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   25899篇
  免费   239篇
  国内免费   160篇
安全科学   582篇
废物处理   1065篇
环保管理   3321篇
综合类   4335篇
基础理论   6909篇
环境理论   13篇
污染及防治   5806篇
评价与监测   1775篇
社会与环境   2341篇
灾害及防治   151篇
  2022年   181篇
  2021年   196篇
  2020年   137篇
  2019年   184篇
  2018年   766篇
  2017年   775篇
  2016年   866篇
  2015年   416篇
  2014年   565篇
  2013年   1788篇
  2012年   846篇
  2011年   1517篇
  2010年   1051篇
  2009年   1155篇
  2008年   1407篇
  2007年   1668篇
  2006年   868篇
  2005年   776篇
  2004年   730篇
  2003年   782篇
  2002年   741篇
  2001年   752篇
  2000年   594篇
  1999年   323篇
  1998年   274篇
  1997年   253篇
  1996年   255篇
  1995年   284篇
  1994年   265篇
  1993年   255篇
  1992年   260篇
  1991年   252篇
  1990年   266篇
  1989年   223篇
  1988年   186篇
  1987年   166篇
  1986年   195篇
  1985年   192篇
  1984年   210篇
  1983年   190篇
  1982年   198篇
  1981年   194篇
  1980年   188篇
  1979年   185篇
  1978年   129篇
  1977年   145篇
  1974年   133篇
  1973年   121篇
  1972年   140篇
  1971年   110篇
排序方式: 共有10000条查询结果,搜索用时 125 毫秒
331.
332.
333.
334.
335.
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   
336.
A mother affected with Apert's syndrome was diagnosed by ultrasound scan at 16–17 weeks to have a fetus similarly affected. The typical features of acrocephaly and symmetrical syndactyly were seen. This is probably the first time that this condition has been diagnosed at such a gestation by ultrasound scan. The patient decided to continue the pregnancy, and intrauterine death occurred at 34 weeks. The diagnosis was confirmed by pathological examination.  相似文献   
337.
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   
338.
339.
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   
340.
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