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   211篇
  免费   10篇
  国内免费   8篇
安全科学   2篇
环保管理   14篇
综合类   155篇
基础理论   25篇
环境理论   3篇
污染及防治   1篇
社会与环境   20篇
灾害及防治   9篇
  2022年   4篇
  2021年   3篇
  2020年   1篇
  2019年   7篇
  2018年   13篇
  2017年   3篇
  2016年   3篇
  2015年   3篇
  2014年   2篇
  2013年   5篇
  2012年   5篇
  2011年   17篇
  2010年   15篇
  2009年   8篇
  2008年   11篇
  2007年   10篇
  2006年   12篇
  2005年   11篇
  2004年   6篇
  2003年   13篇
  2002年   16篇
  2001年   14篇
  2000年   6篇
  1998年   3篇
  1997年   1篇
  1996年   1篇
  1995年   5篇
  1994年   6篇
  1993年   4篇
  1992年   3篇
  1991年   1篇
  1989年   3篇
  1988年   6篇
  1985年   1篇
  1984年   2篇
  1983年   1篇
  1982年   1篇
  1981年   3篇
排序方式: 共有229条查询结果,搜索用时 15 毫秒
71.
中国西部大开发作为历史性的壮举 ,重在要有创新思路及观念的大转变。安全减灾作为一种国策及保障手段 ,必须是西部开发的先决条件 ,如果忽略了安全减灾规划战略的布署和开发行动 ,必然迟早要招致悲惨的后果。笔者提出此建议 ,旨在为中国西部开发探索一条生态、安全、减灾和谐发展之路 ,意在促进西部开发健康而有序的可持续发展。  相似文献   
72.
LNG接收站运行过程中将冷排水排放到海域水体中,冷排水的温降及余氯对附近海域水环境的温度场和生物环境产生影响。为掌握冷排水在海域水体中的扩散规律,利用二维水动力-水质数值耦合模型(MIKE21),采用模型嵌套的方式精细化模拟了湄洲湾东吴港区LNG接收站冷排水对水环境的影响,在模型验证可靠的基础上,计算得到了LNG接收站冷排水在冬季、夏季的温降包络线及余氯包络线,从而判断该工程位置选取的合理性。结果表明:在温降大于0.5 ℃条件下,LNG接收站的冷排水影响范围为0.202 km2,距离湄洲岛生态系统重点保护区约2.81 km,距离最近的养殖区约0.53 km;在余氯浓度为0.01 mg/L条件下,LNG接收站的冷排水中余氯影响范围为0.434 km2,最大影响距离为0.628 km;LNG接收站冷排水的温降及余氯均未对周边敏感目标产生直接影响,该排水口位置选择合理。  相似文献   
73.
Land degradation continues to be a major threat to local and national food security. With limited potential to develop new land, any increase in agricultural production must be sought largely through the better use of land already under cultivation. Concerns for the global environment associated with agriculture worldwide have also increased in recent years and require more coordinated efforts at global and national levels with decentralisation of activities at the local level.
This article presents an overview of land resources potential for food production, the processes and extent of land degradation and its economic and environmental costs and impacts, and highlights some macro-economic policies and institutional measures for the prevention of land degradation and rehabilitation of degraded lands. A people-centred programme is presented as a basis for decentralising activities for sustainable land use and land management. Finally, the need for better coordinated efforts of concerned UN, multinational agencies and NGOs for the implementation of Agenda 21 and related conventions is stressed.  相似文献   
74.
Abstract

Local Agenda 21 (LA21), which has its roots in the UN Conference on Environment and Development held in 1992 in Rio de Janeiro, aims at fostering processes of sustainable development on a local level. In this article, we compare the LA21 processes of two cities, Helsingborg in Sweden and Vienna in Austria, to seek insight into the varying implementation approaches of common international political commitments. Our focus of analysis is on the social organisation of the two processes, the way local residents are integrated into LA21 work, and especially the political images of citizens—which we call ‘imagined citizens’—that different actor groups hold. The results of the study illustrate two almost diametrically opposed organisational forms of local sustainability governance, the Swedish process relying on a more expert-led, technocratic model of implementation and the Austrian process strongly building on deliberative forms of citizen participation.  相似文献   
75.
76.
77.
78.
79.
The great majority of genetic defects underlying steroid 21-hydroxylase deficiency appear to result from intergenic recombinations between the homologous CYP21 and CYP21P genes. For a minority, novel sporadic point mutations have been detected. De novo mutations in CYP21 have also been reported, but only a few studies have systematically screened their occurrence. We here describe a population-based patient sample in order to estimate the rate of single-family (i.e. sporadic) and de novo germline mutations in the human CYP21 locus. Among 76 Finnish families were observed three single-family mutations and two de novo mutations in CYP21. The rates obtained, ∼5% and ∼2% for novel and de novo mutations, respectively, indicate that they are not rare and that their occurrence should not be ignored in genetic diagnostics of this disorder. Copyright © 2001 John Wiley & Sons, Ltd.  相似文献   
80.
Dimeric inhibin A was measured in maternal serum samples from 45 pregnancies affected by trisomy 21 and 493 samples from unaffected pregnancies at 10–14 weeks of gestation. Inhibin A levels in affected pregnancies were compared with levels of free β-hCG and PAPP-A in the same series. In the trisomy 21 group, the median multiple of the median (MoM) inhibin A was not significantly elevated (1.28 vs 1.00) with only 15.5% being above the 95th centile. In contrast, the median MoM free β-hCG was significantly increased (2.05 vs 1.00) with 36% above the 95th centile and PAPP-A was significantly reduced (0.49 vs 1.00) with 42% below the 5th centile. Inhibin A levels in the trisomy 21 group were significantly correlated with gestational age such that median levels rose from 1.04 at 11 weeks to 1.30 at 12 weeks and 1.67 at 13 weeks. These findings suggest that first trimester biochemical screening for trisomy 21, which is currently optimised using maternal serum free β-hCG and PAPP-A and fetal nuchal translucency, will not benefit from the inclusion of inhibin A. Copyright © 2001 John Wiley & Sons, Ltd.  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