全文获取类型
收费全文 | 4432篇 |
免费 | 407篇 |
国内免费 | 8篇 |
专业分类
耳鼻咽喉 | 74篇 |
儿科学 | 105篇 |
妇产科学 | 137篇 |
基础医学 | 520篇 |
口腔科学 | 89篇 |
临床医学 | 566篇 |
内科学 | 809篇 |
皮肤病学 | 49篇 |
神经病学 | 251篇 |
特种医学 | 198篇 |
外科学 | 599篇 |
综合类 | 137篇 |
一般理论 | 1篇 |
预防医学 | 537篇 |
眼科学 | 37篇 |
药学 | 383篇 |
中国医学 | 13篇 |
肿瘤学 | 342篇 |
出版年
2022年 | 32篇 |
2021年 | 62篇 |
2020年 | 47篇 |
2019年 | 63篇 |
2018年 | 65篇 |
2017年 | 58篇 |
2016年 | 57篇 |
2015年 | 82篇 |
2014年 | 103篇 |
2013年 | 138篇 |
2012年 | 238篇 |
2011年 | 258篇 |
2010年 | 113篇 |
2009年 | 119篇 |
2008年 | 144篇 |
2007年 | 209篇 |
2006年 | 218篇 |
2005年 | 172篇 |
2004年 | 181篇 |
2003年 | 174篇 |
2002年 | 134篇 |
2001年 | 128篇 |
2000年 | 139篇 |
1999年 | 125篇 |
1998年 | 69篇 |
1997年 | 68篇 |
1996年 | 62篇 |
1995年 | 54篇 |
1994年 | 51篇 |
1993年 | 49篇 |
1992年 | 117篇 |
1991年 | 100篇 |
1990年 | 82篇 |
1989年 | 82篇 |
1988年 | 84篇 |
1987年 | 84篇 |
1986年 | 76篇 |
1985年 | 81篇 |
1984年 | 54篇 |
1983年 | 54篇 |
1982年 | 32篇 |
1981年 | 38篇 |
1980年 | 49篇 |
1979年 | 48篇 |
1978年 | 31篇 |
1976年 | 39篇 |
1975年 | 36篇 |
1974年 | 36篇 |
1972年 | 31篇 |
1970年 | 32篇 |
排序方式: 共有4847条查询结果,搜索用时 15 毫秒
101.
102.
103.
104.
105.
106.
107.
Christine Ecker Vanessa Rocha-Rego Patrick Johnston Janaina Mourao-Miranda Andre Marquand Eileen M. Daly Michael J. Brammer Clodagh Murphy Declan G. Murphy the MRC AIMS Consortium 《NeuroImage》2010,49(1):44-56
Autistic spectrum disorder (ASD) is accompanied by subtle and spatially distributed differences in brain anatomy that are difficult to detect using conventional mass-univariate methods (e.g., VBM). These require correction for multiple comparisons and hence need relatively large samples to attain sufficient statistical power. Reports of neuroanatomical differences from relatively small studies are thus highly variable. Also, VBM does not provide predictive value, limiting its diagnostic value.Here, we examined neuroanatomical networks implicated in ASD using a whole-brain classification approach employing a support vector machine (SVM) and investigated the predictive value of structural MRI scans in adults with ASD. Subsequently, results were compared between SVM and VBM. We included 44 male adults; 22 diagnosed with ASD using “gold-standard” research interviews and 22 healthy matched controls.SVM identified spatially distributed networks discriminating between ASD and controls. These included the limbic, frontal-striatal, fronto-temporal, fronto-parietal and cerebellar systems. SVM applied to gray matter scans correctly classified ASD individuals at a specificity of 86.0% and a sensitivity of 88.0%. Cases (68.0%) were correctly classified using white matter anatomy. The distance from the separating hyperplane (i.e., the test margin) was significantly related to current symptom severity. In contrast, VBM revealed few significant between-group differences at conventional levels of statistical stringency.We therefore suggest that SVM can detect subtle and spatially distributed differences in brain networks between adults with ASD and controls. Also, these differences provide significant predictive power for group membership, which is related to symptom severity. 相似文献
108.
