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   4388篇
  免费   292篇
  国内免费   179篇
耳鼻咽喉   37篇
儿科学   67篇
妇产科学   62篇
基础医学   1171篇
口腔科学   77篇
临床医学   309篇
内科学   912篇
皮肤病学   83篇
神经病学   274篇
特种医学   47篇
外科学   316篇
综合类   564篇
预防医学   111篇
眼科学   33篇
药学   364篇
  1篇
中国医学   105篇
肿瘤学   326篇
  2023年   28篇
  2022年   51篇
  2021年   97篇
  2020年   85篇
  2019年   147篇
  2018年   145篇
  2017年   109篇
  2016年   99篇
  2015年   113篇
  2014年   323篇
  2013年   256篇
  2012年   235篇
  2011年   295篇
  2010年   294篇
  2009年   315篇
  2008年   331篇
  2007年   275篇
  2006年   227篇
  2005年   182篇
  2004年   151篇
  2003年   145篇
  2002年   106篇
  2001年   93篇
  2000年   77篇
  1999年   67篇
  1998年   63篇
  1997年   53篇
  1996年   64篇
  1995年   68篇
  1994年   33篇
  1993年   30篇
  1992年   16篇
  1991年   17篇
  1990年   7篇
  1989年   14篇
  1988年   10篇
  1987年   5篇
  1986年   7篇
  1985年   45篇
  1984年   25篇
  1983年   34篇
  1982年   27篇
  1981年   22篇
  1980年   18篇
  1979年   20篇
  1978年   13篇
  1977年   5篇
  1976年   4篇
  1975年   4篇
  1973年   5篇
排序方式: 共有4859条查询结果,搜索用时 345 毫秒
131.
目的 探讨瞬间表达的CD4 0反义RNA对EB病毒转染的系统性红斑狼疮 (SLE)患者B淋巴细胞CD4 0分子表达、细胞增生以及免疫球蛋白 (Ig)分泌功能的影响。 方法 构建人CD4 0反义RNA的真核表达载体CD4 0 /pcDNA3,并将其转染入EB病毒转染的SLE患者B淋巴细胞中。应用流式细胞仪 (FACS)检测观察B淋巴细胞膜上CD4 0分子表达的变化 ;应用四甲基偶氮唑盐微量酶反应比色法 (MTT)观察反义CD4RNA对B淋巴细胞增生能力的影响 ;应用酶联免疫吸附试验(ELISA)测定转染后的B淋巴细胞的Ig分泌功能。结果 与转染pcDNA3空载体组相比 ,转染CD4 0 / pcDNA3组的CD4 0分子的表达明显降低 (P <0 0 1) ;细胞的增生能力明显降低 (P <0 0 5 ) ;细胞的Ig分泌功能明显受抑制 (P <0 0 1)。结论 CD4 0反义RNA对SLE患者的B淋巴细胞有明显的免疫调控作用。  相似文献   
132.
Echocardiographic findings from 10 patients without clinical indications of aortic root dissection or aortic valve disease from 1 patient with angiographic confirmation of aortic root dissection are reported and compared. Previously reported echocardiographic findings were confirmed in the patient with aortic root dissection. These include (1) a widened posterior or anterior aortic wall, or both; (2) parallel motion of the separated margins of the aortic walls; and (3) aortic root dilatation (42 mm or more at end-systole). However, all three findings were also noted in 5 of the 10 patients without clinical indications of aortic root dissection or aortic valve disease, and at least two of the three findings were noted in the remaining 5 patients. Echocardiographic detection of aortic root dissection appears to be most reliable when clinical indications of the anomaly are present.  相似文献   
133.
目的:研究CD40炎症分子在癫痫持续状态(status epilepticus,SE)后大鼠大脑皮层及海马的表达。方法:采 用免疫组织化学及免疫荧光双标记方法,观察锂-匹罗卡品癫痫大鼠大脑皮层及海马的不同区域、不同时间点、不同 细胞中CD40的表达情况。结果:癫痫发作显著增加了CD40阳性细胞,以在海马组织中增加为著; SE后CD40主要在 激活的小胶质细胞上表达;CD40阳性细胞在SE后3 d增加达到一个高峰,在SE 7 d后恢复到SE前稍高的水平。结论: CD40在激活的小胶质细胞上高表达,促进了SE大鼠海马炎症反应,提示CD40介导的信号通路参与SE后海马组织的炎 症病理过程。  相似文献   
134.
135.
重组可溶性人CD40L诱导人脐静脉内皮细胞损伤   总被引:10,自引:10,他引:0       下载免费PDF全文
目的:探讨重组可溶性人CD40L(rsh CD40L)对人脐静脉内皮细胞(HUVECs)的损伤作用及其在动脉粥样硬化中的作用。方法:应用rsh CD40L刺激人脐静脉内皮细胞12 h;MTS法观察HUVECs的生存活性,ELISA法测内皮细胞E-选择素(E-selectin)、细胞间黏附分子(ICAM)-1、组织因子(TF)、组织因子途径抑制物(TFPI)表达的变化,比色法测脂质过氧化物丙二醛(MDA)含量及超氧化物歧化酶(SOD)活力。结果:与正常组比较,不同浓度的rsh CD40L(0.5、1、2、3 mg/L)对内皮细胞的生存活性无明显影响;0.5 mg/L rsh CD40L即可增加内皮细胞E-selectin、s ICAM-1、TF、TFPI的分泌,差异有统计学意义(P0.01),同时增加内皮细胞MDA的含量、降低SOD活性(P0.05)。结论:0.5~3 mg/L rsh CD40L对内皮细胞生存活性无明显影响,但已经引起内皮细胞功能障碍,增加内皮细胞炎症和外源性凝血反应,诱导内皮细胞脂质过氧化物损,使其抗氧化能力下降。  相似文献   
136.
PRAS40是蛋白激酶B(PKB/Akt)的作用底物,亦是m TORC1的特异性结合蛋白,有多个位点可发生磷酸化,其中Thr246磷酸化受Akt调控,而Ser183、Ser212及Ser221等磷酸化主要受m TORC1调控。磷酸化修饰的PRAS40可调节与Raptor及14-3-3等蛋白的结合,参与Akt、m TORC1活性的调控。PRAS40具有调控细胞增殖、参与神经损伤保护等作用,在胰岛素抵抗、神经退行性病变及肿瘤中扮演重要角色,有望成为药物作用的新靶点。  相似文献   
137.

