首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   386篇
  免费   25篇
  国内免费   27篇
耳鼻咽喉   1篇
儿科学   11篇
妇产科学   2篇
基础医学   46篇
口腔科学   5篇
临床医学   41篇
内科学   132篇
皮肤病学   2篇
神经病学   16篇
特种医学   90篇
外科学   37篇
综合类   14篇
预防医学   4篇
眼科学   6篇
药学   22篇
肿瘤学   9篇
  2022年   6篇
  2021年   4篇
  2019年   5篇
  2016年   3篇
  2015年   6篇
  2014年   6篇
  2013年   6篇
  2012年   8篇
  2011年   5篇
  2010年   11篇
  2009年   12篇
  2008年   6篇
  2007年   9篇
  2006年   27篇
  2005年   13篇
  2004年   6篇
  2003年   5篇
  2002年   3篇
  2001年   5篇
  2000年   5篇
  1999年   3篇
  1998年   14篇
  1997年   5篇
  1996年   19篇
  1995年   15篇
  1994年   16篇
  1993年   7篇
  1992年   8篇
  1991年   9篇
  1990年   10篇
  1989年   16篇
  1988年   16篇
  1987年   14篇
  1986年   12篇
  1985年   17篇
  1984年   5篇
  1983年   8篇
  1982年   5篇
  1981年   8篇
  1980年   7篇
  1979年   4篇
  1978年   6篇
  1977年   5篇
  1976年   5篇
  1975年   4篇
  1967年   4篇
  1962年   3篇
  1928年   2篇
  1927年   3篇
  1926年   2篇
排序方式: 共有438条查询结果,搜索用时 61 毫秒
11.
12.
Accuracy of fetal echocardiography   总被引:6,自引:0,他引:6  
Benacerraf  BR; Pober  BR; Sanders  SP 《Radiology》1987,165(3):847-849
The reliability of prenatal ultrasound (US) for the detection of structural heart defects was investigated in a consecutive population of patients referred for prenatal US. Twenty-eight of 49 fetuses (57%) shown to have one or more heart defects with physical examination or autopsy were found to have congenital heart disease with prenatal US. There were 66 cardiac defects in 49 fetuses, 33 of which were entirely or partly identified (50%). Defects correctly diagnosed included hypoplasia of either ventricle, common atrioventricular canal, tetralogy of Fallot, transposition of the great vessels, and Ebstein anomaly. Defects rarely diagnosed correctly included semilunar valve stenosis, total anomalous pulmonary venous drainage, coarctation of the aorta, pulmonic atresia, atrioseptal defect, and ventricular septal defect. Many types of heart defects can be diagnosed accurately with prenatal US in a general population of patients not at high risk for congenital heart disease. Some lesions, however, were difficult to detect.  相似文献   
13.
Some details of the growth and initial cellular interactions of optic nerve axons were examined in a parthenogenetic clone of Daphnia magna. Results are summarized as follows: (i) the final structure of the optic lamina is dependent upon interactions between growing optic nerve fibers and optic lamina neuroblasts closest to the midplane of the animal, which trigger the morphological differentiation of the neuroblasts; the specificity of connections is achieved by well-defined sequences of cell migration in the ganglion; (ii) only one of the eight optic nerve axons growing back from each ommatidium in the eye possesses a structure similar to the growth cones seen on termini of nerve fibers growing in vitro; and (iii) undifferentiated neuroblasts in the ganglion react to surface contact by this "lead axon" by enveloping the axon in a glial-like relationship.  相似文献   
14.
15.
16.
17.
Aim The aim of this study was to assess the independent role of cerebral lesions on ultrasound scan, and several other neonatal and obstetric factors, as potential predictors of cerebral palsy (CP) in a large population‐based cohort of very preterm infants. Method As part of EPIPAGE, a population‐based prospective cohort study, perinatal data and outcome at 5 years of age were recorded for 1812 infants born before 33 weeks of gestation in nine regions of France in 1997. Results The study group comprised 942 males (52%) and 870 females with a mean gestational age of 30 weeks (SD 2wks; range 24–32wks) and a mean birthweight of 1367g (SD 393g; range 450–2645g). CP was diagnosed at 5 years of age in 159 infants (prevalence 9%; 95% confidence interval [CI] 7–10%), 97 males and 62 females, with a mean gestational age of 29 weeks (SD 2wks; range 24–32wks) and a mean birthweight of 1305g (SD 386g; range 500–2480g). Among this group, 67% walked without aid, 14% walked with aid, and 19% were unable to walk. Spastic, ataxic, and dyskinetic CP accounted for 89%, 7%, and 4% of cases respectively. The prevalence of CP was 61% among infants with cystic periventricular leukomalacia, 50% in infants with intraparenchymal haemorrhage, 8% in infants with grade I intraventricular haemorrhage, and 4% in infants without a detectable cerebral lesion. After controlling for cerebral lesions and obstetric and neonatal factors, only male sex (odds ratio [OR] 1.52; 95% CI 1.03–2.25) and preterm premature rupture of membranes or preterm labour (OR 1.72; 95% CI 0.95–3.14) were predictors of the development of CP in very preterm infants. Interpretation Cerebral lesions were the most important predictor of CP in very preterm infants. In addition, infant sex and preterm premature rupture of membranes or preterm labour were also independent predictors of CP.  相似文献   
18.
Placental CRH plays a major role in the mechanisms controlling human pregnancy and parturition. Understanding how placental CRH production is regulated is therefore of importance. Previously we have shown that placental expression of CRH peptide and mRNA are inhibited by estrogens, in contrast to the stimulatory effects of estrogen on hypothalamic CRH production. Our current study found that in placental cells cotransfected with a CRH promoter construct and an estrogen receptor-alpha expression vector results in a differential regulation whereby 17beta estradiol (E2) decreased and the putative pure estrogen antagonist, ICI 182780,  相似文献   
19.
20.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号