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   2163428篇
  免费   149224篇
  国内免费   4126篇
耳鼻咽喉   31793篇
儿科学   68279篇
妇产科学   60758篇
基础医学   305352篇
口腔科学   63343篇
临床医学   189391篇
内科学   413078篇
皮肤病学   49155篇
神经病学   169431篇
特种医学   85138篇
外国民族医学   595篇
外科学   329441篇
综合类   48957篇
现状与发展   8篇
一般理论   688篇
预防医学   154054篇
眼科学   51926篇
药学   167019篇
  10篇
中国医学   5209篇
肿瘤学   123153篇
  2018年   21330篇
  2016年   19102篇
  2015年   21438篇
  2014年   29656篇
  2013年   44056篇
  2012年   59078篇
  2011年   62458篇
  2010年   36868篇
  2009年   35113篇
  2008年   58461篇
  2007年   63203篇
  2006年   63971篇
  2005年   61397篇
  2004年   59213篇
  2003年   56918篇
  2002年   55454篇
  2001年   104689篇
  2000年   107457篇
  1999年   90393篇
  1998年   24155篇
  1997年   21695篇
  1996年   21182篇
  1995年   19918篇
  1994年   18490篇
  1993年   17388篇
  1992年   69559篇
  1991年   67219篇
  1990年   66051篇
  1989年   64097篇
  1988年   59096篇
  1987年   57967篇
  1986年   55260篇
  1985年   52379篇
  1984年   38944篇
  1983年   33084篇
  1982年   19322篇
  1981年   17412篇
  1979年   36727篇
  1978年   25804篇
  1977年   22648篇
  1976年   20344篇
  1975年   23081篇
  1974年   27260篇
  1973年   26581篇
  1972年   25313篇
  1971年   23695篇
  1970年   22219篇
  1969年   21378篇
  1968年   19709篇
  1967年   17662篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
62.
63.
To determine if impaired energy metabolism might contribute to some aspects of Alzheimer disease (AD), including the vulnerability of the CA1 region of the hippocampal formation and the altered cytoskeleton evident in neurofibrillary tangles, we examined the effects of metabolic poisons on neuronal damage and cytoskeletal disruption in the hippocampal formation. Intrahippocampal injection of 3-nitropropionic acid (3-NP) and malonic acid resulted in neuronal death, particularly in CA1. Cytoskeletal disruption included loss of dendritic MAP2, but sparing of axonal τ. MK-801 (a noncompetitive NMDA receptor antagonist) did not atenuate the lesions produced by intrahippocampal injection of malonate. MK-801, however, was effective against intrastriatal malonate. Acute systemic 3-NP resulted in neuronal damage and cytoskeletal disruption in the CA1 region of the hippocampal formation, including an extensive loss of MAP2 immuno-reactivity, but sparing of τ. The neuronal loss in CA1 was delayed as compared to striatum. Chronic intraventricular infusion of 3-NP produced a different pattern of neuronal damage. Loss of τ-1 immuno-reactivity was observed in CA3 and CA1 s. oriens, whereas MAP2 immunostaining was preserved. These results demonstrate that chronic and acute administration of metabolic inhibitors produce distinct patterns of neuronal damage and cytoskeletal disruption. The results further suggest a differential involvement of the NMDA receptor in malonate-induced neuronal damage in striatum as compared to the hippocampus. The pattern of neuronal damage and cytoskeletal disruption observed following acute metabolic impairment resembled some aspects of neurofibrillary pathology in AD, but did not result in τ hyperphosphorylation.  相似文献   
64.
AIM: Cardiovascular risk factors can be present in children and young adults. We previously found abnormal microvascular function in children who had glucose intolerance and insulin resistance. The aim of the present study was to investigate whether they also have abnormalities in left ventricular mass (LVM) and arterial stiffness. METHODS: We measured heart dimensions and LVM using echocardiography, and arterial stiffness using pulse wave analysis in 23 children with good glucose handling (postfeeding glucose: 3.9 to 5 mmol/L) and 21 with poor glucose handling (7.7 to 11.4 mmol/L). RESULTS: The time to pulse reflection was slightly shorter in the poorer glucose handlers (mean+/-SD: 143+/-10 vs 153+/-20 ms, P=0.04), suggestive of increased arterial stiffness. Also in this group, there were significant relationships between intraventricular septal thickness, blood pressure and body mass index, but not in the normal glucose handlers. CONCLUSIONS: We have found that normal children who are in the lowest quintile of glucose tolerance in comparison with their peers are exhibiting the first signs of arterial stiffening. In addition, we have seen the beginnings of a relationship between blood pressure, body mass index and left ventricular enlargement in this group. While these changes may not yet be clinically significant, their emergence might be further evidence of early predisposition to cardiovascular disease.  相似文献   
65.
目的:描述胚胎种植前遗传诊断在1例携带Ⅰ型白细胞黏附缺陷病(LAD-1)携带者并完成健康妊娠夫妇中的应用。设计:病例报道。机构:大学医院生殖中心。患者:1例男女双方都是LAD-1携带者的夫妇,女方CD18基因的外显子4携带有G400A置换,男方的外显子5携带有C562T置换。干预:标准体外受精(IVF)后第3天行卵裂期活检和分裂球遗传分析以检测2处突变以及21号染色体标记物。主要观察指标:1个未罹患LAD-1婴儿的出生。结果:得到15个卵母细胞,其中10个受精。8个胚胎适宜胚胎活组织检查。  相似文献   
66.
Using the SF-12 to measure physical and mental functioning, the authors examine the intra-individual changes in health-related quality of life (HRQOL) 6 months post-discharge for depressed older adults. In addition, they examine three sets of predictors that might influence these changes. The sample of depressed older adults was recruited from an inpatient geropsychiatry unit. Although their physical and mental health scores on the SF-12 were lower than comparable norms, the sample showed an average increase in their mental functioning but a decrease in the physical functioning over the 6 months. Negative life-events were significant predictors of people who reported no change in their mental health functioning and decreases in their physical health functioning. Interestingly, those who experienced positive life events were more likely to report declines and younger participants were more likely to report no change in their physical functioning. The findings indicate that the effects of depression on HRQOL can have enduring effects on a sample of previously hospitalized older adults. The significance of life event changes might signify the importance of taking into account non-traditional areas of medical interventions. Further, the findings indicate the usefulness of the SF-12 quantifying HRQOL outcomes.  相似文献   
67.
68.
69.
Setting goals to maintain hope.   总被引:3,自引:0,他引:3  
  相似文献   
70.
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