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   16544篇
  免费   181篇
  国内免费   138篇
安全科学   371篇
废物处理   671篇
环保管理   2037篇
综合类   3716篇
基础理论   3818篇
环境理论   14篇
污染及防治   4085篇
评价与监测   1059篇
社会与环境   1038篇
灾害及防治   54篇
  2022年   125篇
  2021年   135篇
  2019年   121篇
  2018年   237篇
  2017年   227篇
  2016年   357篇
  2015年   267篇
  2014年   388篇
  2013年   1134篇
  2012年   431篇
  2011年   676篇
  2010年   511篇
  2009年   587篇
  2008年   675篇
  2007年   711篇
  2006年   642篇
  2005年   520篇
  2004年   549篇
  2003年   529篇
  2002年   499篇
  2001年   629篇
  2000年   396篇
  1999年   297篇
  1998年   189篇
  1997年   214篇
  1996年   226篇
  1995年   236篇
  1994年   232篇
  1993年   219篇
  1992年   199篇
  1991年   205篇
  1990年   198篇
  1989年   170篇
  1988年   168篇
  1987年   154篇
  1986年   153篇
  1985年   148篇
  1984年   173篇
  1983年   167篇
  1982年   172篇
  1981年   145篇
  1980年   132篇
  1979年   123篇
  1978年   134篇
  1977年   115篇
  1976年   104篇
  1975年   107篇
  1974年   118篇
  1971年   98篇
  1967年   101篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
51.
Ten out of the 12 new EU members, used to belong to the so-called “former eastern block”, with a post WWII environmental policy radically different from the tendencies followed in Western Europe. The lack of conservation regulations has resulted in a rather harmful industrialization, regarding natural resources and environmental quality. While air pollution transfer is a phenomenon of transboundary level, there is a particular interest in examining the contribution of the new EU member states to the environmental pressure faced by the older member states and vice versa. The current study utilises the official data for almost 20 years published by the European Monitoring and Evaluation Program concerning the transboundary transfer of NOx and SO2 in order to analyse the situation and discuss the present and future environmental policy regarding air pollution.  相似文献   
52.
Three hundred and fifty-four women who underwent midtrimester genetic amniocentesis were matched for age, parity, indication, and smoking history, with an equivalent number of women who had declined the procedure, for the purpose of comparing the neonatal respiratory status of their offspring. There was no evidence that the infants exposed to genetic amniocentesis were compromised.  相似文献   
53.
Three different types of chromosome 12 inversion were seen in 15 individuals out of 44 individuals examined in one 8 generation family. Type 1: a pericentric inversion inv(12) (p112; q131) was found in 7 individuals and twice at prenatal diagnosis. Type 2: a paracentric inversion inv(12) (p123; p131) was seen in two individuals. Two individuals carried both inversion chromosomes, namely type 1 and type 2. The two inversion chromosomes were transmitted from each of the parents. Type 3: a double pericentric and paracentric inversion (type 3) inv(12) (p123; p131) (p112; q131) was observed in the daughter of one of the carriers of type 1 and 2 inversions and again at prenatal diagnosis in her son. The double inversion most likely arose through crossing-over in between the two inversion loops. A balanced translocation t(7; 13) and the inversion type 1 was observed in one individual, who transmitted the translocation only to an offspring. The frequency of inversions in amniotic fluid cells observed in our laboratory was 1·9 per cent. The clinical implications of these findings are discussed.  相似文献   
54.
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   
55.
56.
57.
58.
59.
60.
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