全文获取类型
收费全文 | 32372篇 |
免费 | 1574篇 |
国内免费 | 341篇 |
专业分类
耳鼻咽喉 | 334篇 |
儿科学 | 549篇 |
妇产科学 | 101篇 |
基础医学 | 1538篇 |
口腔科学 | 1473篇 |
临床医学 | 3198篇 |
内科学 | 2408篇 |
皮肤病学 | 98篇 |
神经病学 | 1340篇 |
特种医学 | 7612篇 |
外国民族医学 | 12篇 |
外科学 | 2613篇 |
综合类 | 7037篇 |
预防医学 | 1688篇 |
眼科学 | 145篇 |
药学 | 1569篇 |
38篇 | |
中国医学 | 424篇 |
肿瘤学 | 2110篇 |
出版年
2024年 | 29篇 |
2023年 | 298篇 |
2022年 | 821篇 |
2021年 | 1152篇 |
2020年 | 1103篇 |
2019年 | 959篇 |
2018年 | 1085篇 |
2017年 | 1145篇 |
2016年 | 1109篇 |
2015年 | 939篇 |
2014年 | 2138篇 |
2013年 | 1753篇 |
2012年 | 1715篇 |
2011年 | 2164篇 |
2010年 | 1891篇 |
2009年 | 2021篇 |
2008年 | 1800篇 |
2007年 | 1770篇 |
2006年 | 1503篇 |
2005年 | 1224篇 |
2004年 | 936篇 |
2003年 | 947篇 |
2002年 | 915篇 |
2001年 | 702篇 |
2000年 | 616篇 |
1999年 | 485篇 |
1998年 | 401篇 |
1997年 | 348篇 |
1996年 | 274篇 |
1995年 | 294篇 |
1994年 | 267篇 |
1993年 | 153篇 |
1992年 | 157篇 |
1991年 | 124篇 |
1990年 | 96篇 |
1989年 | 91篇 |
1988年 | 74篇 |
1987年 | 84篇 |
1986年 | 67篇 |
1985年 | 130篇 |
1984年 | 116篇 |
1983年 | 48篇 |
1982年 | 91篇 |
1981年 | 92篇 |
1980年 | 64篇 |
1979年 | 46篇 |
1978年 | 26篇 |
1977年 | 21篇 |
1976年 | 3篇 |
排序方式: 共有10000条查询结果,搜索用时 671 毫秒
111.
Richard Tello Reginald F. Munden Stuart Hooton Kris Kandarpa Robert PugatchAuthor vitae 《Computerized medical imaging and graphics》1998,22(6):267-452
Introduction: Features of spiral CT (SCT) — fast scanning, dynamic injection of contrast allowing optimal vessel opacification, and supplemental multiplanar imaging — promises to provide increased accuracy in the diagnosis of acute and non acute thoracic vascular disease. Recent work demonstrating the cost effective triage of hemodynamically stable patients after blunt chest trauma for angiography based on dynamic CT findings has prompted an investigation into the accuracy of SCT in this clinical setting. Methods: A retrospective review of all patients seen in the emergency department over the period of one year for aortic, thoracic, or blunt chest trauma evaluation was performed (74 patients) and all SCT scans available were reviewed and data reformatted for optimal delineation of pathology using maximum intensity projection and multiplanar reformation. The accuracy and predictive positive and negative values of SCT were calculated with respect to angiography, surgical, and/or clinical follow up evaluation. Results: Twenty three (31%) patients went directly to angiography owing to mediastinal widening on chest film and hemodynamic instability, of which four were positive and required emergent surgery. Seven hemodynamically stable patients (9%) had noncontrast SCT owing to mediastinal widening on chest film, all of which had angiography with none having great vessel trauma. Fourty four hemodynamically stable patients (60%) had contrast enhanced SCT (ceSCT), of which five (11%) were abnormal and underwent angiography, four of these were positive for aortic damage, one for a subclavian artery laceration. Of the remaining 39 patients who had normal ceSCT; five had angiography, all of which were normal. Of the remaining 34 patients that had normal ceSCT none had adverse outcome on clinical follow-up, minimum of 12 months. Conclusion: The predictive positive value for aortic trauma of ceSCT in blunt trauma is 80%, with a predictive negative value of 100%, indicating that it is feasible for SCT to be a first line exam in blunt chest trauma in the future. 相似文献
112.
P. Mildenberger H. U. Kauczor Katja Ehrhard W. Schmiedt M. Thelen 《Der Radiologe》1997,37(11):883-890
Purpose: Prospective evaluation of the accuracy of CT angiography (CTA) with different postprocessing for extracranial carotid artery
in comparison with DSA.
Method: one hundred patients were studied with standarized CTA. For postprocessing, MPR, MIP, and 3D reconstruction based on segmentation
with upper and lower threshold were used. Intravascular density profiles were considered. All CTA studies were correlated
with intra-arterial angiography. The degree and classification of stenoses was determined using the guidelines established
by the NASCET collaborators.
Results: Measurement of stenosis was possible by MPR in 82.5 %, by MIP in 85 %, and 3D in 100 %. Correct classification was found
in 65.5 % for MPR, 66 % for MIP and 88.5 % for 3D. The sensitivity for severe stenoses was 74 % for MPR, 82 % for MIP, and
93 % for 3D. The specificity of these methods was 98 %, 96 %, and 97 %, respectively. All carotid occlusions were correctly
identified, no carotid artery was wrongly classified as occluded.
Conclusions: CT angiography allows reliable examinations in carotid artery stenoses and occlusions. 3D reconstruction based on threshold
segmentation is superior to MPR and MIP. In some circumstances, e.g., carotid occlusion, further investigation by invasive
procedures is not necessary.
