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   353篇
  免费   6篇
安全科学   10篇
废物处理   11篇
环保管理   17篇
综合类   127篇
基础理论   66篇
污染及防治   92篇
评价与监测   18篇
社会与环境   15篇
灾害及防治   3篇
  2023年   2篇
  2022年   7篇
  2021年   2篇
  2020年   6篇
  2019年   4篇
  2018年   10篇
  2017年   13篇
  2016年   18篇
  2015年   26篇
  2014年   19篇
  2013年   33篇
  2012年   26篇
  2011年   29篇
  2010年   10篇
  2009年   11篇
  2008年   28篇
  2007年   19篇
  2006年   13篇
  2005年   10篇
  2004年   19篇
  2003年   13篇
  2002年   10篇
  2001年   6篇
  2000年   2篇
  1999年   1篇
  1998年   2篇
  1995年   2篇
  1994年   6篇
  1993年   4篇
  1992年   3篇
  1990年   1篇
  1988年   1篇
  1983年   1篇
  1982年   1篇
  1981年   1篇
排序方式: 共有359条查询结果,搜索用时 15 毫秒
131.
132.
A therapeutic abortion was conducted on a 17-week-old male fetus with a large umbilical cord teratoma associated with an exomphalos. A review of the literature revealed ten other cases of umbilical cord teratoma and shows that these tumors have a very polymorphic presentation. Four fetuses and infants died from various causes indicating that there is a need for close follow-up of pregnancies with umbilical cord teratoma. Copyright © 2001 John Wiley & Sons, Ltd.  相似文献   
133.
134.
Environmental Science and Pollution Research - Particulate matters with a diameter of less than 10 µm (PM10) or less than 2.5 µm (PM2.5) are major air pollutants. Their...  相似文献   
135.
Building waste recycling as aggregates is a modern approach for preventing environmental pollution through both reducing the stocks of waste and decreasing the use of natural aggregates. The reuse of building waste is a relatively new issue for Bulgaria despite the existing considerable quantity of building waste and the significant changes in the environmental rules applied. The paper discusses generated and potential waste streams in Bulgaria in the context of the social and economic restructuring and recent urban development undergone by the country. The main preliminary conditions for developing the recycling activity such as: streams of building waste, experience in recycling, technical and environmental standardization, appropriate technologies, etc. are examined. The authors analyze current practice and research activities with regard to the implementation of advanced EU building-waste recycling methods. Conclusions are drawn about existing opportunities and the priorities of the needed building waste management strategy in the country.  相似文献   
136.
137.
Two populations of Laminaria digitata (Hudson) Lamouroux (Ann Mus Hist Nat Paris 20:21–47, 1813) were examined for their seasonal photosynthetic acclimation to clear and turbid-light environments along the French coast of the English Channel. Photosynthesis–irradiance curves, pigment concentrations and the daily in situ integrated oxygen production rates were measured in both populations. Despite the great differences in light attenuation between the sites, the two populations achieved similar oxygen production rates in the field, in relation to high maximal photosynthetic rates, total pigment concentrations and antenna (fucoxanthin + chlorophyll c)/chl a pigment ratios in sporophytes from the turbid environment. Environmental conditions (i.e. light, temperature and nitrogen availability) changed throughout the year in both sites. While the seasonal acclimation trends were evident in the clear-light environment, the strategy in the turbid-light environment differed, tending to maximize light capture throughout the year. This study highlights the diversity of the response of a single species to contrasted light environments.  相似文献   
138.
Short-term changes in phytoplankton photosynthetic activity were studied during different periods of the years 2009 and 2010 in the coastal waters of a macrotidal ecosystem (the Strait of Dover, eastern English Channel). During each sampling period, samples were taken every 1.45 h., from sunrise to sunset, during at least 5 days distributed along a complete spring–neap tide cycle. The photosynthetic parameters were obtained by measuring rapid light curves using pulse amplitude modulated fluorometry and were related to environmental conditions and phytoplankton taxonomic composition. The maximum quantum yield (F v/F m) showed clear light-dependent changes and could vary from physiological maxima (0.68–0.60) to values close to 0.30 during the course of 1 day, suggesting the operation of photoprotective mechanisms. The maximum electron transport rate (ETRm) and maximal light utilization efficiency (α) were generally positively correlated and showed large diel variability. These parameters fluctuated significantly from hour to hour within each day and the intraday pattern of variation changed significantly among days of each sampling period. Stepwise multiple linear regressions analyses indicated that light fluctuations explained a part of this variability but a great part of variability stayed unexplained. F v/F m, ETRm and α were not only dependent on the light conditions of the sampling day but also on those of the previous days. A time lag of 3 days in the effect of light on ETRm and α variation was highlighted. At these time scales, changes in phytoplankton community structure seemed to have a low importance in the variability in photosynthetic parameters. The photoacclimation index E k showed a lower variability and was generally different from the incident irradiance, indicating a limited acclimation capacity with a poor optimization of light harvesting during the day. However, in well-mixed systems such as the Strait of Dover, the short-term photoacclimation is disrupted by the high level of variability in environmental conditions. Also, the variability observed in the present study can be associated with a particular kind of photosynthetic response: the “E k-independent” variability. The physiological basis of this photosynthetic response is largely unresolved and further researches on this subject are still required to better explain the dynamics of phytoplankton activity in the Strait of Dover.  相似文献   
139.
The purpose of this blinded study was to evaluate potential environmental toxicity in a cohort of neurotypical children (n = 28) living in a suburban area of north-central Texas in the United States (US) with a comparable age- and gender-matched cohort of neurotypical children (n = 28) living in a suburban area of southeastern France using urinary porphyrin testing: uroporphyrin (uP), heptacarboxyporphyrin (7cxP), hexacarboxyporphyrin (6cxP), pentacarboxyporphyrin (5cxP), precoproporphyrin (prcP), and coproporphyrin (cP). Results showed significantly elevated 6cxP, prcP (an atypical, mercury-specific porphyrin), and cP levels, and increasing trends in 5cxP levels, among neurotypical children in the USA compared to children in France. Data suggest that in US neurotypical children, there is a significantly increased body-burden of mercury (Hg) compared to the body-burden of Hg in the matched neurotypical children in France. The presence of lead contributing to the higher levels of cP also needs to be considered. Further, other factors including genetics can not be completely ruled out.  相似文献   
140.
This work investigates the ecotoxicological evaluation of contaminated dredged sediments from French Mediterranean navy harbour (A), commercial port (B) and two composite specimens (C) and (D) coming from the mixture of A and B with other port sediments. The toxicity of elutriates from these sediments is estimated using embryo-toxicity test, Microtox® solid phase test, LuminoTox, phytotoxicity tests and genotoxicity test. Bioassay responses are not clearly correlated with chemical contamination in the whole sediment and vary as a function of tested organisms. The highest contaminated samples (A and C) are almost always more toxic than the less contaminated samples (B and D). Among composite sediments, the mixture effect with other sediments is not efficient to decrease toxicity in sample C, suggesting that other parameters influence toxicity level such as particle size or organic matter content. These parameters should be taken into consideration in order to improve the efficiency of the mixture process and produce composite sediments with low toxicity.  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