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   4020248篇
  免费   284914篇
  国内免费   9068篇
耳鼻咽喉   55866篇
儿科学   131696篇
妇产科学   110631篇
基础医学   573549篇
口腔科学   112029篇
临床医学   370176篇
内科学   775671篇
皮肤病学   92934篇
神经病学   325824篇
特种医学   152112篇
外国民族医学   1141篇
外科学   600589篇
综合类   83670篇
现状与发展   15篇
一般理论   1602篇
预防医学   314706篇
眼科学   93697篇
药学   296207篇
  16篇
中国医学   7855篇
肿瘤学   214244篇
  2019年   32276篇
  2018年   44636篇
  2017年   33833篇
  2016年   38903篇
  2015年   43813篇
  2014年   61191篇
  2013年   92675篇
  2012年   124867篇
  2011年   132604篇
  2010年   79754篇
  2009年   75860篇
  2008年   124127篇
  2007年   131967篇
  2006年   133891篇
  2005年   129215篇
  2004年   124340篇
  2003年   119836篇
  2002年   115892篇
  2001年   183124篇
  2000年   187976篇
  1999年   158936篇
  1998年   47199篇
  1997年   41478篇
  1996年   41630篇
  1995年   40016篇
  1994年   36755篇
  1993年   34577篇
  1992年   124642篇
  1991年   120822篇
  1990年   117511篇
  1989年   113901篇
  1988年   104821篇
  1987年   102733篇
  1986年   96727篇
  1985年   92695篇
  1984年   69301篇
  1983年   59002篇
  1982年   35180篇
  1981年   31684篇
  1979年   62893篇
  1978年   44722篇
  1977年   37766篇
  1976年   35547篇
  1975年   37969篇
  1974年   45282篇
  1973年   43146篇
  1972年   40610篇
  1971年   38143篇
  1970年   35119篇
  1969年   33802篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
102.
103.
OBJECTIVES: To evaluate a novel method for localization of subdural electrodes in presurgical assessment of patients with drug-resistant focal epilepsy. METHODS: We studied eight consecutive patients with posterior epilepsy in whom subdural electrodes were implanted for presurgical evaluation. Electrodes were detected on post-implantation brain CT scans through a semiautomated procedure based on a MATLAB routine. Then, post-implantation CT scans were fused with pre-implantation MRI to localize the electrodes in relation to the underlying cortical structures. The reliability of this procedure was tested by comparing 3D-rendered MR images of the electrodes with electrode position as determined by intraoperative digital photography. RESULTS: In each patient, all electrodes could be correctly localized and visualized in a stereotactic space, thus allowing optimal surgery planning. The agreement between the procedure-generated images and the digital photographs was good according to two independent raters. The mean mismatch between the 3D images and the photographs was 2 mm. CONCLUSIONS: While our findings need confirmation on larger samples including patients with anterior epilepsy, this procedure allowed to localize subdural electrodes and to establish the spatial relationship of each electrode to the underlying brain structure, either normal or damaged, on brain convessity, basal and medial cortex. SIGNIFICANCE: Being simple, rapid, unexpensive, and reliable, this procedure holds promise to be useful to optimize epilepsy surgery planning.  相似文献   
104.
105.
Neurons and related cell types often contain two major classes of neurosecretory vesicles, synaptic vesicles (SVs) and dense-core granules (DCGs), which store and release distinct cargo. SVs store and release classic neurotransmitters, which facilitate propagation of action potentials across the synaptic cleft, whereas DCGs transport, store, and release hormones, proteins, and neuropeptides, which facilitate neuronal survival, synaptic transmission, and learning. Over the past few years, there has been a major surge in our understanding of many of the key molecular mechanisms underlying cargo release from SVs and DCGs. This surge has been driven largely by the use of fluorescence microscopy (especially total internal reflection fluorescence microscopy) to visualize SVs or DCGs in living cells. This review highlights some of the recent insights into cargo release from neurosecretory vesicles provided by fluorescence microscopy, with emphasis on DCGs.  相似文献   
106.
Abstract Guillain-Barré syndrome (GBS) is a disease of the peripheral nervous system, which is caused by aberrant immune responses directed against some components of peripheral nerves. GBS is rarely accompanied by cardiovascular involvement. We describe a case of acute neuropathy complicated by sudden heart failure and left ventricular dysfunction which had a presumably neurogenic origin. Pathogenesis of acute heart failure is probably due to transitorial stunned myocardium and neurogenic cardiac injury. We show a rare case of transitorial and acute cardiac dysfunction by echocardiography and laboratory markers of heart failure.  相似文献   
107.
A 27-year-old man was admitted with high fever and shivers eleven days after returning from vacation in Indonesia. Physical examination, laboratory values, abdominal ultrasound, and chest x-ray were not conclusive. All blood cultures yielded growth of Salmonella enterica serovar Typhi, and typhoid fever was diagnosed. Subsequently, the patient developed septic shock and pulmonary edema.In this case report epidemiological, clinical, and therapeutic aspects of typhoid fever are discussed with special emphasis on criteria for severe typhoid fever, which is treated with additional glucocorticoids.  相似文献   
108.
109.
OBJECTIVE: Spinal reflexes from hand to wrist muscles were investigated in writer's cramp. METHODS: Stimulus-triggered rectified EMG averages after ulnar nerve and cutaneous stimulation, in wrist flexors and extensors during tonic contraction, were compared in 18 controls and 19 patients. RESULTS: On the patient dystonic side, ulnar-induced EMG suppression was decreased in wrist extensors, and facilitation in wrist flexors modified dependent on the dystonic wrist posture during writing. No change was found on the patient non-dystonic side. Cutaneous stimulation increased wrist flexor EMG on both sides of the patients with normal wrist posture during writing, but had no effect in controls and patients with abnormal wrist posture. CONCLUSIONS: Comparison between cutaneous and mixed nerve stimuli suggests that spindle afferents from intrinsic hand muscles may mediate patients' ulnar-induced EMG modulations. Abnormal proprioceptive control was only observed on dystonic side, while bilateral unusual cutaneous control was found in patients. Changes in spinal transmission were partly related to the dystonic wrist posture, suggesting that systems involved in sensory processing can be differentially altered in writer's cramp. SIGNIFICANCE: Changes in spinal transmission, probably related to peripheral and/or cortical inputs, might either take part in primary or adaptive mechanisms underlying writer's cramp.  相似文献   
110.
The numbers of free flap donor site as well as their indications are constantly increasing. Despite increasing popularity of microvascular reconstructive procedures, literature lacks clear and objective outcome criteria. This paper reports on a simple outcome classification that has become a routine part of the unit's large workload of microvascular outcome recording. The classification was formed through a retrospective analysis of 241 consecutive cases from 2000 to 2001 and is a five graded numerical classification. Grade 1 equates to total success without co-morbidity and grade 5 to a major complication such as amputation, etc., whatever the status of the flap itself. From 2002 to 2005 the classification was prospectively used on 527 consecutive cases with ease of integration into routine clinical practice. The Classification would enable a more objective record keeping thus analysis of the outcome. It would allow a more realistic comparison of different techniques or donor types as well set a benchmarking level for further improvement of the results.  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