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   201篇
  免费   8篇
  国内免费   7篇
安全科学   34篇
废物处理   1篇
环保管理   31篇
综合类   79篇
基础理论   23篇
污染及防治   15篇
评价与监测   19篇
社会与环境   7篇
灾害及防治   7篇
  2023年   2篇
  2022年   5篇
  2021年   8篇
  2020年   14篇
  2019年   1篇
  2018年   3篇
  2017年   3篇
  2016年   6篇
  2015年   2篇
  2014年   8篇
  2013年   8篇
  2012年   12篇
  2011年   9篇
  2010年   10篇
  2009年   12篇
  2008年   8篇
  2007年   11篇
  2006年   15篇
  2005年   10篇
  2004年   8篇
  2003年   5篇
  2002年   8篇
  2001年   7篇
  2000年   3篇
  1999年   3篇
  1998年   4篇
  1997年   2篇
  1996年   3篇
  1995年   3篇
  1994年   3篇
  1993年   1篇
  1992年   2篇
  1991年   4篇
  1990年   1篇
  1988年   1篇
  1987年   2篇
  1986年   1篇
  1985年   3篇
  1984年   3篇
  1981年   1篇
  1979年   1篇
排序方式: 共有216条查询结果,搜索用时 156 毫秒
51.
勃利县钢铁厂炼铁车间,每年都要排出四万多立方米的急冷水萃矿渣,污染河流、吞食耕田,不能充分有效利用.然而利用钢铁厂碱度大于1.4的急冷水萃矿渣和勃利县的斜发沸石为主要成分,加入适量的有机和无机助剂,经过特殊工艺,复合制成的新型砂浆及混凝土的掺和料,无毒无味,充分利用了钢铁厂的废渣,变废为宝.用该掺和料配制的不同强度等级的抹面砂浆、砌筑砂浆,不仅可以大量取代水泥,降低工程造价,而且可以改变砂浆的和易性、保水性,提高砂浆的强度和耐久性.  相似文献   
52.
A multinational collaborative study during the summer of 1983 addressed organizational alternatives in natural systems management. Participants were particularly interested in ways different governments attempted to resolve the disparity between the interconnected quality of nature and the compartmentalized structure of bureaucracies. Five patterns of organization have evolved to meet this challenge: mission agencies managing ecosystems; independent or interagency central environmental units: environmental units within mission agencies; environmental components within central planning units; and regional superagencies. The systems developed by five nations—the United States, Korea, Malaysia, the Philippines, and Thailand—are analyzed and compared in terms of these five patterns.  相似文献   
53.
A network of air quality and weather monitoring stations was established under the System of Air Quality Forecasting and Research(SAFAR) project in Delhi. We report observations of ozone(O_3), nitrogen oxides(NO_x), carbon monoxide(CO) and particulate matter(PM_2.5and PM_(10)) before, during and after the Diwali in two consecutive years, i.e., November 2010 and October 2011. The Diwali days are characterised by large firework displays throughout India. The observations show that the background concentrations of particulate matter are between 5 and 10 times the permissible limits in Europe and the United States. During the Diwali-2010, the highest observed PM_(10) and PM_2.5mass concentration is as high as2070 μg/m~3 and 1620 μg/m3, respectively(24 hr mean), which was about 20 and 27 times to National Ambient Air Quality Standards(NAAQS). For Diwali-2011, the increase in PM_(10) and PM_2.5mass concentrations was much less with their peaks of 600 and of 390 μg/m~3 respectively, as compared to the background concentrations. Contrary to previous reports,firework display was not found to strongly influence the NO_x, and O_3 mixing ratios, with the increase within the observed variability in the background. CO mixing ratios showed an increase. We show that the large difference in 2010 and 2011 pollutant concentrations is controlled by weather parameters.  相似文献   
54.
Abstract:  Conservation efforts are only as sustainable as the social and political context within which they take place. The weakening or collapse of sociopolitical frameworks during wartime can lead to habitat destruction and the erosion of conservation policies, but in some cases, may also confer ecological benefits through altered settlement patterns and reduced resource exploitation. Over 90% of the major armed conflicts between 1950 and 2000 occurred within countries containing biodiversity hotspots, and more than 80% took place directly within hotspot areas. Less than one-third of the 34 recognized hotspots escaped significant conflict during this period, and most suffered repeated episodes of violence. This pattern was remarkably consistent over these 5 decades. Evidence from the war-torn Eastern Afromontane hotspot suggests that biodiversity conservation is improved when international nongovernmental organizations support local protected area staff and remain engaged throughout the conflict. With biodiversity hotspots concentrated in politically volatile regions, the conservation community must maintain continuous involvement during periods of war, and biodiversity conservation should be incorporated into military, reconstruction, and humanitarian programs in the world's conflict zones.  相似文献   
55.
Establishing protected areas is the primary goal and tool for preventing irreversible biodiversity loss. However, the effectiveness of protected areas that target specific species has been questioned for some time because targeting key species for conservation may impair the integral regional pool of species diversity and phylogenetic and functional diversity are seldom considered. We assessed the efficacy of protected areas in China for the conservation of phylogenetic diversity based on the ranges and phylogenies of 2279 terrestrial vertebrates. Phylogenetic and taxonomic diversity were strongly and positively correlated, and only 12.1–43.8% of priority conservation areas are currently protected. However, the patterns and coverage of phylogenetic diversity were affected when weighted by species richness. These results indicated that in China, protected areas targeting high species richness protected phylogenetic diversity well overall but failed to do so in some regions with more unique or threatened communities (e.g., coastal areas of eastern China, where severely threatened avian communities were less protected). Our results suggest that the current distribution of protected areas could be improved, although most protected areas protect both taxonomic and phylogenetic diversity.  相似文献   
56.