C D Morgan R S Roberts A Haq R S Baigrie P A Daly M Gent P W Armstrong 《Journal of the American College of Cardiology》1991,17(7):1451-1457
Infarct size, left ventricular function and infarct-related coronary artery patency were examined in 108 patients who took part in a previously reported placebo-controlled trial of recombinant tissue-type plasminogen activator (rt-PA) in acute myocardial infarction. Coronary angiography was performed 17 +/- 0.8 h after initiation of treatment in 47 patients (group A) or at 10 days in 61 patients (group B). Both groups underwent radionuclide ventriculography 3.8 +/- 0.8 h and again on day 9 after treatment and quantitative thallium scintigraphy on day 8. In group A, the infarct-related artery was patent in 53%; these patients had a smaller global (15.1 +/- 2.5% vs. 25.7 +/- 4.7%, p = 0.029) and regional (14.7 +/- 2.5% vs. 24.1 +/- 4.7%, p = 0.044) fixed thallium defect than did those with an occluded artery. Infarct regional ejection fraction improved by 10.1 +/- 2.1% between early and late studies when the infarct-related artery was patent and by 4.8 +/- 1.4% if it was occluded (p = 0.048); changes in global and noninfarct regional ejection fraction were similar irrespective of perfusion status. Infarct regional ejection fraction and fixed thallium defect were inversely related only when the infarct-related artery was occluded (r = -0.83, p less than 0.0001). In group B, 10 day patency of the infarct-related artery was 67%; there was no difference in patency by treatment assignment or in left ventricular function or infarct size between patients with and without infarct-related artery patency. There was no evidence of an effect of rt-PA therapy beyond that expressed through coronary patency alone in either group A or group B. 相似文献
109.
The role of defective fibrinolysis caused by elevated activity of plasminogen activator inhibitor-1 (PAI-1) in promoting fibrin deposition in vivo has not been well established. The present study compared the efficacy of thrombin or ancrod, a venom-derived enzyme that clots fibrinogen, to induce fibrin formation in rabbits with elevated PAI-1 levels. One set of male New Zealand rabbits received intravenous endotoxin to increase endogenous PAI-1 activity followed by a 1-hour infusion of ancrod or thrombin; another set of normal rabbits received intravenous human recombinant PAI-1 (rPAI-1) during an infusion of ancrod or thrombin. Thirty minutes after the end of the infusion, renal fibrin deposition was assessed by histopathology. Animals receiving endotoxin, rPAI-1, ancrod, or thrombin alone did not develop renal thrombi. All endotoxin-treated rabbits developed fibrin deposition when infused with ancrod (n = 4) or thrombin (n = 6). Fibrin deposition occurred in 7 of 7 rabbits receiving both rPAI-1 and ancrod and in only 1 of 6 receiving rPAI-1 and thrombin (P < .01). In vitro, thrombin but not ancrod was inactivated by normal rabbit plasma and by purified antithrombin III or thrombomodulin. The data indicate that elevated levels of PAI-1 promote fibrin deposition in rabbits infused with ancrod but not with thrombin. In endotoxin-treated rabbits, fibrin deposition that occurs with thrombin infusion may be caused by decreased inhibition of procoagulant activity and not increased PAI-1 activity. 相似文献
110.
Eosinophil autofluorescence and its use in isolation and analysis of human eosinophils using flow microfluorometry 总被引:5,自引:1,他引:5
Unstained human eosinophils exhibit unusually bright autofluorescence, which allows them to be distinguished from other leukocytes using fluorescence microscopy. Eosinophil fluorescence is associated with the cytoplasmic granules of the cells. Eosinophil granule extracts, containing an as-yet-undefined eosinophil fluorescence factor, exhibited excitation maxima at 370 nm and 450 nm, with maximum emission at 520 nm. Eosinophils adhering to opsonized parasites in vitro deposit fluorescent material onto the parasite surface. Eosinophil fluorescence was of sufficient intensity to allow the preparation of viable, highly enriched (greater than or equal to 98%), eosinophil suspensions from peripheral blood of normal and eosinophilic donors using a fluorescence- activated cell sorter. Quantitative studies of eosinophil autofluorescence were performed using flow microfluorometry. Fluorescence intensity of blood eosinophils from normal volunteers and eosinophilic patients varied inversely with the log of the donor's absolute eosinophil count regardless of clinical diagnosis. 相似文献