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   1579237篇
  免费   111734篇
  国内免费   4840篇
耳鼻咽喉   19966篇
儿科学   50985篇
妇产科学   41934篇
基础医学   232613篇
口腔科学   42075篇
临床医学   149053篇
内科学   311721篇
皮肤病学   33347篇
神经病学   133874篇
特种医学   55136篇
外国民族医学   471篇
外科学   214511篇
综合类   29873篇
现状与发展   1篇
一般理论   532篇
预防医学   136617篇
眼科学   33551篇
药学   115977篇
  6篇
中国医学   3923篇
肿瘤学   89645篇
  2021年   15677篇
  2019年   16474篇
  2018年   23957篇
  2017年   17292篇
  2016年   18310篇
  2015年   20807篇
  2014年   27491篇
  2013年   42235篇
  2012年   61013篇
  2011年   63807篇
  2010年   35785篇
  2009年   32133篇
  2008年   56873篇
  2007年   60124篇
  2006年   59184篇
  2005年   57558篇
  2004年   54459篇
  2003年   51452篇
  2002年   49532篇
  2001年   66367篇
  2000年   68017篇
  1999年   57217篇
  1998年   15955篇
  1997年   14356篇
  1996年   14069篇
  1995年   13342篇
  1994年   12389篇
  1993年   11610篇
  1992年   44361篇
  1991年   43370篇
  1990年   41881篇
  1989年   39588篇
  1988年   36658篇
  1987年   35681篇
  1986年   34003篇
  1985年   32344篇
  1984年   24309篇
  1983年   20689篇
  1982年   12402篇
  1979年   21926篇
  1978年   15593篇
  1977年   12795篇
  1976年   12510篇
  1975年   12891篇
  1974年   15746篇
  1973年   15420篇
  1972年   14266篇
  1971年   13339篇
  1970年   12338篇
  1969年   11279篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
A 59-year-old man developed dystonia and reflex sympathetic dystrophy after receiving high doses of ergotamine for migraine treatment. Ischemia is suggested as the precipitating factor.  相似文献   
992.
993.
Although iophendylate (Pantopaque) has been largely replaced by water soluble agents for myelography, retained intracranial or intraspinal Pantopaque remains a common occurrence. Pantopaque has signal characteristics similar to fat with both short T1 and T2 relaxation times. In vitro measurements revealed T1 = 170 ms and T2 = 27 ms. Spine radiography is recommended in patients with a history of previous myelography and magnetic resonance abnormalities similar to fat.  相似文献   
994.
Regional cerebral blood flow (rCBF) was assessed by means of HMPAO-SPECT in two experimental groups. In a control condition both groups listened to abstract words, in the experimental condition they heard five names of objects. One group was advised to form visual images of the objects, the other group was advised to form acoustic images of the sounds made by these objects. Post-experimental questionnaires revealed that most of the subjects in the acoustic imagery condition had had visual images in addition to the acoustic ones. Both imagery conditions lead to approximately equal increases of rCBF in the left inferior occipital region and in the left thalamus. Flow increases in both hippocampal regions and the right inferior and superior temporal regions were larger in the acoustic than in the visual imagery condition. It is concluded that only the activation of left inferior occipital and left thalamic regions can be interpreted as being related to modality-specific visual aspects of imagery.  相似文献   
995.
996.
Several investigators have suggested that microcomputers might serve as useful external aids for memory-impaired patients. However, knowledge of basic computer vocabulary may be necessary for patients to use and benefit from a microcomputer. The present paper describes a procedure, the method of vanishing cues, which facilitated the acquisition of computer-related vocabulary in four memory-impaired patients. The method involves the systematic reduction of letter fragments of to-be-learned words across trials. Although learning was slow and strongly dependent on first-letter cues, all patients acquired a substantial amount of the vocabulary and eventually were able to produce the target words in the absence of fragment cues. Further, they retained the vocabulary over a 6-week interval and showed some transfer of the knowledge they had acquired. These findings suggest that memory-impaired patients may eventually be able to use a microcomputer as a prosthetic device.  相似文献   
997.
998.
999.
1000.
Temporoparietal and posterior cingulate metabolism deficits characterize patients with Alzheimer's disease (AD). A H(2)(15)O resting PET scan covariance pattern, derived by using multivariate techniques, was previously shown to discriminate 17 mild AD patients from 16 healthy controls. This AD covariance pattern revealed hypoperfusion in bilateral inferior parietal lobule and cingulate; and left middle frontal, inferior frontal, precentral, and supramarginal gyri. The AD pattern also revealed hyperperfusion in bilateral insula, lingual gyri, and cuneus; left fusiform and superior occipital gyri; and right parahippocampal gyrus and pulvinar. In an independent sample of 23 outpatients with mild cognitive impairment (MCI) followed at 6-month intervals, the AD pattern score was evaluated as a predictor of cognitive decline. In this MCI sample, an H2(15)O resting PET scan was carried out at baseline. Mean duration of follow-up was 48.8 (SD 15.5) months, during which time six of 23 MCI patients converted to AD. In generalized estimating equations (GEE) analyses, controlling for age, sex, education, and baseline neuropsychological scores, increased AD pattern score was associated with greater decline in each neuropsychological test score over time (Mini Mental State Exam, Selective Reminding Test delayed recall, Animal Naming, WAIS-R digit symbol; Ps<0.01-0.001). In summary, a resting PET covariance pattern previously reported to discriminate AD patients from control subjects was applied prospectively to an independent sample of MCI patients and found to predict cognitive decline. Independent replication in larger samples is needed before clinical application can be considered.  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