全文获取类型
收费全文 | 333篇 |
免费 | 13篇 |
国内免费 | 44篇 |
专业分类
安全科学 | 4篇 |
环保管理 | 10篇 |
综合类 | 301篇 |
基础理论 | 53篇 |
污染及防治 | 9篇 |
评价与监测 | 7篇 |
社会与环境 | 5篇 |
灾害及防治 | 1篇 |
出版年
2023年 | 4篇 |
2022年 | 1篇 |
2021年 | 2篇 |
2020年 | 5篇 |
2019年 | 9篇 |
2018年 | 5篇 |
2017年 | 6篇 |
2016年 | 8篇 |
2015年 | 3篇 |
2014年 | 5篇 |
2013年 | 23篇 |
2012年 | 8篇 |
2011年 | 6篇 |
2010年 | 4篇 |
2009年 | 8篇 |
2008年 | 7篇 |
2007年 | 2篇 |
2006年 | 7篇 |
2005年 | 5篇 |
2004年 | 4篇 |
2003年 | 2篇 |
2002年 | 3篇 |
2000年 | 4篇 |
1999年 | 2篇 |
1998年 | 2篇 |
1997年 | 2篇 |
1996年 | 5篇 |
1995年 | 10篇 |
1994年 | 12篇 |
1993年 | 28篇 |
1992年 | 21篇 |
1991年 | 22篇 |
1990年 | 22篇 |
1989年 | 23篇 |
1988年 | 17篇 |
1987年 | 20篇 |
1986年 | 12篇 |
1985年 | 14篇 |
1984年 | 11篇 |
1983年 | 15篇 |
1982年 | 10篇 |
1981年 | 10篇 |
1977年 | 1篇 |
排序方式: 共有390条查询结果,搜索用时 15 毫秒
91.
The prenatal diagnosis of micrognathia is usually based on a subjective impression of the size of the jaw when examining the fetal profile. We have constructed a centile chart for mandibular length between 12 and 27 post-menstrual weeks in a cross-sectional study of 184 fetuses. The application of this chart in clinical practice may permit a more objective diagnosis of micrognathia in the prenatal period. 相似文献
92.
In a fetus with ventricular extrasystoles a congenital aneurysm of the left ventricle was diagnosed prenatally. At 32 weeks of gestation, echocardiography showed a large apical left ventricular aneurysm with a thin, hypokinetic wall. Congestive heart failure did not occur. Prenatal and postnatal examinations did not detect the aetiology of the aneurysm, but excluded the majority of possible causes. The 2-year-old child is now asymptomatic and normally developed. Neither medication nor surgical treatment have been necessary, except for antithrombotic prophylaxis with low-dose aspirin. 相似文献
93.
A case of fetal loss due to infection after first-trimester chorionic villus sampling is described. The fetus was born at 18 3/7 weeks and showed an annular constriction of one of the arms as seen in the amniotic band sequence. Induction of congenital defects might be one of the complications of chorionic villus sampling. 相似文献
94.
A right-sided diaphragmatic hernia presented as a fetal hydrothorax. The fluid-filled hernial sac enveloped the lung and presumably prevented serious compression effects. The implications of fetal thoracic anomalies are discussed. 相似文献
95.
We present a family who sought prenatal diagnosis in order to bear a healthy child to serve as an HLA–identical bone marrow donor for their son affected with Wiskott–Aldrich syndrome. They intended to abort HLA-incompatible fetuses who would have been unsuitable bone marrow donors. This case led us to conclude that prenatal diagnosis should not be used to benefit a third party or facilitate the conception or abortion of a fetus for the purpose of generating an organ for transplantation. The limits of parental autonomy and physician responsibility are discussed. 相似文献
96.
In a pregnancy at risk for carbamoyl-phosphate synthetase (CPS) deficiency, prenatal diagnosis was attempted by fetal liver biopsy, performed at 18 weeks of gestation. CPS activity was absent and the diagnosis was confirmed after termination of the pregnancy. The technique employed for fetal liver biopsy is described together with an evaluation of its possible role in prenatal diagnosis. 相似文献
97.
Richard P. Morse Eileen Rawnsley Steven K. Sargent Dr. John M. Graham Jr. 《黑龙江环境通报》1987,7(9):631-638
Markedly decreased fetal activity (akinesia/hypokinesia) is usually readily apparent to experienced mothers, and frequently this concern leads to attempts at prenatal diagnosis. We report prenatal diagnosis of two fetuses with congenital contractures, markedly decreased fetal movement, and microcephaly due to severe holoprosencephaly. Such familial recurrence to phenotypically normal parents suggests a newly recognized autosomal recessive or X-linked syndrome that is readily detectable by prenatal ultrasonography. 相似文献
98.
The first case of isochromosome 18p as a mosaic in a male fetus diagnosed by amniocentesis is reported. After termination of the pregnancy at 21 weeks gestation biopsies from different fetal organs as well as from the placenta were taken and set up for long term cell cultures. The distribution of the normal and abnormal cell-line in fetal organs was unequal. Unexpectedly the metaphases in the placenta and the lymphocyte culture all showed a normal karyotype. The tetrasomy 18p is associated with a uniform phenotype, even in fetal life, characterized by a small head with protuberant occiput, low-set ears with posterior rotation, epicanthic fold, sharp pinched nose, convex and poorly formed philtrum, high-arched palate, retrognathia, flexion contractures of fingers, short and broad hallux, hypoplastic penis, angulation of clavicles and mild scoliosis. The propositus showed no growth retardation. 相似文献
99.
A series of proteins (albumin, transferrin, a1- antitrypsin, alpha-fetoprotein and pancreatic oncofetal antigen) and enzymes (γ-glutamyltranspeptidase, aminopeptidase M, alkaline phosphatase, a-glucosidase and protease) was measured in fetal meconium extracts. There were 19 fetuses thought to have cystic fibrosis (CF), 13 with neural tube defects, three with chromosome abnormalities and 19 normal controls, all with gestational ages between 18 and 21 weeks. With the exception of alpha-fetoprotein, all the proteins and enzymes were significantly elevated in the CF meconium extracts. The most definitive indicator of a CF fetus was the albumin concentration, where the mean level was five times that found in the control groups. However, five of 19 fetuses assumed to have CF had albumin in the normal range. In these cases the meconium protease levels were grossly elevated. Furthermore, in the same five fetuses meconium concentration of pancreatic oncofetal antigen, a protein synthesized in the fetal pancreas, was also greatly raised. We suggest that post-mortem examination of a fetus thought to have CF should include measurement of meconium albumin, protease and pancreatic oncofetal antigen. 相似文献
100.
A systematic study of microvillar enzyme activities in the amniotic fluid in correlation with their values in different fetal tissues during development has been undertaken. Microvillar enzymes appeared in the amniotic fluid at the time of disappearance of the anal membrane, 12–13 weeks, and declined from the 18th week until the 24th week. The study of fetal tissues and fluids has shown that gamma-glutamyltranspeptidase is mainly of liver origin. The significant decrease of the activities of these amniotic fluid enzymes has been the basis of prenatal diagnosis of cystic fibrosis. These assays may be useful for the diagnosis of certain digestive tract abnormalities at later stages of pregnancy. 相似文献