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   2027篇
  免费   159篇
  国内免费   8篇
耳鼻咽喉   18篇
儿科学   90篇
妇产科学   27篇
基础医学   324篇
口腔科学   33篇
临床医学   176篇
内科学   449篇
皮肤病学   79篇
神经病学   95篇
特种医学   199篇
外国民族医学   1篇
外科学   191篇
综合类   67篇
一般理论   1篇
预防医学   173篇
眼科学   18篇
药学   137篇
中国医学   5篇
肿瘤学   111篇
  2022年   16篇
  2021年   36篇
  2020年   28篇
  2019年   42篇
  2018年   51篇
  2017年   38篇
  2016年   41篇
  2015年   46篇
  2014年   57篇
  2013年   87篇
  2012年   89篇
  2011年   89篇
  2010年   76篇
  2009年   100篇
  2008年   87篇
  2007年   79篇
  2006年   64篇
  2005年   87篇
  2004年   57篇
  2003年   50篇
  2002年   52篇
  2001年   48篇
  2000年   42篇
  1999年   45篇
  1998年   46篇
  1997年   45篇
  1996年   45篇
  1995年   43篇
  1994年   29篇
  1993年   29篇
  1992年   28篇
  1991年   28篇
  1990年   24篇
  1989年   47篇
  1988年   39篇
  1987年   30篇
  1986年   35篇
  1985年   24篇
  1984年   30篇
  1983年   29篇
  1982年   29篇
  1981年   20篇
  1980年   26篇
  1979年   16篇
  1978年   21篇
  1977年   9篇
  1976年   13篇
  1975年   14篇
  1974年   14篇
  1968年   9篇
排序方式: 共有2194条查询结果,搜索用时 109 毫秒
51.

Background  

Human immunodeficiency virus infected individuals are prone to malnutrition due to increased energy requirements, enteropathy and increased catabolism. Trace elements such as zinc and selenium have major role in maintaining a healthy immune system. This study was designed to evaluate the nutritional status of Iranian subjects who were newly diagnosed with human immunodeficiency virus infection and to compare serum level of zinc and selenium in these patients with those of the sex and aged match healthy subjects.  相似文献   
52.
53.
54.
背景目前已开展了对重性精神病患者进提供连续性服务的研究。目的探讨基层对有抑郁症风险患者提供连续性服务的水平,并与对心力衰竭患者的服务水平进行对比。方法采用抑郁症风险患者与心力衰竭患者对比的探索性研究。采用患者问卷评估服务的持续性,包含如下内容:(1)联系的服务提供者数(个人连续性);(2)诊所内服务提供者之间的合作(团队连续性)(6个项目,分数1~5分);(3)诊所外全科医师与服务提供者之间的合作(跨界连续性)(4个项目,分数1~5分)。结果大多数抑郁症风险患者在过去1年中寻遍整个服务提供界联系了几个服务提供者,曾遇到过高水平团队连续性服务及低水平跨界连续性服务。在诊所中可接触到的不同服务提供者要明显多于心力衰竭患者服务提供者(P<0.01)。抑郁症风险患者的服务提供者之间的合作更好一些,每项平均得分4.3分,心力衰竭患者得分为4.0分(P=0.03)。然而,跨界连续性服务方面正好相反:抑郁症风险患者每项平均得分3.5分,心力衰竭患者得分为4.0分(P=0.01)。结论抑郁症风险患者与心力衰竭患者之间的探索性对比显示:体验服务连续性方面的差距不大。对此还应行进一步分析。  相似文献   
55.
