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   42554篇
  免费   397篇
  国内免费   380篇
安全科学   1156篇
废物处理   1647篇
环保管理   5474篇
综合类   7552篇
基础理论   11816篇
环境理论   26篇
污染及防治   10703篇
评价与监测   2750篇
社会与环境   1958篇
灾害及防治   249篇
  2022年   288篇
  2021年   266篇
  2019年   294篇
  2018年   644篇
  2017年   642篇
  2016年   948篇
  2015年   696篇
  2014年   984篇
  2013年   2939篇
  2012年   1524篇
  2011年   1863篇
  2010年   1409篇
  2009年   1444篇
  2008年   1706篇
  2007年   1797篇
  2006年   1625篇
  2005年   1661篇
  2004年   1758篇
  2003年   1604篇
  2002年   1269篇
  2001年   1646篇
  2000年   1131篇
  1999年   739篇
  1998年   537篇
  1997年   559篇
  1996年   559篇
  1995年   617篇
  1994年   569篇
  1993年   499篇
  1992年   532篇
  1991年   512篇
  1990年   512篇
  1989年   519篇
  1988年   461篇
  1987年   377篇
  1986年   359篇
  1985年   398篇
  1984年   372篇
  1983年   412篇
  1982年   410篇
  1981年   364篇
  1980年   306篇
  1979年   344篇
  1978年   300篇
  1977年   264篇
  1976年   270篇
  1975年   254篇
  1974年   250篇
  1973年   240篇
  1972年   274篇
排序方式: 共有10000条查询结果,搜索用时 375 毫秒
651.
652.
One hundred and fifty-one women of advanced maternal age who underwent genetic termination of pregnancy (TOP) were studied for their reproductive behaviour and the type of procedure for prenatal diagnosis in a subsequent pregnancy. A total of 59 women (39 per cent) had a further pregnancy. In all continuing pregnancies prenatal diagnosis was performed, of which 75 per cent consisted of chorionic villus sampling (CVS). Reproductive behaviour following a genetic termination was negatively correlated with maternal age and parity. Both reproductive behaviour and the choice to undergo a diagnostic procedure in the next pregnancy were independent of the type of diagnostic procedure in the previous affected pregnancy.  相似文献   
653.
654.
655.
656.
657.
658.
We report two cases of apparently balanced complex de novo chromosomal rearrangements (BCCR) detected prenatally at 17 weeks and 10 weeks of gestation, respectively. Chromosomes were studied using GTG-banding and fluorescent in situ hybridization (FISH). In one case four chromosomes and in the other case three chromosomes were involved in the rearrangements. One of the pregnancies was terminated and no external or internal abnormalities were detected at autopsy. The other pregnancy continued to term. Level III ultrasound examination showed no abnormalities. The child is now 3 years old and has neither congenital anomalies nor evidence of delayed psychomotor development.  相似文献   
659.
A prenatally detected case of a rare mosaic tetrasomy 12p/trisomy 12p is reported, presenting as the well-known accessory isochromosome 12p and a supernumerary single 12p marker in 17/24 and 6/24 clones of cultured amniotic fluid cells, respectively. The chromosomal nature of both marker chromosomes was investigated in cultured amniotic fluid cells by fluorescent in situ hybridization with various probes: the 12-centromeric probes pa12H8 and D12Z3, a whole chromosome 12 paint, and the chromosome 12p-specific paint M28. DNA analysis revealed a maternal origin of the extra 12p material. After counselling, the parents requested termination of pregnancy. Inspection and autopsy of the fetus revealed many of the dysmorphisms and internal structural abnormalities of the Pallister–Killian syndrome.  相似文献   
660.
In a case of hydrops fetalis, serological examination showed a recent maternal human parvovirus B19 infection. Amniocentesis revealed a unique unbalanced translocation between chromosomes 3 and 11 of the fetus. The mother proved to have a balanced reciprocal translocation between chromosomes 3 and 11. A grossly macerated hydropic male fetus was delivered with a flat nose and low implanted deformed ears. Histopathological examination revealed nuclear inclusion bodies in fetal erythroid cells, confirming human parvovirus B19 infection. Parvovirus B19 DNA was demonstrated by in situ hybridization in the nuclei of heart muscle cells. Our finding of two different disorders in one case illustrates the importance of a complete evaluation of every case of hydrops fetalis, especially concerning counselling on the outcome of future pregnancies. The human parvovirus B19 infection will not recur due to the acquired immunity of the mother, whereas the balanced reciprocal translocation will endanger future pregnancies.  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