全文获取类型
收费全文 | 19554篇 |
免费 | 1897篇 |
国内免费 | 519篇 |
专业分类
耳鼻咽喉 | 77篇 |
儿科学 | 483篇 |
妇产科学 | 277篇 |
基础医学 | 1303篇 |
口腔科学 | 462篇 |
临床医学 | 4498篇 |
内科学 | 7992篇 |
皮肤病学 | 67篇 |
神经病学 | 322篇 |
特种医学 | 636篇 |
外国民族医学 | 14篇 |
外科学 | 1479篇 |
综合类 | 2422篇 |
现状与发展 | 3篇 |
预防医学 | 577篇 |
眼科学 | 59篇 |
药学 | 552篇 |
18篇 | |
中国医学 | 126篇 |
肿瘤学 | 603篇 |
出版年
2024年 | 31篇 |
2023年 | 347篇 |
2022年 | 495篇 |
2021年 | 782篇 |
2020年 | 1058篇 |
2019年 | 869篇 |
2018年 | 831篇 |
2017年 | 640篇 |
2016年 | 638篇 |
2015年 | 733篇 |
2014年 | 1304篇 |
2013年 | 1242篇 |
2012年 | 1041篇 |
2011年 | 1197篇 |
2010年 | 868篇 |
2009年 | 906篇 |
2008年 | 926篇 |
2007年 | 966篇 |
2006年 | 852篇 |
2005年 | 734篇 |
2004年 | 558篇 |
2003年 | 525篇 |
2002年 | 407篇 |
2001年 | 434篇 |
2000年 | 417篇 |
1999年 | 341篇 |
1998年 | 355篇 |
1997年 | 338篇 |
1996年 | 262篇 |
1995年 | 286篇 |
1994年 | 223篇 |
1993年 | 217篇 |
1992年 | 212篇 |
1991年 | 154篇 |
1990年 | 106篇 |
1989年 | 80篇 |
1988年 | 80篇 |
1987年 | 84篇 |
1986年 | 69篇 |
1985年 | 77篇 |
1984年 | 65篇 |
1983年 | 57篇 |
1982年 | 60篇 |
1981年 | 37篇 |
1980年 | 25篇 |
1979年 | 18篇 |
1978年 | 10篇 |
1977年 | 5篇 |
1976年 | 4篇 |
1975年 | 4篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
Greg T. Sutherland Greg Nowak Glenda M. Halliday Jillian J. Kril 《Journal of clinical neuroscience》2007,14(12):1182-1185
In many cases of sporadic frontotemporal dementia (FTD) and in FTD caused by tau mutations (FTDP-17) there is disruption of the normal splicing of tau leading to the aberrant expression of tau isoforms and neurodegeneration. This suggests a central role for tau in the pathogenesis of FTD. However, more than half the cases of sporadic FTD show no tau deposition. We question whether altered expression is also involved in the pathogenesis of tau-negative FTD. Real-time polymerase chain reaction was used to investigate tau isoform expression in tau-negative FTD and age-matched controls. There were no differences in total tau mRNA or 4R versus 3R isoform expression. Our study suggests that perturbed tau mRNA expression is unlikely to be involved in the pathogenesis of tau-negative FTD. 相似文献
102.
103.
Summary It is difficult for conventional transthoracic echocardiography (TTE), by which precise and accurate images of interatrial
septum (IAS) can not be acquired, to diagnose patent foramen ovale (PFO) clearly. To evaluate the diagnostic value of biplanar
transesophageal echocardiography (TEE) for PFO, TTE and biplanar TEE were performed simultaneously in 270 patients. It was
found that in 7 patients patent foramen ovale was detected only through longitudinal planes of biplanar TEE. IAS, which consists
of primitive septum and membrane of fossa ovalis, can be directly visualized by two-dimensional images of TEE; in patients
with PFO, a dull color flow, which shunts from the right atria to the left atria through the gap between primitive septum
and fossa ovalis, can be detected by color Doppler flow images. Furthermore, some right-to-left shunting microbubbles through
the valve of patent fossa ovalis can be discovered by cardiac acoustic contrast echocardiography. In conclusion, biplanar
TEE combined with color Doppler image and cardiac acoustic contrast facilitates a definite diagnosis of patent foramen ovale
as the excellent anatomic images of IAS can be obtained from multiple views under this kind of performance. 相似文献
104.
