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   414篇
  免费   22篇
耳鼻咽喉   1篇
儿科学   3篇
妇产科学   4篇
基础医学   61篇
口腔科学   50篇
临床医学   26篇
内科学   67篇
皮肤病学   10篇
神经病学   29篇
特种医学   20篇
外科学   46篇
综合类   4篇
一般理论   1篇
预防医学   19篇
眼科学   1篇
药学   13篇
肿瘤学   81篇
  2023年   3篇
  2022年   3篇
  2021年   12篇
  2020年   5篇
  2019年   2篇
  2018年   6篇
  2017年   6篇
  2016年   9篇
  2015年   2篇
  2014年   14篇
  2013年   15篇
  2012年   11篇
  2011年   24篇
  2010年   11篇
  2009年   14篇
  2008年   18篇
  2007年   18篇
  2006年   17篇
  2005年   27篇
  2004年   30篇
  2003年   19篇
  2002年   14篇
  2001年   10篇
  2000年   9篇
  1999年   10篇
  1998年   6篇
  1997年   3篇
  1996年   3篇
  1993年   7篇
  1992年   10篇
  1991年   8篇
  1990年   6篇
  1989年   7篇
  1988年   4篇
  1987年   8篇
  1986年   2篇
  1985年   8篇
  1984年   3篇
  1983年   4篇
  1982年   5篇
  1980年   2篇
  1975年   4篇
  1974年   4篇
  1973年   3篇
  1970年   2篇
  1967年   2篇
  1966年   2篇
  1965年   2篇
  1931年   2篇
  1904年   2篇
排序方式: 共有436条查询结果,搜索用时 15 毫秒
21.
22.
BACKGROUND: Immunorelevant gene polymorphisms might influence the susceptibility for periodontal disease. The present study assessed the frequency of a promoter polymorphism (-308G-to-A) of the tumour necrosis factor (TNF)alpha gene in patients with periodontitis and controls. METHODS: Eighty-one patients with generalized chronic periodontitis and 80 healthy controls were genotyped for the -308 polymorphism of the TNF alpha gene by PCR amplification and subsequent restriction fragment length polymorphism analysis. The diagnosis of chronic periodontitis was made for each subject on basis of standardized clinical and radiographic criteria. RESULTS: In patients with peridontitis and controls, the frequency of the TNF alpha-308 A allele was comparable (19.1% [31/162] versus 13.8% [22/160]; p=0.193). CONCLUSION: The present study revealed no association between the -308 TNF alpha gene polymorphism and periodontal disease.  相似文献   
23.
Context  Previous trials of off-pump coronary artery bypass (OPCAB) have enrolled selected patients and have not rigorously evaluated long-term graft patency. A preliminary report showed OPCAB achieved improved inhospital outcomes, similar completeness of revascularization, and shorter lengths of stay compared with conventional coronary artery bypass grafting (CABG). Objective  To assess graft patency, clinical and quality-of-life outcomes, and cost among patients while in the hospital and at 1-year follow-up. Design, Setting, and Patients  Randomized controlled trial of patients unselected for coronary anatomy, ventricular function, or comorbidities between March 10, 2000, and August 20, 2001, at a US academic center. A total of 200 patients were enrolled; 3 patients were withdrawn after randomization for mitral valve repair or replacement. Follow-up was complete for 197 patients at 30 days; 185 at 1 year. Interventions  One surgical session consisting of elective OPCAB or CABG with cardiopulmonary bypass.The surgeon had extensive experience performing off-pump surgery; patients were subsequently managed by blinded protocols. Main Outcome Measures  Coronary angiography documented graft patency prior to hospital discharge and at 1 year; health-related quality of life; and cost of the index and subsequent hospitalization(s). Results  Graft patency was similar for OPCAB and conventional CABG with cardiopulmonary bypass at 30 days (absolute difference, 1.3%; 95% confidence interval [CI], –0.66% to 3.31%; P = .19) and at 1 year (absolute difference, –2.2%; 95% CI, –6.1% to 1.7%; P = .27). Rates of death, stroke, myocardial infarction, angina, and reintervention were similar at 30 days and 1 year. There were no significant differences in health-related quality of life. Mean total hospitalization cost per patient at hospital discharge was $2272 (95% CI, $755-$3732) less for OPCAB (P = .002) and $1955 (95% CI, –$766 to $4727) less at 1 year (P = .08). Conclusions  In this randomized single-surgeon trial among unselected patients with angiographic follow-up, OPCAB achieved similar graft patency in the hospital and at 1 year. Cardiac outcomes and health-related quality of life at 30 days and 1 year were similar and patients incurred a lower cost. OPCAB may provide complete revascularization that is durable and cost-effective.   相似文献   
24.
