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   1220篇
  免费   73篇
  国内免费   69篇
安全科学   61篇
废物处理   5篇
环保管理   356篇
综合类   367篇
基础理论   342篇
污染及防治   57篇
评价与监测   44篇
社会与环境   120篇
灾害及防治   10篇
  2024年   3篇
  2023年   7篇
  2022年   13篇
  2021年   26篇
  2020年   25篇
  2019年   21篇
  2018年   16篇
  2017年   24篇
  2016年   26篇
  2015年   32篇
  2014年   35篇
  2013年   54篇
  2012年   43篇
  2011年   70篇
  2010年   77篇
  2009年   92篇
  2008年   79篇
  2007年   87篇
  2006年   92篇
  2005年   78篇
  2004年   62篇
  2003年   66篇
  2002年   52篇
  2001年   53篇
  2000年   54篇
  1999年   22篇
  1998年   21篇
  1997年   22篇
  1996年   10篇
  1995年   22篇
  1994年   11篇
  1993年   11篇
  1992年   11篇
  1991年   4篇
  1990年   6篇
  1989年   2篇
  1988年   10篇
  1987年   5篇
  1986年   1篇
  1985年   5篇
  1984年   2篇
  1981年   1篇
  1980年   1篇
  1979年   1篇
  1978年   1篇
  1975年   1篇
  1973年   1篇
  1972年   2篇
  1971年   1篇
  1970年   1篇
排序方式: 共有1362条查询结果,搜索用时 789 毫秒
701.
文章采用生态环境影响评价中的景观生态学方法,应用景观生态学的基本观点和原理,通过对我院及相关环评单位所做环境影响报告书的生态评价在区域生态扣线型生态评价的实例按《环境影响评价技术导则非污染生态影响》(HJ/T19—1997)推荐的景观生态学方法评价方法进行对比分析,并得出其适用性。  相似文献   
702.
应用景观生态学基本理论、选用基本方法对大兴安岭(黑龙江省管辖范围内)森林植被的变化进行了分析,其结果由于林木采伐等人为活动对其干扰,使得森林景观发生了根本性的变化,导致原始林斑块数量增多,森林在景观中的面积减少,森林的斑块形状趋于不规则,森林内部生境的面积减少。而森林的斑块被隔离,导致生物多样性下降,景观破碎程度逐期加大。  相似文献   
703.
本文就环境影响评价的发展做了简单的回顾总结,对现阶段环境影响评价的指导理念进行简单分析,提出未来环境影响评价工作将要确立生态学理念为指导,以环境和生态承载力为基础,把生态系统服务功能作为环境影响评价的核心,对拟建项目全过程进行整体性、系统性的分析评价。  相似文献   
704.
Pollinators possess several antipredator adaptations that minimise predation risk during foraging. In addition to morphological adaptations, hoverflies might have behavioural antipredator adaptations. We conducted three field experiments to investigate whether the "hesitation behaviour" of hoverflies Sphaerophoria spp., moving backwards and forwards in front of a flower, is effective in avoiding ambush predators on flowers. First, we compared the behaviour of different flower visitors, including several bees and other hoverflies, with Sphaerophoria spp. behaviour. Only Sphaerophoria spp. exhibited the hesitation behaviour in front of flowers. The flight behaviour was observed more frequently before landing on flowers than on leaves. Second, we investigated rejection by Sphaerophoria spp. to artificially placed corpses of the crab spider Thomisus labefactus. The rejection rate of flowers with a crab spider placed on or under it was significantly higher than that of non-treated flowers. Moreover, the presence of a spider on the flower decreased the number of hesitation displays, compared with non-treated flowers. Finally, to determine whether hesitation behaviour could be a consequence of floral assessment, we investigated hoverfly rejection of previously foraged flowers. Sphaerophoria spp. did not reject flowers that had been visited by the same individual or conspecifics within 3 min. We suggest that hesitation behaviour may be adaptive, enabling assessment of predation risk and hence avoiding ambush predators on flowers.  相似文献   
705.
自80年代初期我国学者开始开展景观生态学研究以来,景观生态学的研究在我国获得了蓬勃发展。文章针对所搜集的2000—2010年我国研究景观生态学的学者发表在国内的18种核心期刊上的中文文献471篇,分不同专题进行分类统计,并在其基础上对我国景观生态学研究进行分析和论述,为我国的景观生态学者了解和把握中国景观生态学研究热点和发展趋势提供依据。  相似文献   
706.
近岸海域生态系统服务功能监测的指标体系研究   总被引:1,自引:0,他引:1  
按照海洋生态系统服务功能的特点,对监测海洋生态服务功能的指标体系进行了初步研究。具体分为三个一级指标,包括供给功能、调节功能和支持功能,又将如上一级指标细分为十个二级指标。本文旨在运用生态系统服务功能的理论框架和方法,为完善近岸海域生态监测的指标体系奠定基础。  相似文献   
707.
