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   810篇
  免费   38篇
  国内免费   3篇
耳鼻咽喉   4篇
儿科学   39篇
妇产科学   33篇
基础医学   54篇
口腔科学   42篇
临床医学   71篇
内科学   222篇
皮肤病学   11篇
神经病学   42篇
特种医学   34篇
外科学   201篇
综合类   10篇
预防医学   36篇
眼科学   8篇
药学   20篇
肿瘤学   24篇
  2024年   1篇
  2023年   1篇
  2022年   7篇
  2021年   10篇
  2020年   9篇
  2019年   22篇
  2018年   16篇
  2017年   18篇
  2016年   17篇
  2015年   27篇
  2014年   32篇
  2013年   34篇
  2012年   77篇
  2011年   60篇
  2010年   44篇
  2009年   50篇
  2008年   60篇
  2007年   65篇
  2006年   67篇
  2005年   73篇
  2004年   41篇
  2003年   29篇
  2002年   26篇
  2001年   17篇
  2000年   10篇
  1999年   8篇
  1998年   2篇
  1997年   2篇
  1996年   3篇
  1995年   6篇
  1994年   4篇
  1993年   2篇
  1992年   4篇
  1990年   2篇
  1989年   2篇
  1976年   1篇
  1975年   1篇
  1973年   1篇
排序方式: 共有851条查询结果,搜索用时 31 毫秒
51.
BACKGROUND: The encouraging results of valve repair in the atrioventricular valves have influenced a decision about aortic valve (AV) reconstruction. We report our experience with pericardial cusp extension to repair rheumatic AV disease. METHODS: From 1993 to 1998, 46 patients (25 women, 21 men) with a mean age of 31.5 +/- 12.2 years (range, 15 to 58 years) underwent AV repair. Twenty-two (47.8%) patients had moderate and 24 (52.2%) had severe aortic insufficiency (AI). Severe cusp retraction was repaired with glutaraldehyde-treated autologous pericardium. Twenty-one patients had more than one maneuver (mean, 1.8) to attain competence besides augmentation, which consisted of the release of stenotic commissures (in 11 cases), thinning of the AV cusps (in 10 cases), and resuspension of the cusps (in 17 cases). Simultaneous mitral valve repair was performed on 17 patients. Eight patients received triple valve reconstruction. RESULTS: There was no early mortality. Thirty patients no longer had AI with any significant transvalvular gradients. Five patients were followed with mild residual AI, and 2 patients with moderate AI not requiring reoperation. Nine patients developing severe AI required AV replacement with a reoperation rate 19.6% (4.26%/patient-year). The mean interval between repair and reoperation was 28.2 +/- 18.3 months (range, 3 to 58 months). The mean observation time was 4.6 +/- 3 years (211.6 patient-years). Late mortality rate was 2.2% with 1 patient. The significant negative predictors of aortic reoperation determined by univariate analysis were preoperative New York Heart Association class (p = 0.002) and postoperative severe AI (p < 0.001). Cox hazard studies identified that all risk factors were insignificant for aortic reoperation. The actuarial rate of freedom from aortic reoperation was 76.1% +/- 7% at 7.5 years. CONCLUSIONS: Although AV repair by extension with pericardium is worth considering with an acceptable solution to achieve a good geometry from unequal cusps, especially in young rheumatic patients for preservation of the native AV, the patients should be followed periodically for reoperation risk.  相似文献   
52.
In 31 consecutive patients with ischemic left ventricular dysfunction and mitral regurgitation ranging from 2/4 to 3/4 (mean, 2.87 +/- 0.34), we performed coronary bypass grafting alone and assessed early and midterm outcomes. Our patients' mean preoperative New York Heart Association functional class was 3.64 +/- 0.48, and their mean left ventricular ejection fraction was 0.25 +/- 0.05. Preoperative thallium imaging revealed that all patients had at minimum a partially reversible defect in the anterior wall. All patients survived the operation. Hospital length of stay ranged from 5 to 21 days (mean, 8.35 +/- 4.07 days), and mean length of follow-up was 21.35 +/- 13.24 months. Postoperatively, patients' functional classification improved to a mean of 1.32 +/- 0.6; left ventricular ejection fraction improved to a mean of 0.43 +/- 0.09; and severity of mitral regurgitation decreased to a mean of 1.35 +/- 0.96. Statistical analysis showed that all improvements were significant. Five late cardiac deaths occurred. Preoperative variables showed no correlation with late death. However, postoperative left ventricular ejection fraction and mitral regurgitation did correlate with late death, which suggests that the reversibility of damaged ischemic myocardium plays an important role after revascularization. This study supports the concept that ischemic mitral regurgitation might well improve after myocardial revascularization regardless of its severity; therefore, it should not be corrected at the primary operation, except in patients with organic valvular changes.  相似文献   
53.
