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   2250篇
  免费   137篇
  国内免费   224篇
安全科学   242篇
废物处理   12篇
环保管理   338篇
综合类   1213篇
基础理论   258篇
环境理论   3篇
污染及防治   86篇
评价与监测   162篇
社会与环境   197篇
灾害及防治   100篇
  2024年   8篇
  2023年   31篇
  2022年   62篇
  2021年   69篇
  2020年   63篇
  2019年   59篇
  2018年   53篇
  2017年   67篇
  2016年   85篇
  2015年   78篇
  2014年   87篇
  2013年   116篇
  2012年   125篇
  2011年   162篇
  2010年   107篇
  2009年   151篇
  2008年   108篇
  2007年   138篇
  2006年   134篇
  2005年   110篇
  2004年   89篇
  2003年   94篇
  2002年   75篇
  2001年   86篇
  2000年   89篇
  1999年   64篇
  1998年   43篇
  1997年   55篇
  1996年   34篇
  1995年   33篇
  1994年   29篇
  1993年   29篇
  1992年   23篇
  1991年   11篇
  1990年   7篇
  1989年   5篇
  1988年   6篇
  1987年   3篇
  1986年   4篇
  1985年   7篇
  1984年   1篇
  1983年   1篇
  1982年   1篇
  1981年   2篇
  1980年   1篇
  1978年   4篇
  1976年   1篇
  1969年   1篇
排序方式: 共有2611条查询结果,搜索用时 15 毫秒
921.
生态退耕对安塞县土地利用及其生态服务功能的影响   总被引:4,自引:1,他引:4  
以生态系统服务价值作为衡量区域生态服务功能的指标,对安塞县1998-2006年间生态服务功能的变化进行了分析。根据黄土丘陵沟壑区耕地坡度与水土流失相关关系以及农户调查数据,对安塞县耕地扰动调节、水分调节、水供应、侵蚀控制以及不同坡耕地食物供应能力的生态服务价值指数进行了修正。在此基础上,分析了安塞县退耕还林还草政策对区域生态服务功能变化的影响。结果表明:生态建设措施使得安塞县生态恶化的趋势得到扭转,其生态服务功能在1998-2006年间增加了12%,其中缓坡耕地、中坡耕地和陡坡耕地的退出,对安塞县生态服务功能增强的贡献率分别为25%,48%,27%。文章还对生态建设的监督与投资进行了讨论,认为基于实验的生态系统功能监测与评估技术才是生态系统服务价值评估的基础;生态建设所带来的生态效益的主要获益者是更大空间范围的利益相关者甚至全社会,因此作为社会代表的政府应成为生态建设的主要投资主体。  相似文献   
922.
Sources of anthropogenic radionuclides in the environment: a review   总被引:1,自引:0,他引:1  
Studies of radionuclides in the environment have entered a new era with the renaissance of nuclear energy and associated fuel reprocessing, geological disposal of high-level nuclear wastes, and concerns about national security with respect to nuclear non-proliferation. This work presents an overview on sources of anthropogenic radionuclides in the environment, as well as a brief discussion of salient geochemical behavior of important radionuclides. We first discuss the following major anthropogenic sources and current developments that have lead, or could potentially contribute, to the radionuclide contamination of the environment: (1) nuclear weapons program; (2) nuclear weapons testing; (3) nuclear power plants; (4) uranium mining and milling; (5) commercial fuel reprocessing; (6) geological repository of high-level nuclear wastes that include radionuclides might be released in the future, and (7) nuclear accidents. Then, we briefly summarize the inventory of radionuclides 99Tc and 129I, as well as geochemical behavior for radionuclides 99Tc, 129I, and 237Np, because of their complex geochemical behavior, long half-lives, and presumably high mobility in the environment; biogeochemical cycling and environment risk assessment must take into account speciation of these redox-sensitive radionuclides.  相似文献   
923.
Within the project “Environmental Modelling for Radiation Safety” (EMRAS) organized by the IAEA in 2003 experimental data of 131I measurements following the Chernobyl accident in the Plavsk district of Tula region, Russia were used to validate the calculations of some radioecological transfer models. Nine models participated in the inter-comparison. Levels of 137Cs soil contamination in all the settlements and 131I/137Cs isotopic ratios in the depositions in some locations were used as the main input information. 370 measurements of 131I content in thyroid of townspeople and villagers, and 90 measurements of 131I concentration in milk were used for validation of the model predictions.A remarkable improvement in models performance comparing with previous inter-comparison exercise was demonstrated. Predictions of the various models were within a factor of three relative to the observations, discrepancies between the estimates of average doses to thyroid produced by most participant not exceeded a factor of ten.  相似文献   
924.
