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   36321篇
  免费   2776篇
  国内免费   1524篇
耳鼻咽喉   186篇
儿科学   662篇
妇产科学   614篇
基础医学   3692篇
口腔科学   549篇
临床医学   3581篇
内科学   5594篇
皮肤病学   649篇
神经病学   1658篇
特种医学   1509篇
外国民族医学   10篇
外科学   6022篇
综合类   6703篇
现状与发展   6篇
预防医学   893篇
眼科学   1289篇
药学   3449篇
  12篇
中国医学   1836篇
肿瘤学   1707篇
  2024年   102篇
  2023年   494篇
  2022年   800篇
  2021年   1175篇
  2020年   1157篇
  2019年   1037篇
  2018年   1052篇
  2017年   1058篇
  2016年   1183篇
  2015年   1250篇
  2014年   2243篇
  2013年   2428篇
  2012年   2061篇
  2011年   2349篇
  2010年   2081篇
  2009年   1884篇
  2008年   1979篇
  2007年   2054篇
  2006年   1953篇
  2005年   1802篇
  2004年   1503篇
  2003年   1314篇
  2002年   1118篇
  2001年   919篇
  2000年   804篇
  1999年   618篇
  1998年   544篇
  1997年   468篇
  1996年   430篇
  1995年   376篇
  1994年   291篇
  1993年   250篇
  1992年   246篇
  1991年   231篇
  1990年   146篇
  1989年   162篇
  1988年   140篇
  1987年   126篇
  1986年   101篇
  1985年   123篇
  1984年   89篇
  1983年   62篇
  1982年   75篇
  1981年   93篇
  1980年   51篇
  1979年   49篇
  1978年   37篇
  1977年   35篇
  1976年   25篇
  1975年   14篇
排序方式: 共有10000条查询结果,搜索用时 9 毫秒
91.
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   
92.
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   
93.
94.
95.
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   
96.
在心肌细胞分化性生长时期,改变新生鼠的哺乳期营养条件对这些鼠的空间隔心肌细胞将会产生暂时性作用和持久性影响。哺乳期高营养的暂时性作用是增加空间隔心肌细胞的大小和数量;而低营养的暂时性作用则是减慢室间隔心肌细胞的生长。哺乳期高营养的持久性作用是限制室间隔心肌细胞的过度肥大;而低营养则促进成熟鼠的室间隔心肌细胞的过度肥大。  相似文献   
97.
应用免疫组化方法完成了胰岛素样生长因子(IGF-I)在48例人前列腺增生中的组织定位。组织经4%甲醛固定,石蜡包埋。IGF-I免疫反应主要定位于腺体基底层上皮细胞浆内,阳性染色也见于腺体分泌上皮、鳞状化生上皮、平滑肌细胞和神经纤维细胞内。证实:IGF-I存在于前列腺增生患者的前列腺组织中,并且与前列腺增生的发病有一定关系。  相似文献   
98.
Riddelliine alters hepatocellular and endothelial cell kinetics and function including stimulating an increase in hepatocytic vascular endothelial growth factor (VEGF) in the absence of increased serological levels of VEGF (Nyska etal. 2002). The objective of this study was to further assess hepatic VEGF and KDR/flk-1 synthesis and expression by hepatic cells under riddelliine treatment conditions. Forty-two male F344/N rats were dosed by gavage with riddelliine (0, 1.0, and 2.5 mg/kg/day) for 6 weeks. Seven animals/group were sacrificed after 8 consecutive daily doses; remaining rats were terminated after 30 daily doses, excluding weekends. Hepatic tissues were evaluated by immunohistochemistry and in situ hybridization. The results showed that VEGF mRNA expression was observed in control and treated animals; however, qualitative differences were noted. Treated animals exhibited VEGF mRNA in clustered, focal hepatocytes and bile duct epithelium, whereas VEGF mRNA in hepatocytes from vehicle control rats was distributed evenly across all hepatocytes. Results evaluating the distribution of the VEGF cognate receptor, KDR/flk-1 showed that randomly distributed, rare sinusoidal endothelium, including those demonstrating karyomegaly and cytomegaly expressed KDR/flk-1. Phosphorylation of KDR/flk-1 at pTyr996 and pTyr1054/1059, but not pTyr951, was also detected, evidence that endothelial cell KDR/flk-1 was activated. These results suggest that both hepatocytes and endothelial cells are targets of riddelliine-induced injury. We speculate that damage to both populations of cells may lead to dysregulated VEGF synthesis by hepatocytes and activation of KDR/flk-1 by endothelium leading to the induction of sustained endothelial cell proliferation, culminating in the development of hepatic hemangiosarcoma.  相似文献   
99.
目的研究人胎盘组织液的主要药效作用。方法建立二甲苯所致小鼠耳肿胀及大鼠棉球肉芽肿的药理模型,观察人胎盘组织液对炎症模型动物的抗炎作用。结果与模型对照组相比,连续7d肌肉注射0.1mL/kg剂量的人胎盘组织液对二甲苯所致小鼠耳肿胀起到明显抑制作用,且差异显著(P〈0.01);连续6d肌肉注射0.1mL/kg剂量的人胎盘组织液对大鼠棉球肉芽组织增生起到明显抑制作用,且差异显著(P〈0.01)。结论人胎盘组织液具有明显的抗炎作用。  相似文献   
100.
We report here the first described case of utilizing gadolinium-based contrast material as the contrast agent during a catheter intervention treatment for pulmonary artery stenosis. The patient, a male infant with complex heart disease associated with a right isomerism, had a history of severe allergic reaction to iodine-containing contrast agents. A combination of digital subtraction angiography and a gadolinium contrast agent, however, provided us with good-quality images both before and after balloon angioplasty without any associated complications. This method should therefore be considered as an alternative angiographic procedure in children with a high risk of iodine-related allergic complications.  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