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   24259篇
  免费   289篇
  国内免费   221篇
安全科学   716篇
废物处理   976篇
环保管理   3225篇
综合类   4079篇
基础理论   6291篇
环境理论   11篇
污染及防治   6277篇
评价与监测   1554篇
社会与环境   1473篇
灾害及防治   167篇
  2022年   210篇
  2021年   188篇
  2020年   162篇
  2019年   190篇
  2018年   329篇
  2017年   363篇
  2016年   523篇
  2015年   414篇
  2014年   573篇
  2013年   1981篇
  2012年   719篇
  2011年   1010篇
  2010年   812篇
  2009年   911篇
  2008年   1027篇
  2007年   1065篇
  2006年   979篇
  2005年   807篇
  2004年   753篇
  2003年   818篇
  2002年   712篇
  2001年   960篇
  2000年   698篇
  1999年   411篇
  1998年   315篇
  1997年   304篇
  1996年   331篇
  1995年   355篇
  1994年   308篇
  1993年   295篇
  1992年   322篇
  1991年   296篇
  1990年   310篇
  1989年   286篇
  1988年   230篇
  1987年   211篇
  1986年   210篇
  1985年   232篇
  1984年   240篇
  1983年   235篇
  1982年   223篇
  1981年   226篇
  1980年   205篇
  1979年   207篇
  1978年   141篇
  1977年   167篇
  1975年   125篇
  1974年   156篇
  1973年   136篇
  1972年   142篇
排序方式: 共有10000条查询结果,搜索用时 328 毫秒
321.
322.
323.
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   
324.
325.
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   
326.
327.
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   
328.
329.
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   
330.
Citrullinaemia was presumed to be excluded in a fetus at risk by the direct assay of argininosuccinate synthetase in chorionic villi. The diagnosis was confirmed after amniocentesis by normal argininosuccinate synthetase activity in the cultured amniotic fluid cells and by a normal citrulline concentration in the amniotic fluid. The prediction of a normal fetus was confirmed at term by the birth of a non-citrullinaemic boy.  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