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   431篇
  免费   11篇
  国内免费   26篇
安全科学   35篇
废物处理   2篇
环保管理   145篇
综合类   156篇
基础理论   44篇
污染及防治   25篇
评价与监测   23篇
社会与环境   22篇
灾害及防治   16篇
  2023年   5篇
  2022年   5篇
  2021年   17篇
  2020年   22篇
  2019年   7篇
  2018年   12篇
  2017年   13篇
  2016年   16篇
  2015年   17篇
  2014年   17篇
  2013年   28篇
  2012年   18篇
  2011年   19篇
  2010年   23篇
  2009年   19篇
  2008年   22篇
  2007年   16篇
  2006年   16篇
  2005年   15篇
  2004年   9篇
  2003年   15篇
  2002年   12篇
  2001年   14篇
  2000年   16篇
  1999年   12篇
  1998年   10篇
  1997年   9篇
  1996年   4篇
  1995年   7篇
  1994年   4篇
  1993年   3篇
  1992年   3篇
  1990年   2篇
  1989年   4篇
  1988年   4篇
  1986年   5篇
  1985年   5篇
  1984年   1篇
  1983年   1篇
  1982年   1篇
  1981年   2篇
  1980年   3篇
  1979年   4篇
  1978年   1篇
  1977年   1篇
  1976年   1篇
  1975年   1篇
  1974年   2篇
  1973年   1篇
  1971年   1篇
排序方式: 共有468条查询结果,搜索用时 13 毫秒
241.
阐述了当前环境监测的现状,指出了新常态下环境监测的机遇和挑战,提出了环境监测要抓住机遇,面对挑战,充分发挥职能,保证环境监测数据真实,完善环境监测体系,深度运用环境监测数据,实行信息公开。  相似文献   
242.
我国的木材加工企业普遍存在严重的噪声污染 ,极大地损害了工作者的身心健康 ,是迫切需要解决的重要问题。为了控制木工机床的噪声 ,分析和讨论了产生噪声的原因 ,指出切削机构是噪声的主要声源。探讨了降低噪声的途径 ,综合评述了国外木工刀具降噪新技术。在工业发达的国家 ,现代木工刀具的设计与制造均考虑了降噪措施 ,其技术原理集中于控制气流在刀槽或齿槽中涡流产生的空气动力性噪声和防止刀具振动时产生的机械噪声两方面。这些新技术已用于生产中 ,降噪效果明显 ,值得借鉴。笔者强调 ,开发低噪声木工刀具 ,保障劳动者的人体健康 ,是我国木材加工工业文明发展的标志  相似文献   
243.
Relational thinking has recently gained increasing prominence across academic disciplines in an attempt to understand complex phenomena in terms of constitutive processes and relations. Interdisciplinary fields of study, such as science and technology studies (STS), the environmental humanities, and the posthumanities, for example, have started to reformulate academic understanding of nature-cultures based on relational thinking. Although the sustainability crisis serves as a contemporary backdrop and in fact calls for such innovative forms of interdisciplinary scholarship, the field of sustainability research has not yet tapped into the rich possibilities offered by relational thinking. Against this background, the purpose of this paper is to identify relational approaches to ontology, epistemology, and ethics which are relevant to sustainability research. More specifically, we analyze how relational approaches have been understood and conceptualized across a broad range of disciplines and contexts relevant to sustainability to identify and harness connections and contributions for future sustainability-related work. Our results highlight common themes and patterns across relational approaches, helping to identify and characterize a relational paradigm within sustainability research. On this basis, we conclude with a call to action for sustainability researchers to co-develop a research agenda for advancing this relational paradigm within sustainability research, practice, and education.  相似文献   
244.
Introduced ungulates, e.g., deer and Himalayan tahr, are variously considered as both pests and resources in New Zealand. Much ecological research has occurred into these species and into the ecosystems in which they live. Concurrently, much has been done to develop ‘management’ plans for these species. We reviewed ecological research relevant to these ungulates and developed ecologically relevant criteria to assess the extent to which these have been considered in these plans. Nine criteria were developed within four thematic areas: ecological principles, objectives and outcomes, adaptive management, and use of science information. Four planning documents were then evaluated. All four poorly or at best marginally considered fundamental ecological principles: only the Himalayan thar control plan scored well in terms of having objectives and outcomes that were clearly ecologically based; the thar plan was very strong in terms of its commitment to implementing adaptive management; and, in terms of using the best available science both the thar plan and the deer issues and options paper scored well. Overall, ecological science and principles have not played major roles in the development of some of these plans, probably because ultimately they reflect political choices that are difficult to support with the available ecological research.  相似文献   
245.
