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   901篇
  免费   7篇
安全科学   35篇
废物处理   31篇
环保管理   86篇
综合类   175篇
基础理论   253篇
环境理论   1篇
污染及防治   209篇
评价与监测   67篇
社会与环境   46篇
灾害及防治   5篇
  2023年   4篇
  2021年   9篇
  2020年   10篇
  2019年   5篇
  2018年   18篇
  2017年   33篇
  2016年   23篇
  2015年   22篇
  2014年   21篇
  2013年   47篇
  2012年   34篇
  2011年   48篇
  2010年   35篇
  2009年   33篇
  2008年   53篇
  2007年   53篇
  2006年   46篇
  2005年   26篇
  2004年   24篇
  2003年   38篇
  2002年   31篇
  2001年   20篇
  2000年   28篇
  1999年   12篇
  1998年   5篇
  1997年   6篇
  1996年   8篇
  1995年   15篇
  1994年   9篇
  1993年   14篇
  1992年   9篇
  1991年   8篇
  1990年   5篇
  1989年   7篇
  1988年   9篇
  1987年   8篇
  1986年   5篇
  1985年   7篇
  1984年   14篇
  1983年   4篇
  1982年   8篇
  1981年   10篇
  1980年   9篇
  1979年   17篇
  1978年   9篇
  1977年   13篇
  1976年   12篇
  1975年   9篇
  1974年   3篇
  1968年   2篇
排序方式: 共有908条查询结果,搜索用时 15 毫秒
41.
Systematic geochemical mapping based on sampling and analysis of surface soils (0–2 cm) has been carried out in several Norwegian cities. The soils in the oldest parts of the cities are contaminated with metals (especially Pb) and polycyclic aromatic hydrocarbons (PAH). Due to the fact that children are often in contact with surface soil, it was realized that special focus had to be directed towards soils in day-care centers and playgrounds. The first mapping and remedy program was initiated in Trondheim in 1996. Here, the importance of copper–chromium–arsenic (CCA)-pressure-impregnated wood in playing equipment as a pollution source for soils was documented, and a process was started with the aim to ban this product. Soils from day-care centers in the inner city of Bergen were polluted to a degree that required remediation in 45% out of 87 centers, mainly due to high concentrations of Pb and benzo(a)pyrene. In Oslo, 38% of 700 day-care centers needed remediation due to soil pollution by Pb, BaP, Cd, Hg, Ni and PCB. Removal of CCA-impregnated wood was necessary in more than half of the day-care centers The Norwegian parliament has decided to investigate all outdoor playing areas in day-care centers, playgrounds and schoolyards in Norway, starting in 2007 with day-care centers in the ten largest cities and five most important industrial areas. The Norwegian Institute of Public Health has developed quality criteria for soils in day-care centers and playgrounds for As, Cd, Cr6+, Hg, Ni, Pb, zinc, PAHsum16, benzo(a)pyrene, and PCBsum7. The Geological Survey of Norway has developed guidance for mapping of soil pollution (sampling, chemical analysis and reporting) in day-care centers. Especially the sampling strategy has been developed in the period 1996–2007, and the preferred sampling strategy is to collect at least 10 samples of surface soil (0–2 cm) from (1) “original soil” on the site, (2) artificial man-made “hills”, and (3) soils used for growing vegetables. A total number of 2,000 day-care-centres are to be investigated, and necessary remediation should be completed before the end of 2010.  相似文献   
42.
43.
Global climate change is expected to severely impact Arctic ecosystems, yet predictions of impacts are complicated by region-specific patterns and nonuniform trends. Twentyfour open-water overwintering areas (or "microhabitats") were identified to be of particular importance for eight seabird and marine mammal species in the eastern Canadian High Arctic and Baffin Bay. Localized trends in the available fraction of open-water were examined in March during 1979--2001, derived from approximate sea ice concentrations from satellite-based microwave telemetry. Declines in the fraction of open-water were identified at microhabitats in Baffin Bay, Davis Strait, coastal West Greenland, and Lancaster Sound. Increases in open-water were observed in Hudson Bay, Hudson Strait, and Foxe Basin. The biological importance of each microhabitat was examined based on species distribution and abundance. Potential consequences of reduced open-water for top marine predators include impacts on foraging efficiency and oxygen and prey availability.  相似文献   
44.