BACKGROUND: Testing of tendon (T) reflex is the basic method used in the diagnostic procedure of clinical neurology. Measurement of T reflexes precisely can be a valuable adjunct to clinical examination. Quantification of T reflexes may provide more accurate results. AIMS: To analyze the effect of elbow position on biceps T reflex. SETTINGS AND DESIGN: A self-controlled clinical trial of biceps T reflex testing at the Electrophysiology Unit of the Department of Physical Medicine and Rehabilitation. METHODS AND MATERIALS: Biceps T reflex was obtained utilizing a hand-held electronic reflex hammer in 50 extremities of 25 healthy volunteers and the effect of elbow position (at 90 degrees , 120 degrees and 150 degrees ) on reflex response was evaluated. STATISTICAL ANALYSIS: Repeated-measures analysis of variance by the General Linear Model and Pearson correlation test procedures. RESULTS: Onset latency was significantly shorter at 120 degrees of elbow position. The maximum amplitude value of biceps T reflex was obtained at 90 degrees of elbow position. Onset latency of the reflex correlated significantly with the height and arm length but not with age. CONCLUSIONS: The electrophysiological measurement of T reflexes is an easy and useful method in the quantification of reflexes, supplying more objective data. However, when performing T reflex studies, the position of the extremity should be taken into consideration to achieve more reliable results.  相似文献   
54.
55.
BACKGROUND AND OBJECTIVE: To compare the antiemetic efficacy of ondansetron with two different hypnotic drugs (propofol 15 mg, midazolam 1 and 2 mg) for the treatment of established postoperative nausea and vomiting (PONV). METHODS: Four-hundred-and-fifty-three patients scheduled for elective gynaecological or abdominal surgery were enrolled. One-hundred-and-twenty patients (26%) experienced postoperative emesis, and when nausea scores reached 2 or greater on a five-point scale, they were randomized to receive intravenously: propofol 15 mg (1.5 mL) in Group P, midazolam 1 mg in Group M1, midazolam 2 mg in Group M2 and ondansetron 4 mg in Group O. RESULTS: Four patients (13.3%) in Group P, 13 patients (43.3%) in Group M1, five patients (16.6%) in Group M2 and one patient (3.3%) in Group O required a second dose of the study drug. After administration of the study drugs, nausea scores were significantly lower in all groups than before these drugs were given. No patient had a sedation score over 3 (the patients remained awake and/or responded to verbal contact). The sedative effects of midazolam and propofol lasted for a much shorter time than the antiemetic effects of these drugs. CONCLUSIONS: Propofol and midazolam used in subhypnotic doses were as effective as ondansetron in treating PONV in patients undergoing abdominal or gynaecological surgery without untoward sedative or cardiovascular effects.  相似文献   
56.
PURPOSE: The purpose of this study was to determine the value of the intraoperative gamma probe and the efficacy of dual-phase Tc-99m sestamibi imaging in patients with primary hyperparathyroidism. METHODS: Twenty-one patients with primary hyperparathyroidism were examined prospectively. Results of same-day dual-phase Tc-99m sestamibi scintigraphy and intraoperative gamma probe evaluations were compared with the intraoperative findings and histopathologic diagnoses. A 15-mm handheld gamma probe was used to measure gamma activity in the neck and upper mediastinum. Nuclear mapping by gamma probe showed a single quadrant of neck that emitted gamma radiation significantly greater than the other three quadrants, which correlated with the sestamibi scan. RESULTS: Dual-phase Tc-99m sestamibi scintigraphy determined and localized parathyroid lesions in 20 patients (sensitivity, 94%). Of the 20 parathyroid lesions removed, 15 were located in normal positions, whereas five were explored in ectopic sites (one within the thyroid, one in the anterior mediastinum, one in a retrotracheal position, one in the carotid sheath, and one in the retroesophageal region). Although the index of thyroid nodules varied from 15.8% to 22.9%, the index for parathyroid lesions was 77.3% to 112.8%. CONCLUSIONS: These results confirm that parathyroid lesions, especially at ectopic sites, can be treated successfully in shorter operative times with minimal complications with the help of the intraoperative gamma probe.  相似文献   
57.
