全文获取类型
收费全文 | 237篇 |
免费 | 0篇 |
专业分类
综合类 | 235篇 |
污染及防治 | 2篇 |
出版年
2021年 | 2篇 |
2013年 | 1篇 |
2011年 | 10篇 |
2010年 | 12篇 |
2009年 | 2篇 |
2008年 | 7篇 |
2007年 | 9篇 |
2006年 | 10篇 |
2005年 | 4篇 |
2004年 | 6篇 |
2003年 | 10篇 |
2002年 | 10篇 |
2001年 | 8篇 |
1995年 | 18篇 |
1994年 | 28篇 |
1993年 | 9篇 |
1992年 | 14篇 |
1991年 | 9篇 |
1990年 | 11篇 |
1989年 | 10篇 |
1988年 | 14篇 |
1987年 | 10篇 |
1986年 | 10篇 |
1985年 | 6篇 |
1984年 | 4篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1981年 | 1篇 |
排序方式: 共有237条查询结果,搜索用时 281 毫秒
231.
232.
233.
234.
Susan Clement Wilson Marleen Susman Sharon Bain Monica Wohlferd Daniel L. Van Dyke Art Daniel Beverly White R. J. McKinlay Gardner 《黑龙江环境通报》2002,22(8):681-685
We present six cases of 47,+i(5p)/46 mosaicism diagnosed at chorionic villus sampling (CVS), this being the first prospective series to be reported. The clinical indication in each was advanced maternal age. Further prenatal studies in four (amniocentesis, plus fetal blood sampling in one) did not show the isochromosome. In one case, subsequent amniocentesis showed 1/48 in situ colonies with the isochromosome, but fetal blood was karyotypically normal. These five pregnancies resulted in phenotypically normal livebirths; further normal follow-up reports (from age 4 months through 4 years) are noted in four of these. Analysis of placental tissue in one case confirmed the presence of the i(5p) mosaicism. In the remaining case, in which 100% of CVS cultured cells had the i(5p), the pregnancy was terminated. Fetal skin fibroblasts did not show the i(5p). Thus, in none of these six cases was true fetal mosaicism detected, nor an abnormal phenotype noted. We suggest that a 47,+i(5p)/46 karyotype, detected at CVS, may frequently reflect confined placental mosaicism. In addition, we report a case of the primary diagnosis of 47,+i(5p)/46 mosaicism at amniocentesis. The infant appeared normal at birth, but a brain malformation was subsequently identified. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献
235.
Yifat Ochshorn Michael J. Kupferminc Igal Wolman Avi Orr-Urtreger Ariel J. Jaffa Yuval Yaron 《黑龙江环境通报》2001,21(7):547-549
Combined first trimester screening using pregnancy associated plasma protein-A (PAPP-A), free β-human chorionic gonadotrophin, and nuchal translucency (NT), is currently accepted as probably the best combination for the detection of Down syndrome (DS). Current first trimester algorithms provide computed risks only for DS. However, low PAPP-A is also associated with other chromosome anomalies such as trisomy 13, 18, and sex chromosome aneuploidy. Thus, using currently available algorithms, some chromosome anomalies may not be detected. The purpose of the present study was to establish a low-end cut-off value for PAPP-A that would increase the detection rates for non-DS chromosome anomalies. The study included 1408 patients who underwent combined first trimester screening. To determine a low-end cut-off value for PAPP-A, a Receiver–Operator Characteristic (ROC) curve analysis was performed. In the entire study group there were 18 cases of chromosome anomalies (trisomy 21, 13, 18, sex chromosome anomalies), 14 of which were among screen-positive patients, a detection rate of 77.7% for all chromosome anomalies (95% CI: 55.7–99.7%). ROC curve analysis detected a statistically significant cut-off for PAPP-A at 0.25 MoM. If the definition of screen-positive were to also include patients with PAPP-A<0.25 MoM, the detection rate would increase to 88.8% for all chromosome anomalies (95% CI: 71.6–106%). This low cut-off value may be used until specific algorithms are implemented for non-Down syndrome aneuploidy. Copyright © 2001 John Wiley & Sons, Ltd. 相似文献
236.
H. Zhao O. P. Van Diggelen R. Thoomes J. Huumans E. Young T. Mazurczak Dr. W. J. Kleijer 《黑龙江环境通报》1990,10(2):85-91
A new fluorogenic substrate, 4 methylumbelliferylβ-D-6-sulphogalactoside, was used for the assay of galactose-6-sulphate sulphatase activity in chorionic villi, cultured villus cells, and amniocytes. The fluorometric assay is much more convenient than the conventional assay using radiolabelled, sulphated oligosaccharides. Both types of substrate were used in the prenatal diagnosis of three pregnancies at risk for Morquio type A disease using amniocytes. These enzyme tests, as well as electrophoresis of glycosaminoglycans in the amniotic fluid, indicated affected fetuses in two pregnancies and a non-affected fetus in one. 相似文献
237.
Professor B. Dallapiccola G. Novelli G. Ferrant A. Pachi M. L. Cristiani M. Magnani 《黑龙江环境通报》1986,6(2):101-107
First trimester prenatal diagnosis was offered to the mother of a child affected by severe haemolytic anaemia due to glucose phosphate isomerase (GPI) deficiency. The mutant enzyme was characterized by an increased thermal lability. Both parents had 50 per cent normal red cell GPI activity. We have shown that the homozygous and heterozygous genotypes can be clearly distinguished from each other and controls by combinations of the measurement of enzyme activity and enzyme thermal lability. Examination of trophoblast cells obtained at 9 weeks of gestation led to the diagnosis of a GPI heterozygous fetus. The result was confirmed by analysis on uncultured and cultured amniotic fluid cells sampled at 16 weeks and by red blood cell studies of the healthy newborn. Prenatal diagnosis of GPI deficiency is indicated in families with previous cases resulting in severe haemolysis and mainly with the conservative view of arranging appropriate therapeutic measures for affected fetuses. 相似文献