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   1988386篇
  免费   137832篇
  国内免费   23395篇
耳鼻咽喉   24023篇
儿科学   58294篇
妇产科学   49363篇
基础医学   275620篇
口腔科学   53491篇
临床医学   191197篇
内科学   374548篇
皮肤病学   41247篇
神经病学   147920篇
特种医学   73918篇
外国民族医学   442篇
外科学   284572篇
综合类   83916篇
现状与发展   77篇
一般理论   564篇
预防医学   141023篇
眼科学   48812篇
药学   153094篇
  428篇
中国医学   20591篇
肿瘤学   126473篇
  2022年   17128篇
  2021年   27443篇
  2020年   20022篇
  2019年   23898篇
  2018年   29717篇
  2017年   23977篇
  2016年   24898篇
  2015年   31200篇
  2014年   41244篇
  2013年   50644篇
  2012年   71537篇
  2011年   76941篇
  2010年   45950篇
  2009年   40853篇
  2008年   64983篇
  2007年   68406篇
  2006年   69053篇
  2005年   66575篇
  2004年   59211篇
  2003年   55942篇
  2002年   52917篇
  2001年   97886篇
  2000年   100406篇
  1999年   84583篇
  1998年   24652篇
  1997年   22146篇
  1996年   21172篇
  1995年   20326篇
  1994年   18274篇
  1993年   16114篇
  1992年   59933篇
  1991年   57442篇
  1990年   54864篇
  1989年   52449篇
  1988年   47608篇
  1987年   46203篇
  1986年   43248篇
  1985年   40872篇
  1984年   29859篇
  1983年   25274篇
  1982年   14075篇
  1979年   25749篇
  1978年   17639篇
  1977年   14966篇
  1976年   13937篇
  1975年   14624篇
  1974年   17695篇
  1973年   17014篇
  1972年   15747篇
  1971年   14531篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
992.
993.
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   
994.
995.
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   
996.
997.
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   
998.
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   
999.
1000.
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   
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