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   2633篇
  免费   142篇
  国内免费   11篇
耳鼻咽喉   12篇
儿科学   39篇
妇产科学   34篇
基础医学   322篇
口腔科学   97篇
临床医学   171篇
内科学   621篇
皮肤病学   73篇
神经病学   399篇
特种医学   98篇
外科学   299篇
综合类   8篇
预防医学   89篇
眼科学   22篇
药学   168篇
中国医学   5篇
肿瘤学   329篇
  2023年   24篇
  2022年   45篇
  2021年   63篇
  2020年   32篇
  2019年   49篇
  2018年   71篇
  2017年   46篇
  2016年   67篇
  2015年   91篇
  2014年   119篇
  2013年   126篇
  2012年   167篇
  2011年   182篇
  2010年   107篇
  2009年   102篇
  2008年   158篇
  2007年   173篇
  2006年   173篇
  2005年   179篇
  2004年   176篇
  2003年   149篇
  2002年   139篇
  2001年   37篇
  2000年   21篇
  1999年   32篇
  1998年   25篇
  1997年   30篇
  1996年   19篇
  1995年   23篇
  1994年   12篇
  1993年   17篇
  1992年   11篇
  1991年   11篇
  1990年   13篇
  1989年   12篇
  1988年   6篇
  1987年   7篇
  1986年   8篇
  1985年   4篇
  1984年   12篇
  1983年   5篇
  1982年   9篇
  1981年   7篇
  1980年   3篇
  1979年   2篇
  1976年   2篇
  1975年   4篇
  1974年   3篇
  1972年   2篇
  1937年   1篇
排序方式: 共有2786条查询结果,搜索用时 15 毫秒
21.
With the aim of assessing whether fenoldopam can help to preserve renal function after liver transplantation, we randomized 140 consecutive recipients with comparable preoperative renal function to receive fenoldopam 0.1 microg/kg/minute (group F, 46 patients), dopamine 3 microg/kg/minute (group D, 48 patients), or placebo (group P, 46 patients) from the time of anesthesia induction to 96 hours postoperatively. There were no differences between the groups in intraoperative urinary output or furosemide administration (both P =.1). Daily recordings made during the first 4 postoperative days revealed no significant differences in urinary output (P =.1), serum creatinine (P =.5), the incidence of renal insufficiency (P =.7), the need for loop diuretics (P =.9) or vasoactive drugs (P =.8). In comparison with preoperative levels, creatinine clearance at the end of the study in the patients receiving fenoldopam remained substantially unchanged, whereas it decreased by 39 and 12.3%, respectively, in the subjects receiving placebo or dopamine (P <.001); blood cyclosporine A (CsA) levels were similar in the 3 groups (P =.1). Three subjects died in the intensive care unit (1 in each group, P =.9), 2 of them had renal failure. In conclusion, our results confirm the inefficacy of dopamine in preventing or limiting early renal dysfunction after liver transplantation, and suggest that fenoldopam may preserve creatinine clearance by counterbalancing the renal vasoconstrictive effect of CsA, as it has been reported in previous experimental studies.  相似文献   
22.
Congenital 21-alpha hydroxylase deficiency is a syndrome characterized by a cortisol synthesis deficiency and, rarely, by testicular masses. We present a case of bilateral nodular hyperplasia of the testis without adrenal hyperplasia in a patient affected by 21-alpha hydroxylase deficiency. This mass mimicked a testicular tumor and made differential diagnosis with a Leydig cell tumor extremely difficult. Multiple hard nodules (1 cm in diameter) could be palpated in both testes but were more prominent on the right. After an unsuccessful 30-day trial of an adrenocorticotropic hormone suppression regimen with dexamethasone (0.5 mg/qid), a right total orchifunicolectomy was performed. The final histological diagnosis was that of multiple, well-circumscribed nodules consisting of cord-like and microalveolar-like gonadal stroma, typical of an adrenogenital syndrome, and fibrosis. Differential diagnosis between testicular nodules in patients with congenital adrenal hyperplasia and Leydig cell tumors is a major clinical challenge. In cases of cortisol suppression resistant testicular masses, a serum adrenal hormone profile obtained from the gonadal vein and histology of the testicular nodule (with parenchyma sparing surgery) are recommended to obtain a correct diagnosis.  相似文献   
23.
