1962年   6篇
  1961年   13篇
  1960年   6篇
  1959年   6篇
  1957年   6篇
  1955年   8篇
  1952年   6篇
  1942年   6篇
  1941年   8篇
  1940年   9篇
  1938年   6篇
  1937年   12篇
  1936年   10篇
  1935年   9篇
  1934年   12篇
  1933年   7篇
  1931年   7篇
  1929年   8篇
  1922年   6篇
  1921年   7篇
  1918年   6篇
  1913年   6篇
排序方式: 共有700条查询结果,搜索用时 562 毫秒
431.
Storm surges: perspectives and options   总被引:4,自引:1,他引:3  
This review paper attempts to summarize the scattered and fragmented knowledge about past and possible future changing storm-surge statistics using the particularly well-studied case of the North Sea as an example. For this region, a complete and robust analysis methodology has been developed in recent years. This methodology is based on dynamical and statistical models. Using the concept of dynamical downscaling, development during recent decades, when sufficiently good and homogeneous weather data exist, has been “reconstructed,” and scenarios of possible future change are described. “Localization” allows estimation of changes at specific sites, e.g., harbors. As local water-level statistics depend not only on climate variations but also on local modifications of the local bathymetry, new options for adaptation emerge. For the case of Hamburg, an option for such future adaptations is discussed.  相似文献   
432.
433.
为了评价东非不同空间尺度(1m尺度~l00km尺度)红树林分布区等足类甲壳动物蛀木虫钻刺团水虱(团水虱属)在美国红树红茄冬气生根中出现的情况,进行了野外调查研究.  相似文献   
434.
435.
436.
The territory establishment of male marine iguanas and their subsequent mating success were analysed to identify spatial spillover (hotshot) and temporal spillover effects on lek formation. Males started to establish small display territories 2 months ahead of the mating season. Males did not establish territories in temporal synchrony and did not settle at sites where the probability of encountering females was highest. However, males arriving later preferentially established their territories in the neighbourhood of already established territories independently of the density of female-sized iguanas in these territories. Although settling in close proximity, there were no fights between those males. The number of fights between territorial males increased towards, and peaked during, the mating season. Fights did not result in the transfer of space, indicating that space per se was no resource. Instead, fights were directed towards central (hotshot) males. These central males had higher mating success than marginal males. Female density during the time of territory establishment did not predict the mating success of males, because females changed their spatial preferences between early establishment and mating periods. Similarly, the areas where males achieved the highest numbers of copulations changed during 4 years of our study. Thus, there was no evidence for temporal spillover between subsequent seasons. However, most male-male interactions served to distract successful males and may lead to spatial spillover of females into territories of unsuccessful males. In marine iguanas, territorial establishment appears largely governed by hotshot processes.  相似文献   
437.
438.
High-volume PM2.5 samples were collected at Summit, Greenland for approximately six months from late May through December of 2006. Filters were composited and analyzed for source tracer compounds. The individual organic compounds measured at Summit are orders of magnitude smaller than concentrations measured at other sites, including locations representative of remote oceanic, and remote and urban continental aerosol. The measured tracers were used to quantify the contribution of biomass burning (0.6–0.9 ng C m?3), vegetative detritus (0.3–0.9 ng C m?3), and fossil fuel combustion (0.1–0.8 ng C m?3) sources, 4% of OC total, to atmospheric organic carbon concentrations at the remote location of Summit, Greenland. The unapportioned organic carbon (96%) during the early summer period correlates well with the fraction of water soluble organic carbon, indicating secondary organic aerosol as a large source of organic carbon, supported by the active photochemistry occurring at Summit. To the author's knowledge, this paper represents the first source apportionment results for the polar free troposphere.  相似文献   
439.
Biofuels are heavily debated as to their potential to reduce transport-related greenhouse gas emissions. Life cycle thinking gave rise to formal evaluations of the energy balance of such fuels, which led to the vigorously conducted “corn to ethanol” debates. Just as consensus was building on such evaluations came the “carbon debt” insights, a result of applying consequential Life Cycle Assessment (LCA) backed by advanced economic modeling. Increasingly, hopes have shifted to the 2nd generation biofuels, viewed as a “technological home run”. Could this also backfire? We investigate a simple South African case in which there might not be improvements in environmental performance: a sugar mill sells its bagasse, currently used at low efficiency to provide process heat, to an advanced biofuels producer, and buys an equivalent amount of coal without investing in efficiency improvements. Seven scenarios are generated, ranging from the status quo, where no bagasse is diverted, to 100% bagasse diversion, with one scenario including an energy efficiency improvement in the sugar mill. A consequential LCA is applied to the seven scenarios, covering global warming potential (GWP), non-renewable energy use, aquatic eutrophication and terrestrial acidification. A basic financial analysis of the proposed scenarios shows that they are realistic, with potentially lucrative returns. Results show that diverting bagasse without efficiency improvements from its current use to an ethanol bio-refinery would indeed backfire for all environmental impacts studied. The base case outperforms all the other scenarios, with the 100% bagasse diversion scenario emerging the worst. Investments into energy efficiency are therefore a precondition for diverting cellulosic residues into biofuel production.  相似文献   
440.
Following the introduction of automobile catalysts in the middle of the 1980s in Germany there is an increasing emission of the platinum-group-metals platinum, palladium (Pd) and rhodium. Still, it remains unclear if these metals are bioavailable for aquatic animals and to which extent they become accumulated by the aquatic biosphere. Because of analytical problems in detecting Pd in small biological samples the present investigation concentrates on the bioavailability of this metal. To answer the question of a Pd uptake by aquatic organisms experimental studies were conducted with European eels maintained in water containing road dust at a concentration of 10 kg/100 l. Following an exposure period of four weeks, samples of liver and kidney were analysed by total-reflection X-ray fluorescence analysis after co-precipitation of Pd with mercury. These experiments revealed an uptake of traffic related Pd by European eels which showed a mean liver Pd concentration of 0.18 +/- 0.05 ng/g (wet wt.), whereas the Pd concentration in the kidney ranged below the detection limit. Thus, in this study we can demonstrate for the first time that automobile catalyst emitted Pd is bioavailable for aquatic animals.  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