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   1303207篇
  免费   99005篇
  国内免费   4280篇
耳鼻咽喉   16600篇
儿科学   41493篇
妇产科学   35396篇
基础医学   193938篇
口腔科学   35541篇
临床医学   122898篇
内科学   253499篇
皮肤病学   27701篇
神经病学   103643篇
特种医学   48178篇
外国民族医学   282篇
外科学   182750篇
综合类   32613篇
现状与发展   15篇
一般理论   583篇
预防医学   107561篇
眼科学   29352篇
药学   96444篇
  64篇
中国医学   4402篇
肿瘤学   73539篇
  2021年   11723篇
  2019年   11455篇
  2018年   15020篇
  2017年   11739篇
  2016年   12586篇
  2015年   14967篇
  2014年   20360篇
  2013年   29665篇
  2012年   40610篇
  2011年   43309篇
  2010年   25193篇
  2009年   24050篇
  2008年   39908篇
  2007年   42455篇
  2006年   42076篇
  2005年   40898篇
  2004年   38850篇
  2003年   37079篇
  2002年   35793篇
  2001年   56813篇
  2000年   57788篇
  1999年   48879篇
  1998年   13907篇
  1997年   12690篇
  1996年   12996篇
  1995年   12226篇
  1994年   11424篇
  1992年   38414篇
  1991年   37847篇
  1990年   36586篇
  1989年   35432篇
  1988年   32815篇
  1987年   32161篇
  1986年   30582篇
  1985年   28857篇
  1984年   21983篇
  1983年   19218篇
  1982年   11387篇
  1979年   20969篇
  1978年   15403篇
  1977年   12795篇
  1976年   11848篇
  1975年   12818篇
  1974年   15597篇
  1973年   15366篇
  1972年   14513篇
  1971年   13552篇
  1970年   12789篇
  1969年   12067篇
  1968年   11229篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
992.
993.
994.
995.
996.
COWEN ED 《Lancet》1949,2(6573):316-320
  相似文献   
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.
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   
999.
We describe a modified keyhole laminoforaminotomy (LF) using anatomic landmarks on the posterior aspect of the cervical vertebral body to decompress the intervertebral foramen with minimal bone removal. Twenty-four procedures were performed at C3-4, C4-5, and C5-6; 12 at C6-7; and 3 at C7-Tl. Facets and laminae structures were identified based on relative surgical perspectives. Bony resection was limited as follows: 1) inferior limit; inferior border of the superior facet; 2) superior limit, superior border of the superior facet; 3) lateral limit, a vertical line linking the junction of the lamina-facet to the lateral end of the superior limit; and 4) lateral aspect of the dural sac. Fluoroscopy was used to confirm that the intervertebral space was reached. The amount of bony removal was quantified for the superior and inferior laminae and facets. The length of the exposed nerve root was measured. The intervertebral foramen was exposed and the intervertebral disc reached in all specimens. Fluoroscopy showed that the center of the exposure remained at the same height with the intervertebral space. The mean length of the nerve root was 4.6 mm; the mean percentage of bony resection was 21.8%, 7.5%, 11.3%, and 11.5% for the superior and inferior laminae and facets, respectively. Opening the intervertebral foramen posteriorly consistently exposed sufficient nerve root length and allowed access to the intervertebral disc. The technique offers the most direct and safest method of decompressing the intervertebral foramen while minimizing bony resection. This simple surgical procedure may help reduce postoperative morbidity.  相似文献   
1000.
Complement is a multifunctional system of receptors and regulators as well as effector molecules. Both the pathogenic and diagnostic power of complement is based on the capacity of the complement system to amplify innate and adaptive immunity. This amplification is accomplished through two strategies: (1) enzymatic reactions in the complement cascade, and (2) stimulation of leukocytes, platelets and parenchymal cells through specific receptors or receptor-independent pore formation. The mechanisms by which complement mediates and modifies nonspecific inflammation, antibody-mediated injury and T-cell responses are of particular significance to the pathogenesis of transplant rejection. Understanding the mechanisms by which complement integrates the interactions of leukocytes, platelets and parenchymal cells offers opportunities to further refine the diagnosis of rejection.  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