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   994篇
  免费   3篇
  国内免费   4篇
安全科学   77篇
废物处理   21篇
环保管理   51篇
综合类   674篇
基础理论   112篇
环境理论   7篇
污染及防治   24篇
评价与监测   3篇
社会与环境   28篇
灾害及防治   4篇
  2023年   13篇
  2022年   5篇
  2021年   23篇
  2020年   22篇
  2019年   14篇
  2018年   18篇
  2017年   40篇
  2016年   34篇
  2015年   31篇
  2014年   44篇
  2013年   89篇
  2012年   6篇
  2011年   33篇
  2010年   32篇
  2009年   35篇
  2008年   26篇
  2007年   38篇
  2006年   43篇
  2005年   55篇
  2004年   46篇
  2003年   47篇
  2002年   60篇
  2001年   27篇
  1999年   1篇
  1996年   1篇
  1995年   29篇
  1994年   43篇
  1993年   22篇
  1992年   14篇
  1991年   25篇
  1990年   11篇
  1989年   11篇
  1988年   14篇
  1987年   11篇
  1986年   5篇
  1985年   12篇
  1984年   11篇
  1983年   4篇
  1982年   2篇
  1981年   4篇
排序方式: 共有1001条查询结果,搜索用时 15 毫秒
111.
112.
We report an interstitial deletion of chromosome 3q26-q28 in a fetus in which anophthalmia had been detected prenatally. FISH analysis, using BAC clones encompassing the SOX2 locus, showed that SOX2 gene was involved in the chromosomal breakpoint of the deletion. This case confirms that haploinsufficiency for SOX2 plays a crucial role in human eye development and emphasizes the necessity of careful chromosomal analysis, including FISH analysis of the 3q region, in case of prenatal discovery of anophthalmia. Copyright © 2004 John Wiley & Sons, Ltd.  相似文献   
113.
114.
Double trisomies are a rare occurrence. We report the first case of a Down and Klinefelter's syndrome (48,XXY,+21) in a fetus that was prenatally diagnosed during the 15th week of pregnancy. Even though the nasal bone was present, and the color-Doppler study of the ductus venosus and the nuchal thickness were normal, the maternal serum test results indicated an increased risk of Down syndrome and consequentially a genetic amniocentesis was performed. A 48,XXY,+21 karyotype was observed and the patient decided to terminate the pregnancy. In this case, we did not find the typical ultrasound (US) signs that would have led us to the chromosomopathy; furthermore, we emphasize the advantages of using biochemical screening which, in our case, were crucial in arriving at the correct diagnosis. Copyright © 2006 John Wiley & Sons, Ltd.  相似文献   
115.
<正>The power and efficiency of gasoline engines is often improved through the use of fuel with high octane ratings.The octane rating of fuel could be further increased with oxygenate additives such as alcohols and ethers, with methyl tert-butyl ether (MTBE) being one of the most common gasoline additives. The Agency for Toxic Substances and Disease  相似文献   
116.
Several animal (lamb, poultry and swine) fatty wastes were pyrolyzed under nitrogen, in a laboratory scale fixed-bed reactor and the main products (liquid bio-oil, solid bio-char and syngas) were obtained. The purpose of this study is to produce and characterize bio-oil and bio-char obtained from pyrolysis of animal fatty wastes. The maximum production of bio-oil was achieved at a pyrolysis temperature of 500 °C and a heating rate of 5 °C/min. The chemical (GC–MS analyses) and spectroscopic analyses (FTIR analyses) of bio-oil showed that it is a complex mixture consisting of different classes of organic compounds, i.e., hydrocarbons (alkanes, alkenes, cyclic compounds…etc.), carboxylic acids, aldehydes, ketones, esters,…etc. According to fuel properties, produced bio-oils showed good properties, suitable for its use as an engine fuel or as a potential source for synthetic fuels and chemical feedstock. Obtained bio-chars had low carbon content and high ash content which make them unattractive for as renewable source energy.  相似文献   
117.
In recent years, an increasing number of inherited diseases in man have been recognized in which there is an impairment in the peroxisomal β-oxidation of very-long-chain fatty acids. In general, these disorders are associated with severe neurological and physical abnormalities and death within the first years of life. In this paper we describe our experience with regard to the prenatal diagnosis of a number of different inborn errors of peroxisomal β-oxidation. Eleven pregnancies at risk were monitored by measuring very-long-chain fatty acid levels as well as very-long-chain fatty acid β-oxidation in cultured chorionic villous fibroblasts and/or amniotic fluid cells. Five affected fetuses were identified. It is concluded that prenatal diagnosis in this group of diseases can be done reliably using cultured chorionic villous fibroblasts or amniotic fluid cells.  相似文献   
118.
The prenatal diagnosis of The Turner Syndrome is described at a menstrual age of 12 weeks. Detection of cystic hygroma was followed by vaginal chorionic villous sampling (CVS) which revealed a 45,X karyotype. Early documentation of fetal karyotype in the presence of a cystic hygroma is essential for accurate diagnosis and genetic counselling.  相似文献   
119.
120.
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