Masticatory muscle electromyograms (EMGs) were recorded while patients with bulbar myasthenia gravis chewed artificial food and compared with those of patients with ocular myasthenia gravis, patients in clinical remission who had previously suffered from bulbar myasthenia gravis and healthy individuals. Masticatory performance and EMGs were significantly smaller in the bulbar group. There were no indications of subclinical masticatory muscle weakness in patients with bulbar myasthenia gravis in remission and in patients with ocular myasthenia gravis. Patients with bulbar myasthenia gravis barely compensated for muscular weakness by chewing at a higher percentage of their maximal EMG. These quantitative findings, when combined with subjective reports of masticatory muscle weakness, show that a need to support the jaw is characteristic of patients with bulbar myasthenia gravis who produce low EMG activity.  相似文献   
25.
The authors compared a conventional two-directional three-dimensional (3D) display for computed tomography (CT) colonography with an alternative method they developed on the basis of time efficiency and surface visibility. With the conventional technique, 3D ante- and retrograde cine loops were obtained (hereafter, conventional 3D). With the alternative method, six projections were obtained at 90 degrees viewing angles (unfolded cube display). Mean evaluation time per patient with the conventional 3D display was significantly longer than that with the unfolded cube display. With the conventional 3D method, 93.8% of the colon surface came into view; with the unfolded cube method, 99.5% of the colon surface came into view. Sensitivity and specificity were not significantly different between the two methods. Agreements between observers were kappa = 0.605 for conventional 3D display and kappa = 0.692 for unfolded cube display. Consequently, the latter method enhances the 3D endoluminal display with improved time efficiency and higher surface visibility.  相似文献   
26.
Comminution of food is the composite result of selection and breakage. Selection is characterised by the chance that a food particle will at least be damaged by the teeth during chewing. For any size, this chance equals the ratio between the weight of damaged or broken particles and that of all initial particles. The breakage process refers to fracturing of selected particles. The aim was to examine whether a reduced chewing performance of pre-orthognathic surgery patients is due to an impairment of selection, breakage or both. Eight cubes of 8.0 mm of the silicone-rubber Optosil " were used as a test food to determine chewing efficiency for 12 patients (skeletal Angle Class II and dental Angle Class II, subdivision 1) and 12 controls (class I molar relation). Selection and breakage were determined in one-chew experiments using various particle sizes. Chewing efficiency was significantly lower for the patients than for the controls. The selection chance was significantly smaller for the patients, in particular for smaller (< or = 4.8 mm) particles. The degree of breakage was lower for the patients, in particular for medium-sized particles of 4.8 mm. These findings suggest that the reduced chewing performance of pre-orthognathic surgery patients is due to an impairment of both selection and breakage.  相似文献   
27.
28.
29.
Somato-sensory evoked potentials (SSEP) were found to be pathological mostly in the lower extremities in 26 out of 45 children suffering from so called idiopathic scoliosis. We examined the vertebral spine and the spinal cord of 8 of them (with controlled SSEP-findings) by use of conventional MR-imaging and (where necessary) 3-dimensional-data-set following the Fournier-procedure. 6 of the 8 children showed alterations as follows: 1. A lipoma spreading partly extra-, partly intraspinally. 2. Subligamentous protrusions of the intervertebral disc (2 patients). 3. Dysraphic processes (2 patients). 4. An abnormally cranial ending myelon surrounded by a widened spinal channel. The findings are demonstrated and discussed concerning the questions whether the pathological SSEP and, furthermore, the deformity of the vertebral spine could be explained thereby. We are at least able to prove that some of the children with so called idiopathic scoliosis show pathological evoked potentials and MRI-findings.  相似文献   
30.
The decrease in sex steroid hormone levels after the onset of menopause is associated with bone loss and subsequent osteoporosis. Tamoxifen has antiestrogenic properties and may thus theoretically decrease bone mineral density, particularly after long-term treatment. Bone mineral density (BMD) was assessed in 75 recurrence-free postmenopausal breast cancer patients included in a randomized trial of adjuvant tamoxifen (40 mg daily) for 2 or 5 years versus no adjuvant endocrine therapy. The measurements were done about 7 years after the initial randomization. BMD was measured with single-photon absorptiometry (SPA) at two levels of the distal forearm representing cortical and trabecular bone. The BMD was found to be similar among tamoxifen patients compared with the controls. For cortical bone, the BMD was 1.03 g/cm2 (95% confidence interval [Cl], 0.97 to 1.09) among tamoxifen patients and 1.03 g/cm2 (95% Cl, 0.96 to 1.11) in controls. For trabecular bone, the values were 0.74 g/cm2 (95% Cl, 0.70 to 0.79) and 0.73 g/cm2 (95% Cl, 0.68 to 0.79), respectively. The results thus did not indicate an accelerated postmenopausal bone loss with long-term adjuvant tamoxifen.  相似文献   
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