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   432篇
  免费   16篇
  国内免费   6篇
耳鼻咽喉   5篇
儿科学   21篇
妇产科学   9篇
基础医学   37篇
口腔科学   5篇
临床医学   18篇
内科学   108篇
皮肤病学   7篇
神经病学   37篇
特种医学   7篇
外科学   124篇
综合类   3篇
预防医学   20篇
眼科学   16篇
药学   15篇
肿瘤学   22篇
  2022年   7篇
  2021年   9篇
  2020年   8篇
  2019年   4篇
  2018年   10篇
  2017年   10篇
  2016年   10篇
  2015年   9篇
  2014年   9篇
  2013年   13篇
  2012年   19篇
  2011年   23篇
  2010年   14篇
  2009年   4篇
  2008年   15篇
  2007年   19篇
  2006年   24篇
  2005年   23篇
  2004年   17篇
  2003年   14篇
  2002年   16篇
  2001年   15篇
  2000年   11篇
  1999年   13篇
  1998年   4篇
  1996年   4篇
  1994年   3篇
  1993年   3篇
  1992年   10篇
  1991年   5篇
  1990年   9篇
  1989年   9篇
  1988年   4篇
  1987年   5篇
  1986年   4篇
  1985年   4篇
  1984年   6篇
  1983年   5篇
  1979年   3篇
  1978年   5篇
  1977年   2篇
  1976年   9篇
  1975年   5篇
  1974年   3篇
  1973年   3篇
  1972年   9篇
  1970年   7篇
  1969年   3篇
  1967年   2篇
  1966年   2篇
排序方式: 共有454条查询结果,搜索用时 62 毫秒
1.
The paper report the case of a patient brought to the Authors' attention suffering from megaesophageal cardial achalasia who had already undergone gastroduodenal resection according to BII. It was considered worthwhile to report this case due to the problems which arose concerning the choice of a thoracic rather than abdominal route owing to the impossibility of associating cardiomyotomy with anti-reflux plastica surgery because of the reduced dimensions of the stomach.  相似文献   
2.
Somatostatin Receptor Localization of Pancreatic Endocrine Tumors   总被引:2,自引:0,他引:2  
n = 39) than conventional imaging studies (MRI, n = 25; CT, n = 13); 23 of 24 patients had positive octreotide scintigraphy, 17 of 24 had positive MRI-scans, and 12 of 24 patients had positive CT scans. It was concluded that 111 In-octreotide scintigraphy combined with conventional imaging improves the preoperative localization of presumably tumorous lesions in patients with gastroenterohepatic endocrine tumors.  相似文献   
3.
Mucosal hemodynamics (by reflectance spectrophotometry) and mucosal damage (by histologic examination) following acute colonic ischemia were evaluated in different anatomic locations in the colon of anesthetized rats. The reflectance spectrophotometer provides an index of mucosal hemoglobin concentration (IHB) and an index of oxygen saturation of hemoglobin (ISO2). The patterns of ischemia without congestion (IHB, ISO2) during superior mesenteric artery occlusion, and ischemia with congestion (IHB, ISO2) during portal vein occlusion, previously demonstrated in the stomach and duodenum, are also applicable to the colon. The significant linear correlations between changes (as percent of baseline) in IHB, ISO2, and hydrogen gas clearance suggest that changes in these indices are adequate indicators of changes in colonic mucosal perfusion. Superior mesenteric artery ligation produced significant reductions in both indices, and an increase in damage in the mucosa of the cecum, transverse colon, splenic flexure, and left colon, but not the rectum. Inferior mesenteric artery ligation produced only slight reduction in these indices and minimal damage only in the mucosa of the splenic flexure. These results support the hypothesis that the superior mesenteric artery is more important than the inferior mesenteric artery in maintaining colonic perfusion and colonic mucosal integrity in the rat.Supported by the American Society for Gastrointestinal Endoscopy Career Development Award (H850208, H870212), Veterans Administration Medical Research Funds; and in part by research grants (0162-01, 0162-02; 0291-01) from the Smokeless Tobacco Research Council, Inc.; and by funds provided by the Cigarette and Tobacco Surtax Fund of the State of California through the Tobacco Related Disease Research Program of the University of California.  相似文献   
4.
