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   44449篇
  免费   3451篇
  国内免费   1053篇
耳鼻咽喉   297篇
儿科学   1611篇
妇产科学   916篇
基础医学   2192篇
口腔科学   938篇
临床医学   6335篇
内科学   9780篇
皮肤病学   453篇
神经病学   2300篇
特种医学   1532篇
外国民族医学   1篇
外科学   4817篇
综合类   5993篇
现状与发展   3篇
预防医学   5146篇
眼科学   393篇
药学   3130篇
  52篇
中国医学   1528篇
肿瘤学   1536篇
  2024年   189篇
  2023年   1083篇
  2022年   2107篇
  2021年   2711篇
  2020年   2426篇
  2019年   2207篇
  2018年   2153篇
  2017年   1751篇
  2016年   1636篇
  2015年   1597篇
  2014年   3225篇
  2013年   3142篇
  2012年   2599篇
  2011年   2799篇
  2010年   2273篇
  2009年   2162篇
  2008年   2036篇
  2007年   2048篇
  2006年   1591篇
  2005年   1436篇
  2004年   1109篇
  2003年   997篇
  2002年   701篇
  2001年   640篇
  2000年   470篇
  1999年   421篇
  1998年   380篇
  1997年   373篇
  1996年   296篇
  1995年   304篇
  1994年   277篇
  1993年   211篇
  1992年   216篇
  1991年   183篇
  1990年   153篇
  1989年   146篇
  1988年   112篇
  1987年   93篇
  1986年   94篇
  1985年   110篇
  1984年   107篇
  1983年   61篇
  1982年   70篇
  1981年   61篇
  1980年   50篇
  1979年   40篇
  1978年   29篇
  1977年   24篇
  1976年   24篇
  1974年   8篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
Thrombosis of the hepatic artery (HAT) is a severe complication of liver transplantation, and most cases need regrafting. The aim of this study was to review our experience with this complication. From January 1986 through January 1992, 76 liver transplants were performed in 59 pediatric patients at the Children's Hospital La Paz, Madrid. The diagnosis of HAT was made in 12 cases (15.7%). The common patterns of clinical presentation were: fulminant liver necrosis (5), bile leak due to necrosis of the bile duct (4), and relapsing bacteremia (3). Clinical symptoms of fulminant liver necrosis started within the first 2 weeks after transplantation, with rapid deterioration and steep rises in SGOT and SGPT levels. All these patients were retransplanted on an urgent basis, but only 1 is alive 4 years later. Four patients developed bile leaks 13 to 60 days after transplantation; SGOT, SGPT, and total bilirubin were only slightly increased. Three children were retransplanted electively and are alive with a mean follow-up of 3 years. One exceptional patient had a Roux-en-Y jejunostomy and is doing well 30 months later with his original graft. The 3 remaining children had episodes of septicemia with hepatic abscess, liver infarction, and pleural effusion. Liver function tests were normal, with bilirubin levels below 2 mg/dl. All patients were retransplanted, but only 1 is alive and well 13 months later. In the present series, we found that early HAT produces fulminant clinical deterioration requiring an urgent regraft. Late HAT presenting with either infection or bile leak allows time for treatment by elective retransplantation. The best survival was obtained in the latter group. Correspondence to: J. Vázquez  相似文献   
72.
AIM: To determine current clinical practice in the radiological diagnosis of acute pulmonary embolism and assess the use of spiral volumetric computed tomography. METHOD: A survey of 327 acute hospitals including cardiothoracic and orthopaedic tertiary referral centres was undertaken to assess current utilization of lung scintigraphy, spiral computed tomography and pulmonary angiography in the investigation of suspected pulmonary embolism. Responses were received from 215/327 (66%) centres. RESULTS: Lung scintigraphy was provided by 208 hospitals (144 on-site and 64 off-site). Spiral CT services were provided by 111 (52%) hospitals (on- or off-site), 142 (66%) units had access to angiographic facilities. Sixty-three centres out of 215 (29%) offered both on-site lung scintigraphy and spiral CT while only 41/215 (19%) hospitals were able to undertake all three tests on-site. On average, 501 perfusion (Q) or ventilation-perfusion (V/Q) scintigrams were performed per hospital per year with 26 spiral CT studies and just 4.6 pulmonary angiograms. CONCLUSION: These data suggest that lung scintigraphy is frequently the only imaging test in patients other than chest radiography, despite the large number of indeterminate results reported in most series.  相似文献   
73.
豚鼠应激性胃溃疡模型的制作与验证的实验研究   总被引:5,自引:0,他引:5  
该实验首次应用豚鼠水浸拘束法制作应激性胃溃疡的模型,从胃溃疡指数、应激前后胃电活动的变化、胃粘膜病理改变等方面观察应激性胃溃疡的发生、发展过程。该实验模型易制作,重复性好,适合应用于应激性胃溃疡的实验研究。  相似文献   
74.
