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   309篇
  免费   1篇
  国内免费   11篇
安全科学   10篇
废物处理   11篇
环保管理   26篇
综合类   30篇
基础理论   45篇
污染及防治   149篇
评价与监测   33篇
社会与环境   16篇
灾害及防治   1篇
  2023年   11篇
  2022年   37篇
  2021年   27篇
  2020年   11篇
  2019年   15篇
  2018年   9篇
  2017年   19篇
  2016年   18篇
  2015年   6篇
  2014年   14篇
  2013年   27篇
  2012年   6篇
  2011年   16篇
  2010年   7篇
  2009年   8篇
  2008年   11篇
  2007年   9篇
  2006年   8篇
  2005年   7篇
  2004年   10篇
  2003年   8篇
  2002年   2篇
  2001年   3篇
  2000年   4篇
  1999年   1篇
  1998年   2篇
  1996年   1篇
  1995年   1篇
  1994年   1篇
  1993年   1篇
  1991年   1篇
  1990年   1篇
  1988年   1篇
  1985年   2篇
  1983年   3篇
  1982年   2篇
  1981年   2篇
  1979年   4篇
  1977年   2篇
  1975年   1篇
  1974年   1篇
  1961年   1篇
排序方式: 共有321条查询结果,搜索用时 109 毫秒
131.
132.
Ultrasonography was performed during the second trimester (17 weeks) in a pregnancy at risk for osteogenesis imperfecta congenita (OI). The scan showed that the femur was short, bent and dense. Radiologic examination of the fetus after interruption of pregnancy showed typical X-ray changes of OI.  相似文献   
133.
Vicia faba as a bioindicator of oil pollution   总被引:3,自引:0,他引:3  
In 1990, the Gulf War caused an unprecedented environmental catastrophe. More than 700 oil wells were set on fire, emitting thousands of tons of oxides of nitrogen, sulfur, soot and oil mist at high temperatures. The blazing oil wells and lakes were the major cause of environmental pollution, damaging flora and fauna throughout Kuwait and the surrounding region. We set up this study in order to investigate whether Vicia faba could be used as a bioindicator of oil pollution. Growth parameters of Vicia faba, such as levels of photosynthetic pigments, proteins, free amino acids, phenols, sugars, biomass, moisture and fatty acids, were studied. Levels of total reducible sugars, phenols, proteins, free amino acids and proline were found to be higher in plants grown in hydrocarbon-polluted soil, compared to those grown in control soil. However, biomass, moisture, pheophytin, the 435/415 nm ratio for chlorophylls and the chlorophyll a/carotenoid ratio, were higher in the plants grown in control soil than those grown in polluted soil. Our results indicate that Vicia faba can be used as a bioindicator of pollution and a ratio of the fatty acid C(20:1)/C(18:1) is an important index of environmental oil pollution.  相似文献   
134.
Chlorpyrifos (an insecticide) and chlorothalonil (a fungicide) are transported in stormwater runoff and can be lethal to receiving aquatic system biota. This study determined removal rates of chlorpyrifos and chlorothalonil in simulated stormwater runoff treated in constructed wetland mesocosms. Using sentinel species, Ceriodaphnia dubia and Pimephales promelas, observed declines in toxicity of the simulated runoff after treatment were 98 and 100%, respectively. First order removal rates were 0.039/h for chlorpyrifos and 0.295/h for chlorothalonil in these experiments. Constructed wetland mesocosms were effective for decreasing concentrations of chlorpyrifos and chlorothalonil in simulated stormwater runoff, and decreasing P. promelas and C. dubia mortality resulting from these exposures. The results from this study indicate that constructed wetlands could be part of an efficient mitigation strategy for stormwater runoff containing these pesticides.  相似文献   
135.
Prediction models relating pheromone trap catches of (H) with several onvironmental factors are worked out. It is expected that those models will help overcome indiscriminate use of pesticides.  相似文献   
136.
Glycolic acid is a known algal excretory product which is found in marine waters and is readily metabolized by marine bacteria. The following parameters were measured over the course of a year in Ipswich Bay: chlorophyll a, temperature, viable bacteria, heterotrophic uptake of glycolate, and glycolate concentrations. The latter two were combined to give estimates of the flux of glycolate for a station 3 km out in the bay and for an inshore station. Pronounced seasonal changes were found for all parameters. Statistically significant correlations between heterotrophic V max and glycolic acid concentrations and temperature were found, but not between planktonic chlorophyll a and any of the other parameters. Measurements of glycolic acid flux yielded an annual flux of 2.84 g m-2 for the bay station, which is about 0.5% of the bay phytoplankton production. Glycolic acid turns over roughly 12 times per year in the bay. It contributes perhaps as much to bacterial metabolism as any other single substrate, but is apparently not of dominating importance.  相似文献   
137.
The correlation study of secondary aerosol (nitrate and sulfate) with RPM in ambient air at different traffic junctions of Vadodara city is reported. RPM was analyzed using Ion Chromatography technique and measured the level of nitrate and sulfate in ambient air. The correlation studies of these particulates with RPM have been established. The average concentration of sulfate and nitrate in ambient air was found 35.74 microg/m3 and 24.22 microg/m3, which ranged of 5.33-84.69 and 1.93-77.86 microg/m3 respectively. The correlation of RPM and SO4 (r = 0.813, P<0.01), RPM-NO3 (r = 0.5549, P<0.01) and SO4-NO3 (r = 0.6133, P<0.01) were found significant. The presence of sulfate and nitrate in RPM is 8.25% and 5.60% . The pH of water extract of RPM averaged 6.81, which ranged 6.17-7.28. Regression analysis result showed that the relationship between RPM-SO4 was significantly (R2=0.66215) correlated. This indicate that probably the secondary aerosols such as nitrate and sulfate in excess may cause irritation and increasing lung disease.  相似文献   
138.
Glycolic acid, a known algal excretory product, represents a potentially important energy source for heterotrophic bacteria in marine waters. Measurements of heterotrophic uptake and mineralization by the natural microbes in the plankton indicate quantitative use of glycolic acid comparable to other common microbial substrates. This activity shows vertical and horizontal variations that correlate in a general way with primary productivity. Glycolic acid appears to be present at higher concentrations than other low molecular weight substrates, and it also shows a lower rate of turnover. It is mineralized (respired) to a greater extent than other recorded substrates, an average of 70% of total uptake. Two-thirds of a total of 141 colonies of bacteria cultured from seawater on marine agar proved capable oftaking up and respiring glycolic acid. These same bacteria, however, were unable to utilize glycolic acid for growth when it was the sole carbon source. Glycolate may therefore occur at higher concentrations and show erratic fluctuations in natural waters because microbial use is not tied to glycolate production but to the presence of other substrates. The fact that so many bacteria are able to metabolize it indicates a possibly important trophic role as an energy source. It is suggested that glycolic acid may be a major source of energy for active transport of other substrates by marine bacteria.  相似文献   
139.
140.
Environmental Science and Pollution Research - This study evaluates the characteristics of water along the Swat River, Northern Pakistan. For this purpose, water samples (n = 30) were...  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