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   3247827篇
  免费   244867篇
  国内免费   5679篇
耳鼻咽喉   44732篇
儿科学   106240篇
妇产科学   89729篇
基础医学   473792篇
口腔科学   89775篇
临床医学   295980篇
内科学   627482篇
皮肤病学   72990篇
神经病学   260100篇
特种医学   121670篇
外国民族医学   905篇
外科学   487570篇
综合类   72089篇
现状与发展   15篇
一般理论   1197篇
预防医学   257230篇
眼科学   75840篇
药学   238775篇
  11篇
中国医学   6859篇
肿瘤学   175392篇
  2021年   25750篇
  2019年   26579篇
  2018年   36901篇
  2017年   27784篇
  2016年   31373篇
  2015年   35232篇
  2014年   50038篇
  2013年   75068篇
  2012年   102803篇
  2011年   109781篇
  2010年   64994篇
  2009年   61548篇
  2008年   102223篇
  2007年   108719篇
  2006年   109899篇
  2005年   106672篇
  2004年   102237篇
  2003年   98050篇
  2002年   94706篇
  2001年   150346篇
  2000年   154098篇
  1999年   129231篇
  1998年   37784篇
  1997年   33437篇
  1996年   33493篇
  1995年   31630篇
  1994年   29186篇
  1993年   27412篇
  1992年   99445篇
  1991年   96564篇
  1990年   93873篇
  1989年   90430篇
  1988年   83282篇
  1987年   81299篇
  1986年   76230篇
  1985年   73160篇
  1984年   54930篇
  1983年   46673篇
  1982年   28112篇
  1979年   50097篇
  1978年   35576篇
  1977年   29636篇
  1976年   28263篇
  1975年   30008篇
  1974年   36236篇
  1973年   34532篇
  1972年   32541篇
  1971年   30476篇
  1970年   28352篇
  1969年   26810篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
MATTHEW  B.  COLLIER  C.  ANDERSON  ENGH  JR.  JAMES  P.  MCAULEY  STUART  D.  GINN  GERARD  A.  ENGH  蔡迅梓 《骨科动态》2006,2(2):93-99
背景:从关节和胫骨假体聚乙烯衬垫后表面转移磨损碎屑,是全膝关节置换术后假体周围骨溶解的主要原因。全膝人工关节假体设计随时问而发生变化,例如对胫骨盘近端表面的粗糙度和聚乙烯衬垫的灭菌方法。我们假设胫骨盘表面抛光和采用空气中γ射线照射之外的其他方法对衬垫灭菌,可降低骨溶解的发生率。方法:从1987年至1998年,我们采用后十字韧带保留型的解剖型组配式全膝人工关节假体系列。对300名患者施行365例全膝关节置换术。术后5至10年,对这些患者的膝关节摄正、侧位X线片。由两位关节置换专家对X线片上的骨溶解状况进行单独评定(骨溶解的界定标准为假体周围存在边缘清晰的非线性松质骨丢失区)。结果:在粗糙表面的胫骨盘的242例膝关节中,使用空气中γ射线照射灭菌的衬垫固定,有34%(82例)骨溶解阳性。用惰性气体中γ射线照射或没有照射的衬垫与抛光表面连接的98例膝关节中,有9%(9例)骨溶解阳性。骨溶解与六项因素相关,这些因素为:一项与患者(男性)相关、一项与胫骨盘(近端表面抛光)相关、三项与聚乙烯衬垫(加工的原材料、灭菌方法及存放时间)相关及一项与手术技术(股骨假体与胫骨假体间的过伸)相关。结论:在这类假体设计中,胫骨盘近端表面采用抛光及衬垫采用更为先进的灭菌方法(不用空气中γ射线照射灭菌)能显著减少骨溶解的发生率,但不能避免骨溶解。  相似文献   
992.
993.
994.
995.
