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   270578篇
  免费   20041篇
  国内免费   8551篇
耳鼻咽喉   2247篇
儿科学   9495篇
妇产科学   2001篇
基础医学   23670篇
口腔科学   4074篇
临床医学   30102篇
内科学   64691篇
皮肤病学   3185篇
神经病学   28295篇
特种医学   7477篇
外国民族医学   4篇
外科学   20693篇
综合类   38708篇
现状与发展   36篇
一般理论   10篇
预防医学   22979篇
眼科学   2570篇
药学   20488篇
  244篇
中国医学   13510篇
肿瘤学   4691篇
  2024年   767篇
  2023年   5378篇
  2022年   10020篇
  2021年   14027篇
  2020年   12943篇
  2019年   9881篇
  2018年   9731篇
  2017年   9815篇
  2016年   10410篇
  2015年   10040篇
  2014年   19194篇
  2013年   20689篇
  2012年   15950篇
  2011年   17190篇
  2010年   13602篇
  2009年   12869篇
  2008年   12594篇
  2007年   12416篇
  2006年   11183篇
  2005年   9320篇
  2004年   8026篇
  2003年   7123篇
  2002年   5491篇
  2001年   4833篇
  2000年   3973篇
  1999年   3477篇
  1998年   3222篇
  1997年   2833篇
  1996年   2552篇
  1995年   2321篇
  1994年   2151篇
  1993年   1838篇
  1992年   1764篇
  1991年   1536篇
  1990年   1263篇
  1989年   1088篇
  1988年   1016篇
  1987年   915篇
  1986年   774篇
  1985年   933篇
  1984年   781篇
  1983年   488篇
  1982年   565篇
  1981年   462篇
  1980年   389篇
  1979年   329篇
  1978年   251篇
  1977年   227篇
  1976年   183篇
  1974年   76篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
981.
Little has been done to investigate the biochemical basis of chronic daily headache (CDH). Our group has recently demonstrated an increase in the cerebrospinal fluid (CSF) levels of nerve growth factor (NGF) in CDH patients, supporting the involvement of this growth factor in the abnormal processing of head pain in this pathological condition. Other members of the neurotrophin family, especially brain-derived neurotrophic factor (BDNF), have been hypothesized as being involved in the development of chronic head pain in patients affected by CDH, but so far no data are available on this subject. BDNF, NGF and glutamate levels were determined in the CSF of 25 patients affected by CDH with a previous history of migraine. These levels were compared with those of a group of 20 control subjects, for whom the CSF examination and other instrumental investigations excluded diseases of the central and peripheral nervous systems. Significantly higher levels of BDNF, NGF and glutamate were found in CDH patients compared with control subjects (p<0.0001, p<0.0002 and p<0.001, respectively). A significant positive correlation emerged between CSF values of BDNF and those of NGF (r=0.61, p<0.001) and glutamate (r=0.44, p<0.025) in CDH patients. No significant differences were detected in BDNF, NGF and glutamate levels between CDH patients with analgesic overuse and those without. These results support the involvement of BDNF in CDH through the potentiation of glutamatergic transmission involved in the processing of head pain. The significant correlation between BDNF and NGF levels suggests that NGF-mediated up-regulation of BDNF in central sites involved in long-term sensitization plays a key role in persistent head pain in CDH patients. Correspondence to P. Sarchielli  相似文献   
982.
医源性腓总神经伤分析   总被引:5,自引:0,他引:5  
目的:总结40a来收治的48例医源性腓总神经损伤的临床资料,探讨其损伤机制和特点。方法:通过随访,依据其损伤原因和机制分类统计。结果:牵拉压迫伤33例,占69%;手术切割伤12例,占25%。导致腓总神经损伤的原因中以石膏压迫为最多,占37%,牵伸性损伤占31%。结论:骨科医师必须具备丰富的解剖知识和责任心,重在预防,一旦发生损伤,应早期诊断,采用有效的方法及时治疗。  相似文献   
983.
We assessed the prevalence of Parkinson's disease in Cantalejo, Spain. In 1994, we screened 1,579 persons (age > or = 40 years) using a high-sensitivity method. Cases fulfilling established clinical criteria were followed for a minimum of 3 years. Prevalences were compared with those from other door-to-door surveys. We detected 27 individuals with parkinsonism, 20 of whom had Parkinson's disease. The prevalence of Parkinson's disease increased with age and, when age-adjusted to European standards, was 9.01 per 1,000 (age 40 years and over; 10.78 in men and 5.23 in women). Of the 11 men, three were in Hoehn & Yahr grades III-IV, but six of the nine women were more severely affected. Overall, we found 18 newly diagnosed cases of parkinsonism, 13 of which were Parkinson's disease, and the majority of which were in men aged 80 years or older with a mean duration of illness of 5 years. Our prevalence figures are the highest reported, apparently because of the inclusion of several very elderly men. Parkinson's disease in Cantalejo is less severe in men than in women, particularly in those newly diagnosed. Despite the low numbers, the high prevalence and sex-related pattern are unexplained but they probably relate to the high sensitivity of the screening method.  相似文献   
984.
