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   25991篇
  免费   247篇
  国内免费   202篇
安全科学   709篇
废物处理   1029篇
环保管理   3068篇
综合类   6295篇
基础理论   6009篇
环境理论   4篇
污染及防治   6467篇
评价与监测   1514篇
社会与环境   1232篇
灾害及防治   113篇
  2022年   204篇
  2018年   331篇
  2017年   328篇
  2016年   503篇
  2015年   368篇
  2014年   537篇
  2013年   1828篇
  2012年   658篇
  2011年   925篇
  2010年   811篇
  2009年   915篇
  2008年   993篇
  2007年   1002篇
  2006年   900篇
  2005年   782篇
  2004年   793篇
  2003年   790篇
  2002年   726篇
  2001年   1026篇
  2000年   700篇
  1999年   458篇
  1998年   321篇
  1997年   314篇
  1996年   322篇
  1995年   379篇
  1994年   361篇
  1993年   303篇
  1992年   321篇
  1991年   332篇
  1990年   364篇
  1989年   346篇
  1988年   260篇
  1987年   252篇
  1986年   233篇
  1985年   258篇
  1984年   278篇
  1983年   269篇
  1982年   258篇
  1981年   263篇
  1980年   221篇
  1979年   243篇
  1978年   182篇
  1977年   187篇
  1976年   181篇
  1974年   194篇
  1973年   194篇
  1972年   174篇
  1971年   171篇
  1968年   178篇
  1967年   208篇
排序方式: 共有10000条查询结果,搜索用时 297 毫秒
491.
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   
492.
493.
494.
495.
496.
497.
498.
Ninety-two families with spinal muscular atrophy (SMA) applied for genetic counselling and further prenatal diagnosis. To minimize expenses, only one tightly linked informative marker was determined in the course of preliminary examination, and non-radioactive allele detection was preferably used. Four prenatal diagnoses of SMA type I, four of SMA type II, and one of SMA type III were made. This trial programme shows the considerable requirements, importance, and potential effectiveness of prenatal prediction of SMA in Russia.  相似文献   
499.
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   
500.
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