全文获取类型
收费全文 | 15826篇 |
免费 | 162篇 |
国内免费 | 126篇 |
专业分类
安全科学 | 379篇 |
废物处理 | 669篇 |
环保管理 | 1811篇 |
综合类 | 2678篇 |
基础理论 | 4364篇 |
环境理论 | 6篇 |
污染及防治 | 4069篇 |
评价与监测 | 1072篇 |
社会与环境 | 973篇 |
灾害及防治 | 93篇 |
出版年
2022年 | 127篇 |
2021年 | 107篇 |
2020年 | 100篇 |
2019年 | 108篇 |
2018年 | 203篇 |
2017年 | 241篇 |
2016年 | 332篇 |
2015年 | 274篇 |
2014年 | 459篇 |
2013年 | 1216篇 |
2012年 | 502篇 |
2011年 | 701篇 |
2010年 | 621篇 |
2009年 | 591篇 |
2008年 | 676篇 |
2007年 | 721篇 |
2006年 | 600篇 |
2005年 | 516篇 |
2004年 | 527篇 |
2003年 | 511篇 |
2002年 | 492篇 |
2001年 | 649篇 |
2000年 | 476篇 |
1999年 | 262篇 |
1998年 | 175篇 |
1997年 | 207篇 |
1996年 | 207篇 |
1995年 | 238篇 |
1994年 | 238篇 |
1993年 | 181篇 |
1992年 | 195篇 |
1991年 | 183篇 |
1990年 | 205篇 |
1989年 | 187篇 |
1988年 | 154篇 |
1987年 | 163篇 |
1986年 | 156篇 |
1985年 | 159篇 |
1984年 | 148篇 |
1983年 | 142篇 |
1982年 | 126篇 |
1981年 | 121篇 |
1980年 | 115篇 |
1979年 | 126篇 |
1978年 | 101篇 |
1977年 | 113篇 |
1975年 | 87篇 |
1974年 | 88篇 |
1973年 | 98篇 |
1972年 | 87篇 |
排序方式: 共有10000条查询结果,搜索用时 187 毫秒
341.
342.
343.
Hydrops fetalis was diagnosed at 22 weeks. An ultrasound examination demonstrated cardiomegaly and a fetal blood specimen obtained by cordocentesis revealed thrombocytopenia, anaemia, and neutropenia. Fetal paracentesis yielded straw-coloured fluid with electrolytes indicative of a transudate. Non-enveloped icosahedral viral particles approximately 23 mm in diameter were visualized in the ascitic fluid by electron microscopy. Immune electron microscopy confirmed human parvovirus B19. Direct fetal digitalization led to a reduction in umbilical artery resistance, a decline in the abdominal circumference from 20·3 to 17·8 cm, and resolution of the ascites within 72 h. Despite this dramatic response to therapy, fetal death occurred on day 5 of treatment. The initial maternal serum was positive for anti-B19 IgM and IgG antibodies. Electron microscopy of fetal cardiac tissue obtained post-mortem revealed intranuclear viral particles typical of B19, confirming the antenatal diagnosis of myocarditis. This case demonstrates that direct viral identification is applicable to prenatal diagnosis. To our knowledge, this is the first reported case of the antenatal diagnosis and palliative treatment of fetal viral infection. 相似文献
344.
A 46,XX; 47,XX,+9; 47,XX, + ?mar karyotype was detected in an amniotic fluid cell culture and confirmed in a subsequent fetal blood sample from a 40-year-old woman. After termination of the pregnancy, none of the 186 mitoses obtained from a second blood sample was trisomic for chromosome 9 (p<0.001). Selection against cells containing trisomy 9 is postulated to explain the disappearance of the lymphocyte clone. 相似文献
345.
346.
347.
348.
349.
In this paper we describe the use of five-colour fluorescence in situ hybridization for prenatal diagnosis of aneuploidy using uncultured amniotic fluid cells. The analysis is based on ratio mixing of dual-labelled probes and digital imaging for the detection and visualization of five different probes specific for the five target chromosomes, 13, 18, 21, X, and Y. A retrospective blind analysis of 30 coded uncultured amniotic fluid samples correctly detected fetal sex and five trisomy 21 cases. Multicolour fluorescence in situ hybridization used in this way allows rapid and simultaneous detection of the most frequent aneuploidies. 相似文献
350.
Dr. Yash P. Agrawal Päivi Ylikangas Markku T. Parviainen Ilkka M. Penttilä 《黑龙江环境通报》1994,14(12):1141-1149
The histochemical measurement of urea-resistant alkaline phosphatase from maternal blood neutrophils is known to have a high detection rate for the prenatal detection of Down's syndrome pregnancies. However, because the histochemical method is laborious and subjective to use, it has not gained widespread acceptance in prenatal screening programmes. We present a simple and objective method for the measurement of urea-resistant alkaline phosphatase by flow cytometry. The method should allow the design of larger studies aimed at evaluating the role of neutrophil urea-resistant alkaline phosphatase in the prenatal screening for Down's syndrome. 相似文献