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   1278849篇
  免费   98067篇
  国内免费   1989篇
耳鼻咽喉   18423篇
儿科学   44353篇
妇产科学   35022篇
基础医学   182213篇
口腔科学   33592篇
临床医学   111301篇
内科学   258276篇
皮肤病学   28023篇
神经病学   100425篇
特种医学   51201篇
外国民族医学   660篇
外科学   196417篇
综合类   27055篇
现状与发展   1篇
一般理论   377篇
预防医学   95764篇
眼科学   27914篇
药学   94815篇
  2篇
中国医学   2423篇
肿瘤学   70648篇
  2018年   13141篇
  2017年   9968篇
  2016年   10899篇
  2015年   12377篇
  2014年   17170篇
  2013年   26216篇
  2012年   36030篇
  2011年   38063篇
  2010年   22811篇
  2009年   21818篇
  2008年   36659篇
  2007年   39270篇
  2006年   39521篇
  2005年   38456篇
  2004年   37607篇
  2003年   36459篇
  2002年   35808篇
  2001年   63998篇
  2000年   66510篇
  1999年   56429篇
  1998年   15132篇
  1997年   13760篇
  1996年   14200篇
  1995年   13454篇
  1994年   12770篇
  1993年   11792篇
  1992年   44561篇
  1991年   43474篇
  1990年   42224篇
  1989年   40122篇
  1988年   36902篇
  1987年   36247篇
  1986年   33621篇
  1985年   32285篇
  1984年   24141篇
  1983年   20272篇
  1982年   11729篇
  1981年   10696篇
  1980年   9515篇
  1979年   21342篇
  1978年   14824篇
  1977年   12535篇
  1976年   11693篇
  1975年   12625篇
  1974年   14663篇
  1973年   14118篇
  1972年   12945篇
  1971年   11731篇
  1970年   11051篇
  1969年   10024篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
992.
993.
994.
995.
996.
997.
Conjugated linoleic acid (CLA) is a unique lipid that elicits dramatic reductions in adiposity in several animal models when included at < or = 1% of the diet. Despite a flurry of investigations, the precise mechanisms by which conjugated linoleic acid elicits its dramatic effects in adipose tissue and liver are still largely unknown. In vivo and in vitro analyses of physiological modifications imparted by conjugated linoleic acid on protein and gene expression suggest that conjugated linoleic acid exerts its de-lipidating effects by modulating energy expenditure, apoptosis, fatty acid oxidation, lipolysis, stromal vascular cell differentiation and lipogenesis. The purpose of this review shall be to examine the recent advances and insights into conjugated linoleic acid's effects on obesity and lipid metabolism, specifically focused on changes in gene expression and physiology of liver and adipose tissue.  相似文献   
998.
999.
OBJECTIVE: To identify the possible contribution of electromyogram (EMG) to scalp electroencephalogram (EEG) rhythms at rest and induced or evoked by cognitive tasks. METHODS: Scalp EEG recordings were made on two subjects in presence and absence of complete neuromuscular blockade, sparing the dominant arm. The subjects undertook cognitive tasks in both states to allow direct comparison of electrical recordings. RESULTS: EEG rhythms in the paralysed state differed significantly compared with the unparalysed state, with 10- to 200-fold differences in the power of frequencies above 20 Hz during paralysis. CONCLUSIONS: Most of the scalp EEG recording above 20 Hz is of EMG origin. Previous studies measuring gamma EEG need to be re-evaluated. SIGNIFICANCE: This has a significant impact on measurements of gamma rhythms from the scalp EEG in unparalysed humans. It is to be hoped that signal separation methods will be able to rectify this situation.  相似文献   
1000.
In six patients with slowly progressive sporadic cerebellar ataxia and cortical multifocal action myoclonus, cerebrospinal fluid (CSF) IgG index was persistently very high (1.2–6.7) and numerous oligoclonal bands were detected. Progressive cognitive impairment and MRI cerebellar and cerebral atrophy were observed. No serum antibodies were found. Various degenerative, metabolic, inflammatory and systemic diseases were excluded. The cerebellum may be the main target of a degenerative or immune process and releases antigens that, enhancing a compartmentalised (auto)immune response, as suggested by the persistent intrathecal activation, could lead to further cerebellar damage. As the frequency of CSF oligoclonal banding in myoclonic ataxia is unknown, our patients’ disease might represent a hitherto unreported entity or a subset of progressive myoclonic ataxia.
Sommario Descriviamo sei pazienti con atassia cerebellare sporadica e mioclono corticale d’azione multifocale, nel cui liquor i valori dell’indice IgG si mantenevano persistentemente elevati ed erano presenti numerose bande oligoclonali. I pazienti manifestavano un progressivo declino cognitivo e la RM mostrava atrofia cerebellare e cerebrale. In assenza di anticorpi identificabili non era possibile formulare una diagnosi di malattia nota. Suggeriamo che il cervelletto possa essere il principale bersaglio di un processo degenerativo o immuno-mediato e che gli antigeni liberati inducano la produzione di anticorpi che ulteriormente provocano danno cerebrale. Poiché non è nota la frequenza delle bande oligoclonali nel liquor di pazienti con atassia mioclonica, non sappiamo se la malattia qui descritta sia una entità nuova o un sottogruppo delle atassie miocloniche.
  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