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   646篇
  免费   86篇
  国内免费   69篇
安全科学   106篇
废物处理   2篇
环保管理   124篇
综合类   348篇
基础理论   63篇
污染及防治   27篇
评价与监测   22篇
社会与环境   76篇
灾害及防治   33篇
  2024年   3篇
  2023年   9篇
  2022年   21篇
  2021年   22篇
  2020年   30篇
  2019年   33篇
  2018年   21篇
  2017年   34篇
  2016年   33篇
  2015年   28篇
  2014年   30篇
  2013年   41篇
  2012年   44篇
  2011年   82篇
  2010年   49篇
  2009年   39篇
  2008年   34篇
  2007年   55篇
  2006年   58篇
  2005年   28篇
  2004年   27篇
  2003年   21篇
  2002年   11篇
  2001年   10篇
  2000年   8篇
  1999年   5篇
  1998年   4篇
  1995年   5篇
  1994年   7篇
  1993年   1篇
  1992年   2篇
  1989年   1篇
  1982年   2篇
  1980年   1篇
  1979年   1篇
  1975年   1篇
排序方式: 共有801条查询结果,搜索用时 15 毫秒
251.
为了验证在钢铁企业中人的失效过程同服役年限有某种规律性的联系,采用马尔萨斯模型对人的服役年限--工龄与伤害事故频数之间的规律性进行机理推证.在对典型钢铁企业40年间工伤事故数据库中的1 465起伤害事故进行统计分析、建立回归模型后,结论显示伤害事故频数y与受害人员的本工种工龄x存在显著指数相关关系:y=167.13e0.012x、相关系数R=0.93,证实了马尔萨斯模型应用于"工龄-伤害事故频数"指数规律的准确性.改进后的指数规律模型对实际钢铁企业安全管理工作有着重要的研究价值和指导意义,且可以在其他领域中进行探索和推广.  相似文献   
252.
European Union (EU) member states set aside between 5 and 15% of arable land during the last two decades, but abolition of the set-aside scheme in 2008 caused a sudden loss in habitat availability and biodiversity in agricultural landscapes. Management of set-aside has many facets and in this perspective paper we focus on the biodiversity effects of successional age, sowing strategies and landscape context. Young, 1-2-year-old set-asides have been initially considered to be too ephemeral to have any conservation value. However, when a rich seed and bud bank is available, a species-rich natural (secondary) succession can be observed. Arable (annual) weed communities in the first two years of succession can even include endangered plant species with associated rare insect consumers. Furthermore, many bird species benefit from early-successional habitats, whereas small mammal communities are richer in older habitats. If the local plant species pool is poor, sowings of diverse mixtures from regional seed collections can be recommended. Set-aside managers using species-rich sowings often experience that dominant weeds suppress the less competitive annual species. This trend to species-poor communities can be avoided by intraspecific aggregation of competitively weak species. Broadening the spatial scale from the plot to the landscape, efficiency of set-aside is highest in simple landscapes, where set-aside exhibits greatest effect in enhancement of biodiversity and associated services such as pollination and biological control. In complex landscapes, however, additional set-aside does not add much to the high level of biodiversity and ecological processes already present. Twenty percent of semi-natural, non-crop habitat appears to be a rough threshold for enhancing biodiversity and sustaining services such as pollination and biological control, but improved set-aside management should have the potential to reduce the percentage of semi-natural non-crop habitat needed. EU policy should tailor set-aside schemes for the maintenance of biodiversity and also consider that management efficiency is higher in simple than complex landscapes.  相似文献   
253.
本文通过收集近30年鸟类种类及种群数据变化的资料,分析乌梁素海不同鸟类栖息环境的栖息地服务功能,从而评估乌梁素海湿地鸟类栖息地的综合生态服务功能。评估结果表明:乌梁素海湿地鸟类栖息地综合生态服务功能为不好。  相似文献   
254.
基于Costanza对生态系统服务价值理论的研究成果,结合谢高地等对中国陆地生态系统单位面积生态服务价值表,计算了2003—2007年间上海市生态系统服务价值变化情况和敏感性指数,03年-07年,生态服务价值减少了1.1亿元,各种土地利用方式的生态系统服务价值的敏感性指数均小于1,表明生态系统服务价值对价值系数的变化是缺乏弹性的。  相似文献   
255.
以太子河观音阁水库下游地区为例,通过野外采样分析和相关数据的收集和整理,从生态功能的角度出发,探讨和研究该地区不同经济发展模式对当地水环境的影响,并就适宜于当地的生态发展模式进行了探讨。  相似文献   
256.