There are few reports of positron emission tomography (PET) in juvenile parkinsonism (JP). We report on the results of (18)F-6-fluoro-L-dopa (FD) PET in a 14-year-old patient with JP of 5 years duration associated with atypical features. This is the youngest subject to be investigated to date. There was a severe asymmetric reduction in striatal FD uptake, with a rostrocaudal gradient in the putamen similar to that seen in adult-onset idiopathic parkinsonism. Extensive DNA analysis in this patient did not show mutations in the parkin gene.  相似文献   
985.
青少年型帕金森病的临床特征   总被引:2,自引:1,他引:1  
目的 探讨青少年型帕金森病 (PD)的临床特征。方法 对 2 8例青少年型PD患者的临床资料进行回顾性分析。结果  2 8例中 5例有家族史 ,呈常染色体隐性遗传 (AR JP) ;症状轻、病程长 ,症状常左右不对称 ,腱反射活跃和症状波动较常见 ;头部CT或MRI检查一般正常 ;对多巴制剂反应良好 ,但其所诱发的症状波动出现早。与散发性PD患者相比 ,AR JP患者发病年龄更早 ,为 (2 0 6± 5 6 8)岁 ,病程更长 ,为 (9 5±5 77)年 ,而病情较轻、症状波动和腱反射活跃更多见 ,多巴制剂不良反应更常见。结论 青少年型PD具有独特的临床特征 ,可能是一个独立的疾病实体。AR JP与散发性青少年型PD临床特征不同 ,提示二者可能具有不同的发病机制。  相似文献   
986.
异体造血干细胞移植的重要并发症是移植物抗宿主病(GVHD),免疫抑制剂是有效防治GVHD的一类药物.在异体造血干细胞移植后应用免疫抑制剂,使得GVHD发生率下降,严重程度减轻.本文对几类主要的免疫抑制剂的作用机理以及在异体造血干细胞移植中作为预防和治疗GVHD的应用作一综述.  相似文献   
987.
The diagnosis of idiopathic Parkinson's disease (PD) can be achieved with high degrees of accuracy in cases with full expression of classical clinical features. However, diagnostic uncertainty remains in early disease with subtle or ambiguous signs. Functional imaging has been suggested to increase the diagnostic yield in parkinsonian syndromes with uncertain clinical classification. Loss of striatal dopamine nerve terminal function, a hallmark of neurodegenerative Parkinsonism, is strongly related to decreases of dopamine transporter (DAT) density, which can be measured by single photon emission computed tomography (SPECT). The use of DAT‐SPECT facilitates the differential diagnosis in patients with isolated tremor symptoms not fulfilling PD or essential tremor criteria, drug‐induced, psychogenic and vascular Parkinsonism as well as dementia when associated with Parkinsonism. This review addresses the value of DAT‐SPECT in early differential diagnosis, and its potential as a screening tool for subjects at risk of developing PD as well as issues around the assessment of disease progression. © 2007 Movement Disorder Society  相似文献   
988.
131I对甲状腺细胞凋亡的影响   总被引:1,自引:0,他引:1  
由于每个患者特异性基因决定的个体辐射敏感性不同,使得每个接受131I治疗的患者对治疗的反应不一,因而疗效差异较大.针对不同的个体,采用不同的剂量治疗才可以提高131I治疗的效率,降低甲状腺功能减退症的发病率.通过目前的分子生物学技术,我们已经了解到一些基因的蛋白表达产物(Fas/FasL、Bcl-2等)与细胞凋亡和射线诱导凋亡的联系,使对凋亡基因表达产物的体外监测成为可能.也许通过对这些指标的监测,可以使我们在131I治疗过程中实现对不同的个体给予恰当的个体剂量.  相似文献   
989.
目的 探讨鼻窦CT扫描在内窥镜鼻窦手术中的应用价值。方法 回顾性对80例慢性鼻窦炎患者鼻窦CT扫描与手术中所见进行分析总结。结果 冠状位CT扫描鼻窦病变发现率高,辅以水平CT扫描,鼻窦精细结构、病变范围和程度能够清楚地显示,符合术中所见。结论 鼻窦CT扫描能精确显示鼻窦结构及病变,能正确指导鼻窦内窥镜手术。  相似文献   
990.
目的:检测各种肾小球疾病患者血清中抗中性粒细胞胞浆抗体(ANCA)并探讨其临床意义。方法:应用间接免疫荧光法(IIF)检测20例正常人及131例各种肾小球疾病患者血清中ANCA。结果:131例患者中有11例ANCA阳性性(阳性率为8.4%),且均为P-ANCA阳性,而20例正常对照组无1例阳性(P<0.05)。ANCA阳性中以新月体性肾炎、狼疮性肾炎、紫癜性肾炎的阳性率较高,分别为67%、25%、16.7%。新月体性肾炎与IgA肾病等原发性肾小球疾病组比较有显著性差异(P<0.05)。结论:ANCA在各种肾小球疾病中并不少见,尤其是新月体性肾炎、狼疮性肾炎、紫癜性肾炎的阳性率较高,推测ANCA可能在这些疾病的发病机理中起了一定的作用。  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