全文获取类型
收费全文 | 259篇 |
免费 | 2篇 |
国内免费 | 5篇 |
专业分类
安全科学 | 1篇 |
废物处理 | 1篇 |
环保管理 | 2篇 |
综合类 | 232篇 |
基础理论 | 6篇 |
污染及防治 | 11篇 |
评价与监测 | 8篇 |
社会与环境 | 2篇 |
灾害及防治 | 3篇 |
出版年
2022年 | 1篇 |
2021年 | 1篇 |
2020年 | 4篇 |
2019年 | 3篇 |
2018年 | 1篇 |
2017年 | 1篇 |
2014年 | 1篇 |
2013年 | 9篇 |
2012年 | 2篇 |
2011年 | 7篇 |
2010年 | 2篇 |
2009年 | 4篇 |
2008年 | 1篇 |
2007年 | 3篇 |
2006年 | 3篇 |
2005年 | 6篇 |
2003年 | 2篇 |
1995年 | 49篇 |
1994年 | 27篇 |
1993年 | 40篇 |
1992年 | 43篇 |
1991年 | 28篇 |
1990年 | 16篇 |
1989年 | 8篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1983年 | 1篇 |
1981年 | 1篇 |
排序方式: 共有266条查询结果,搜索用时 15 毫秒
251.
Two cases are presented which illustrate the association of elevated maternal serum alpha feteprotein (MSAFP) levels and chorioangiomas. These cases emphasize the importance of ultrasound study of the placenta in MSAFP elevation evaluation. In addition, placentas from pregnancies with otherwise unexplained MSAFP elevations should be submitted for pathologic study. A definitive retrospective diagnosis may thus be provided. 相似文献
252.
We assayed maternal serum samples from 134 black and 268 white women from 16 to 18 weeks of gestation for intact human chorionic gonadotropin (hCG), and unconjugated oestriol (uE3). Serum from women with high ( ⩾ 2·5 MOMs) or low (risk for Down syndrome ⩾ 1/365) maternal serum alpha-fetoprotein (MSAFP) levels were excluded. After correcting for maternal weight, we found that median hCG levels were 16 per cent higher in black women but uE3 levels were not significantly different. These results confirm three other studies for hCG and one study for uE3. Corrections are recommended for both maternal serum hCG and AFP before calculating the risk for Down syndrome in black women. 相似文献
253.
A. S. P. M. Breed MD A. Mantingh R. Vosters J. R. Beekhuis J. M. M. van Lith G. J. P. A. Anders 《黑龙江环境通报》1991,11(8):577-580
In 2103 consecutive diagnostic chorionic villus samples, examined in a 4-year period in our clinical genetics unit, 26 samples (1.2 per cent) presented chromosomal mosaicism in the direct and/or long-term culture preparations. Only once (46,XX/47,XX,+9) was the mosaicism confirmed in the fetus. In the cytogenetic follow-up studies of the remaining 25 pregnancies, in no cases could the aberration be confirmed in amniotic fluid or fetal tissue. One patient requested a termination after the CVS result. Of the remaining 24 pregnancies, four (16.7 per cent) ended in a spontaneous abortion. These findings suggest an association between placental mosaicism and fetal loss. 相似文献
254.
A prenatal diagnosis of right atrial isomerism is often inferred through the recognition of a constellation of cardiac anomalies on the four-chamber view or by the detection of visceral heterotaxy and asplenia. However, the actual occurrence of discordance between the arrangement of the atria and thoracic and abdominal organs makes the identification of the morphology of both atrial appendages the only reliable way to make a final diagnosis of atrial isomerism. Three cases of right atrial isomerism with visceral heterotaxy and a complex cardiac defect, diagnosed in utero by cross-sectional and colour flow Doppler echocardiography, are reported. In all the patients, the right atrial isomerism was associated with an atrioventricular septal defect, a single aortic outlet from the right ventricle, and total anomalous venous return. The diagnosis of right atrial isomerism, always confirmed by neonatal re-evaluation and/or by post-mortem examination, was made through identifying two pyramidal atrial appendages in an echocardiographic transverse plane at the level of the atria and of the origin of the great arteries. This report demonstrates that a final intrauterine diagnosis of atrial isomerism is possible, whatever the visceral situs is. 相似文献
255.