Abstract The future challenge for improving stroke patients’ outcome will be to implement new Stroke Units (SUs) worldwide. However the best SU model remains uncertain. The aim of this study was to evaluate the number of SUs and the quality characteristics of acute stroke care in Italy. We conducted a SU survey in Italy, interviewing the directors of the hospital wards that discharged at least 50 acute stroke patients a year. A SU was defined as an acute ward area with stroke-dedicated beds and staff. To compare the quality of care provided in SUs with that in general wards (GWs) we investigated the characteristics of five domains: hospital setting, unit setting, staffing, process of care and diagnostic investigations. We identified 68 SUs and 677 GWs. Multivariate logistic regression analyses demonstrated that SUs compared to GWs had higher quality scores in unit setting (ROC area=0.9721), staffing (ROC area=0.8760) and care organisation (ROC area=0.7984). The hospital setting (ROC area=0.7033) and the availability of rapid diagnostic investigations (ROC area=0.7164) had lower power in discriminating SU from GW. In Italy in 2003/04 only 9% of the hospital services had organised SU care. The study demonstrated that SUs admitted more than 100 patients per year, had more monitoring equipment and staffing time, and practised multidisciplinary meetings and early mobilisation. The utility of these structural and performance characteristics needs validation from outcome studies.  相似文献   
996.
OBJECTIVE: To study the effect of high-frequency (100 Hz) repetitive conditioning electrical stimulation (CES, 10 min) on human somatosensory evoked potentials (SEPs) to evaluate if short-term cortical plasticity could be induced. METHODS: Painful electrical stimulations were applied to thumb (D1) and little finger (D5) fingertips, respectively. The 124-channel EEG was recorded from 10 healthy male volunteers. Peak stages around 34, 45, 212, 331 ms were analyzed with focal maximum amplitude (FA) and area magnitude (AM) of scalp field potential, topography, and equivalent current dipole source localisation, comparing before and after two-level CES (high- vs. low-level) applied to the He-Gu acupoint. RESULTS: After a high-level CES, the positive FA and AM of the current efflux showed a significant increase at the early phase 34 ms, and significantly decreased at 45 ms in D1 SEPs. The negative FA and AM of the current influx were significantly increased at late phase 350 ms of the D5 SEPs. Only 36 ms, the z-axis position of dipole was significantly changed from (x: -15.9 mm, y: 29.6 mm, z: 43.9 mm) to (x: -12.9 mm, y: 29.4mm, z: 51.5mm) for the D5 SEPs. CONCLUSIONS: The high-level CES significantly attenuated the subsequent cortical activation (45 ms peak for D1 stimulation). Both low- and high-level CES significantly enhanced the late activities (226, 350 ms) in D5 stimulation. This may be explained by pain sensation change at the level of subcortical cingulate cortex induced by the site-dependent post-effect of CES. SIGNIFICANCE: This study showed cortical plasticity induced by conditioning somatosensory stimulation.  相似文献   
997.
目的:确定UVB靶向光疗治疗局限性银屑病是否安全有效及是否存在量效关系。设计:随机、对评估者设盲对照研究。机构:泰国曼谷大学医院皮肤病门诊。患者:14例稳定性局限性斑块型银屑病患者。干预:依据预定的最小红斑量(M EDs),随机给予患者不同通量的UVB靶向光线治疗,3次/周。在4  相似文献   
998.
INTRODUCTION: Vasopressin, mainly through the V1a-receptor, is thought to be a major player in the maintenance of hyperfiltration. Its inhibition could therefore lead to a decrease in progression of chronic renal failure. To this end, the effect of the vasopressin V1a-receptor-selective antagonist, YM218, was studied on proteinuria and focal glomerulosclerosis in early and late intervention after 5/6 nephrectomy in rats, and compared with an angiotensin-converting enzyme inhibitor (ACE-I). MATERIALS AND METHODS: After 5/6 nephrectomy, early intervention was performed between week 2 and 10 thereafter with the V1a-receptor-selective antagonist (VRA, 10 mg/kg/day, n=10), enalapril (ACE-I, 10 mg/kg/day, n=9), or vehicle (n=8). Late intervention was performed in another group between week 6 and 12 with VRA (10 mg/kg/day, n=7), lisinopril (ACE-I, 5 mg/kg/day, n=7), or vehicle (n=7). RESULTS: In early intervention, proteinuria and focal glomerulosclerosis were significantly decreased by VRA compared to vehicle (44+7% and 59+8% respectively). ACE-I significantly decreased proteinuria (67+7%) and a trend towards a decrease in focal glomerulosclerosis was observed (30+18%). In late intervention, VRA did not decrease proteinuria and focal glomerulosclerosis compared to vehicle (21+20% and 0%, respectively), ACE-I significantly lowered proteinuria (92+2%) and a focal glomerulosclerosis (69+1%) lowering trend was observed. CONCLUSION: These results indicate that VRA may protect against early progression of renal injury after 5/6 nephrectomy, whereas its effectiveness seems limited in established renal damage.  相似文献   
999.
1000.
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