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   710篇
  免费   33篇
  国内免费   30篇
安全科学   32篇
废物处理   2篇
环保管理   295篇
综合类   148篇
基础理论   140篇
环境理论   1篇
污染及防治   35篇
评价与监测   49篇
社会与环境   59篇
灾害及防治   12篇
  2024年   1篇
  2023年   4篇
  2022年   11篇
  2021年   13篇
  2020年   20篇
  2019年   13篇
  2018年   18篇
  2017年   20篇
  2016年   27篇
  2015年   15篇
  2014年   26篇
  2013年   44篇
  2012年   28篇
  2011年   46篇
  2010年   32篇
  2009年   52篇
  2008年   48篇
  2007年   53篇
  2006年   41篇
  2005年   24篇
  2004年   20篇
  2003年   15篇
  2002年   17篇
  2001年   19篇
  2000年   19篇
  1999年   15篇
  1998年   11篇
  1997年   7篇
  1996年   8篇
  1995年   13篇
  1994年   10篇
  1993年   6篇
  1992年   6篇
  1991年   7篇
  1990年   1篇
  1989年   7篇
  1988年   3篇
  1987年   10篇
  1986年   8篇
  1985年   4篇
  1984年   3篇
  1983年   2篇
  1982年   5篇
  1981年   3篇
  1980年   8篇
  1979年   5篇
  1978年   4篇
  1973年   1篇
排序方式: 共有773条查询结果,搜索用时 46 毫秒
31.
Land use in the Chittagong Hill Tracts (CHT) of Bangladesh had undergone changes over the past several centuries. The landscape, which was mostly covered with forest with interspersed shifting cultivation plots until the beginning of the colonial period, has gradually changed into a landscape with a blend of land uses. Overall, the forest area has gradually declined, while the area under shifting cultivation and sedentary agriculture has expanded. The process of the change was multi-directional. National forestry, land use, land taxation, population migration policies, and development activities, such as construction of a hydroelectric dam and roads, played an important role in this process. Shifting cultivation had inflicted little damage on the forest until the beginning of the colonial period. The pace of deforestation accelerated with the nationalization of forests which abolished tribal people's customary use and management rights to the forest, and allowed large-scale commercial logging both legally and illegally. The pace was further intensified by the policy encouraging population migration to CHT and construction of a reservoir on the Karnafuli River. Efforts were made to replace shifting cultivation with more productive types of sedentary agriculture. However, much change could not take place in the absence of secure land rights, supportive trade policies, and the required support services and facilities, including infrastructure. Locationally suitable land use evolved in areas where transportation facilities were available and farmers were granted land title with the necessary extension services and credit facilities. These findings have important policy implications for the promotion of environmentally and economically sound land use in CHT.  相似文献   
32.
杨静 《环境与发展》2020,(1):238-239
在第二次全国污染源普查的基础上,利用污染源普查期间配置的软硬件,开发市级区域环境污染源管理平台,进行污染源数据的年度更新,拓展污染源普查软件应用,实现环境管理及环境执法移动终端的应用。拓展二污普一张图的功能,利用移动客户端机动实时及地定位导航等为环境管理执法和环境突发事件应急处置提供技术支持。  相似文献   
33.
随着国民经济的快速发展,我国人民的生活水平和质量也随之而提高,对于生态环境以及居住环境的要求也相应提升。水是万物之源,是保障人们生产生活的基本要素之一,为了有效提升水环境质量,先进的水环境监测技术必不可少。随着科学技术的飞速发展,水环境监测技术也在不断调整和优化,逐渐向信息化方向发展,在生态环境保护工作中发挥着不可替代的作用。本文将详细阐述现阶段我国在水环境监测工作中实施的信息化新技术,希望能为相关研究人员提供参考和借鉴。  相似文献   
34.
能源环境管理是各界关注的热点话题,也是科学研究的重要方向.以国家自然科学基金资助能源环境管理领域的科研项目为基础数据信息,本文重点分析了"十三五"期间国家自然科学基金在该领域资助项目的总体特征、研究主题和热点变化,并结合新时代科学基金资助导向提出了可能的发展趋势.主要结论包括:①能源环境管理领域面上、青年、地区等自由探索类项目的立项绝对数和学科占比均呈上升趋势,并更多向青年学者倾斜,资助强度保持稳定;②碳、能源和环境是自由探索项目中出现频率最高的热词,与之相关的研究主题随着政策等调整具有动态变化特征;③能源环境管理领域重点、重大等引导类项目和优青、杰青、创新研究群体等人才类项目不断实现突破,增速明显,学科占比优势突出;④问题导向与本土情景、理论体系和一般规律、学科交叉融合,以及市场和微观主体作用是研究选题确立与项目申请时可能需要重点关注的方向.  相似文献   
35.