结合我国环境数据共享与服务面临的问题,对国家环境数据共享与服务体系的时代背景、概念和实质、技术框架、主要建设内容等进行了研究。指出国家环境数据共享与服务体系是政府主导建设的环境信息资源网,核心由三级环境数据中心、依托于四级专网的环境数据传输与交换平台以及分别依托于内网、专网和互联网的各级共享服务门户构成。  相似文献   
257.
医疗废物处置行业是我国确定的优先控制的无意产生POPs重点行业之一。该行业以二噁英减排为目的开展最佳可行技术的研究及示范推广是《履行<关于持久性有机污染物的斯德哥尔摩公约>国家实施计划》确定的任务之一。本文详细对江西南昌和湖南益阳医疗废物集中处置设施二噁英控制最佳可行技术示范改造的主要技术内容进行了分析,提出未来一段时间医疗废物集中处置设施污染控制管理趋势,以及技术升级改造的主要方向和技术重点。  相似文献   
258.
通过运用生态服务效能指数的概念,选择5种指标因子(吸收二氧化硫量、吸收热量、蒸腾水量、涵养水源量、滞尘降尘量)构建了淮安生态新城绿地系统生态服务效能评估模型,并运用全排列多边形图示指标法,针对"现状条件"、"概念规划"、"控制性详细规划"、"理想状态"4种情景下的绿地系统进行了生态服务效能评价与预测.结果表明,4种不同的土地利用方式下,绿地系统生态服务效能综合指数分别为0.24、0.56、0.70和0.89,生态服务效能逐步改善.研究结果进一步表明,在"概念规划"和"控制性详细规划"两种情景下,应使城市绿地系统面积大于1200hm2,采用复合式绿地结构并调整林地与草地面积的比例达到7∶3,同时应保证本地植物指数大于70%,研究结果可为生态城市建设提供一定的参考.  相似文献   
259.
Sustainable innovation represents a current challenge for companies, as firms need to change the way they design, develop, produce and distribute products and services. Therefore, this paper proposes a new framework to be used as a reference guideline for organisations to define a roadmap, specific actions and projects to achieve sustainable innovation, integrating four key enablers. The first enabler is mass customisation (MC), which targets the identification and compliance with customers' specific needs and requirements in order to achieve customer‐driven design. At the same time, the sustainable development (SD) paradigm is taken into consideration, where for any new product or service, companies analyse the benefits, risks and impacts of not only economic factors, but also social and environmental implications. The third enabler is linked to the value network (VN), where innovations happen owing to the active collaboration and distributed knowledge of partners inside and outside the company. Finally, the fourth and last considers the complete product and service life cycle (PSLC), where the three sustainable elements are identified and analysed in each single business process. Two case studies, (footwear sector and water treatment plants) are described to show the validity and successful deployment of the proposed framework in real industrial scenarios.  相似文献   
260.
As a special ecosystem, an urban forest park, which is different from a regular “forest park”, is one of the key elements involved in improving the urban ecological environment and promoting the sustainable development of a city. The “urban forest park” can also significantly improve living conditions by acting as a greenbelt. The Chengdu Longquan Mountain Urban Forest Park is a rare mountain urban forest park located in the center of the city. This “urban forest park” not only provides more ecological products and maintains ecological security but also meets the growing needs of people for food, environmental quality, and spirituality. To comprehensively assess the ecological value of the Chengdu Longquan Mountain Urban Forest Park, this study used the literature analogy and questionnaire survey methods to establish a targeted ecosystem service assessment system in this study area. In addition, combined with the hierarchical analysis method, the indicator system was tested, and the specific evaluation index was determined. In the Longquan Mountain Urban Forest Park Ecosystem Service Value Index System, three first-level indicators, such as ecological material products (with a weight of 0.412 6), ecological regulation (0.327 5), and dwelling culture (0.259 9); eight secondary indicators, such as product production (0.206 3), resource supply (0.206 3), and biodiversity (0.194 4); and twenty-three tertiary indicators, such as air negative oxygen ion (0.154 7), habitat quality (0.095 9), and ecological health benefit (0.075 5), were identified. From the weights of the first and second indicators, it was clear that the supply of ecological material products is the main service function in the Longquan Mountain Urban Forest Park ecosystem. Moreover, from the weights of the third indicator, the public’s cognition and concept of the ecosystem service value of the “urban forest park” gradually shifted from the supply service of products and resources to cultural services. In summary, the ecosystem service value assessment system designed for the Longquan Mountain Urban Forest Park in this study has certain feasibility and extensibility that lays a theoretical foundation for the scientific assessment of ecological value and ecological value realization mechanism for other “forest parks” worldwide. © 2022 Authors. All rights reserved.  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