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   1278659篇
  免费   98051篇
  国内免费   1990篇
耳鼻咽喉   18424篇
儿科学   44359篇
妇产科学   35022篇
基础医学   182199篇
口腔科学   33588篇
临床医学   111256篇
内科学   258239篇
皮肤病学   28028篇
神经病学   100371篇
特种医学   51199篇
外国民族医学   660篇
外科学   196442篇
综合类   27053篇
现状与发展   1篇
一般理论   378篇
预防医学   95731篇
眼科学   27918篇
药学   94769篇
  2篇
中国医学   2422篇
肿瘤学   70639篇
  2018年   13134篇
  2017年   9965篇
  2016年   10897篇
  2015年   12372篇
  2014年   17165篇
  2013年   26214篇
  2012年   36023篇
  2011年   38055篇
  2010年   22801篇
  2009年   21808篇
  2008年   36642篇
  2007年   39256篇
  2006年   39507篇
  2005年   38447篇
  2004年   37603篇
  2003年   36459篇
  2002年   35810篇
  2001年   64001篇
  2000年   66500篇
  1999年   56415篇
  1998年   15136篇
  1997年   13754篇
  1996年   14197篇
  1995年   13457篇
  1994年   12768篇
  1993年   11792篇
  1992年   44554篇
  1991年   43468篇
  1990年   42218篇
  1989年   40117篇
  1988年   36898篇
  1987年   36239篇
  1986年   33625篇
  1985年   32283篇
  1984年   24139篇
  1983年   20270篇
  1982年   11725篇
  1981年   10693篇
  1980年   9516篇
  1979年   21347篇
  1978年   14823篇
  1977年   12533篇
  1976年   11693篇
  1975年   12624篇
  1974年   14661篇
  1973年   14118篇
  1972年   12945篇
  1971年   11730篇
  1970年   11050篇
  1969年   10025篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
992.
993.
994.
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   
995.
996.
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   
997.
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   
998.
Presented in this work is a rare injury of a blunt abdominal trauma in a child. Besides a partial rupture of the kidney and a retro-/intraperitoneal haematoma, a further injury occurred from the accident: an initially clinically indetectable tear of the A. iliaca communis which was found intraoperatively and with systematic CT analysis. Traumatic blood vessel lesions of the abdominal aorta and in particular the iliac blood vessels are very rare in children. By such violent impact injuries, it is therefore vital to perform a clinical examination of the foot pulse, systematic analysis of radiology diagnostics, and intraoperative exploration. The growth phase should be considered for therapy of the blood vessels depending on the child's age group. As the long-term results of graft implants are practically unknown, if possible a primary suture or vein patch should be performed.  相似文献   
999.
1000.
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   
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