文章从万寿菊无土栽培技术要点出发,对万寿菊无土栽培技术进行简单的研究,力图筛选出万寿菊适于生产应用的栽培基质和营养液的配方,为研究万寿菊的无土栽培和应用提供理论依据。进而为花卉无土栽培提供科学依据,从而更好的保护土壤环境。  相似文献   
57.
In the electricity sector, innovation in large-scale storage is anticipated to reduce costs and improve performance. The effect on greenhouse gas emissions of lower storage costs depends on the interactions between storage and the entire grid. The literature has disagreed on the role of storage in reducing emissions. In this paper we present a stylized model, which suggests that the effect of storage costs on emissions depends on the supply responsiveness of both fossil and renewable generators. Under common conditions in the United States, lower storage costs are more likely to reduce emissions when wind investment responds to equilibrium electricity prices and when solar investment does not. Simulations of a computational model of grid investment and operation confirm these intuitions. Moreover, because of its effect on coal and natural gas–fired supply responsiveness, introducing a carbon dioxide emissions price may increase the likelihood that lower storage costs reduce emissions.  相似文献   
58.
Integration of environmental science in society is impeded by the large gap between science and policy that is characterised by weaknesses in societal relevance and dissemination of science and its practical implementation in policy. We analyse experiences from BONUS, the policy-driven joint Baltic Sea research and development programme (2007–2020), which is part of the European Research Area (ERA) and involves combined research funding by eight EU member states. The ERA process decreased fragmentation of Baltic Sea science and BONUS funding increased the scientific quality and societal relevance of Baltic Sea science and strengthened the science-policy interface. Acknowledging the different drivers for science producers (academic career, need for funding, peer review) and science users (fast results fitting policy windows), and realising that most scientists aim at building conceptual understanding rather than instrumental use, bridges can be built through strategic planning, coordination and integration. This requires strong programme governance stretching far beyond selecting projects for funding, such as coaching, facilitating the sharing of infrastructure and data and iterative networking within and between science producer and user groups in all programme phases. Instruments of critical importance for successful science-society integration were identified as: (1) coordinating a strategic research agenda with strong inputs from science, policy and management, (2) providing platforms where science and policy can meet, (3) requiring cooperation between scientists to decrease fragmentation, increase quality, clarify uncertainties and increase consensus about environmental problems, (4) encouraging and supporting scientists in disseminating their results through audience-tailored channels, and (5) funding not only primary research but also synthesis projects that evaluate the scientific findings and their practical use in society – in close cooperation with science users − to enhance relevance, credibility and legitimacy of environmental science and expand its practical implementation.  相似文献   
59.
Abstract: Biodiversity is too complex to measure directly, so conservation planning must rely on surrogates to estimate the biodiversity of sites. The species richness of selected taxa is often used as a surrogate for the richness of other taxa. Surrogacy values of taxa have been evaluated in diverse contexts, yet broad trends in their effectiveness remain unclear. We reviewed published studies testing the ability of species richness of surrogate taxa to capture the richness of other (target) taxa. We stratified studies into two groups based on whether a complementarity approach (surrogates used to select a combination of sites that together maximize total species richness for the taxon) or a richness‐hotspot approach (surrogates used to select sites containing the highest species richness for the taxon) was used. For each comparison of one surrogate taxon with one target, we used the following predictor variables: biome, spatial extent of study area, surrogate taxon, and target taxon. We developed a binary response variable based on whether the surrogate taxon provided better than random representation of the target taxon. For studies that used an evaluation approach that was not based on better than random representation of target taxa, we based the response variable on the interpretation of results in the original study. We performed a categorical regression to elucidate trends in the effectiveness of surrogate taxa with regard to each of the predictor variables. A surrogate was 25% more likely to be effective with a complementarity approach than with a hotspot approach. For hotspot‐based approaches, biome, extent of study, surrogate taxon, and target taxon significantly influenced effectiveness of the surrogate. For complementarity‐based approaches, biome, extent, and surrogate taxon significantly influenced effectiveness of the surrogate. For all surrogate evaluations, biome explained the greatest amount of variation in surrogate effectiveness. From most to least, extent, surrogate taxon, and target taxon explained the most variation after biome. Surrogate taxa were most effective in grasslands and in some cases boreal zones, deserts, and tropical forests; surrogate taxa also were more effective in studies examining larger areas. Herpetofauna were the most effective taxon as both surrogate and target when a richness‐hotspot approach was used; however, herpetofauna were analyzed in fewer studies, so this result is tentative. For complementarity approaches, taxa that are easy to measure and tend to have a large number of habitat specialists distributed collectively across broad environmental gradients (e.g., plants, birds, and mammals) were the most effective surrogates.  相似文献   
60.
Stakeholder participation is considered a key principle for sustainable development in the context of natural resource and disaster risk management. Participatory modelling (PM) is an interactive and iterative process in which stakeholder involvement is supported by modelling and communication tools. Planning and decision-making for sustainable development (SD)integrate three substantive dimensions − social, ecological and economic. The procedural dimension of SD, however, is equally important, and here we see great potential for PM. In this study, we evaluate five PM research projects against criteria for the procedural dimension of SD. This provides a basis for identifying key issues and needs for further research into PM for SD. While the cases show great potential, especially for supporting knowledge integration, learning and transparent handling of values and perspectives, they indicate a particular need to develop PM in respect of organizational integration. This issue is closely connected to the possibility of effectively implementing PM in practice.  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