Background

Patients with atrial fibrillation (AF) experience symptom burden, exercise intolerance, weight gain, poor mental health, and diminished quality of life (QoL). Cardiac rehabilitation (CR) is recommended for patients with heart disease, and its benefits are well established, yet clinical guidelines for patients with AF do not include the referral to CR.

Methods

In this matched retrospective, case-control study, we examined the impact of CR on changes in QoL, mental health, and cardiometabolic health indicators in patients with or without persistent or permanent AF. Patients attended CR that addressed risk factor management and provided support services and exercise training twice weekly for 3 months. Height, body mass, waist circumference, blood pressure, and heart rate were measured, and the Short Form-36 and Hospital Anxiety and Depression Scale were administered at baseline and 3 months follow-up.

Results

A total of 94 patients (AF, n = 47; no AF, n = 47) (aged 70 ± 8 years) participated. Significant improvements in 2 of the 8 subscales and the Physical Component Summary of the Short Form-36 were observed across groups after CR (P < 0.05). Significant interactions revealed that the effect of CR was greater for energy, emotional well-being, social functioning, pain, and the Physical Component Summary in patients without AF (P < 0.05 for each). No significant improvements in anxiety (AF: ?1.3 ± 3.4; no AF: ?1.3 ± 4.3), depression (AF: ?1.1 ± 2.9; no AF: ?0.4 ± 2.7), body mass index (AF: ?0.5 ± 1.2; no AF: ?0.8 ± 1.5, kg/m2), waist circumference (AF: ?1.7 ± 4.6; no AF: 0.4 ± 8.1, cm), or blood pressure (AF: ?2.3 ± 17.1/?3.9 ± /9.3; no AF: 1.8 ± 16.4/?0.8 ± /9.3 mm Hg) were observed across groups after CR.