AIMS: To estimate the consequences of managing bradycardia due to sinoatrial node disease or atrioventricular block with dual-chamber vs. single-chamber ventricular pacemakers. METHODS AND RESULTS: A discrete-event simulation was conducted to predict outcomes over 5 years. Patients could develop post-operative complications, clinically relevant pacemaker syndrome leading to replacement of single-chamber with dual-chamber, atrial fibrillation (AF; which if chronic might require anticoagulants) or stroke. Survival, quality-adjusted life years (QALYs), complications, and associated direct medical costs were estimated (2003 British Pounds pounds sterling). Identical patients were simulated after receiving a single-chamber device or a more expensive dual-chamber pacemaker. Probabilities of conditions were obtained from clinical trials. Benefits were discounted at 1.5% and costs at 6%. Post-operative complications increased from 6.4% with single-chamber to 7.7% with dual-chamber but AF decreased (22 vs. 18%) as did clinically relevant pacemaker symptoms (16.8 vs. 0%). Approximately 4300 pounds sterling were accrued per patient over 5 years. Additional health benefits with dual-chamber are achieved at a mean net cost of 43 pounds sterling per patient, leading to 0.09 QALY with a cost-effectiveness ratio of 477 pounds sterling/QALY. CONCLUSION: Implanting the costlier device increases the cost of the initial operation; however, this is expected to be offset by a reduction in costs associated with re-operations and AF.  相似文献   
56.
Parkinson's disease (PD) is characterised by motor alterations, which are commonly treated with L-DOPA. However, long-term L-DOPA use may cause dyskinesia. Although the pathogenic mechanism of L-DOPA-induced dyskinesia is unclear, the condition has been associated with alterations in dopamine receptors, among which D2 receptors (D2R) have received little attention. This study aims to: (i) develop and standardise an experimental model of L-DOPA-induced dyskinesia in rats with hemiparkinsonism; and (ii) evaluate the correlation between D2R expression and presence of abnormal involuntary movements (AIM). We allocated 21 male Wistar rats into 3 groups: intact controls, lesioned rats (with neurotoxin 6-OHDA), and dyskinetic rats (injected with L-DOPA for 19 days). Sensorimotor impairment was assessed with behavioural tests. Dyskinetic rats gradually developed AIMs during the treatment period; front leg AIMs were more severe and locomotor AIMs less severe (P < .05). All AIMs were significantly evident from day 5 and persisted until the last day of injection. D2R density was greater in the striatum and the medial anterior brain of the lesioned and dyskinetic rats than in those of controls. Our results suggest an association between D2R expression and locomotor AIMs. We conclude that RD2 is involved in L-DOPA-induced dyskinesia.  相似文献   
57.
BackgroundResequencing DNA microarray (RMA) technology uses probes designed to identify a panel of viral sequences. It can be used for detecting emerging viruses by revealing the nucleotide polymorphisms within the target of interest.Objectives/study designAs a new tool for molecular diagnosis of arbovirus infection, high density PathogenID v2.0 RMA (PID2-RMA) was assessed for the detection and genetic analysis of dengue, West Nile, and Chikungunya viruses in spiked blood samples or sera from individuals infected with dengue virus. Viral RNAs extracted from biological samples were retrotranscribed into cDNA and amplified using the Phi 29 polymerase-based method. This amplified cDNA was used for hybridization on PID2-RMA.ResultsA good specificity of RMA-based detection was demonstrated using a panel of arboviruses including Dengue, West Nile and Chikungunya viruses. This technology was also efficient for the detection and genetic analysis of the different serotypes of dengue virus in sera of infected patients. Furthermore, the mixing of dengue, West Nile and Chikungunya prototype viruses within a single sample of human blood did not interfere with the sensitivity of PID2-RMA.ConclusionsOur data show that high density PID2-RMA was suitable for the identification of medically important arboviruses. It appears to be particularly adapted to the genetic analysis of dengue, West Nile, and Chikungunya viruses in urgent clinical situations where the rapid identification and characterization of the pathogen is essential.  相似文献   
58.
59.
Nielsen  OJ; Schuster  SJ; Kaufman  R; Erslev  AJ; Caro  J 《Blood》1987,70(6):1904-1909
Production of immuno and biologically active erythropoietin was documented to occur in the human hepatoblastoma cell line HepG-2. The expression of the erythropoietin gene was further verified by Northern blot analysis using a single stranded RNA probe. In vitro studies showed that erythropoietin production by these cells was not stimulated by hypoxia or cobalt chloride, but was related to the proliferative activity of the cells in culture. In addition it was found that the secretion of erythropoietin was almost completely abrogated by tunicamycin, an inhibitor of N-linked glycosylation. This effect of tunicamycin was also observed in a permanently transfected cell line that secretes erythropoietin in large quantities.  相似文献   
60.
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