The mercury-based gold extraction processes prevalent within small-scale mining are both efficient and harmful. While ensuring relatively high levels of gold recovery, they cause environmental and health problems for people living within mining settlements. This mercury consumption can be minimized by using a simple mercury recycling device known as a retort. While mining legislation in Tanzania dictates the use of retorts for gold recovery, virtually no miners use them, indicating the inadequacy of previous introduction attempts. During action research, retorts were introduced in two mining settlements through a thorough and participatory approach. Twenty miners were given retorts and their attitudes and receptiveness to them were studied. Of the recipients, 18 used the retorts over a period of five months, recycling 10 kilos of mercury. Less mercury was spilled into the environment and miners saved money normally spent on purchasing mercury. The findings have implications for the strategies of development interventions targeting mercury-instigated problems within small-scale gold mining.  相似文献   
45.
46.
Summary Territorial male yellow-headed blackbirds that were dyed solid black were similar to controls in their ability to attract mates. They also had no difficulty in defending their territories from floating males. The only remarkable effect of this dramatic color manipulation was that five of the 12 blackened males that regained a territory after being dyed also later took over the better quality territory of another male. Not one of the 11 control males that regained a territory succeeded in such an eviction. This surprising result is interpretable under the theory that conspicuous and distinctive coloration sometimes evolves as an arbitrary recognition badge by making good fighters more memorable to their opponents. With insight gained from these results, we modify and considerably expand the theoretical treatment of this Arbitrary Identity Badge Hypothesis. We also explain why our results for yellow-headed blackbrids should differ so dramatically from those for red-winged blackbirds where blackened males often lost their territories to floating males.  相似文献   
47.
48.
A study was undertaken to establish the role of free amino acids (FAA) in aerobic energy dissipation in embryos of turbot (Scophthalmus maximus) which contain an oil globule in the egg. Laboratory-reared developing eggs and larvae (15°C, 34 salinity) were measured for oxygen uptake, ammonia excretion, contents of FAA, protein, and ammonium, and volumes of yolksac and oil globule. Newly spawned eggs from different batches contained 55 to 90 nmol egg–1 of FAA. Resorption of FAA occurred in parallel with the consumption of yolk. Resorption of the oil globule, however, occurred predominantly after hatching and mainly after yolk resorption. The combined data suggest that approximately 70% of the FAA are utilized as an energy substrate, while the rest are polymerized into body proteins. FAA become a significant energy substrate in the early egg stage and account for 100% of the aerobic energy dissipation 2 d after Fertilization then decrease to ca. 60% at the time of hatching. Lipids derived from the oil globule seem to be the main fuel after hatching and account for ca. 90% of the energy dissipation at the onset of first-feeding. Thus, the energetics of fish embryos which contain an oil globule seems to be different from those that depend exclusively on the nutritional reserves of the yolk.  相似文献   
49.
The 137Cs activity of salt marsh and tidal flat sediments of the northern part of the European Wadden Sea was studied based on a comprehensive dataset of 210Pb dated cores. The 137Cs inventory of salt marsh sediments shows a major peak corresponding to the Chernobyl accident in 1986, and a minor peak located in the late 1960s interpreted as the combined effect of atmospheric testing of nuclear weapons. Emissions from the nuclear reprocessing plant Sellafield are not reflected as peaks in 137Cs activity, but may contribute to the rising 137Cs activity in the years prior to 1986. The 137Cs activity of tidal flat sediments differs from salt marsh sediment in two respects. First, the activity is much lower and, second, the major peak in the 1980s is located in the beginning instead of in the middle of the decade. The differences in 137Cs inventory between the two environments are interpreted to result from repeated cycles of deposition/resuspension and mixing on tidal flats. A simple model illustrating the consequence of mixings returns an apparent shift of major peaks in 137Cs activities backwards in time corresponding to the mixing depth divided by the deposition rate.  相似文献   
50.
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