Conclusions

CR improved QoL to a greater extent in patients with heart disease without than with persistent or permanent AF.  相似文献   
138.
Summary Ro 40-5967 is a calcium channel blocker with a novel chemical structure. The purpose of this study was to evaluate the effects of Ro 40-5967 on systemic hemodynamics and regional contractile function in a canine model of chronic coronary artery stenosis in which no contractile dysfunction is observed at rest, but dynamic exercise elicits regional myocardial ischemia and contractile dysfunction. Thirteen dogs were chronically instrumented with sonomicrometers for the measurement of wall thickness in the anterior and posterior left ventricular walls, a micromanometer for measuring left ventricular pressure (LVP) and its first derivative (dP/dt), and a catheter in the aorta for measuring systemic arterial pressure. An ameroid constrictor on the left circumflex coronary artery produced gradual constriction of the vessel such that treadmill exercise elicited regional contractile dysfunction. Runs were repeated 3 hours later after the administration of Ro 40-5967 (0.3 mg/kg, IV). During the control run, regional systolic wall thickening in the posterior wall fell from 25.5 ± 6.3% (SD) to 15.9 ± 5.1% (p<0.05). Ro 40-5967 did not change resting function in the poststenotic myocardium (26.9 ± 8.4%) but improved regional function during the run to 18.2 ± 6.2% (p<0.05). This improvement was associated with a slight decrease in the exercise heart rate (213 ± 18 vs. 200 ± 16 bpm, NS), no change in peak ventricular pressure (156 ± 22 vs. 157 ± 20 mmHg), mean aortic pressure (123 ± 19 vs. 118 ± 20 mmHg), dP/dt (5129 ± 1143 vs. 5288 ± 1120 mm Hg/sec), or systolic wall thickening in a distant control region. Thus, in the exercising dog with fixed coronary stenosis, Ro 40-5967 had an antiischemic effect with no detectable negative inotropic effect.Studies were performed at the Seaweed Canyon Laboratory, Division of Cardiology, Department of Medicine, University of California, San Diego  相似文献   
139.
目的观察2型糖尿病(T2DM)患者血清可溶性CD40配体(sCD40L)水平的变化,以及阿司匹林(ASP)对其水平的影响。方法T2DM患者55例按是否服用阿司匹林(ASP)分为DM不服用ASP(DMwithoutASP)组24例和DM服用ASP组(DMwithASP)31例,设对照组33例。采用ELISA法测定血清sCD40L水平。结果DM-ASP组较对照组的sCD40L水平升高(2.14±0.74VS1.89±1.07,P〉0.05),DM+ASP组CD40L较DM组下降(1.19±0.76,P〈0.01),较对照组下降(P〈0.01)。结论DM患者血清sCD40L升高;服用ASP可降低DM患者sCD40L水平。  相似文献   
140.
Aims/hypothesis Inflammation plays a pathogenic role in the development of accelerated atherosclerosis in diabetes. Soluble CD40 ligand (sCD40L) is enhanced in diabetes; however, the molecular mechanisms linking sCD40L to accelerated atherosclerosis in diabetes are still unclear. We tested the hypothesis that sCD40L may be involved in the vascular complications in diabetes and exerts its effect by triggering inflammatory reactions on mononuclear and endothelial cells (ECs).Methods We studied 70 patients, 40 with type 2 and 30 with type 1 diabetes, with a history or physical examination negative for cardiovascular disease, and 40 non-diabetic and 30 healthy subjects, matched with the type 2 and type 1 diabetic patients, respectively. Plasma and serum sCD40L, and plasma soluble intercellular adhesion molecule-1, soluble vascular cell adhesion molecule-1, E-selectin and monocyte chemo-attractant protein-1 (MCP-1) were measured. Adhesion molecules and MCP-1 release, the ability to repair an injury in ECs, and O2 generation in monocytes were analysed in vitro after stimulation with serum from patients or controls.Results Type 2 and type 1 diabetic patients had significantly higher sCD40L levels than controls. Furthermore, high sCD40L was associated with in vitro adhesion molecules and MCP-1 release, impaired migration in ECs and enhanced O2 generation in monocytes. Improved metabolic control was associated with a reduction of plasma sCD40L by 37.5% in 12 type 1 diabetic patients. Furthermore, elevated sCD40L in diabetic patients was significantly correlated with HbA1c levels.Conclusions/interpretation Upregulation of sCD40L as a consequence of persistent hyperglycaemia in diabetic patients results in EC activation and monocyte recruitment to the arterial wall, possibly contributing to accelerated atherosclerosis development in diabetes.  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