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   2052篇
  免费   115篇
  国内免费   199篇
安全科学   73篇
废物处理   5篇
环保管理   512篇
综合类   813篇
基础理论   564篇
污染及防治   76篇
评价与监测   83篇
社会与环境   221篇
灾害及防治   19篇
  2024年   9篇
  2023年   12篇
  2022年   29篇
  2021年   45篇
  2020年   46篇
  2019年   42篇
  2018年   40篇
  2017年   63篇
  2016年   67篇
  2015年   75篇
  2014年   65篇
  2013年   105篇
  2012年   108篇
  2011年   143篇
  2010年   135篇
  2009年   142篇
  2008年   129篇
  2007年   140篇
  2006年   147篇
  2005年   137篇
  2004年   97篇
  2003年   110篇
  2002年   79篇
  2001年   81篇
  2000年   73篇
  1999年   46篇
  1998年   26篇
  1997年   27篇
  1996年   24篇
  1995年   26篇
  1994年   17篇
  1993年   13篇
  1992年   13篇
  1991年   4篇
  1990年   8篇
  1989年   2篇
  1988年   9篇
  1987年   6篇
  1986年   2篇
  1985年   5篇
  1984年   6篇
  1981年   2篇
  1980年   3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2366条查询结果,搜索用时 593 毫秒
451.
Modern agriculture is subject to a metaphysical as well as an ethical critique. As a casual review of the beliefs associated with food production in the past suggests, modern agriculture is embedded in and informed by the prevailing modern world view, Newtonian Mechanics, which is bankrupt as a scientific paradigm and unsustainable as an agricultural motif. A new holistic, organic world view is emerging from ecology and the new physics marked by four general conceptual features: Each level of organization from atoms to ecosystems (1) exhibits emergent properties, (2) exerts downward causation from whole to part, (3) is a systemically integrated whole, (4) the parts of which are internally related. Organic agriculture has been favourably compared with industrial agriculture by the United States National Academy of Science's Board on Agriculture. Aldo Leopold was among the first to criticize industrial agriculture and to envision a new motif for agriculture informed by ecology. A future post-modern ecological agriculture will help to solve the ethical problems engendered by modern mechanical agriculture.  相似文献   
452.
Spartina alterniflora was transplanted into dieback areas of a salt marsh in southeast Louisiana at two elevations (ambient and +30 cm) with and without macro- (N, P, and K) and micronutrient (Fe, Mn, Cu, and Zn) additions to determine if transplant success is dependent on increasing elevation or nutrients.Spartina alterniflora transplanted into elevated plots had more than twice the above- and belowground biomass as compared to nonelevated plots after three months of growth. Additionally, there was significantly more vegetative reproduction (greater culm density and number of newly produced culms) in elevated plots as compared to plots at ambient elevation. Macronutrient additions increased culm densities only in elevated plots.Spartina alterniflora transplanted into nonelevated plots had lower survival rates even when transplants received nutrient additions. These results suggest thatS. alterniflora may be transplanted successfully into degraded salt-marsh areas if elevation is increased. The addition of nutrients without a concomitant increase in elevation is not sufficient for transplant success.  相似文献   
453.
Extensive losses of semi‐natural rural biotopes have led to pressures for conservation and habitat creation. Of particular concern is the loss of large‐scale structure and regional distinctiveness. If this is to be regained, planners will require both an effective body of theory relating to large‐scale visual and ecological cohesion, and effective methods of implementation. This study reviews the value of landscape ecology as a theoretical framework and discusses some applications, with particular reference to the re‐forestation of lowland Britain.  相似文献   
454.
This paper presents the pattern and changes of fragmented forest in relation with changes of total forest cover in the state of Selangor in three decades.In this study,inventoried forest cover maps of Selangor in 1971/1972,1981/1982 and 1991/1992 produced by the Forestry Department of Peninsular Malaysia were digitized to examine the changes in area and number of fragmented forest.Results showed that in 1971/1972,16 fragmented forests were identified in Selangor.All fragmented forests were identified as diptercoarp forest.A decade later the number of fragmented forests increased by approximately 44%(23).Of the 23 fragmented forests,two were peat swamp forests whereas the remaining were dipterocarp forests.In 1991/1992 the number of fragmented forests(12)was reduced by 47.8%.Two of the fragmented forests were Fragmentation of both dipterocrp and peat swamp forests occurred profoundly during the period between 1971/1972and 1981/1982,which consequently increased the number of fragmented forests compared with before the period of 1971/1972 where fragmentation happened only at dipterocarp forests.However,many fragmented forests vanished between the 1981/1982 and 1991/1992 periods.  相似文献   
455.
协同论、城市生态学及苏州河综合整治   总被引:1,自引:0,他引:1  
从协同论和城市生态学的角度,对苏州河综合整治的定义、目的、方式进行了阐述了探讨。  相似文献   
456.
底泥黑臭,向水面冒气泡是福州西湖水体富营养化现象的一个突出表现。目前,有关管理部门主要靠定期挖泥清淤来控制底泥富营养状况。然而1999年秋季福州西湖底栖动物种类和数量调查结果却显示,由于底栖动物贫乏,西湖底泥富营养化问题将由于生态失调而进一步深化。建议将控制入湖泥沙量、减少挖泥频度、恢复底栖生态作为一项治淤措施予以考虑。  相似文献   
457.
农业生态与土壤环境中硼元素的关系   总被引:12,自引:0,他引:12  
曾昭华 《环境科技》2002,15(4):35-36
论述了硼元素的地球化学特征及其分布状况,与硼元素有关的主要作物分类,作物产量和质量与硼元素的关系,影响硼元素有效态和作物吸收硼元素的因素,硼肥的种类和施用方法与效果。  相似文献   
458.
在开封市生态建设现状分析的基础上,运用景观生态学的理论和方法,从廊道、斑块、基质三个方面提出了改善开封城市景观结构,优化城市生态环境的基本思路和建议.  相似文献   
459.
Since the introduction of the industrial ecology concept by Frosch and Gallopoulos in 1989, and the apparent success of the Kalundborg Industrial Symbiosis project, attention to planned eco-industrial park (EIP) development projects has grown all over the world. This article includes data from six of these EIP development projects. Three of the projects discussed are located in the Netherlands and three in the US. This article compares the differences in project approach and results on a national level. The approach suggested is derived from the available EIP development literature.Initial research indicates that the Dutch EIP projects are more successful than their US counterparts. This difference in success can be, mostly, attributed to the fact that the US projects are initiated by local and regional governments that see the project as a way to improve the local/regional economy with access to substantial government funds. Because of this heavy government involvement, US companies are, in general, not interested in the project. The more successful Dutch projects, on the other hand, are mostly initiated by the companies themselves with financial and advisory support from the local and regional government.  相似文献   
460.
森林生态效益补偿在改善生态环境、促进经济与社会、人与社会和谐发展过程中有着重要的现实意义,中国在这方面的立法尚不完善,在着重论述了中国森林生态效益补偿的对象和基本原则时,提出了自己的观点和看法.  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