In this work, the activities of radionuclides in a marine sediment sample have been determined. The gamma spectrometer comprises an N type coaxial HPGe detector with active shielding to reduce cosmic background. The mass activities of radionuclides have been derived and found to be around a few Bq kg−1 to several hundreds Bq kg−1 with relative uncertainties in this paper quoted corresponding to the combined standard uncertainties (k = 1).  相似文献   
925.
Abstract

The overgrowth of population and deterioration of environment are two serious problems of China. They pose a strong challenge to China's economic and social development. This article discusses the challenge and proposes some countermeasures for China to cope with these problems.  相似文献   
926.
Abstract

Spring water in the city of Jinan comes from the limestone areas. Understanding the capacity of wellspring conservation is a critical point to resume the perennial spewing of the spring water. The vegetation, soil, and other natural and human aspects related to the conservation are studied by using the methods of geographic information systems (GIS), remote sensing (RS), and field investigation. In the end, suggestions for administration and planning as well as countermeasures are put forward.  相似文献   
927.
Environmental organizations often use visual material to inform society about environmental concerns and their associated policy issues. This case study examines the process by which the International League of Conservation Photographers (iLCP) and the Chesapeake Bay Foundation (CBF) use a Rapid Assessment Visual Expedition (RAVE) to draw attention to the environmental issues surrounding the Chesapeake Bay watershed. In addition, the study analyzes the resulting photographs captured during the event. The CBF and the iLCP strategically use the RAVE to create scientific and local knowledge that they use to present their understanding of the Chesapeake Bay. An analysis of the slideshows generated from the RAVE shows how the strategies the photographers employ help to depict power relations among the stakeholders in the watershed area. The strategies may encourage audiences to develop a regional collective identity of concerned citizens who will work together to help to protect and clean the watershed.  相似文献   
928.
Contemporary manufacturing organisations recognise sustainability as an important concept for survival. Environmental awareness and recycling regulations have been compelling manufacturers and consumers to evolve sustainable strategies. The modern customers' voices need to be translated with care into technical requirements. Quality function deployment (QFD) is a technique extensively used for this purpose. In order to cope with the vagueness associated with relationships and correlations in QFD, fuzzy numbers have been integrated within a QFD framework and fuzzy QFD has been used in this study. The study is concerned with the application of fuzzy QFD for enabling sustainability in an Indian modular switches manufacturing organisation. The approach is effective in the identification of sustainable competitive bases, sustainable decision domains, sustainable attributes and sustainable enablers for the organisation. The improvement in sustainability has been measured from three perspectives. The results gained as a result of the study indicated that fuzzy QFD could be used as an enabler of sustainability.  相似文献   
929.
南京城市滨江带功能演变及现代景观规划研究   总被引:3,自引:0,他引:3  
南京城市滨江带具有山、水、城、林、洲相融合的特色环境,近百年以来滨江地段由于经济和旅游利用而发展迅速。城市滨江带功能的演变具有其独特的历史过程。合理利用南京城市滨江自然与人文条件进行滨江景观规划,对于南京市的进一步发展是很重要的。通过对历史时期南京城市滨江带功能演变的分析,对滨江带景观现状深入的研究,对滨江带各个区域的景观要素进行探讨, 提出了南京城市滨江带景观规划的指导思想与设计手法,依此进行了景观规划研究。将南京城市滨江带划分为6个特色区域: 河西滨江段以塑造现代化城市建筑群体景观为主, 下关滨江段以塑造港区风貌和反映城市近现代历史为主,幕燕滨江段以塑造自然山水风光为主和江中洲地区以现代化田园风光景观为主,大厂滨江段以塑造现代工业景观为主,浦口—珠江段以塑造现代化滨江城市景观为主。  相似文献   
930.
基于新经济地理学相关理论,针对江苏省沿江开发战略实施以后,制造业空间可能存在的变动,在整理和分析调查问卷资料的基础上,选择专业化指数和基尼系数2种方法来定量分析江苏省21个沿江省级以上开发区空间分工、制造业集聚和转移态势。结果表明:(1)2002~2006年江南沿江开发区通过向江北沿江开发区转移部分传统产业,逐渐形成了江南沿江技术/资本密集型制造业“中心”和江北沿江劳动密集型制造业“外围”的空间分工格局;(2)江南沿江开发区内部、江北沿江开发区内部尚未形成良好的分工关系;(3)受开发区发展阶段、区域产业政策、本地化资源供给和市场需求等因素影响,并未发现理论预期的普遍存在的产业集聚现象,仅纺织服装、石化、电力、塑料橡胶等产业呈现集中趋势.  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