Second Life is a virtual, open-access, and user-generated environment that has served as a platform for hosting everything from rock concerts to scientific conferences. Many institutions have also used Second Life as an educational tool, for example by, showcasing scientific exhibits or embedding video and images for learning purposes. Here we discuss the creation and use of an interactive, virtual industrial facility - the Elihu Paper Company - as a way to complement a traditional facility tours in a course in industrial environmental management. Virtual facilities offer a number of educational advantages over real-life ones: they are always open and available for tours, they can be accessed instantaneously from anywhere where there is an adequate internet connection, and most importantly, tours and embedded information can be tailored to specific educational objectives. Our experience in using Elihu Paper as a formal facility visit for the past several years shows that students had significantly more time than usual to ask questions, could and did explore the facility independently, and were still able to produce facility reports that fulfilled the educational objectives of the visits, including mapping material flows and explaining pollution prevention and sustainability opportunities.  相似文献   
708.
Industrial symbioses (ISs) and eco-industrial parks (EIPs) are key concepts of industrial ecology (IE). The aim of ISs and EIPs is to minimise inefficient material and energy use by utilising local by-product and energy flows. Industrial symbioses tend to develop through spontaneous action of economic actors, for gaining of economic benefit, but these systems can be designed and promoted via policy instruments as well. A literature review showed that national programmes for eco-industrial parks can be found in different parts of the world. In the action programmes and other sustainable consumption and production (SCP) policy documents of the EU, on the other hand, industrial symbioses gain less recognition as a path to enhanced sustainable production. In this article, we consider this and also analyse how the evolution and environmental performance of an industrial symbiosis system centred on a Finnish pulp and paper mill have been affected by SCP policy instruments. With regard to the system forming the subject of the case study, and Finnish industrial systems in general, policy instruments have succeeded in reducing emissions but not in systematically encouraging operators toward symbiosis-like activities. All in all, few studies exist on the overall impact of policy instruments promoting design of eco-industrial parks. It is not self-evident that symbiosis-like production systems would be sustainable in every case, as the background assumptions for political promotion of EIPs suggest. We concluded that industrial symbioses should be analysed and developed on a life cycle basis, with documentation of the real environmental benefits due to efficient resource use and decreased emissions in comparison to standalone production. ISs can then bring eco-competitiveness to companies in relation to SCP tools, such as environmental permits, ecolabels, and future product regulation based on the Ecodesign Directive in Europe. Indirect encouragement of symbiosis through land-use regulation and planning, in such a way that material fluxes between companies are possible both in operations and in financial terms, may prove effective. The same holds for waste policies that encourage increased reuse of a company’s waste by other enterprises.  相似文献   
709.
燕山北部山地人工林和天然次生林的生物碳贮量   总被引:1,自引:0,他引:1  
为了了解人工林与天然次生林碳汇功能的差异,以燕山北部山地华北落叶松人工林和杨桦天然次生林为研究对象,对不同年龄阶段的两种林分的生物碳贮量进行了研究。结果表明:13、18、28 a生杨桦天然次生林总生物碳贮量分别为27.33、35.77、46.13 t/hm2,9、13、30 a华北落叶松人工林分别为21.97、34.14、55.62 t/hm2; 0~13 a,14~18 a,19~28 a杨桦林生物总碳贮量的年碳积累速率分别为2.10、1.69、1.04 t/hm2, 0~9 a,10~13 a,14~30 a落叶松林分别为2.44、3.04、1.34 t/hm2;华北落叶松单木生物量增长速率明显高于白桦和山杨,在10~25 a的年龄段,落叶松生长速度是白桦、山杨的1.63~5.83、2.26~7.87倍;华北落叶松的BCEF(生物量转化和扩展因子)和BEF(生物量扩展因子)随年龄和胸径的增长有逐渐降低的趋势,而白桦和山杨的两个参数则有逐渐增加的趋势。由此得出结论,在燕山北部山地,与杨桦天然次生林相比,华北落叶松人工林表现出更强的碳吸存能力,该地区大面积的华北落叶松幼、中龄林具有巨大的碳汇潜力;同时,使用生物量碳计量参数时应考虑树种、林龄和胸径的差异。  相似文献   
710.
Many species are restricted to a marginal or suboptimal fraction of their historical range due to anthropogenic impacts, making it hard to interpret their ecological preferences from modern-day data alone. However, inferring past ecological states is limited by the availability of robust data and biases in historical archives, posing a challenge for policy makers . To highlight how historical records can be used to understand the ecological requirements of threatened species and inform conservation, we investigated sperm whale (Physeter macrocephalus) distribution in the Western Indian Ocean. We assessed differences in information content and habitat suitability predictions based on whale occurrence data from Yankee whaling logs (1792–1912) and from modern cetacean surveys (1995–2020). We built maximum entropy habitat suitability models containing static (bathymetry-derived) variables to compare models comprising historical-only and modern-only data. Using both historical and modern habitat suitability predictions  we assessed marine protected area (MPA) placement by contrasting suitability in- and outside MPAs. The historical model predicted high habitat suitability in shelf and coastal regions near continents and islands, whereas the modern model predicted a less coastal distribution with high habitat suitability more restricted to areas of steep topography. The proportion of high habitat suitability inside versus outside MPAs was higher when applying the historical predictions than the modern predictions, suggesting that different marine spatial planning optimums can be reached from either data sources. Moreover, differences in relative habitat suitability predictions between eras were consistent with the historical depletion of sperm whales from coastal regions, which were easily accessed and targeted by whalers, resulting in a modern distribution limited more to steep continental margins and remote oceanic ridges. The use of historical data can provide important new insights and, through cautious interpretation, inform conservation planning and policy, for example, by identifying refugee species and regions of anticipated population recovery.  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