Extremely high concentrations of cadmium (3.5 μg/g dry wgt.) and elevated concentrations of chromium (>10 μg/g dry wgt.) and mercury (1.6 μg/g dry wgt.) were reported in waterbird tissues at Agassiz National Wildlife Refuge in northwestern Minnesota in 1994. Tree swallows (Tachycineta bicolor) were studied during 1998–2001 at three drainages into the Refuge, two pools on the Refuge, and at a nearby reference location to document whether high levels of contaminants were still present, and if so to quantify the source and severity of the contamination. Trace elements were measured in tree swallow eggs, livers, and diet. Reproductive success and bioindicator responses were monitored. In 2000, water was drawn down on Agassiz Pool, one of the main pools on the Refuge. This presented an opportunity to evaluate the response of trace element concentrations in the diet and tissues of tree swallows after reflooding. High concentrations of trace elements were not detected in swallow tissues, nor were there differences among locations. Less than 20% of swallow samples had detectable concentrations of cadmium or chromium. Mercury concentrations were low and averaged <0.25 μg/g dry wgt. in swallow tissues. Trace elements, including mercury, did not increase in tree swallows following the 2000 drawdown at Agassiz Pool. Hatching success and survival of nestlings to 12 days-of-age for tree swallows on the Refuge were similar to the national average and consistent with background trace element concentrations. Bioindicator measurements were within the normal ranges as well.  相似文献   
36.
随着中国共产党第十九次全国代表大会的顺利召开,环保"大部制"改革、环境监测垂直管理制度改革以及国家"大气十条""水十条""土十条"的全面实施均对生态环境保护、环境监测乃至环境质量综合分析工作提出了新要求。新形势下,环境质量综合分析应与时俱进、开拓创新,进一步优化工作机制,加强系统分析,增强综合分析报告的科学性、规范性、时效性、精准性、客观性等,强化技术与能力支撑,更好发挥环境监测对环境管理和决策的引领作用。  相似文献   
37.
This article deals with how nature is articulated in public discourse and more specifically how humans’ relationship to nature is constructed via such articulations. Based on critical cultural analyses of ads presented in a Norwegian context, the article claims articulations of nature serve to a depoliticization of nature, which silence social differences and reduce environmental politics to individual moral action. Several rhetorical patterns of particular relevance to the articulation of nature are discussed, pointing out how disparate, sometimes conflicting, understandings of nature are rhetorically configured and aligned in ways that benefit a global market economy. There is a discursive distancing of nature and everyday life, even as nature remains valorized and very much central to national identity. This constrains citizens’ political engagement and undermines understandings of how to govern nature.  相似文献   
38.
Evolutionary psychology has been proposed as an analytic framework for the behavioral effects of landscapes displayed in advertising. In this study, an evolutionary and environmental psychology approach is used to analyze affective reactions to advertising depicting specific natural environments or urban scenes, both prominent ingredients of contemporary advertising imagery. The experimental field study exposed 750 participants at random to one advert of a set of 13 experimental green energy advertisements, each displaying a different biome. Six basic emotional responses (pleasure, arousal, happiness, freedom, safety, and interest) as well as attitude toward the ad and brand attitude were assessed subsequently. Anova and structural equation analysis were used for data analysis. Results of the study confirm the leading opinion on generalized more positive behavioral effects toward visual stimuli representing nature scenes with biospheric contents as opposed to pictures of urban environments or desert settings. In line with earlier empirical research, further findings do not support the hypothesis on an innate preference for savanna landscapes in adults but confirm preferences for images of lush green landscapes with water and familiar biomes. Overall results give significant support to the application of environmental and evolutionary psychology to advertising.  相似文献   
39.
Five studies utilizing survey, experimental, and diary methods assessed the effects of being outdoors on subjective vitality. In Study 1, we used a vignette method to examine whether being outdoors was associated with vitality, above and beyond the influences of physical activity and social interactions. Study 2 explored the effects of being outdoors on vitality through an experimental design contrasting indoor and outdoor walks. In Study 3, participants were exposed to photographic scenes of either nature or buildings. Results showed that only the nature scenes enhanced subjective vitality. Studies 4 and 5 used a diary methodology to examine within-person variations in subjective energy as a function of being outdoors, again controlling for physical and social activity. Being outdoors was associated with greater vitality, a relation that was mediated by the presence of natural elements. Limitations of these studies are discussed, as well as their implications for research on energy and vitalization.  相似文献   
40.
Smith, Monica Lipscomb, Weiqi Zhou, Mary Cadenasso, Morgan Grove, and Lawrence E. Band, 2010. Evaluation of the National Land Cover Database for Hydrologic Applications in Urban and Suburban Baltimore, Maryland. Journal of the American Water Resources Association (JAWRA) 46(2):429-442. DOI: 10.1111/j.1752-1688.2009.00412.x Abstract: We compared the National Land Cover Database (NLCD) 2001 land cover, impervious, and canopy data products to land cover data derived from 0.6-m resolution three-band digital imagery and ancillary data. We conducted this comparison at the 1 km2, 9 km2, and gauged watershed scales within the Baltimore Ecosystem Study to determine the usefulness and limitations of the NLCD in heterogeneous urban to exurban environments for the determination of land-cover information for hydrological applications. Although the NLCD canopy and impervious data are significantly correlated with the high-resolution land-cover dataset, both layers exhibit bias at <10 and >70% cover. The ratio of total impervious area and connected impervious area differs along the range of percent imperviousness – at low percent imperviousness, the NLCD is a better predictor of pavement alone, whereas at higher percent imperviousness, buildings and pavement together more resemble NLCD impervious estimates. The land-cover composition and range for each NLCD urban land category (developed open space, low-intensity, medium-intensity, and high-intensity developed) is more variable in areas of low-intensity development. Fine-vegetation land-cover/lawn area is incorporated in a large number of land use categories with no ability to extract this land cover from the NLCD. These findings reveal that the NLCD may yield important biases in urban, suburban, and exurban hydrologic analyses where land cover is characterized by fine-scale spatial heterogeneity.  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