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   182746篇
  免费   9567篇
  国内免费   321篇
耳鼻咽喉   2805篇
儿科学   5897篇
妇产科学   4181篇
基础医学   27065篇
口腔科学   6258篇
临床医学   15791篇
内科学   33717篇
皮肤病学   4756篇
神经病学   18875篇
特种医学   8140篇
外科学   28118篇
综合类   845篇
一般理论   46篇
预防医学   9873篇
眼科学   3856篇
药学   12100篇
中国医学   291篇
肿瘤学   10020篇
  2023年   1071篇
  2022年   1129篇
  2021年   2278篇
  2020年   1897篇
  2019年   2404篇
  2018年   3925篇
  2017年   3364篇
  2016年   4224篇
  2015年   4037篇
  2014年   4603篇
  2013年   7313篇
  2012年   9748篇
  2011年   10690篇
  2010年   6280篇
  2009年   4860篇
  2008年   10326篇
  2007年   10813篇
  2006年   10420篇
  2005年   10379篇
  2004年   9655篇
  2003年   9469篇
  2002年   9197篇
  2001年   5942篇
  2000年   7110篇
  1999年   4439篇
  1998年   2021篇
  1997年   1657篇
  1996年   1316篇
  1995年   1144篇
  1994年   1081篇
  1993年   989篇
  1992年   1445篇
  1991年   1287篇
  1990年   1309篇
  1989年   1301篇
  1988年   1150篇
  1987年   1220篇
  1986年   1046篇
  1985年   1165篇
  1984年   1074篇
  1983年   888篇
  1982年   784篇
  1981年   746篇
  1980年   662篇
  1979年   791篇
  1978年   667篇
  1977年   652篇
  1976年   571篇
  1975年   608篇
  1974年   614篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
Depressive symptoms are common in patients with neurodegenerative disorders. Imaging studies suggest that a disruption of frontal-subcortical pathways may underlie depression associated with basal ganglia disease. This pilot study tested the hypothesis that frontal dysfunction contributes to depression associated with multiple system atrophy (MSA) and progressive supranuclear palsy (PSP). Depressed patients with MSA (n = 11), PSP (n = 9), and age-matched controls (n = 25) underwent measures of cerebral glucose metabolism applying positron emission tomography with (18)F-fluorodeoxyglucose. Regional metabolism in the patient groups was compared to the normal subjects using the voxel-based statistical parametric mapping. Depressive symptom severity (Hamilton Depression Rating) and degree of locomotor disability (Hoehn & Yahr) were assessed in the patient groups. The association between prefrontal metabolism and the occurrence of depressive symptoms and the degree of locomotor disability was investigated. When compared to controls, MSA patients revealed significant metabolic decreases in bilateral frontal, parietal, and cerebellar cortex and in the left putamen. In PSP patients, significant hypometabolism was demonstrated in bilateral frontal cortex, right thalamus, and midbrain. Depression severity but not the patients' functional condition was significantly associated with dorsolateral prefrontal glucose metabolism in both patient groups. The findings of this pilot study support the hypothesis that depressive symptoms in MSA and PSP are associated with prefrontal dysfunction.  相似文献   
92.
There are fundamental biomechanical differences between fixed-angle plate systems, also referred to as internal fixators, and conventional plate-screw fixation systems. Fixed-angle systems have rapidly gained widespread acceptance in recent years for almost all indications and anatomical sites. This contribution presents tips and tricks on their implantation and on the management of complications. Much of the information has already been presented elsewhere, in print or orally. Some of it is based on the authors’ own experience in their hospitals. The tips and tricks presented here are intended to help surgeons find pragmatic solutions to intraoperative problems.  相似文献   
93.
Modern radiologic diagnostics show a variety of pathological changes in the mediastinum, pleura, and lung but no evidence on their histogenesis. Transbronchial and transthoracal fine-needle aspiration biopsy usually cannot yield detailed diagnostic results because of its small size. Sufficient and representative material can be obtained by thoracoscopy. Video-assisted thoracoscopy allows safe and fast diagnosis of diffuse lung diseases, pleural diseases including malignant mesothelioma, indeterminate peripheral lung nodule, and mediastinal masses. This gentle diagnostic method can give invaluable information guiding further management of the thoracic injury. Video-assisted thoracoscopy is a safe and effective guiding tool if performed by experienced thoracic surgeons able to convert to thoracotomy. It is to be noted that interpretation of intraoperative findings plays a decisive role in interdisciplinary diagnostics of intrathoracal diseases.  相似文献   
94.
95.
96.