OBJECTIVE: To compare the Helicobacter pylori-associated pathology in gastric biopsies taken from patients living at sea level with those taken from patients living at high altitude. METHODS AND RESULTS: We included 38 patients from a hospital in the Andean city of La Oroya, Peru, located at 3700 m in altitude, and 40 control patients taken from Comas Clinic located in the city of Lima at sea level. Fibrepanendoscopy and multiple biopsies were performed in all the patients followed by histopathological examination. In the antrum, patients from the Andean town had a higher prevalence of glandular lymphoid adherence lesions, active germinal centres, moderate to severe chronic atrophic gastritis, intestinal metaplasia and moderate to severe total deep gland loss, than did patients from the coastal town. Furthermore, the severity of the histological lesions seen in the gastric body and cardia was significantly greater in the high-altitude patients than in those from sea level. CONCLUSION: This study suggests that the severity of H. pylori-associated gastric lesions seen on histopathological examination is greater in patients living at high altitude, the cause of which is most probably multifactorial but nonetheless principally altitude related.  相似文献   
5.
· Background: The aim of this study was to evaluate the focal electroretinogram (FERG), an objective indicator of outer retinal function, in nonexudative age-related macular degeneration (NE-AMD), and to compare FERG results with morphological lesions assessed by stereoscopic fundus photographs and fluorescein angiograms. · Methods: Twenty-five patients (25 eyes) with bilateral NE-AMD (visual acuity of the study eyes ≥0.4) as well as 10 age- and sex-matched control subjects (10 eyes) were evaluated. FERGs were recorded from the macular region (9°) in response to sinusoidal stimuli flickered at 32 Hz. Amplitude and phase angle of the Fourier-analyzed FERG fundamental component were measured. Fundus lesions were graded from color slides according to the Wisconsin age-related maculopathy grading system [15]. Fluorescein angiograms were evaluated by an image analysis technique to compute the area with pathological hyperfluorescence (associated with drusen and/or retinal pigment epithelial atrophy) within the macular (approximately 9°×9°) region. · Results: Compared to control eyes, NE-AMD eyes had a reduction in the mean FERG amplitude (57% loss, P<0.001) with no phase changes. Amplitudes of individual affected eyes were negatively correlated with either the Wisconsin grading score (r=–0.63, P<0.001) or the percentage area of pathological hyperfluorescence (r=–0.70, P<0.01). Eyes with minimal NE-AMD lesions (Wisconsin score ≤6) and normal acuity had a lower mean amplitude (47% loss, P<0.05) than that of control eyes. · Conclusions: The results indicate that, in NE-AMD, the FERG is altered in parallel with the extent and severity of fundus lesions. However, a functional impairment of outer macular layers, which is detected by FERG losses, could precede morphological changes typical of more advanced disease. Received: 6 March 1998 Revised version received: 5 June 1998 Accepted: 17 June 1998  相似文献   
6.
This work is aimed to present an innovative technology for the reinforcement of beams for urban furniture, produced by in-mold extrusion of plastics from solid urban waste. This material, which is usually referred to as “recycled plastic lumber”, is characterized by very poor mechanical properties, which results in high deflections under flexural loads, particularly under creep conditions. The Prowaste project, founded by the EACI (European Agency for Competitiveness and Innovation) in the framework of the Eco-Innovation measure, was finalized to develop an innovative technology for selective reinforcement of recycled plastic lumber. Selective reinforcement was carried out by the addition of pultruded glass rods in specific positions with respect to the cross section of the beam, which allowed optimizing the reinforcing efficiency. The reinforcement of the plastic lumber beams with pultruded rods was tested at industrial scale plant, at Solteco SL (Alfaro, Spain). The beams obtained, characterized by low cost and weight, were commercialized by the Spanish company. The present paper presents the most relevant results of the Prowaste project. Initially, an evaluation of the different materials candidates for the reinforcement of recycled plastic lumber is presented. Plastic lumber beams produced in the industrial plant were characterized in terms of flexural properties. The results obtained are interpreted by means of beam theory, which allows for extrapolation of the characteristic features of beams produced by different reinforcing elements. Finally, a theoretical comparison with other approaches which can be used for the reinforcement of plastic lumber is presented, highlighting that, among others, the Prowaste concept maximizes the stiffening efficiency, allowing to significantly reduce the weight of the components.  相似文献   
7.
Femoral neck fractures in the elderly are frequent, represent a serious health care problem, and have a significant impact on health costs. Reconstruction options using hip arthroplasty include bipolar hemiarthroplasty (HA) and total hip arthroplasty (THA). The purpose of this review is to discuss the indications, limitations, and pitfalls of each of these techniques.  相似文献   
8.
