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   57454篇
  免费   4882篇
  国内免费   1877篇
耳鼻咽喉   657篇
儿科学   684篇
妇产科学   1121篇
基础医学   8714篇
口腔科学   1465篇
临床医学   5011篇
内科学   10839篇
皮肤病学   1073篇
神经病学   4017篇
特种医学   1850篇
外国民族医学   6篇
外科学   8003篇
综合类   4901篇
现状与发展   1篇
一般理论   5篇
预防医学   3287篇
眼科学   1518篇
药学   5346篇
  1篇
中国医学   1065篇
肿瘤学   4649篇
  2023年   284篇
  2022年   465篇
  2021年   831篇
  2020年   527篇
  2019年   805篇
  2018年   1305篇
  2017年   1030篇
  2016年   1025篇
  2015年   1205篇
  2014年   1549篇
  2013年   1868篇
  2012年   2535篇
  2011年   2463篇
  2010年   1497篇
  2009年   1431篇
  2008年   2101篇
  2007年   2266篇
  2006年   2103篇
  2005年   1777篇
  2004年   1550篇
  2003年   1525篇
  2002年   1415篇
  2001年   4747篇
  2000年   4678篇
  1999年   4024篇
  1998年   1447篇
  1997年   1070篇
  1996年   668篇
  1995年   568篇
  1994年   498篇
  1993年   435篇
  1992年   1960篇
  1991年   1703篇
  1990年   1554篇
  1989年   1521篇
  1988年   1319篇
  1987年   1207篇
  1986年   1083篇
  1985年   905篇
  1984年   597篇
  1983年   474篇
  1982年   252篇
  1981年   185篇
  1980年   142篇
  1979年   280篇
  1978年   78篇
  1974年   76篇
  1973年   98篇
  1972年   72篇
  1969年   69篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
72.
This paper is a summary of our observations on 105 cases of infantile spasms. The age of onset was around six months after birth, but the patients came for treatment mainly about one year after onset. Fever of unknown cause, asphyxia, birth injury, infection of the central nervous system, tuberous sclerosis, phenylketonuria and recent immunization etc. were complained. Clinically, it is characterized by head nodding, mental retardation, myoclonic jerks and various neurologic deficits. EEG findings showed classical or modified arrythmia or other epileptiform patterns. About one third of 22 cases examined had abnormal brain stem auditory evoked potentials. Among 42 patients who underwent CT scanning before ACTH treatment, 18 were normal and 7 abnormal; during ACTH treatment 3 normal and 4 abnormal; after completion of treatment, 4 normal and 6 abnormal, suggesting no further atrophy of the brain. Examination of trace elements of the hair by particle-induced X-ray emission (PIXE) method in 23 patients revealed a significant difference in lead, calcium and zinc contents between patients and 101 controls, but no statistical difference in iron and copper contents between the two groups. Sodium valproate, prednisone and ACTH appear to be effective in the treatment of infantile spasms. Eight patients fully recovered, and they can go to school without difficulty. Many patients derived various degrees of improvement to the satisfaction of their parents. Two patients were still amented and often attacked by myoclonus. The effects, side effects of these drugs, and the possible pathogenesis were discussed.
  相似文献   
73.
The effects of some antirheumatics on the formation and retraction of collagen lattices seeded with fibroblasts have been studied. Among the antirheumatics, diclofenac was the most active inhibitor of lattice retraction, then tropesin and to a lesser extent indomethacin. Ibuprofen which is known as a very slight inhibitor of protein synthesis was able to significantly enhance lattice retraction when 10 micrograms/ml (48.5 microM) and 50 micrograms/ml (242 microM) were used.  相似文献   
74.
75.
目的 评价诊断中老年男子部分雄激素缺乏综合征(PADAM)的游离睾酮指数(FTI).方法 对129例45岁以上健康男性的FTI进行年龄相关分析.以推算的游离睾酮(CFT)值为依据,对FTI进行有效性检验.结果 男子在中老年期FTI与增龄呈明显的负相关.FTI敏感性97.78%,特异性58.33%.结论 计算简单的FTI可用于PADAM病人的筛选和随访,尤其对70岁以上男子是血清FT较为有效的参数.  相似文献   
76.
77.
