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   16327篇
  免费   210篇
  国内免费   137篇
安全科学   468篇
废物处理   612篇
环保管理   2217篇
综合类   3146篇
基础理论   4046篇
环境理论   11篇
污染及防治   4013篇
评价与监测   1063篇
社会与环境   965篇
灾害及防治   133篇
  2022年   145篇
  2021年   145篇
  2020年   117篇
  2019年   145篇
  2018年   219篇
  2017年   252篇
  2016年   356篇
  2015年   293篇
  2014年   394篇
  2013年   1366篇
  2012年   492篇
  2011年   653篇
  2010年   527篇
  2009年   587篇
  2008年   657篇
  2007年   679篇
  2006年   636篇
  2005年   510篇
  2004年   500篇
  2003年   513篇
  2002年   457篇
  2001年   555篇
  2000年   435篇
  1999年   247篇
  1998年   200篇
  1997年   192篇
  1996年   209篇
  1995年   216篇
  1994年   208篇
  1993年   209篇
  1992年   215篇
  1991年   203篇
  1990年   205篇
  1989年   175篇
  1988年   152篇
  1987年   132篇
  1986年   157篇
  1985年   158篇
  1984年   160篇
  1983年   162篇
  1982年   156篇
  1981年   162篇
  1980年   151篇
  1979年   146篇
  1978年   108篇
  1977年   121篇
  1974年   109篇
  1973年   91篇
  1972年   107篇
  1971年   88篇
排序方式: 共有10000条查询结果,搜索用时 718 毫秒
231.
232.
233.
234.
235.
The product service systems’ (PSS) sustainability potential is described in the framework of the new types of stakeholder relationships and/or partnerships, producing new convergence of economic interests, and a potential concomitant systemic resources optimization.In this perspective, it is argued that the design competencies should move towards those of the ‘strategic design’, thus introducing the concept of ‘strategic design for sustainability’: the design of an innovation strategy, shifting the business focus from designing (and selling) physical products only, to designing (and selling) a system of products and services which are jointly capable of fulfilling specific client demands, while re-orienting current unsustainable trends in production and consumption practices.Some examples of PSS are presented and discussed using the PSS categories ‘services providing added value to the product life cycle’, ‘services providing final results to customers’, and ‘services providing enabling platforms for customers’. The cases derive from an analysis of the ‘environmental friendly innovation’ yearly endowed prize submissions. The Politecnico di Milano University together with the Bocconi University and Legambiente (an environmental NGO) promotes the initiative in Italy.  相似文献   
236.
We describe a new method for the post-mortem examination of the fetal central nervous system. The brain is immobilized in gelatin prior to ultrasonic examination. Correlation with prenatal ultrasound is excellent and subsequent pathological examination is enhanced and facilitated.  相似文献   
237.
238.
The impact of prenatal sonographic diagnosis of oesophageal and gastrointestinal obstructions has been analysed over a 10-year period. Three groups of patients were evaluated. The first group consisted of 46 newborns with abnormal prenatal sonogratns, 41 of which were confirmed to have intestinal obstruction postnatally. The second group consisted of 17 neonates with normal prenatal sonograms who had intestinal obstruction postnatally. The third group included 56 newborns who did not undergo a prenatal sonogram but who had intestinal obstruction confirmed at surgery. Polyhydramnios without the appearance of a stomach on ultrasound was diagnostic of pure oesophageal atresia. Polyhydramnios with intestinal dilation was diagnostic of intestinal obstruction. Although surgery was performed earlier in the infants diagnosed prenatally with ultrasound, mortality was no less than in the group that did not undergo a prenatal sonogram, probably because of the high incidence of associated anomalies.  相似文献   
239.
240.
Prenatal diagnosis of trisomy 20 mosaicism was made in two pregnancies by chromosome analysis of cultured amniotic fluid cells. In both cases, the pregnancy continued to term and a healthy male infant was delivered. Regular assessments up to the age of 6-5 years revealed normal physical and intellectual development in both children.  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