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   232篇
  免费   0篇
安全科学   4篇
废物处理   6篇
环保管理   40篇
综合类   93篇
基础理论   34篇
污染及防治   42篇
评价与监测   9篇
社会与环境   4篇
  2018年   5篇
  2017年   2篇
  2016年   3篇
  2014年   2篇
  2013年   13篇
  2012年   8篇
  2011年   3篇
  2010年   4篇
  2009年   3篇
  2008年   4篇
  2007年   5篇
  2006年   5篇
  2005年   3篇
  2004年   2篇
  2003年   6篇
  2002年   12篇
  2001年   8篇
  2000年   6篇
  1998年   2篇
  1997年   8篇
  1996年   4篇
  1995年   5篇
  1994年   7篇
  1993年   4篇
  1992年   5篇
  1990年   4篇
  1988年   2篇
  1968年   2篇
  1966年   2篇
  1964年   3篇
  1963年   2篇
  1962年   3篇
  1961年   4篇
  1960年   6篇
  1959年   3篇
  1958年   5篇
  1957年   7篇
  1955年   3篇
  1954年   2篇
  1950年   2篇
  1944年   2篇
  1941年   5篇
  1939年   6篇
  1936年   2篇
  1935年   3篇
  1932年   2篇
  1927年   2篇
  1926年   2篇
  1922年   3篇
  1913年   2篇
排序方式: 共有232条查询结果,搜索用时 15 毫秒
211.
212.
For the pilotproject ?Effect Monitoring — Biomonitoring of Immission Effects in the Testing Area of Munich”, standardized grass cultures were exposed at 19 locations during 10 series for two weeks each. The grass was analyzed for the accumulation of lead, antimony arsenic, cadmium, and copper. Highest accumulation was observed with antimony near traffic situations. The comparison of the results from the different sampling points identifies motor vehicle traffic as the source of antimony. First examinations of brake linings support this conclusion. Lead is only slightly increased near traffic. Immission-caused copper contents in the grass were found near the overhead tramway cables. The accumulation detection limits for arsenic and cadmium were not exceeded at any of the measuring points.  相似文献   
213.
In order to better formulate an artificial shrimp diet, the protein composition of shrimp was assessed and the essential amino acids determined. Penaeus aztecus were treated to remove lipids, carbohydrates and other interfering substances, and the protein was hydrolyzed to its constituent amino acids. The amino acids were then quantitatively analyzed by gasliquid chromatography as their trimethylsilyl derivatives. The essential amino acids were then determined. Shrimp were injected with 14C-labeled glucose and analyses performed to determine which amino acids then exhibited radioactivity, i.e., were synthesized from the labeled glucose. Those amino acids which were not manufactured from the glucose were categorized as essential.  相似文献   
214.
215.
216.
217.
The interaction of predation pressure with lethal and sublethal effects of temefos (Abate®) an organophosphorous insecticide, were studied in field populations of Uca pugnax (S.I. Smith). Changes in fiddler crab population densities were followed in open-marsh temefos-treated and untreated test plots and in treated and untreated plots which were caged over to reduce predation by marsh birds. Temefos significantly reduced the population density of U. pugnax in the open test plots but not in the caged plots. These results indicate that temefos has a primarily sublethal effect on the crabs, the effect becoming lethal only after interaction with avian predation. Evidence from the presence of a time-lag effect in the population decrease, from a calculated predation index, and from laboratory studies reported elsewhere of behavioral alteration by temefos also supports the conclusion that temefos primarily impairs the escape response of U. pugnax: this leads to increased predation and subsequently to a decreased fiddler crab population. Such studies of sublethal effects of toxicants and field studies of interactions of lethal and sublethal effects of such compounds with natural population dynamics of affected species are necessary to evaluate possible effects of toxicants on populations.  相似文献   
218.
In 1996 within a country-wide research project, the epiphytic lichen vegetation throughout Bavaria was mapped according to Guideline VDI 3799, Part I (1995). The data providing information about air quality was collected in 190 sites. Most of the sites demonstrated little to moderate pollution, while both very high and very low levels of air pollution could be found locally. The methods outlined in Guideline VDI 3799 were slightly modified and adapted to the situation in Bavaria. Comparison of the lichen vegetation on different species of trees showed that a rigid classification of tree species as proposed in the guideline is not necessary in Bavaria. The use of several species of trees per site has proven to be favourable. The influence of the natural heterogeneity of the air-quality index in the investigated area was examined. Here, the geology turned out not to be a crucial factor. With respect to climate, it is especially the alpine region with its high levels of precipitation that stands out against the other parts of Bavaria. The results from that area may not be freely compared to those from the remaining sites. It could be shown that the Guideline VDI 3799 is applicable for large-area lichen mapping in Bavaria.  相似文献   
219.
The spatial variation of the immission patterns of Cr, Fe, Pb and V in the region Leipzig-Halle is dicussed in terms of similarities as well as dissimilarities. The representation by isopleths enables the identification of areas with high and low air pollution. The immission patterns can be used as criteria to select areas suitable for in-field testing so that possible effects on fauna und flora and xenobiotic fluxes can be studied at representative sites. The comparison with literature data yields a first characterization of the ecotoxic potential of the heavy-metal immission for the region. By the principal component analysis a comparative evaluation of the spatial structure of all element contents is performed, which leads to conclusions about emission sources and the physicochemical behaviour of the elements.  相似文献   
220.
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