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   25561篇
  免费   2235篇
  国内免费   1302篇
耳鼻咽喉   134篇
儿科学   362篇
妇产科学   332篇
基础医学   2623篇
口腔科学   318篇
临床医学   2590篇
内科学   4702篇
皮肤病学   399篇
神经病学   1588篇
特种医学   1056篇
外国民族医学   10篇
外科学   3003篇
综合类   4899篇
现状与发展   6篇
预防医学   546篇
眼科学   1247篇
药学   2658篇
  10篇
中国医学   1361篇
肿瘤学   1254篇
  2024年   78篇
  2023年   390篇
  2022年   620篇
  2021年   874篇
  2020年   882篇
  2019年   816篇
  2018年   794篇
  2017年   779篇
  2016年   863篇
  2015年   946篇
  2014年   1554篇
  2013年   1818篇
  2012年   1453篇
  2011年   1573篇
  2010年   1417篇
  2009年   1340篇
  2008年   1409篇
  2007年   1423篇
  2006年   1390篇
  2005年   1268篇
  2004年   1075篇
  2003年   936篇
  2002年   826篇
  2001年   659篇
  2000年   596篇
  1999年   441篇
  1998年   366篇
  1997年   309篇
  1996年   288篇
  1995年   267篇
  1994年   203篇
  1993年   168篇
  1992年   161篇
  1991年   162篇
  1990年   104篇
  1989年   96篇
  1988年   90篇
  1987年   93篇
  1986年   70篇
  1985年   90篇
  1984年   69篇
  1983年   44篇
  1982年   51篇
  1981年   72篇
  1980年   36篇
  1979年   37篇
  1978年   30篇
  1977年   21篇
  1976年   15篇
  1975年   12篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
111.
Acute renal failure and acute heart failure are rare in Kawasaki disease. We experienced two patients with Kawasaki disease who presented acute renal failure and acute heart failure. These two patients gave us an important insight into the understanding of water balance and fluid therapy in Kawasaki disease. One patient showed acute prerenal failure due to fluid exudation from the intravascular to the extravascular space, and subsequent acute heart failure. The other patient showed acute heart failure caused by fluid infusion for the treatment of dehydration. It is suggested that acute renal failure could be caused by a fluid shift from the intravascular to the extravascular space in Kawasaki disease. It is also demonstrated that the reserve of cardiac function could be decreased in patients with Kawasaki disease due to myocarditis even with normal echocardiography and chest X-rays.  相似文献   
112.
Although present sonomicrometer techniques for measuring continuous changes in vascular diameter are very useful, two problems with available methods are difficulty in maintaining crystal alignment throughout an acute experiment and inability to measure absolute dimensions less than 1 mm. We have designed and ultrasonic dimension gauge system to over come these problems. The design uses a gate to pass a 20 MHz signal to a counter during the sonic travel time between crystals, and then converts the digital count to an analogue voltage. Interference from the transmitting impulse in the received signal was minimised using MOSFET transistors allowing measurements of absolute dimensions from 0.00 mm to 99.9 mm. An averaging effect which depends upon the asynchrony between the basic timer and the counter clock results in a resolution of at least 10 μm. Repeated calibration curves showed an accuracy of 2.5 μm without significant bias. Piezoelectric crystals were mounted to a lighweight stainless-steel clip to facilitate attachment to the vessel and to maintain the crystals in focus during changes in diameter. Mean and phasic diameters measured in the femoral artery with the clip device correlated well with measurements obtained with crystals sewn to the adventitia of the femoral artery of the dog (slope =0.97, r=0.99).  相似文献   
113.
乳腺癌患者血清Leptin和VEGF的表达   总被引:4,自引:3,他引:1  
目的:研究瘦素(Leptin)、血管内皮生长因子(VEGF)在乳腺癌患者血清中的表达,探讨其在乳腺癌诊断中的意义。方法:选择乳腺癌患者36例,乳腺良性增生病变患者31例,另选56例健康女性作为对照。分别用放射免疫分析(RIA)和酶联免疫吸附试验(ELISA)测定这些患者术前血清Leptin、VEGF。结果:正常对照组与良性病变组、乳腺癌组Leptin存在明显差异,正常对照组与乳腺癌组,良性病变组与乳腺癌组VEGF存在明显差异。乳腺癌患者术前血清Leptin、VEGF含量与有无淋巴结转移具有相关性。结论:乳腺癌患者术前血清Leptin、VEGF可作为鉴别乳腺良恶性肿瘤有无转移的指标。  相似文献   
114.