Objective: Increased dimension of the aortic root and proximal aorta is considered a significant risk factor for catastrophic events that involve the ascending aorta. The objective of this study was to determine the possible correlation between pre-dissection aortic diameter and the occurrence of Stanford type A aortic dissection. Methods: Samples of dissected ascending aortas were obtained from 220 patients at the time of their operation. Two groups were identified: patients with connective tissue disorders (Group 1, n = 94) and those without (Group 2, n = 126). Measurements of the true (intimal) lumen were conducted and extrapolated as reliable approximation of pre-dissection aortic diameter. The possible association of intimal diameter with anthropometric and demographic data was analyzed. Results: Median aortic diameter was, respectively, 41.8 and 41.3 mm for patients with and without connective tissue disorders (41.4 mm for the entire cohort). Data analysis indicated that 57% of patients had aortic diameter above 40 mm, while patients with frank aneurysm accounted only for 10%; this proportion was higher in Group 1 compared to Group 2 (17.2% vs 4.7%). Poor or no correlation was demonstrated between aortic size and any of the anthropometric or demographic variables essayed. Significant subgroup differences were found among patients with a history of cigarette smoking, hypertension, diabetes, chronic renal insufficiency, and bicuspid aortic valve. Conclusion: Although aortic diameter remains a strong indication for preventive surgery in patients with inherited connective tissue disorders, acute aortic dissection occurs rarely in the setting of true ascending aortic aneurysms, and despite normal or near-normal aortic size in more than one-third of subjects. Dissection superimposing on small aortic diameters can be regarded as an expression of substantial functional tissue susceptibility to aortic catastrophic events.  相似文献   
24.
Glantz L  Ezri T  Cohen Y  Konichezky S  Caspi A  Geva D  Leviav A 《Anesthesia and analgesia》2003,96(6):1566-71, table of contents
Coronary revascularization reduces cardiac complications associated with noncardiac surgery in patients with severe coronary disease. However, patients undergoing emergency noncardiac surgery soon after coronary bypass operations may still be vulnerable to ischemic myocardial events. We prospectively evaluated the incidence of myocardial ischemia in 82 consecutive patents scheduled for sternectomy in the first (Group 1; 35 patients) or second (Group 2; 47 patients) week after coronary artery bypass graft (CABG) surgery. The interval between CABG surgery and sternectomy in Groups 1 and 2 was 6 days (range, 4-7 days) and 11 days (range, 8-14 days), respectively. Electrocardiographic (ECG) changes consistent with myocardial ischemia were assessed with a two-channel Holter system for 48 h. There were no between-group differences in updated Acute Physiology and Chronic Health Evaluation score, use of beta-blockers, or perioperative hemodynamic changes. The incidence of ECG changes consistent with myocardial ischemia was fivefold more frequent in Group 1 (22.85% versus 4.25%; P < 0.05). Of the ischemic patients in Group 1, 25% experienced a perioperative acute myocardial infarction (one was fatal). There were no infarcts in Group 2. Thus, patients appear to be prone to coronary events during sternectomy performed early after CABG surgery. Although the incidence of ischemia did not differ from that previously reported after CABG surgery alone, further investigation is required to determine whether the findings obtained in this high-risk population are generalizable to patients undergoing noncardiac surgery soon after uneventful CABG surgery. IMPLICATIONS: This study demonstrates an increased incidence of myocardial ischemia when sternectomy for mediastinitis is performed within one week of coronary artery bypass graft surgery, and this ischemia is associated with a 25% incidence of myocardial infarction.  相似文献   
25.
Stapled hemorrhoidopexy is widely accepted to treat hemorrhoids, but serious complications have been reported. In this prospective audit, we correlated clinical outcome with pathological findings. From January 2003 to April 2007, 94 patients underwent hemorrhoidopexy. Macroscopic appearance of the specimen (shape, size, and depth) was recorded. Microscopically, the presence of columnar, transitional, and squamous epithelium, the involvement of circular/longitudinal smooth muscle, and features of mucosal prolapse were assessed. Clinical outcome was evaluated by a validated questionnaire. Postoperative pain, secretion, and bleeding durations were 12.7 +/− 10.6, 5.6 +/− 9.6, and 6.3 +/− 8.4 days. Patient’s return to work averaged 16.7 +/− 10.7 days. Fissure, skin tags, and anal strictures were observed in 23.4%. Seven patients experienced pain for a significantly longer period of time. All specimens contained columnar mucosa, but 29.8% contained columnar and transitional epithelium and 12.8% contained columnar, anal transitional, and stratified squamous epithelium. Smooth muscle was observed in 62.7%. Pain was significantly increased if transitional epithelium was present in the specimen. No correlation or differences were observed if smooth muscle was present, although postoperative bleeding was more frequent. Hemorrhoidopexy is safe and effective. The specimen should always be sent for pathology examination. Only columnar epithelium should be present and, although the presence of smooth muscle does not influence the outcome in terms of functional results, its presence may play a role in postoperative bleeding. Presented as poster at the Digestive Disease Week, May 2007, Washington, USA  相似文献   
26.