Some newborns with congenital diaphragmatic hernia (CDH) and severe pulmonary hypertension cannot be saved by conventional treatment and may obtain some benefit from extracorporeal membrane oxygenation (ECMO) as a bridging measure until adequate hematosis is possible. Early prediction of the insufficiency of optimal assistance is still unclear; we reviewed our recent experience with CDH patients in an attempt to evaluate the real need for ECMO in our institution. Between 1987 and 1994, 47 newborns with CDH manifested in the first 24 h were treated with maximal ventilatory assistance (including high-frequency ventilation in 12 cases) and vasoactive drugs prior to surgical repair. In order to summarize the ventilatory and blood-gas parameters, we determined oxygenation index (OI) and ventilatory index (VI) and compared the results in survivors and nonsurvivors. Overall survival was 60% (2 cases of Fryns' syndrome were excluded from analysis). OI was 10.3±5.7 (mean ± SD) for survivors and 46.2 ± 37.8 for nonsurvivors (P < 0.01). VI was 460.9±303 and 1,532±500.6, respectively (P <0.01). Bayesian analysis and receiver operating characteristic curves enabled us to select a threshold value of OI of 20 as the best means of predicting survival in our current conditions (sensitivity: 0.7, specificity: 0.83). The generally accepted figure of 40 had a sensitivity of 1 but a specificity of only 0.44. For VI, the best threshold value was 1,100 (sensitivity: 0.93, specificity: 0.94), whereas the generally used figure of 1,000 had 0.89 and 1, respectively. According to our results, with our current management conditions, approximately 50% of our CDH patients might have obtained some benefit from ECMO.  相似文献   
75.
Renal vein thrombosis and selective arterial or venous thrombolytic therapy   总被引:2,自引:0,他引:2  
Summary Background: Renal vein thrombosis (RVT) complicating the nephrotic syndrome is associated with a poor prognosis. Methods/Results: RVT was diagnosed in 12 of 60 patients with a diagnosis of nephrotic syndrome suggested by computed tomography (CT) and subsequently confirmed by selective renal angiography. Fifty patients carried a diagnosis of primary glomerulonephritis with various pathological findings, and 10 patients had lupus nephritis. Renal vein and peripheral vein blood samples were collected in the 12 patients with RVT and were assayed for fibrin(ogen) degradation products (FDP), antithrombin III (AT III), VIIIR:AG, and fibrinogen. The results suggested a state of hypercoagulation. Of these 12 patients, 7 were given 200,000 units of urokinase (UK) over 60 minutes in divided doses selectively via the renal vein. Five patients were given 200,000 units UK selectively into the renal artery. All patients also received 2.5 mg/day warfarin and 75 mg/day persantine. Except for three patients with focal glomerulosclerosis, all patients received 40 mg/day prednisone. After 1 month, the CT scan and blood samples for FDP, AT III, VIIIR:AG, and fibrinogen were repeated. Patients receiving intra-arterial UK had complete resolution of their thrombi. Complete resolution was also suggested in 2 of the 7 patients receiving UK by renal vein, and there was partial resolution in the other five. The hypercoagulation state decreased in all patients. Conclusions: We conclude that RVT is not an uncommon event in patients with nephrotic syndrome. The diagnosis can be supported reliably using abdominal CT scanning. Although a small number of patients were included in this nonrandomized study, it appeared that intra-arterial thrombolytic therapy yielded better results. The patients with minimal change disease have a good prognosis.  相似文献   
76.
Purpose. A QSAR study based on electrotopological state (E-state) indices was conducted for a series of flavone HIV-1 integrase inhibitors to guide drug design. Methods. E-state indices formulated to encode electronic and topological information for each skeletal atom in a molecule (Kier and Hall Pharm. Res. 7:801–807 (1990)) were calculated using the Molconn-X program, and partial least squares (PLS) multivariate regression was used to derive QSAR models. Results. Predictive models with correlation coefficients (r2) of 0.98 (3 PLS components) and 0.99 (5 PLS components) and corresponding cross-validated correlation coefficients (c.v. r2) of 0.51 and 0.73, were obtained for inhibition of cleavage and integration, respectively, with one molecule omitted from the analysis. Conclusions. E-state indices at C6, C3, C5, C5, and O4 were found to be more important for prediction of activity than those for any of the other 12 flavone skeletal atoms that are common to the molecules in the data set.  相似文献   
77.
Brain single-photon emission tomography (SPET) withN,N-1,2-ethylene-diylbis-l-cysteine diethyl ester dihydrochloride (ECD) was performed on ten patients with a clinically high grade late whiplash syndrome and on 11 controls. Two independent readers blinded to the clinical diagnosis were able to separate the ten patients from normal controls. All these patients had qualitative bilateral parieto-occipital hypoperfusion. To confirm this, the perfusion rate of parieto-occipital over global (perfusion index) was calculated after drawing elliptical regions of interest in transversal-oblique slices. The perfusion indices in patients were significantly lower than in controls as tested by the Mann-WhitneyU test. This quantitative study proves our recent qualitatively analysed observation (Lancet 1995; 345: 1513–1514).  相似文献   
78.
Summary Cardiac thrombosis due to atrial fibrillation (AF) has been recognized as the most common cause of cerebral embolism. However, sometimes no macroscopic thrombus is found at autopsy in the heart of a victim of this type of cerebral embolism. We investigated morphological changes in the left atrial endocardium of 31 patients (including 21 cases with AF) who had died of cerebral embolism. Rough endocardium (RE) seen macroscopically provided evidence for the existence of atrial thrombosis. The RE that appeared in AF cases was due to a granular and wrinkled appearance of the endocardium associated with oedematous and fibrous thickening. Fibrin-thread deposits were also always distinguishable. Mural thrombi and oedema with neutrophil infiltration in the subendocardium could be seen under the microscope. Small areas of endothelial denudation and thrombotic aggregations were commonly observed by scanning electron microscopy (SEM). These SEM lesions were significantly more frequent in cases with AF than in controls (P< 0.001). The diagnostic success rate for atrial thrombosis among cases with AF increased from 33.3% to 81% when thrombi proven by histological investigation of the areas with RE were added. Left atrial RE may be an anatomically relevant finding for the existence of atrial thrombosis with AF, when the thrombosis cannot be detected upon gross observation at autopsy.  相似文献   
79.
80.
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