Claudine Savy Fatima Moussafi Jacques Durand Jrme Yelnik Axelle Simon Jeanine Nguyen-Legros 《The Journal of comparative neurology》1995,355(3):392-404
The morphology and distribution of dopaminergic interplexiform cells in adult rat and monkey retinas were analyzed to determine any correlation with the function of dopamine in the outer retinal layers. The retinas were processed as whole mounts for tyrosine hydroxylase immunohistochemistry. There was a network formed by the sclerally directed processes of interplexiform cells in the inner nuclear, outer plexiform, and outer nuclear layers running throughout the retina. Their density was higher in the superior retina than in the inferior retina of the rat and was especially high in the superior temporal quadrant. The external network in this quadrant was significantly less dense in the monkey than in the rat, as are the interplexiform cells. The somata of interplexiform and other dopaminergic cells were about the same size in both rats and monkeys. Computer-assisted reconstruction of external arborizations of individual cells showed that external processes lay very close to horizontal and photoreceptor cells and also to blood capillaries. Because they were long, thin, and highly varicose; branched at right angles; and often arose from an axon hillock, the external processes were identified as axons. Therefore, we define the dopaminergic interplexiform cells as multiaxonal neurons, with at least one outwardly directed axon that reaches the outer plexiform layer. The function of the network of external processes from the interplexiform dopaminergic cells is discussed in terms of modulating the release of dopamine to external layers. 相似文献
105.
Two hundred and ten patients with clinical evidence of heartfailure, developing after an acute myocardial infarction, wererandomized to treatment with the ß1 antagonist metoprolol50100mg b.i.d. (n=106) or the ß1 partial agonistxamoterol 100200 mg bid. (n=104). Left ventricular systolicand diastolic function were assessed with echocardiography andtransmitral Doppler cardiography before and after 3 and 12 monthsof double-blind treatment. E-point septal separation and percent left ventricular fractional shortening were used as indicesof systolic function. The ratio between peak early and latemitral diastolic flow (E/A ratio) and isovolumic relaxationtime were used as indices of diastolic function. In the xamoterol group, there was a deterioration in E-pointseptal separation (P<0·05). A difference between thetreatment groups was present both at 3 months (E-point septalseparation 11·4 vs 13·0 mm, P<0·0l,fractional short ening 271 vs 252%, P<005) and 12 months(E-point septal separation Ill vs 13·2 mm, P<0·05fractional shortening 26·9 vs 25·0%, P<0·05).E/A ratio increased in the metoprolol group (P<0·05)but not in the xamoterol group. At 3 months there was a significantdifference (0·85 vs 0·67, P<0·005 betweenthe groups but not at 12 months. In comparison with the ß1-receptor antagonist metoprolol,the ß1 partial agonist xamoterol impaired left ventricularsystolic function in patients with clinical evidence of heartfailure after an acute myocardial infarction. 相似文献
106.
用电子计算机对核素、多普勒和心尖搏动图中的8项左室舒张功能指标进行判别分析,比较各指标与冠心病的密切程度。结果显示患者年龄和各项舒张功能指标明显不同于正常组。判别方程为:Z=0.21X_1+23.86X_2-22.88X_3-0.18X_4+2.83X_5+2.06X_6+66.86X_7+1.66X_8。临界值为42.99。判别正确率为100%。各指标的贡献率大小依次为EV/AV,1/3FF,A/E-O,PFR,DATI,EDC,IRT和1/3FFd。提示:多普勒EV/AV与冠心病的关系最为密切,核素的1/3FF次之,心尖搏动图的A/E~O亦是一个较好的指标。 相似文献
107.
应用ATL-ultramark超6型彩色多普勒超声诊断仪诊断扩张型心肌病100例,并与性别、年龄相应的正常人对比分析。结果:除扩张型心肌病各组室间隔及左室后壁舒张期厚度与相应正常对照组相比无显著性差异(P>0.05)外,其左室舒张内径及收缩内径、左房内径明显大于正常对照组(P<0.01),左室射血分数及左室内径缩短分数较正常对照组明显降低(P<0.01),并见心腔内血流速度缓慢,颜色变淡。另在77例病人中探及40例瓣膜返流。提示该诊断方法对扩张型心肌病具有直观、简便、准确、迅速的优点,为本病的诊断及鉴别诊断提供了良好的手段。 相似文献
108.
Christine Boutin John Dyck Lee Benson Christine Houde Robert M. Freedom 《Pediatric cardiology》1992,13(3):176-177
Summary Balloon atrial septostomy is an established method of palliation for several forms of congenital heart disease. Previously performed under fluoroscopic x-ray control, recent reports have demonstrated the utility of transthoracic echocardiographic monitoring. We report the first application of uniplane transesophageal echocardiography (TEE) (6.7-mm probe) as an alternative imaging modality for control of ballon atrial septostomy on neonates in the intensive care unit. 相似文献
109.
近年来,超声定量检查技术在临床的应用为心血管疾病患者的心功能评估提供了量化的依据,本文介绍了超声诊断仪的使用部分最新定量检查技术。 相似文献
110.
桂永浩 《中国超声医学杂志》1995,(12)
对20个16三体染色体异常小鼠胚胎进行了多普勒超声心动图研究。胎龄从10天至15天。9例发现流入道返流波型,6例发现流出道返流波型。120例染色体正常胚胎无一例发现返流波型。16三体小鼠模型作为先天性心脏病研究的理想模型,本文首次提供了对此类模型胚胎血液动力学研究的非创伤性监测方法。 相似文献