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   27034篇
  免费   3875篇
  国内免费   363篇
安全科学   3066篇
废物处理   358篇
环保管理   6079篇
综合类   12631篇
基础理论   2620篇
环境理论   47篇
污染及防治   1394篇
评价与监测   3218篇
社会与环境   1270篇
灾害及防治   589篇
  2025年   170篇
  2024年   613篇
  2023年   775篇
  2022年   767篇
  2021年   894篇
  2020年   963篇
  2019年   782篇
  2018年   664篇
  2017年   1126篇
  2016年   1138篇
  2015年   1231篇
  2014年   1207篇
  2013年   1588篇
  2012年   1735篇
  2011年   1727篇
  2010年   1311篇
  2009年   1319篇
  2008年   989篇
  2007年   1508篇
  2006年   1494篇
  2005年   1256篇
  2004年   1091篇
  2003年   1116篇
  2002年   894篇
  2001年   784篇
  2000年   740篇
  1999年   571篇
  1998年   439篇
  1997年   375篇
  1996年   337篇
  1995年   313篇
  1994年   222篇
  1993年   197篇
  1992年   139篇
  1991年   105篇
  1990年   67篇
  1989年   53篇
  1988年   50篇
  1987年   48篇
  1986年   41篇
  1985年   30篇
  1984年   32篇
  1983年   32篇
  1982年   40篇
  1981年   33篇
  1980年   46篇
  1979年   43篇
  1978年   29篇
  1977年   26篇
  1973年   23篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
Abstract:  Broadly conceived and considered in its many usages, sustainability has grave defects as a planning goal, particularly when used by conservationists: it confuses means and ends; it is vague about what is being sustained and who or what is doing the sustaining; it is uninspiring; it is little more than Pinchot-era conservation (and thus ignores the many lessons learned since then); it need not be linked to land, to the land's functioning, or to any ecological science; it need not include a moral component; it is consistent with the view of humans as all-powerful manipulators of the planet; and, in general, it is such a malleable term that its popularity provides only a facade of consensus. When sustainability is defined broadly to include the full range of economic and social aspirations, it poses the particular risk that ecological and biodiversity concerns will be cast aside in favor of more pressing human wants. Given these many defects, the conservation movement should discard the term in favor of a more alluring goal, attentive to nature and its ecological functioning. A sound goal would incorporate and distill the considerable ecological and moral wisdom accumulated since Pinchot's day while giving conservationists the rhetorical tools needed to defend the land against competing pressures. In our view, conservation would be well served by an updated variant of "land health," Aldo Leopold's ecologically grounded goal from the 1940s. Land health as an independent understanding should set the essential terms of how we live and enjoy the earth, providing the framework within which we pursue our many social and economic aims.  相似文献   
2.
中国环境保护产业协会王心芳会长在2006年7月18-19日在北京召开的全国环境保护产业协会工作会议上,就我国环保产业的现状及存在的主要问题、环保产业“十一五”期间面临的形势及“十一五”期间中国环境保护产业协会主要的工作思路做了讲话(本文为讲话摘录)。  相似文献   
3.
通过对移动通信基站天线的电磁辐射分析和探讨,归纳了移动通信基站建设在施工期、营运期环境保护工作的重点与措施,对电磁环境影响评价制度与方法进行了系统的描述,并指出了今后的工作方向。  相似文献   
4.
依据《500kV超高压送变电工程电磁辐射环境影响评价技术规范》(HJ/T24-1998)中的预测模式,分析不同技术参数对输电线路周围环境工频电磁场强度的影响,并有针对性地提出减少输电线路对周围环境影响的环境保护措施及优化输电线路的架设方式。  相似文献   
5.
选取了沈阳市lO条主干道,通过实地调查监测与文献资料分析相结合的方法,分析了主干道交通噪声的影响因素,结果表明,车流量与车型是影响城市主干道交通噪声的重要因素,并提出控制城市主干道交通噪声的防治措施,改善声环境质量。  相似文献   
6.
介绍了一般工业固废填埋场工程的特点和环境监理的现状;结合填埋场项目环境监理工作的实践,分析并总结了填埋场建设项目环境监理要点,即制订切实的监理方案,对工程的关键部位、关键工序做好巡视、旁站监理工作,在实施过程中做好水土保持、生态保护的监理工作。  相似文献   
7.
Transportation system has contributed significantly to the development of human civilization; on the other hand it has an enormous impact on the ambient air quality in several ways. In this paper the air and noise pollution at selected sites along three sections of National Highway was monitored. Pakistan National Highway Authority has started a Highway Improvement program for rehabilitations and maintenance of National highways to improve the traffic flows, and would ultimately improve the air quality along highways. The ambient air quality and noise level was monitored at nine different locations along these sections of highways to quantify the air pollution. The duration of monitoring at individual location was 72 h. The most of the sampling points were near the urban or village population, schools or hospitals, in order to quantify the air pollution at most affected locations along these roads. A database consisting of information regarding the source of emission, local metrology and air quality may be created to assess the profile of air quality in the area.  相似文献   
8.
Abstract:  Population monitoring is central to most demographic studies and conservation efforts, but it may not always be directed at the most appropriate life stage. We used stochastic simulation modeling to evaluate the effectiveness of a monitoring program for a well-studied population of Eastern Imperial Eagles ( Aquila heliaca ) in Kazakhstan. Specifically, we asked whether the most appropriate data were being collected to understand system state and population dynamics. Our models were parameterized with data collected over the course of 25 years of study of this population. We used the models to conduct simulation experiments to evaluate relationships between monitored or potentially monitored parameters and the demographic variables of interest—population size ( N ) and population growth (λ). Static analyses showed that traditional territory-based monitoring was a poor indicator of eagle population size and growth and that monitoring survivorship would provide more information about these parameters. Nevertheless, these same traditionally monitored territory-based parameters had greater power to detect long-term changes in population size than did survivorship or population structure. Regardless of the taxa considered, threats can have immediate impacts on population size and growth or longer-term impacts on population dynamics. Prudently designed monitoring programs for any species will detect the demographic effects of both types of threats.  相似文献   
9.
采用国家环境保护部新颁布的《环境空气质量标准》对2013年秦皇岛市环境空气质量进行评价,其污染物浓度评价结果为未达标。评价结果表明,PM10、PM2.5、O3是环境空气中主要的污染物。秦皇岛市环境空气具有较明显的月变化规律,O3峰值出现在8月,其他污染物峰值出现在1月。PM2.5小时浓度随时间推移呈峰谷型变化,O3小时浓度呈单峰型分布,NO2小时浓度夜间维持相对稳定。  相似文献   
10.
目前我国页岩气的开发正处于初级阶段,很多生产关键技术尚不成熟,页岩气开发过程中的废压裂液、甲烷漏失、水资源污染等都将会带来一系列环境问题。针对页岩气带来的环境问题,在对开采区域地质情况充分认识的基础上,通过采用先进的钻完井技术,控制压裂液和甲烷的漏失,减少对地层的破坏和水资源的污染;加强对返排废液处理技术的研究力度,优化处理结果;落实针对页岩气开发与环境保护的法律法规等,规避页岩气开采对环境的影响。在借鉴国外开采经验的同时,建议研发适合我国页岩气储层特点的开采技术,改进已有工艺,创新技术和理论。  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