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   3529篇
  免费   262篇
  国内免费   8篇
耳鼻咽喉   20篇
儿科学   86篇
妇产科学   105篇
基础医学   647篇
口腔科学   70篇
临床医学   375篇
内科学   764篇
皮肤病学   110篇
神经病学   380篇
特种医学   81篇
外科学   307篇
综合类   23篇
一般理论   3篇
预防医学   338篇
眼科学   41篇
药学   226篇
中国医学   6篇
肿瘤学   217篇
  2024年   2篇
  2023年   55篇
  2022年   65篇
  2021年   125篇
  2020年   75篇
  2019年   127篇
  2018年   163篇
  2017年   109篇
  2016年   113篇
  2015年   135篇
  2014年   171篇
  2013年   219篇
  2012年   313篇
  2011年   311篇
  2010年   174篇
  2009年   186篇
  2008年   240篇
  2007年   233篇
  2006年   211篇
  2005年   205篇
  2004年   162篇
  2003年   139篇
  2002年   111篇
  2001年   9篇
  2000年   8篇
  1999年   27篇
  1998年   28篇
  1997年   16篇
  1996年   3篇
  1995年   12篇
  1994年   6篇
  1993年   5篇
  1992年   5篇
  1991年   3篇
  1990年   5篇
  1989年   1篇
  1988年   1篇
  1987年   1篇
  1986年   7篇
  1985年   2篇
  1984年   3篇
  1983年   2篇
  1980年   1篇
  1978年   2篇
  1977年   3篇
  1976年   1篇
  1975年   1篇
  1972年   1篇
  1969年   1篇
  1964年   1篇
排序方式: 共有3799条查询结果,搜索用时 0 毫秒
91.
92.
93.
94.
95.

Background

Endoscopic ampullectomy is established as a valuable treatment for adenomas of the Vaterian papilla. Few large series are available, however, let alone any with long-term follow-up. Moreover, multiple tangible issues remain. The aim of our study was to evaluate efficacy, safety, and outcome of endoscopic ampullectomy and compare it to existing literature

Methods

This is a single-center, retrospective study with a minimal follow-up of 3 years including 91 patients, including familial adenomatous polyposis (FAP) and non-FAP, who had an endoscopic ampullectomy between 2000 and 2008. Outcome parameters included ampulloma characteristics, biotical accuracy as well as safety, efficacy, recurrence rate, and survival after endoscopic ampullectomy.

Results

Endoscopic resection was successful in 71 patients (78 %). Histological review of the resected specimens revealed nonspecific changes (13.8 %), low or medium grade dysplasia (52.9 %), high grade dysplasia (21.8 %) and carcinoma (18.3 %). Bioptic accuracy was 38.3 %. Overall complications were observed in 23 patients (25.2 %): pancreatitis (15.4 %), hemorrhage (12.1 %) and cholangitis (4.9 %). Recurrence occurred in 18.3 %. Fourteen patients underwent pancreaticoduodenectomy. Survival after complete endoscopic ampullectomy was excellent for patients with low to moderate grade dysplasia and high grade dysplasia. Incomplete endoscopic resection of high grade dysplasia or invasive carcinoma was associated with unfavorable outcome when treated merely endoscopically.

Conclusions

Endoscopic ampullectomy is obligatory for assessment of the true histological nature of an ampulloma. Endoscopic resection is a safe and efficient procedure for adenomas with low to moderate dysplasia but also for high grade dysplastic lesions, provided that a complete endoscopic resection is achieved.  相似文献   
96.
97.
98.
99.
Everyday action impairments often are observed in demented older adults, and they are common potential barriers to functional independence. We evaluated whether the ability to segment and efficiently encode activities is related to the ability to execute activities. Further, we evaluated whether brain regions important for segmentation also were important for action performance. Cognitively healthy older adults and those with very mild or mild dementia of the Alzheimer's type watched and segmented movies of everyday activities and then completed the Naturalistic Action Test. Structural MRI was used to measure volume in the dorsolateral prefrontal cortex (DLPFC), medial temporal lobes (MTL), posterior cortex, and anterior cingulate cortex (ACC). Dementia status and the ability to segment everyday activities strongly predicted naturalistic action performance, and MTL volume largely accounted for this relationship. In addition, the current results supported the Omission-Commission Model: Different cognitive and neurological mechanisms predicted different types of action error. Segmentation, dementia severity, and MTL volume predicted everyday omission errors, DLPFC volume predicted commission errors, and ACC volume predicted action additions. These findings suggest that event segmentation may be critical for effective action production, and that the segmentation and production of activities may recruit the same event representation system.  相似文献   
100.
The most common cause of familial frontotemporal lobar degeneration with TAR DNA-binding protein-43 pathology (FTLD-TDP) has been found to be an expansion of a hexanucleotide repeat (GGGGCC) in a noncoding region of the gene C9ORF72. Hippocampal sclerosis (HpScl) is a common finding in FTLD-TDP. Our objective was to screen for the presence of C9ORF72 hexanucleotide repeat expansions in a pathologically confirmed cohort of “pure” hippocampal sclerosis cases (n = 33), outside the setting of FTLD-TDP and Alzheimer’s disease (AD). Using a recently described repeat-associated non-ATG (RAN) translation (C9RANT) antibody that was found to be highly specific for c9FTD/ALS, we identified a single “pure” HpScl autopsy case with a repeat expansion in C9ORF72 (c9HpScl). Mutation screening was also performed with repeat-primed polymerase chain reaction and further confirmed with Southern blotting. The c9HpScl patient had a 14-year history of a slowly progressive amnestic syndrome and a clinical diagnosis of probable AD. Neuropsychological testing revealed memory impairment, but no deficits in other cognitive domains. Autopsy showed hippocampal sclerosis with TDP-43 immunoreactive neuronal inclusions relatively limited to limbic lobe structures. Neuritic pathology immunoreactive for p62 was more frequent than TDP-43 in amygdala and hippocampus. Frequent p62-positive neuronal inclusions were present in cerebellar granule neurons as is typical of C9ORF72 mutation carriers. There was no significant FTLD or motor neuron disease. C9RANT was found to be sensitive and specific in this autopsy-confirmed series of HpScl cases. The findings in this patient suggest that the clinical and pathologic spectrum of C9ORF72 repeat expansion is wider than frontotemporal dementia and motor neuron disease, including cases of progressive amnestic dementia with restricted TDP-43 pathology associated with HpScl.  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