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   1855473篇
  免费   124494篇
  国内免费   3784篇
耳鼻咽喉   22782篇
儿科学   61565篇
妇产科学   48917篇
基础医学   256187篇
口腔科学   50167篇
临床医学   162452篇
内科学   361421篇
皮肤病学   39279篇
神经病学   146184篇
特种医学   72157篇
外国民族医学   242篇
外科学   283768篇
综合类   41179篇
现状与发展   4篇
一般理论   533篇
预防医学   140624篇
眼科学   42771篇
药学   132257篇
  7篇
中国医学   5107篇
肿瘤学   116148篇
  2021年   12807篇
  2019年   13544篇
  2018年   40060篇
  2017年   31028篇
  2016年   34406篇
  2015年   19790篇
  2014年   26898篇
  2013年   38587篇
  2012年   58986篇
  2011年   74716篇
  2010年   49943篇
  2009年   41245篇
  2008年   69399篇
  2007年   74702篇
  2006年   55670篇
  2005年   54447篇
  2004年   53856篇
  2003年   52132篇
  2002年   48641篇
  2001年   92014篇
  2000年   93986篇
  1999年   77102篇
  1998年   19903篇
  1997年   17447篇
  1996年   17449篇
  1995年   16830篇
  1994年   15378篇
  1993年   14121篇
  1992年   57406篇
  1991年   55346篇
  1990年   53083篇
  1989年   50815篇
  1988年   46183篇
  1987年   44971篇
  1986年   42242篇
  1985年   40010篇
  1984年   29362篇
  1983年   24930篇
  1982年   13921篇
  1979年   25535篇
  1978年   17583篇
  1977年   14910篇
  1976年   13881篇
  1975年   14569篇
  1974年   17649篇
  1973年   16946篇
  1972年   15673篇
  1971年   14456篇
  1970年   13449篇
  1969年   12537篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Hallucinations and associated factors in Alzheimer's disease.   总被引:1,自引:0,他引:1  
In a consecutive sample of 230 community-dwelling patients with probable Alzheimer's disease, a structured interview yielded evidence of current hallucinations in 29.1% and misperceptions in another 11.3%. Visual and auditory modalities were similarly represented in apparent hallucinations. Hallucinations prior to the current monitoring period were rare among patients with misperceptions or with no perceptual abnormality. The probability of hallucinations was associated with the severity of cognitive dysfunction, the degree of other behavioral disturbances, and the presence of extrapyramidal signs. A logistic regression model predicting hallucinations based on these diverse clinical features accurately classified 87.0% of the sample.  相似文献   
992.
993.
S Ii  S Minnerath  K Ii  P J Dyck  S S Sommer 《Neurology》1991,41(6):893-898
We analyzed 11 consecutive unrelated cases of polyneuropathy due to transthyretin amyloidosis. Direct sequencing of the promoter region, exons, and splice junctions revealed that each patient was heterozygous for a mutation: six patients had valine 30 substituted by methionine (V30----M; Portuguese-Japanese type), one had threonine 60 substituted by alanine (T60----A; Appalachian type), and two had serine 77 substituted by tyrosine (S77----Y; Illinois type). In addition, two patients had previously undescribed mutation: phenylalanine 33 substituted by leucine (F33----L) and phenylalanine 64 substituted by leucine (F64----L). From present information, the probands of these novel mutations do not exhibit any pathology that clearly distinguishes them from individuals with the other mutations. The mutations extend the range of mutations associated with amyloidotic polyneuropathy. In our 11 patients, the different mutations did not seem to correlate with distinct clinical phenotypes. We developed PASA assays (PCR amplification of specific alleles) for each of the five mutations. PASA can be used by any diagnostic laboratory that can perform PCR to rapidly detect any of the known mutations. The minority of samples with an undescribed mutation can be sent to a specialty laboratory for delineation of the mutation by direct genomic sequencing. The presently described combination of methods may have widespread utility in the diagnosis of genetic disease.  相似文献   
994.
995.
Soluflazine, a specific adenosine transport inhibitor, was intracerebroventricularly administered to rats in a dose range of 10, 25, and 50 nmoles. At a dose of 50 nmoles, soluflazine decreased waking and increased sleep during the first hour of EEG recording. Our previous work has shown that chronic intracerebroventricular administration of soluflazine to rats decreased radioligand binding to adenosine A1 and A2 receptors in specific brain regions. The present data show that administration of an adenosine transport inhibitor to rats produces a transient hypnotic effect presumably through increases in synaptic adenosine levels.  相似文献   
996.
Despite current intensive research, the pathophysiology of tardive dyskinesia (TD), a serious neurological side effect of neuroleptic treatment, is poorly understood. Prompted by the observation of an increased incidence and severity of abnormal perioral movements in neuroleptic-treated pinealectomized, as compared to intact rats, we suggested that the pineal gland exerts a protective effect which mitigates against the development of TD and, by inference, that reduced melatonin secretion may be related to the pathophysiology of TD. To investigate this proposition further, we studied the association of TD with pineal calcification (PC) on CT scan in chronic schizophrenic patients. Our findings revealed a significant association between TD and PC and suggest, furthermore, that PC may be a neuroradiological marker of TD. Since PC may reflect diminished secretory activity of the gland, these findings support the hypothesis that the pathophysiology of TD is linked to disturbances of melatonin secretion. The clinical and therapeutic implications of these novel findings are discussed. In the following communication, in which we introduce the hypothesis that disturbances of 5-HT and melatonin secretion are related to the pathophysiology of TD. Subsequently, we present a series of studies which relate to the association of TD with PC. We conclude by presenting the hypothesis that disturbances in melatonin secretion may also be relevant to the pathophysiology of Tourette's syndrome.  相似文献   
997.
998.
The purpose of this study was to evaluate three subcutaneous injection sites for low-dose heparin therapy (5,000 units). One hundred and one subjects were randomly placed in one of three groups. Group A received injections in the abdomen, Group B, in the thigh, and Group C in the arm. Each subject received three injections at the one site. Activated partial thromboplastin time (APTT) was measured prior to initiation of heparin and again four hours after the first injection. Bruising was measured at 48, 60, and 72 hours postinjection. There were no statistically significant differences among groups for either changes in APTT or bruising at 60 and 72 hours postinjection. Thus the clinical practice of utilizing the abdomen as the only or preferred site for subcutaneous heparin injections was not supported.  相似文献   
999.
1000.
Computed tomography (CT) was performed in 14 cases of tuberculous meningitis (TBM), 12 of which were examined during the acute phase of the disease. CT findings in these cases included internal hydrocephalus (6/12), internal combined with external hydrocephalus (2/12), focal lesions consistent with localized encephalitis (3/12), diffuse brain edema (1/12), and middle cerebral artery infarction (1/12). In comparison to 32 cases of nonspecific bacterial meningitis, internal hydrocephalus was found significantly more often in TBM than in nonspecific meningitis (p less than 0.01) making CT an additional tool for the differentiation of these conditions in doubtful cases. In addition, CT features of 2 cases of cerebral tuberculoma are presented.  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