Hypertrophic anterior cervical osteophytes have been reported as a cause of dysphagia, with about 100 cases described in the literature; on the other hand, chronic or acute dyspnea due to edema of the laryngeal inlet or bilateral vocal cord adduction-fixation is rare. We report a 57-year-old patient with a 2-year history of dysphagia and episodic dyspnea, who suffered sudden, severe respiratory distress necessitating emergency tracheotomy. A voluminous anterior cervical osteophyte at the C5 level was diagnosed by computed tomography (CT) and barium swallow test and removed by an anterior approach to the cervical spine, with clinical remission. The incidence, pathogenetic mechanisms, radiological diagnosis, and surgical indications of anterior cervical osteophytes associated with dysphagia and dyspnea are discussed. We advise examining cervical spine patients with dysphagia and/or dyspnea by radiography and CT when other investigations are not conclusive for a digestive or respiratory pathology.  相似文献   
27.
The use of nonpenetrating clips (NPC) for vascular anastomosis is quickly becoming accepted. Studies attest to decreased anastomotic time, comparable patency rates, and decreased blood loss. Few human studies on the use of NPC have been done to date. The purpose of this study was to evaluate primary patency rates, operative time, and complications associated with NPC compared to those with standard sutures for arterial venous graft (AVG). We retrospectively reviewed the clinical course of 82 patients with a mean age of 45 years (range, 22 to 87) from February 1996 to July 1999. All patients underwent upper extremity AVG construction. The procedures were performed at a single institution, by a single, well-experienced surgeon who has extensive experience with NPC. Primary patency rates, operative time, and complications were analyzed. Overall thrombotic incidence of AVG when NPC were used (27/48, 56%) was similar to that of sutures (17/34, 50%). Thrombotic incidence within the first year was similar as well (23/48, 48% and 13/34, 38%). The mean time to primary thrombosis was similar in both groups (6.9 and 6.8 months). The operative time required to construct an AVG with NPC (83 min) was significantly less than that with sutures (96 min) (p = 0.015). There was no significant difference in incidence of graft infection or pseudoaneurysm formation. NPC for AVG reduced operative time and resulted in primary patency and complication rates similar to those associated with use of sutures. The mean time to primary thrombosis was similar for both groups. Our findings suggest an intimai hyperplastic response of a similar nature resulting in thrombosis of both NPC and sutured AVGs. Presented at the Twenty-fifth Annual Meeting of the Peripheral Vascular Surgery Society, Toronto, Ontario, Canada, June 10, 2000.  相似文献   
28.
A specific split liver transplantation (SLT) program has been pursued in the North Italian Transplant program (NITp) since November 1997. After 5 yr, 1,449 liver transplants were performed in 7 transplant centers, using 1,304 cadaveric donors. Whole liver transplantation (WLT) and SLT were performed in 1,126 and 323 cases, respectively. SLTs were performed in situ as 147 left lateral segments (LLS), 154 right trisegment liver (RTL) grafts, and 22 modified split livers (MSL), used for couples of adult recipients. After a median posttransplant follow-up of 22 months, SLTs achieved a 3-yr patient and graft survival not significantly different from the entire series of transplants (79.4 and 72.2% vs. 80.6 and 74.9%, respectively). Recipients receiving a WLT or a LLS showed significantly better outcomes than patients receiving RTL and MSL (P < 0.03 for patients and P < 0.04 for graft survival). At the multivariate analysis, donor age of >60 yr, RTL transplant, <50 annual transplants volume, urgent transplantation (United Network for Organ Sharing (UNOS) status I and IIA), ischemia time of >7 hours, and retransplantation were factors independently related to graft failure and to significantly worst patient survival. Right grafts procured from RTL and either split procured as MSL had a similar outcome of marginal whole livers. In conclusion, in 5 yr, the increased number of pediatric transplants due to split liver donation reduced to 3% the in-list children mortality, and a decrease in the adult patient dropout rate from 27.2 to 16.2% was observed. Such results justify a more widespread adoption of SLT protocols, organizational difficulties not being a limit for the application of such technique.  相似文献   
29.
While the beneficial impact of physical activity has been ascertained in a variety of pathological scenarios, including diabetes and low-grade systemic inflammation, its potential remains still putative for periodontal health. Periodontal disease has been associated with inflammatory systemic alterations, which share a common denominator with type 2 diabetes mellitus and cardiovascular disease. Physical exercise, along with nutritional counseling, is a cornerstone in the treatment and prevention of type 2 diabetes, also able to reduce the prevalence of periodontal disease and cardiovascular risk. In addition, considering the higher incidence of periodontitis in patients with type 2 diabetes compared to healthy controls, the fascinating research question would be whether physical activity could relieve the inflammatory pressure exerted by the combination of these two diseases. This multi-disciplinary viewpoint discusses available literature in order to argument the hypothesis of a “three–way relationship” linking diabetes, periodontitis, and physical activity.  相似文献   
30.
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