相似文献
113.
114.
S. Takahashi K. Ishii K. Matsumoto S. Higano T. Ishibashi M. Suzuki K. Sakamoto 《Neuroradiology》1994,36(5):337-339
We reviewed 12 cases of infarcts in the territory of the anterior choroidal artery (AChA) on CT and/or MRI. In each case vascular occlusion in the region was verified angiographically. Although the extent of the lesion on CT/MR images was variable, all were located on the axial images within an arcuate zone between the striatium anterolaterally and the thalamus posteromedially. The distribution of the lesions on mutiplanar MRI conformed well to the territory of the AChA demonstrated microangiographically. The variability of the extent of the infarcts may be explained by variations in the degree of occlusive changes in the AChA or the development of collateral circulation through anastomoses between the AChA and the posterior communicating and posterior cerebral arteries. The extent of the lesion appeared to be closely related to the degree of neurological deficit. 相似文献
115.
目的:分析立体定向X-刀放射治疗颅内肿瘤后的近期疗效,并进行阶段性工作总结。材料和方法:53例不同类型脑瘤患者,以CT、MR、DSA图像资料作为定位依据,用德国Brain LAB治疗计划系统设计三维优化方案,西门子MD-2型直线加速器旋转照射。结果:53例患者经X-刀治疗后,近期均取得了满意效果,诸如以卡氏评分法评价,临床症状有所改善;以CT增强扫描复查观察,肿瘤大小趋于缩小或消失。结论:立体定向放射治疗后的追踪观察表明,只要严格掌握适应症,精确定位,精确计划,精心治疗,X-刀是一种安全、有效、无痛苦的治疗脑肿瘤的方法。它可起到改善临床症状,提高患者生活质量,延长生存期限的作用。 相似文献
116.
R. Raininko I. Elovaara E. Poutiainen A. Virta L. Valanne M. Haltia J. Lhdevirta 《European journal of neurology》1997,4(2):143-151
The course of the organic brain disease caused by human immunodeficency virus (HIV-1) was evaluated in a follow-up study. The primary material included 200 consecutive HIV-1 infected persons. Sixty-one subjects, in whom other brain-affecting factors were excluded, consented to the follow-up. They underwent 278 radiologic examinations: computed tomography, magnetic resonance imaging, or a combination of both (mean 4.6 examinations/subject). Clinical neurologic status and, in 40 subjects, cognitive performance were repeatedly evaluated. Sixteen subjects were followed up until death and 11 of them were autopsied. Median follow-up time was 27 mo (range 2.5–66 mo). The most common radiologic finding was atrophy, found in 19 subjects at study entry and developing in 10 subjects during the study. Twenty-four subjects (39%) showed the development and/or progression of atrophy. Atrophic changes progressed most rapidly in acquired immunodeficiency syndrome (AIDS), but mild developing/progressive atrophy was found even in 33% of asymptomatic or neurologically intact subjects. Cognitive and radiologic worsening were simultaneous in 6/7 subjects with declining neuropsychologic test performance. Signal intensity changes including HIV-1 leukoencephalopathy appeared in AIDS patients with clear cognitive decline. 相似文献
117.
Intracranial alveolar echinococcosis: CT and MRI 总被引:1,自引:0,他引:1
A. H. Bensaid J. L. Dietemann M. M. Filippi de la Palavesa A. Klinkert B. Kastler A. Gangi G. Jacquet F. Cattin 《Neuroradiology》1994,36(4):289-291
Intracranial alveolar echinococcosis is uncommon. We report a patient with right frontal lobe and palpebral lesions secondary to a primary hepatic focus with secondary lesion in the lung. The intracranial and palpebral cystic masses were totally removed and both proved to be alveolar hydatid cysts. An unusual feature in this case is CT and MRI demonstration of dural and bony extension. 相似文献
118.
Patrick M. Rao M.D. James T. Rhea M.D. Robert A. Novelline M.D. 《Emergency radiology》1997,4(5):268-275
This article reviews a focused helical appendiceal computed tomographic technique and discusses an approach to appendiceal computed tomographic interpretation. 相似文献
119.
An audit of adverse events in children sedated with chloral hydrate or propofol during imaging studies 总被引:2,自引:1,他引:1
CRAIG MEROLA MD CYNTHIA ALBARRACIN RN PHILIP LEBOWITZ MD ROBERT S. BIENKOWSKI PhD SAMUEL M. BARST MD 《Paediatric anaesthesia》1995,5(6):375-378
We examined records of sedations provided by the paediatric anaesthesiology staff for 455 children (ages 1 mo-17 yr) undergoing MRI or CT scans at our institution over a twelve-month period with regard to the monitoring of adverse events: excessive sedation, agitation, vomiting, hypoxaemia, and major airway compromise. One hundred-and-thirty-one patients (29%) received chloral hydrate; 324 patients (71%) received propofol. All patients were monitored with continuous noninvasive pulse oximetry and received supplemental oxygen via nasal cannulae. Of the patients who received chloral hydrate, 64 (49%) were over one year of age; of the patients who received propofol, 318 (98%) were one year of age or older. In the chloral hydrate group, 23 patients (19%) were deemed excessively sedated and four patients (3%) were agitated; no patients in the propofol group experienced any of the adverse outcomes reviewed. Furthermore, no patients in either group had significant airway compromise and none was admitted to the hospital as a result of the sedation. 相似文献
120.
We describe characteristic findings in a patient with Marchiafava-Bignami disease who was serially imaged with CT and MR. Involvement of the entire corpus callosum was visualized with both types of imaging. Following administration of gadolinium-DTPA, the lesion was clearly enhanced in the subacute stage.
Correspondence to: S. Otake 相似文献