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   256831篇
  免费   16319篇
  国内免费   36705篇
安全科学   24108篇
废物处理   11710篇
环保管理   29583篇
综合类   105708篇
基础理论   48161篇
环境理论   211篇
污染及防治   51074篇
评价与监测   16790篇
社会与环境   15206篇
灾害及防治   7304篇
  2024年   681篇
  2023年   3283篇
  2022年   9041篇
  2021年   9076篇
  2020年   8714篇
  2019年   6821篇
  2018年   8006篇
  2017年   9300篇
  2016年   9324篇
  2015年   9456篇
  2014年   11645篇
  2013年   21266篇
  2012年   16354篇
  2011年   18335篇
  2010年   15995篇
  2009年   15769篇
  2008年   16180篇
  2007年   15833篇
  2006年   14919篇
  2005年   11534篇
  2004年   8977篇
  2003年   7960篇
  2002年   7097篇
  2001年   6405篇
  2000年   5472篇
  1999年   3814篇
  1998年   2607篇
  1997年   2397篇
  1996年   2373篇
  1995年   2422篇
  1994年   2104篇
  1993年   1606篇
  1992年   1607篇
  1991年   1404篇
  1990年   1289篇
  1989年   1158篇
  1988年   1030篇
  1987年   913篇
  1986年   864篇
  1985年   873篇
  1984年   898篇
  1983年   825篇
  1982年   921篇
  1981年   818篇
  1980年   628篇
  1979年   687篇
  1978年   585篇
  1977年   513篇
  1975年   467篇
  1974年   461篇
排序方式: 共有10000条查询结果,搜索用时 234 毫秒
281.
A case of type III congenital cystic adenomatoid malformation of the lung was successfully diagnosed prenatally by fetal lung biopsy. We performed this procedure at 22 weeks of gestation, using a biopsy gun system under ultrasound guidance. The pregnancy was undisturbed by the procedure but as the condition was incompatible with life, an abortion was performed. The diagnosis was confirmed at post-mortem examination. Fetal lung biopsy appears to be a useful method for prenatal diagnosis of fetal lung disorders.  相似文献   
282.
This paper is concerned with developing a model for group decision making under multiple criteria. The multiple criteria group decision making (MCGDM)problem involves a set of feasible land use patterns that are evaluated on the basis of multiple, conflicting and noncommensurate criteria by a group of individuals. The model integrates the Analytic Hierarchy Process (AHP) and an integer mathematical programming method. The former provides a tool for structuring the decision problem and determining land suitability for different socio-economicactivities (the uses of land), the latter is used to identify the land use pattern that maximizes consensus among interest groups. The model is used to analyze environmental conflict over land resource allocation in the Cape Region of Mexico.  相似文献   
283.
284.
285.
A combination of poor mining methods, waste storage and disposal systems, as well as the day-to-day activities associated with tribute and contract chromite mining are primarily responsible for environmental problems on the Zimbabwe Great Dyke. For instance, the unsystematic dumping of waste rocks in rivers blocks channels and results in flooding, which further sterilizes agricultural land and mineral resources. Erosion of these haphazardly located dumps causes siltation of water bodies and results in the dispersion of heavy metals in soils and watercourses. Vegetation growth on waste dumps is limited and constrained by the high pH levels from phytotoxic metals in soils, the lack of nutrients, poor moisture retention qualities of the mining waste and critical cation imbalances within dumps. This article attributes poor environmental management on the Dyke to poverty, a direct result of the nature of tribute agreements and output prices. Prices based on output targets are exploitative and undervalue labour and thus perpetuate poverty. By absolving claim holders from environmental liability, tribute agreements contribute directly to environmental problems. Thus, the incorporation of enforceable dual environmental responsibility requirements in contract mining agreements is needed to overcome this problem. This article recommends that, to break the poverty cycle, the primary cause of environmental mismanagement in the sector, miners need to be empowered through claim ownership and the enhancement of their capacity to negotiate prices with buyers of chrome.  相似文献   
286.
287.
湿法烟气脱硫废水的处理   总被引:18,自引:5,他引:13  
简述了湿法烟气脱硫废水的特性及处理原理,分析了废水在反应池的停留时间,投加药品量等主要因素对处理效果的影响,并就工艺控制过程和最终处理结果进行讨论。  相似文献   
288.
289.
Collaborative policy making has become increasingly significant in environmental management, but it is often evaluated by whether or not agreement is reached and implemented. The most important outcomes of such policy dialogues are often invisible or undervalued when seen through the lens of a traditional, modernist paradigm of government and accountability. These dialogues represent a new paradigm of governance that can be best understood in the light of a complex adaptive system model of society. From this perspective collaborative policy making is a way of making a system more flexible, adaptive and intelligent. The authors document such outcomes in three cases of water policy making in California, including the San Francisco Estuary Project, the CALFED Bay-Delta Program and the Sacramento Area Water Forum. The outcomes include social and political capital, agreed-on information, the end of stalemates, high-quality agreements, learning and change, innovation and new practices involving networks and flexibility.  相似文献   
290.
三峡工程与长江中游沿江产业带建设   总被引:3,自引:0,他引:3  
讨论了长江中游沿江产业带发展条件、限制因素和未来发展,指出三峡工程的建设将对长江中游产业的布局和经济发展带来深刻的变化;防洪作用促进中游两岸大型工业项目的兴建,调整现有沿江城镇的布局,使之结构趋于合理化;电力供应经解能源的紧张状态,改善航运条件,发挥长江黄金水道的综合效益。当然,由于坝下河道冲刷,对现有的码头带来一定的影响,由于冬季水位抬升引起两岸低湖田地下水位上升,加剧两岸土壤潜育化和沼泽化。  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