OBJECTIVES: The purpose of this study was to investigate the use of coronary magnetic resonance angiography (MRA) for assessing human epicardial coronary artery vasodilation. BACKGROUND: Coronary vasodilation plays a vital role in the human coronary circulation. Previous studies of epicardial coronary vasodilation have used invasive coronary angiography. Coronary MRA may provide an alternative noninvasive method to directly assess changes in coronary size. METHODS: Thirty-two subjects were studied: 12 patients (age 55 +/- 18 years) and 20 healthy subjects (age 34 +/- 4 years). High-resolution multi-slice spiral coronary MRA (in-plane resolution of 0.52 to 0.75 mm) was performed before and after sublingual nitroglycerin (NTG). Quantitative analysis of coronary vasodilation was performed on cross-sectional images of the right coronary artery (RCA). A time-course analysis of coronary vasodilation was performed in a subset of eight subjects for 30 min after NTG. Signal-to-noise ratio was also measured on the in-plane RCA images. RESULTS: Coronary MRA demonstrated a 23% increase in cross-sectional area after NTG (16.9 +/- 7.8 mm2 to 20.8 +/- 8.9 mm2, p <0.0001), with significant vasodilation between 3 and 15 min after NTG on time-course analysis. The MRA measurements had low interobserver variability (< or =5%) and good correlation with X-ray angiography (r=0.98). The magnitude of vasodilation correlated with baseline cross-sectional area (r=0.52, p=0.03) and age (r=0.40, p=0.019). Post-NTG images also demonstrated a 31% improvement in coronary signal-to-noise ratio (p = 0.002). CONCLUSIONS: Nitroglycerin-enhanced coronary MRA can noninvasively measure coronary artery vasodilation and is a promising noninvasive technique to study coronary vasomotor function.  相似文献   
9.
Purpose  This study was designed to assess the long-term results of stapled hemorrhoidopexy in 291 patients with Grade III and Grade IV hemorrhoids after a minimum follow-up of five years. Methods  Records of patients submitted to stapled hemorrhoidopexy for Grade III and Grade IV hemorrhoids between January 1999 and December 2002 were retrospectively analyzed. Long-term outcome was evaluated with a standardized questionnaire and an office visit, including anorectal examination and rigid proctoscopy. Results  A total of 291 patients with Grade III (57.4 percent) and Grade IV (42.6 percent) hemorrhoids were evaluated. Intraoperative (20.3 percent) and postoperative (4.8 percent) bleeding was the most frequent complication. The questionnaire was submitted to all patients at a median follow-up of 73 (range 60–93) months. There were no symptoms related to hemorrhoids in 65.3 percent of patients, moderate symptoms in 25.4 percent of patients, and severe symptoms in 9.3 percent of patients. Fifty-three (18.2 percent) patients had recurrence. Reoperation was necessary in 21 (7.2 percent) patients (4 in Grade III hemorrhoids and 17 in Grade IV hemorrhoids; P < 0.001), with no recurrent symptoms and/or prolapse. Patient satisfaction for operation was 89.7 percent. Conclusions  Stapled hemorrhoidopexy is a safe and effective treatment for Grade III and Grade IV hemorrhoids. Recurrence requiring reoperation was higher in Grade IV hemorrhoids than in Grade III hemorrhoids. Reprints are not available.  相似文献   
10.
In rat colon damaged by 10% acetic acid and by dinitrochlorobenzene, we test the following hypotheses: (1) mucosal hemodynamic changes are significantly different at the ulcer base, the ulcer margin, and the inflamed non-ulcer-bearing mucosa; and (2) these mucosal hemodynamic changes also vary with time after induction of the colonic injury. Mucosal hemodynamic changes were documented by reflectance spectrophotometry, and variations in gross mucosal morphology were confirmed by hematoxylin and eosin histologic sections. Results revealed that in the acute stage, the ulcer base, which was covered by necrotic debris, showed ischemia without congestion. The ulcer margin at the edge of the ulcer base showed ischemia with congestion. The nonulcerated mucosa, which appeared erythematous, showed increased perfusion. In the convalescent stage, all the altered perfusion patterns returned to normal. These observations offer plausible explanations for the variability in colonic perfusion observed in experimentally damaged colons.  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