Abdominal infection has the fifth highest incidence of all posttraumatic infections but has the second highest mortality rate with 25%,pneumonia,with 29%, being the only posttraumatic infection that is more frequently lethal.Posttraumatic abdominal sepsis, on the other hand, has a mortality rate of almost 50%.This rate cannot be reduced except by prompt identification of the correct diagnosis of the underlying injury or complication.This means that delayed laparotomy is strikingly detrimental in these patients, with 46% mortality as opposed to 11% in patients who undergo laparotomy promptly. In parallel with this, the mortality of fresh-onset and localized peritonitis is 14%,whereas that of diffuse purulent peritonitis is up to a devastating 42%.  相似文献   
97.
We report the first large-scale double-blind, randomly assigned study to compare two active dopaminergic therapies for Restless Legs Syndrome (RLS), the dopamine agonist cabergoline (CAB) and levodopa/benserazide (levodopa). Patients with idiopathic RLS were treated with fixed daily doses of 2 or 3 mg CAB or 200 or 300 mg levodopa for 30 weeks. Efficacy was assessed by changes in the IRLS (International RLS Severity Scale) and by time to discontinuation of treatment due to loss of efficacy or augmentation. 361 of 418 screened patients (age 58 +/- 12 years, 71% females) were randomly assigned and treated (CAB: n = 178; levodopa: n = 183) in 51 centers of four European countries. Baseline IRLS total score was 25.7 +/- 6.8. The baseline-adjusted mean change from baseline to week 6 in IRLS sum score was d = -16.1 in the CAB group and d = -9.5 in the levodopa group (d = -6.6, P < 0.0001). More patients in the levodopa group (24.0%) than in the CAB group (11.9%, P = 0.0029, log-rank test) discontinued because of loss of efficacy (14.2% vs. 7.9%, P = 0.0290) or augmentation (9.8% vs. 4.0%, P = 0.0412). Adverse events (AEs) occurred in 83.1% of the CAB group and in 77.6% of the levodopa group. In both groups, most frequent AEs were gastrointestinal symptoms (CAB: 55.6%, levodopa: 30.6%, P < 0.0001). This first large-scale active controlled study in RLS showed superior efficacy of cabergoline versus levodopa after a 30-week long-term therapy. Tolerability was found more favorable with levodopa than with cabergoline.  相似文献   
98.
PURPOSE: A simple technical solution is presented to provide video transmission from the tip of a Bullard laryngoscope to a bedside video display, while the operator is still able to look through the viewing ocular of the Bullard laryngoscope during tracheal intubation. EQUIPMENT: This is achieved by insertion of an ultrathin fibreoptic video-endoscopic system into the working channel of the Bullard laryngoscope. Thereby the view from the distal blade tip is transmitted to a bedside monitor, without interfering with the use of the Bullards laryngoscope's original eyepiece. The presented technical solution allows video transmission without considerable additional weight normally associated with attaching video endoscopy cameras, light and camera cables to endoscopic devices. Thus, the Bullard laryngoscope remains lightweight and easy to maneuver. A screw-threaded adapter with a side-port is proposed to prevent displacement of the fibreoptic cable while still allowing application of oxygen. CONCLUSION: Experience and skills with tracheal intubation using the presented video-enhanced Bullard laryngoscope can be achieved in the originally intended way, while the supervisor or attending viewers can follow the tracheal intubation procedure on the video display.  相似文献   
99.
Large mandibular defects caused by trauma, infection or resection of a tumour are still a major problem for plastic and maxillofacial surgeons. The modern concept of tissue engineering combines the osteoinductive effects of osteogenic cells with a suitable scaffold structure to promote differentiation of osteoblasts and optimal matrix production. Critical size mandibular bone defects were therefore made to investigate the osteogenic potential of periosteal cells and a bioabsorbable polymer fleece (Ethisorb 510) in minipigs. Periosteal cells were isolated from four minipigs, expanded in vitro and seeded with fibrin glue into Ethisorb 510 fleeces. Tissue constructs were used to repair critical size mandibular defects and compared with two minipigs with untreated bone defects. Bone healing was evaluated after 90 and 180 days by radiographs and a histological scoring system. The radiographs showed increased radiodensity of defects filled with the cell-fibrin-fleece-constructs compared with the untreated control group after 90 and 180 days in vivo. The defects repaired by the cell-fibrin-scaffolds (180 days in vivo) obtained the highest histological mean score 2.9 (range 2-3), while defects filled by cell-fibrin-scaffolds (90 days in vivo) achieved a mean score of 2.1 (range 2-3). In contrast, the control group (n = 2) scored 1 and 2. The results show that a combination of periosteal cells and polymer fleeces may be a promising approach for clinical mandibular augmentation.  相似文献   
100.
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