以雄安新区雄县、容城县、安新县2019年9月Landsat-8卫星遥感影像为依据,采用监督分类法将土地利用类型分为5种,分析雄安新区土地利用结构特征;利用辐射传输法反演地表温度,依据均值-标准差法对地表温度进行分级,分析雄安新区地表温度空间变化及热岛强度分级情况;通过信息点(point of information,POI)对城市进行功能分区,分析高温分布影响因素。结果表明:雄安新区5种土地利用类型中耕地和建筑用地面积较大,占比分别达56.19%和31.81%,5种土地利用类型面积占比在三县的分布差异较大。雄安新区地表温度的分布特征总体是北部温度较高,南部温度较低,温度极差约为21 ℃,且容城县地表温度变异较大。三县的热岛强度等级面积差异较大,中温区面积最大,低温区面积最小,热岛强度等级面积占比较高的城市,其建筑用地面积占比也会较高。热岛强度的不同温区地表温度平均值与POI数量具有显著的线性正相关;不同城市功能区对地表温度具有不同影响,人类活动大的功能区地表温度高,且高温区分布在建筑用地周围,低温区分布在水域周围,中温区分布在耕地和林地。  相似文献   
246.
This study utilized telemetric systems to sample microbes and pathogens in forest, burned forest, rangeland, and urban watersheds to assess surface water quality in northern New Mexico. Four sites included remote mountainous watersheds, prairie rangelands, and a small urban area. The telemetric system was linked to dataloggers with automated event monitoring equipment to monitor discharge, turbidity, electrical conductivity, water temperature, and rainfall during base flow and storm events. Site data stored in dataloggers was uploaded to one of three types of telemetry: 1) radio in rangeland and urban settings; 2) a conventional phone/modem system with a modem positioned at the urban/forest interface; and 3) a satellite system used in a remote mountainous burned forest watershed. The major variables affecting selection of each system were site access, distance, technology, and cost. The systems were compared based on operation and cost. Utilization of telecommunications systems in this varied geographic area facilitated the gathering of hydrologic and water quality data on a timely basis.  相似文献   
247.
Particle density is an important physical property of atmospheric particles.The information on high time-resolution size-resolved particle density is essential for understanding the atmospheric physical and chemical aging processes of aerosols particles.In the present study,a centrifugal particle mass analyzer(CPMA) combined with a differential mobility analyzer(DMA) was deployed to determine the size-resolved effective density of 50 to 350 nm particles at a rural site of Beijing during summer 2016.The measured particle effective densities decreased with increasing particle sizes and ranged from 1.43 to 1.55 g/cm~3,on average.The effective particle density distributions were dominated by a mode peaked at around 1.5 g/cm~3 for 50 to350 nm particles.Extra modes with peaks at 1.0,0.8,and 0.6 g/cm3 for 150,240,and 350 nm particles,which might be freshly emitted soot particles,were observed during intensive primary emissions episodes.The particle effective densities showed a diurnal variation pattern,with higher values during daytime.A case study showed that the effective density of Aitken mode particles during the new particle formation(NPF) event decreased considerably,indicating the significant contribution of organics to new particle growth.  相似文献   
248.
华北地区城市绿地固碳能力测算研究   总被引:1,自引:0,他引:1  
文章通过对位于华北地区的7个案例的城市绿地植被固碳能力的研究,形成一套系统的计算方法.结果表明:适用于雄安新区的城市绿地单位面积固碳能力约为2.62 kg/a m2;各个植被群落的固碳能力从大到小依次为乔木(2.66kg/am2)、灌木(2.59kg/a·m2)、地被(2.01 kg/a·m2).研究结果将为实现城市绿...  相似文献   
249.
滨海新区资源丰富,经济规模不断扩大,呈现出良好的发展趋势,但也面临资源利用不合理、环境污染严重等问题.在分析天津滨海新区海洋经济发展现状和优势的基础上,探讨了该区域面临的资源与环境约束问题,并对这些问题进行了原因剖析,主要原因包括缺少科学规划引导、管理矛盾突出等.最后从建立环境与经济持续发展的综合决策机制、直接管制与间...  相似文献   
250.
近年来,中石油集团公司发生了多起安全事故,而相关方事故占有相当大的比例.本文以中石油集团下属的新世纪机械制造公司相关方HSE管理为例,详细阐述了相关方HSE管理前期存在的问题以及后期HSE管理的改进措施,并探讨了相关方管理工作的全新方法,以为强化相关方的HSE管理提供参考.  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