Heubner回返动脉显微外科解剖及其临床应用   总被引:2,自引:0,他引:2  
目的 :为前交通动脉复合体部位显微手术避免损伤Heubner回返动脉提供相关的应用解剖学资料。方法 :对经双侧椎动脉 (VA)、颈内动脉 (ICA)乳胶灌注的尸头标本 2 2例 ,按翼点入路方向 ,在手术显微镜下解剖观测 2 0例Heubner回返动脉的起点、管径、行径及其毗邻关系。 2例模拟手术操作。结果 :(1)本组观测到 4 3支回返动脉 ,其中 39支Heubher回返动脉 ;4支副Heubner回返动脉。 (2 )Heubner回返动脉 4 6 .5 % (2 0 / 4 3)起于A2 段 ,2 5 .6 % (11/ 4 3)起于A1段 ,2 7.9% (12 /4 3)起于前交通动脉 (ACOA)水平的大脑前动脉 (ACA)。 (3)Heubner回返动脉起点管径 :左侧 0 .81± 0 .2 1mm(0 .35~ 1.17mm) ;右侧 0 .84± 0 .2 6mm(0 .37~ 1.2 1mm)。 (4 )回返动脉发出后 ,与ACA反方向成锐角 ,沿A1上壁、外侧及后内侧 ,越过ICA两分叉 ,经大脑中动脉 (MCA)始段前面穿通入脑 ,少数回返动脉行走于前穿质 (APS)的后部。A1近端 3~ 5mm或中 1/ 3段穿通支少。结论 :在前交通动脉复合体部位手术时 ,A1近端 3~ 5mm或中 1/ 3段夹闭 ,并解剖寻找、剥离Heubner回返动脉 ,可避免损伤Heubner回返动脉及其它穿通支 ,最大限度减少术后并发症  相似文献   
78.
Selecting an appropriate working correlation structure is pertinent to clustered data analysis using generalized estimating equations (GEE) because an inappropriate choice will lead to inefficient parameter estimation. We investigate the well‐known criterion of QIC for selecting a working correlation structure, and have found that performance of the QIC is deteriorated by a term that is theoretically independent of the correlation structures but has to be estimated with an error. This leads us to propose a correlation information criterion (CIC) that substantially improves the QIC performance. Extensive simulation studies indicate that the CIC has remarkable improvement in selecting the correct correlation structures. We also illustrate our findings using a data set from the Madras Longitudinal Schizophrenia Study. Copyright © 2008 John Wiley & Sons, Ltd.  相似文献   
79.
Tick-borne encephalitis (TBE) virus is an important human pathogenic flavivirus that is endemic in Europe and Asia. The disease can be effectively prevented by inactivated vaccines and vaccination breakthroughs (VBTs) are rare. We investigated the characteristics of antibody responses in such VBTs in comparison to those in unvaccinated TBE patients. In contrast to the unvaccinated controls, most of the VBTs displayed a delayed IgM antibody response and had high avidity and strongly neutralizing antibodies already in the first sample taken upon hospitalization. The antibody profile of these patients therefore had the characteristics of an anamnestic immune response. In the VBTs analyzed, immunological priming and memory were apparently not sufficient or fast enough to prevent the disease.  相似文献   
80.
The recent global resurgence of mumps has drawn attention to the continued need for robust mumps immunization programs. Unfortunately, some vaccines derived from inadequately attenuated vaccine strains of mumps virus have caused meningitis in vaccinees, leading to withdrawal of certain vaccine strains from the market, public resistance to vaccination, or in some cases, cessation of national mumps vaccination programs. The most widely implicated mumps vaccine in cases of postvaccination meningitis is derived from the Urabe AM9 strain, which remains in use in some countries. The Urabe AM9 vaccine virus has been shown to exhibit a considerable degree of nucleotide and amino acid heterogeneity. Some studies have specifically implicated variants containing a lysine residue at amino acid position 335 in the hemagglutinin-neuraminidase (HN) protein with neurotoxicity, whereas a glutamic acid residue at this position was associated with attenuation. To test this hypothesis we generated two modified Urabe AM9 cDNA clones coding either for a lysine or a glutamic acid at position 335 in the HN gene. The two viruses were rescued by reverse genetics and characterized in vitro and in vivo. Both viruses exhibited similar growth kinetics in neuronal and non-neuronal cell lines and were of similar neurotoxicity when tested in rats, suggesting that amino acid 335 is not a crucial determinant of Urabe AM9 growth or neurovirulence.  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