R. Achiron MD O. Pinhas-Hamiel S. Lipitz Z. Heiman B. Reichman S. Mashiach 《黑龙江环境通报》1994,14(7):523-526
Cytomegalovirus is the most common cause of congenital viral infection. In utero infection is usually suspected in patients with growth-retarded fetuses or when maternal illness precipitates serological investigations. A case is presented where routine ultrasound examination at 30 weeks' gestation in an asymptomatic patient demonstrated mild fetal ventriculomegaly. Transvaginal ultrasound enabled the visualization of intraventricular adhesions and small periventricular cysts. The suspected diagnosis of in utero cytomegalovirus infection was confirmed by the presence of IgM antibodies in fetal blood and subsequently by isolation of the virus from the infant's urine. The presence of mild fetal ventriculomegaly should prompt transvaginal brain imaging. 相似文献
256.
257.
Ring chromosome 21 is a rare chromosome anomaly often associated with mental retardation and dysmorphic features. Less commonly, the ring chromosome can be familial and associated with a normal phenotype. Phenotypically normal female carriers, however, are at increased risk of having children with Down syndrome, mosaic monosomy 21, and variable duplication or deletion of chromosome 21. Because of the relative mitotic and meiotic instability of ring chromosomes, abnormal cytogenetic findings encountered during prenatal diagnosis may not reflect the true genetic status of the fetus. This is a report of a phenotypically normal female carrier of a familial ring 21 chromosome. Prenatal diagnosis on her twin pregnancy revealed a mosaic 46,XX,r(21)(p13;q22) (77 per cent)/45,XX, – 21 in one fetus and a normal male karyotype in the second. The pregnancy was carried to term. Both infants are completely normal, with a non-mosaic ring 21 karyotype from the lymphocytes of one twin. The diagnostic uncertainty and problematic genetic counselling related to fetal cytogenetic abnormalities are the subjects of this report. 相似文献
258.
Lee P. Shulman MD Sherman Elias Richard N. Andersen Owen P. Phillips Aubrey Milunsky Karen A. Holbrook Lynne T. Smith Jo-David Fine Joe Leigh Simpson 《黑龙江环境通报》1991,11(11):813-818
Junctional epidermolysis bullosa, Herlitz variant (junctional EB-Herlitz) is a lethal autosomal recessive skin disorder currently amenable to prenatal diagnosis only by direct analysis of fetal skin. However, elevated levels of alpha-fetoprotein, as well as the presence of acetylcholinesterase in amniotic fluid, have been associated with other severe fetal genodermatoses. Fetal skin samplings were performed in ten pregnancies at risk for fetal junctional EB-Herlitz, with three fetuses affected on the basis of electron microscopic detection of blisters within the lamina lucida and abnormal hemidesmosomes. In neither affected nor unaffected pregnancies were maternal serum or amniotic fluid alpha-fetoprotein levels elevated. Moreover, alphafetoprotein levels in both maternal serum and amniotic fluid were not statistically different comparing affected and unaffected fetuses. Acetylcholinesterase was not present in the amniotic fluid samples of the three affected pregnancies. Unlike other severe fetal genodermatoses, neither alpha-fetoprotein nor acetylcholinesterase was predictive of junctional EB-Herlitz. 相似文献
259.
Kinetic adsorption of application of carbon nanotubes for Pb(Ⅱ) removal from aqueous solution 总被引:2,自引:0,他引:2
Nassereldeen A Kabbashi Muataz A Atieh Abdullah Al-Mamun Mohamed E S Mirghami MD Z Alam Noorahayu Yahya 《环境科学学报(英文版)》2009,(4)
The capability of carbon nanotubes (CNTs) to adsorb lead (Pb) in aqueous solution was investigated. Batch mode adsorption experiment was conducted to determine the effects of pH, agitation speed, CNTs dosage and contact time. The removal of Pb(Ⅱ) reached maximum value 85% or 83% at pH 5 or 40 mg/L of CNTs, respectively. Higher correlation coeffcients from Langmuir isotherm model indicates the strong adsorptions of Pb(Ⅱ) on the surface of CNTs (adsorption capacity Xm = 102.04 mg/g). The results indicates tha... 相似文献
260.