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   163篇
  免费   1篇
  国内免费   6篇
安全科学   11篇
废物处理   3篇
环保管理   25篇
综合类   33篇
基础理论   43篇
污染及防治   38篇
评价与监测   8篇
社会与环境   7篇
灾害及防治   2篇
  2023年   4篇
  2022年   2篇
  2021年   2篇
  2020年   3篇
  2019年   3篇
  2018年   2篇
  2017年   3篇
  2016年   14篇
  2015年   7篇
  2014年   8篇
  2013年   19篇
  2012年   8篇
  2011年   12篇
  2010年   7篇
  2009年   10篇
  2008年   12篇
  2007年   6篇
  2006年   8篇
  2005年   7篇
  2004年   7篇
  2002年   2篇
  2001年   2篇
  1999年   2篇
  1998年   4篇
  1997年   1篇
  1996年   2篇
  1995年   3篇
  1993年   1篇
  1992年   1篇
  1991年   2篇
  1990年   1篇
  1989年   2篇
  1981年   2篇
  1958年   1篇
排序方式: 共有170条查询结果,搜索用时 15 毫秒
91.
Previous research has shown that plant diversity influences N and P cycles. However, the effect of plant diversity on complete ecosystem N and P budgets has not yet been assessed. For 20 plots of artificially established grassland mixtures differing in plant diversity, we determined N and P inputs by bulk and dry deposition and N and P losses by mowing (and subsequent removal of the biomass) and leaching from April 2003 to March 2004. Total deposition of N and P was 2.3 +/- 0.1 and 0.2 +/- 0.01 g m(-2) yr(-1), respectively. Mowing was the main N and P loss. The net N and P budgets were negative (-6.3 +/- 1.1 g N and -1.9 +/- 0.2 g P m(-2) yr(-1)). For N, this included a conservative estimate of atmospheric N(2) fixation. Nitrogen losses as N(2)O were expected to be small at our study site (<0.05 g m(-2) yr(-1)). Legumes increased the removal of N with the harvest and decreased leaching of NH(4)-N and dissolved organic nitrogen (DON) from the canopy. Reduced roughness of grass-containing mixtures decreased dry deposition of N and P. Total dissolved P and NO(3)-N leaching from the canopy increased in the presence of grasses attributable to the decreased N and P demand of grass-containing mixtures. Species richness did not have an effect on any of the studied fluxes. Our results demonstrate that the N and P fluxes in managed grassland are modified by the presence or absence of particular functional plant groups and are mainly driven by the management.  相似文献   
92.
Currently, there is no nationally representative human milk biomonitoring program in the United States (U.S.) and no studies have reported non-persistent pesticides in the milk of U.S. women. In this pilot study we developed a multiresidue laboratory method to measure non-persistent and persistent pesticides and polychlorinated biphenyl (PCB) congeners in human milk samples from women residing in the agricultural region of Salinas, CA (n = 13) and the urban San Francisco Bay Area, CA (n = 21). Samples were collected from 2002-2007. Median concentrations in pg g(-1) milk among urban and agricultural women, respectively were reported for: chlorpyrifos (24.5 and 28.0), cis-permethrin (81.9 and 103), trans-permethrin (93.1 and 176), hexachlorobenzene (191 and 223), β-hexachlorocyclohexane (220 and 443), o,p'-DDT (36.6 and 62.4), p,p'-DDT,(107 and 102), o,p'-DDE (5.65 and 5.17), p,p'-DDE (3170 and 3490), dacthal (2.79 and 3.43), PCB 118 (92.8 and 17.0), PCB 138 (183 and 38.2), PCB 153 (242 and 43.6) and PCB 180 (239 and 683). Among urban women, median concentrations were 4.02 and 4.32 pg g(-1) milk for chlorpyrifos-methyl and propoxur, respectively. These results suggest that neonates and young children may be exposed to persistent and non-persistent pesticides and PCBs via breast milk.  相似文献   
93.
Environmental Chemistry Letters - Microplastics are of rising health concerns because they have been detected even in remote and pristine environments, from the Artic snow to the Marianne Trench....  相似文献   
94.