BACKGROUND: Our aim was to compare the effect of single dose caudal tramadol, tramadol plus bupivacaine and bupivacaine on the management of postoperative pain in children. METHODS: Sixty-three children in ASA groups I-II, between the ages of 1 and 5 were evaluated for postoperative pain randomly divided into three groups as follows: In group T, only tramadol was given caudally; in group TB, tramadol-bupivacaine was given caudally; in group B, bupivacaine was given alone. Pain was evaluated by using the paediatric objective pain scale (POPS). Sedation was evaluated with a 5-point test. There were no differences with age, weight, haemodynamic and respiratory parameters between groups. RESULTS: For 24 h postoperatively, the POPS value showed no statistically significant difference among groups (P > 0.05). Postoperative analgesia was maintained for 24 h. Nausea and vomiting was found to be higher in the tramadol group than in the bupivacaine group and tramadol-bupivacaine group (P < 0.001 and P < 0.01, respectively). CONCLUSION: Tramadol used caudally is as effective as bupivacaine in the management of postoperative pain in children and the addition of tramadol to bupivacaine, when both drugs were administered caudally, did not prolong the duration of action of bupivacaine and is a safe agent in children.  相似文献   
58.
Nine patients with massive combat injuries of the lower extremities were treated with Ilizarov bone transport in conjunction with free muscle flap coverage. In 4 patients soft-tissue coverage was applied first, and distraction osteogenesis was initiated 4 to 6 weeks later. In 3 patients both methods were applied simultaneously, and in 2 patients soft-tissue coverage occurred after distraction. The bones healed well, and all flaps survived. The segmental defects ranged from 8 to 16.5 cm in greatest dimension. The total disability time from initial injury ranged from 16 to 25.5 months. In all patients, full union of the tibia was achieved, and no osteomyelitis occurred. However, in 2 patients the applied flap became depressed, necessitating another flap operation. Despite late treatment in all 9 patients, successful results were obtained. Maintaining the original length of the tibia and providing timely, definitive treatment offer the best outcome for repair of massive injuries of the lower extremities. The Ilizarov transport method, used in combination with muscle flap coverage, represents an effective therapy for repair of massive injury of the lower extremities.  相似文献   
59.
Abstract

Endocrine system dysfunctions are the significant complications of excessive iron overload in beta thalassemia patients. The aim of this study was to evaluate the long-term effect of chelation with deferasirox on endocrine complications. The study group consisted of children with beta thalassemia who had been evaluated for the growth and pubertal development, bone metabolism, thyroid/parathyroid functions, glucose metabolism dysfunctions in the department of pediatric hematology of Ankara D??kap? Child Health and Diseases Hematology Oncology Training And Research Hospital between 2009-2011 and reevaluated after deferasirox chelation therapy in 2018. Thirty-one transfusion dependent beta-thalassemia patients were enrolled for the study. Seventeen (54.8%) patients were male and the mean age was 16.9?±?3.8 (9-23) years. Splenectomy was performed in 11 patients (35.5%). In the initial evaluation, 26 patients (84%) received deferoxamine and/or deferiprone and five (17%) patients received deferasirox as a chelator; in the final evaluation all patients were receiving deferasirox. The mean duration of deferasirox treatment was 5.9?±?2.02?years (1-10?years). Of the 26 patients who had endocrine complications between 2009-2011, 18 were recovered. In the final evaluation, eight patients (25%) developed new endocrinopathies. The frequency of endocrine complications seen before the deferasirox treatment (83%) was higher than the frequency of complications while receiving deferasirox treatment (25.8%) (p?<?0,05). In this study, it was determined that both existing endocrine abnormalities were reduced and recent developed problems were less likely with long-term deferasirox treatment in thalassemia patients.  相似文献   
60.
The aim of this study is to investigate immunoreactivity for p53, p21 and metallothionein in diffuse malignant pleural mesothelioma (DMPM) and to determine the relationships between the age, sex, asbestos exposure time, survival of DMPM patients with environmental asbestos exposure and immunoreactivity to p53, p21 and metallothionein. Sixty-seven histopathologically-confirmed DMPMs, 38 of whom had environmental and 29 had occupational asbestos exposure, were included. The tumour tissue samples were immunostained with antibodies against p53, p21 and metallothionein. Epidemiological data and the survival times for the DMPM patients with environmental asbestos exposures were obtained from hospital records. Thirty-three per cent of the DMPMs were positive for p53, 35% for p21 and 52% for metallothionein. There was no statistical difference between the histological subtypes of DMPM in terms of immunoreactivity for p53, p21 and metallothionein. For p21 and metallothionein there was a statistically significant difference between the exposure characteristics: patients with environmental asbestos exposure had shown more immunopositivity. There were statistically significant differences between age groups and between asbestos exposure times for metallothionein, and between asbestos exposure times and p21. The patients with positive immunostaining had longer exposure times and were older than those having negative immunostaining. The differences between survival of the patients were not statistically significant in terms of the immunohistochemical results for p53, p21 and metallothionein.  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