目的:总结X刀治疗脑内病变的长期随访结果.方法:对283例X刀治疗的脑瘤和脑血管畸形患者进行临床和影像学随访,随访时间为1~8年,平均(2.05±4.66)年.结果:82例转移瘤消失35例(42.7%),缩小28例(34.1%),无变化11例(13.4%),增大8例(9.8%);61例胶质瘤消失10例(16.4%),缩小19例(31.1%),无变化16例(26.2%),增大16例(26.2%);55例动静脉畸形消失29例(52.7%),缩小20例(36.4%),无变化6例(10.9%);17例海绵状血管瘤缩小4例(23.5%),无变化13例(76.5%);35例脑膜瘤消失5例(14.3%),缩小15例(42.9%),无变化13例(37.1%),增大2例(5.7%);12例神经鞘瘤消失3例(25.0%),缩小6例(50.0%),无变化2例(16.7%),增大1例(8.3%);10例生殖细胞瘤消失8例(80.0%),缩小2例(20.0%);11例其他肿瘤消失2例(18.2%),缩小4例(36.4%),无变化4例(36.4%),增大1例(9.0%).影像检查还发现病灶有坏死表现99例,囊性变19例,周边环状强化73例,胶质细胞增生20例,暂时性反应性肿大23例,放射性脑水肿28例.结论:X刀对小型脑肿瘤和血管畸形是一种安全有效的治疗方法,X刀治疗的主要并发症是放射性脑水肿.  相似文献   
115.
新型血管吻合用支架对血管内膜的影响   总被引:7,自引:4,他引:3  
目的:研制一种可溶性血管内支架辅助血管断端吻合,并检测该支架在血管吻合的过程中对血管内膜的影响。方法:选用高纯度低分子量明胶为主要原料制备血管吻合用支架,利用该支架进行血管吻合操作,观察支架对血管内膜的作用,并从超微结构方面进行研究。结果:明胶类可容性血管内支架表面光滑,在血管吻合的过程中不会对血管壁造成损伤;与同类支架相比具有明显的优势。结论:明胶类可溶性血管内支架具有光滑的外表面,适合于进行血管吻合操作。  相似文献   
116.
脑动静脉畸形存在活跃的血管重构,本文就其重构的分子生物学机制作一综述。  相似文献   
117.
BACKGROUND: Histamine plays an important role in vascular disease. Tissue factor (TF) expression is induced in vascular inflammation and acute coronary syndromes. OBJECTIVES: This study examined the effect of histamine on tumor necrosis factor-alpha- (TNF-alpha-) vs. thrombin-induced endothelial TF expression. METHODS AND RESULTS: Histamine (10(-8)-10(-5) mol L-1), TNF-alpha (5 ng mL-1), and thrombin (1 U mL-1) induced TF expression in human endothelial cells. Although TF expression by TNF-alpha and thrombin was identical, histamine augmented TNF-alpha-induced expression 7.0-fold, but thrombin-induced expression only 2.6-fold. Similar responses occurred with TF activity. The H1-receptor antagonist mepyramine abrogated these effects. Differential augmentation by histamine was also observed at the mRNA level. Histamine-induced p38 activation preceded a weak second activation to both TNF-alpha and thrombin. Histamine-induced c-Jun NH2-terminal kinase (JNK) activation was followed by a strong second activation to TNF-alpha, and less to thrombin. Selective inhibition of this second JNK activation by SP600125 reduced TF induction to histamine plus TNF-alpha by 67%, but to histamine plus thrombin by only 32%. Histamine augmented TNF-alpha- and thrombin-induced vascular cell adhesion molecule 1 (VCAM-1) expression to a similar extent. Consistent with this observation, VCAM-1 induction to TNF-alpha and thrombin was mediated by p38, but not by JNK. CONCLUSIONS: Histamine differentially augments TNF-alpha- vs. thrombin-induced TF expression and activity, which is mediated by the H1-receptor, occurs at the mRNA level, and is related to differential JNK activation.  相似文献   
118.
119.
120.
Four selected cases of emergent IABP insertion in PV patients are presented. After angiographic documentation of critical iliac stenosis, conservative peripheral angioplasty was performed prior to IABP insertion. No patient experienced a peripheral ischemic event associated with IABP use. © 1992 Wiley-Liss, Inc.  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