Fluorinated compounds (FC) are high-global warming potential (GWP) greenhouse gases used and emitted during the manufacture of silicon semiconductor devices. Following the U.S. EPA's PFC Emissions Vintage Model (PEVM), uncontrolled FC emissions are modeled as proportional to total manufactured layer area (TMLA) of silicon. FC emissions of World Semiconductor Council (WSC) charter member countries (Europe, Japan, Korea, Taiwan and the United States), which voluntarily committed in 1999 to lower FC emissions by 2010 to 10% of baseline year emissions, are modeled for the period 1995–2020. For this same period, emissions from Chinese manufacturers under alternative emission reduction scenarios are modeled. If Chinese manufacturers were to adopt a baseline year of 2005 and a reduction target of 10% below baseline year emissions to be achieved by 2020, emissions would be 3.4 MMTCO2eq, comparable to the similarly projected controlled emissions of an average WSC charter member country (=16.3/5 MMTCO2eq) in 2020. The relative stringency of the alternative reduction scenarios considered for China vary between 50 and 95% reduction compared to business as usual (BAU). This is comparable to the stringency of the WSC charter members’ goals for which FC emission reduction technologies are currently available.  相似文献   
95.
臭氧与活性炭结合对水中有机物去除的研究   总被引:2,自引:0,他引:2  
阐明了臭氧及活性炭去除有机物的作用,以及在水处理中应用的现状。将臭氧,活性炭及臭氧-活性炭应用到水处理中,臭氧对水中的UV254、COD、TOC去除率分别为14.3%、12.5%、17%,活性炭对UV254、COD、TOC去除率分别为60.5%、52.7%、50.8%,臭氧-活性炭联合运用对水中UV254、COD、TOC去除率分别为66.8%、58.3%、65%。臭氧与活性炭的结合工艺有较好的去除效果。  相似文献   
96.
Prenatal diagnosis of mosaicism involving an apparently unstable 13/14 Robertsonian trans-location is reported. This illustrates the difficulties encountered in counselling when mosaicism is ascertained prenatally. Other reported examples of apparently unstable Robertsonian translocations are discussed.  相似文献   
97.
The aim of this study was to examine the relationship between workaholism and mental health among 126 Polish academic workers. The participants' mean age was 45.9 years, 51.6% of them were women. The participants completed 2 questionnaires: the work addiction risk test and the general health questionnaire. Even though 66% of the subjects were classified in the group of moderate-to-high risk of workaholism, the overall state of mental health was categorized as average. The results revealed that workaholism was associated with poorer mental health. Employees with higher levels of workaholism had worse state of health, i.e., more somatic symptoms, higher levels of anxiety, insomnia, social dysfunction and symptoms of depression. Emotional arousal/perfectionism was the strongest predictor of the state of general health and was mostly responsible for harmful effects on mental health. However, the general effect of workaholism on health was not as strong as expected.  相似文献   
98.
99.
ABSTRACT: We investigated the effect of technical clarity on success in multi-party negotiations in the Federal Energy Regulatory Commission (FERC) licensing process. Technical clarity is the shared understanding of dimensions such as the geographic extent of the project, range of flows to be considered, important species and life stages, and variety of water uses considered. The results of four hydropower licensing consultations are reported. Key participants were interviewed to ascertain the level of technical clarity present during the consultations and the degree to which the consultations were successful. Technical clarity appears to be a prerequisite for successful outcomes. Factors that enhance technical clarity include simple project design, new rather than existing projects, precise definition of issues, a sense of urgency to reach agreement, a sense of fairness among participants, and consistency in participation. Negotiators should not neglect the critical pre-negotiation steps of defining technical issues and determining appropriate studies, deciding how to interpret studies, and agreeing on responses to study results.  相似文献   
100.
The purpose of this study is to offer an analysis of how two UN Conferences of Parties, COP15 in Copenhagen 2009 and COP21 in Paris 2015, were covered and debated in Swedish newspapers. Two national and two regional newspapers were selected for the study, and a qualitative frame analysis was conducted on 309 articles. A typology of frames applicable to science-related policy and climate change debates was used and its relevance for global climate summit context was discussed. Having territory in the Arctic region, indigenous populations affected by climate change measures, and political and public sensitivity to environmental issues, the climate debate has particular significance in the Swedish case. Findings indicate a trust in the role of national and supra-national governance to address climate change problems, but also that newspapers in Sweden maintained a focus on the global aspects of the two meetings, rather than framing them as surrogate battlefields for domestic politics.  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