全文获取类型
收费全文 | 653篇 |
免费 | 2篇 |
国内免费 | 3篇 |
专业分类
安全科学 | 8篇 |
环保管理 | 1篇 |
综合类 | 631篇 |
基础理论 | 8篇 |
污染及防治 | 3篇 |
评价与监测 | 2篇 |
社会与环境 | 3篇 |
灾害及防治 | 2篇 |
出版年
2021年 | 6篇 |
2020年 | 1篇 |
2018年 | 2篇 |
2017年 | 3篇 |
2016年 | 2篇 |
2013年 | 4篇 |
2012年 | 5篇 |
2011年 | 31篇 |
2010年 | 32篇 |
2009年 | 34篇 |
2008年 | 26篇 |
2007年 | 37篇 |
2006年 | 40篇 |
2005年 | 54篇 |
2004年 | 42篇 |
2003年 | 43篇 |
2002年 | 57篇 |
2001年 | 25篇 |
1999年 | 1篇 |
1996年 | 1篇 |
1995年 | 27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 | 4篇 |
1985年 | 11篇 |
1984年 | 10篇 |
1983年 | 3篇 |
1982年 | 2篇 |
1981年 | 4篇 |
排序方式: 共有658条查询结果,搜索用时 15 毫秒
401.
402.
The prenatal diagnosis of thrombocytopenia absent radius (TAR) syndrome, utilizing ultrasound and cordocentesis, is described. To our knowledge, this represents the first prenatal diagnosis of this condition in an index case. The diagnostic evaluation of a fetus with upper extremity limb reduction defects is discussed. 相似文献
403.
Professor D. J. H. Brock Lilias Barron Susan Holloway W. A. Liston S. G. Hillier M. Seppala 《黑龙江环境通报》1990,10(4):245-251
A set of 21 early maternal serum samples (19 first-trimester and two at 14 weeks) from pregnancies resulting in a child with Down syndrome was matched for gestation and length of storage with 63 samples from unaffected pregnancies. The concentrations of alpha-fetoprotein (AFP), unconjugated oestriol (uE3), human chorionic gonadotrophin (hCG), pregnancy-specific β1–glycoprotein (SP1), and placental alkaline phosphatase (PALP) were measured. The ratios of the medians for Down syndrome pregnancies compared with the medians for controls were AFP 0·71, uE3 0·67, hCG 1·43, SP1 0·79, and PALP 0·92. Although the differences between the medians for affected and unaffected pregnancies were not significant, the trends for AFP, uE3, and hCG confirm earlier findings on first-trimester samples. 相似文献
404.
A simple enzyme immunoassay measuring human chorionic gonadotropin in undiluted maternal serum has been developed in order to be used as a prenatal screening test for Down' s syndrome. A retrospective study of maternal serum sampled during pregnancies associated with trisomy 21 shows that with a 5% amniocentesis rate determined on a single test, the detection rate of trisomy 21 would be around two-thirds of the affected pregnancies. A prospective study of 9040 pregnant women under 38 years has confirmed the usefulness of the assay. 相似文献
405.
M. J. Le Bris-Quillevere D. Riviere E. Pluchon-Riviere J. J. Chabaud P. Parent A. Volant G. Boog 《黑龙江环境通报》1990,10(6):405-411
A case of del(15)(q11q13) was detected in amniotic fluid cell cultures and confirmed by cordocentesis in a 27-year-old woman with a low maternal serum alpha-fetoprotein level. The fetus was shown to have a short femoral length on ultrasonography. This structural chromosome abnormality associated with the prenatal ultrasonographic findings and the morphological characteristics visualized after termination of pregnancy strongly suggest Prader-Willi syndrome. 相似文献
406.
Prof. F. Roels V. Verdonck M. Pauwels L. de Catte W. Lissens I. Liebaers M. Elleder 《黑龙江环境通报》1987,7(7):525-530
Peroxisomes and their metabolites the plasmalogens were visualized in chorionic villi by quick and simple procedures. Villi were stained and mounted in toto, and can also be embedded. These methods may contribute to early prenatal diagnosis of peroxisomal disorders (Zellweger syndrome, neonatal adrenoleukodystrophy, infantile Refsum's disease a.o.). 相似文献
407.
It has been suggested that vaginal bleeding in pregnancy is associated with an increased risk of fetal Down syndrome. To investigate this, information on vaginal bleeding, collected at the first antenatal visit, was abstracted from the medical notes of 70 pregnancies associated with Down syndrome and 140 unaffected controls matched for maternal age. Fourteen cases (20 per cent) and 23 controls (16 per cent) had some evidence of bleeding (relative risk estimated as the odds ratio= 1.3; P=0.26, one-sided; 95 per cent confidence interval 0.6–2.8). When these results were pooled with those from the two other controlled studies already published the combined relative risk estimate was 1.8 (P=0.02, two-sided; 95 per cent confidence interval 1.1–3.0). On the basis of present evidence, there is some reason to regard vaginal bleeding prior to the first antenatal visit as a risk factor for Down syndrome but the association and its biological significance remains uncertain. 相似文献
408.
Dorothy I. Bulas MD Howard M. Saal Jill Fonda Allen Sudesh Kapur Barbara M. Nies Kurt Newman 《黑龙江环境通报》1992,12(11):867-875
We report a case of cystic hygroma and diffuse lymphangiectasia detected by sonogram at 12 weeks' gestation. Fetal karyotype was normal. At 20 weeks' gestation, herniation of the bowel into the chest was noted. At delivery, the infant was diagnosed as having Fryns' syndrome. This is the first reported case of Fryns' syndrome presenting with cystic hygroma. 相似文献
409.
While second-trimester prenatal screening programmes for Down's syndrome have become established in prenatal care, it would be advantageous to be able to offer screening in earlier preganancy. To this end, we have evaluated a new potential maternal serum marker, dimeric inhibin A, as a possible first-trimester marker. Dimeric inhibin A was measured in propsectively collected maternal serum from 23 cases of Down's syndrome and matched chromosomally normal controls, at 11–13 weeks' gestation. Levels of this protein were significantly elevated in the Down's pregnancies compared with the control pregnancies. The median multiple of the normal median (MOM) for the Down's samples was 2.46 (95 per cent confidence interval: 2.11–3.26, P<0.0001 vs. controls). These results suggest that dimeric inhibin A is a useful discriminator of Down's-affected pregnancies from normal pregnancies in the first trimester and that sensitive screening in combination with maternal age and other possible markers may be practicable in the first trimester. 相似文献
410.