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   42112篇
  免费   3198篇
  国内免费   1707篇
耳鼻咽喉   79篇
儿科学   567篇
妇产科学   226篇
基础医学   2744篇
口腔科学   157篇
临床医学   5240篇
内科学   12959篇
皮肤病学   231篇
神经病学   1248篇
特种医学   2098篇
外国民族医学   1篇
外科学   2039篇
综合类   8504篇
现状与发展   2篇
预防医学   2286篇
眼科学   311篇
药学   5083篇
  34篇
中国医学   2207篇
肿瘤学   1001篇
  2024年   39篇
  2023年   518篇
  2022年   784篇
  2021年   1501篇
  2020年   1401篇
  2019年   1202篇
  2018年   1197篇
  2017年   1170篇
  2016年   1313篇
  2015年   1339篇
  2014年   2623篇
  2013年   3095篇
  2012年   2285篇
  2011年   2654篇
  2010年   2162篇
  2009年   2003篇
  2008年   2107篇
  2007年   2176篇
  2006年   2132篇
  2005年   1813篇
  2004年   1570篇
  2003年   1388篇
  2002年   1162篇
  2001年   1203篇
  2000年   989篇
  1999年   817篇
  1998年   712篇
  1997年   666篇
  1996年   540篇
  1995年   510篇
  1994年   503篇
  1993年   403篇
  1992年   362篇
  1991年   331篇
  1990年   281篇
  1989年   239篇
  1988年   251篇
  1987年   219篇
  1986年   185篇
  1985年   223篇
  1984年   197篇
  1983年   137篇
  1982年   130篇
  1981年   122篇
  1980年   89篇
  1979年   76篇
  1978年   51篇
  1977年   44篇
  1976年   31篇
  1974年   22篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
BackgroundDiabetes mellitus (DM) is the most common metabolic disorder that increases the risk of cardiovascular disease by two to four times compared with the general population. There are limited data on the prevalence of heart diseases in subjects with DM in Greece. In this study, we examined the prevalence of self-reported DM as well as cardiac and other main comorbidities in a representative sample of the adult Greek population.MethodsThe target study population included 30,843 participants stratified by gender, age, and district, and this was a representative sample of the adult Greek population in 2010. A structured questionnaire was built to report the prevalence of self-reported DM and the main comorbidities in participants with and without DM. Collection of data was performed through telephone interviews.ResultsThe prevalence of self-reported DM was 6.6%. The prevalence of the main comorbidities in participants with DM vs. those without DM was as follows: heart diseases 24.0% vs. 8.9%, p<0.001; lung diseases 11.3% vs. 5.3%, p<0.001; kidney diseases 3.4% vs. 1.2%, p=0.001; liver diseases 1.4% vs. 0.7%, p=0.001; benign blood diseases 1.6% vs. 0.9%, p=0.005; and solid organ and/or blood malignancies 2.9% vs. 1.5%, p<0.001.ConclusionsThe prevalence of self-reported DM in a representative sample of the adult Greek population in 2010 was 6.6%. The prevalence of heart diseases in subjects with DM was 2.7-fold higher than the prevalence in those without DM. Diseases of the lung, kidney, liver, and blood as well as malignancies were significantly more common among participants with DM.  相似文献   
992.
Background and aimsLow serum albumin (SA) is associated with an increased risk of long-term adverse events (AEs) among patients with chronic coronary syndromes. Its prognostic role in patients with ST-elevation myocardial infarction (STEMI) is less clear. To investigate the association between low SA and in-hospital AEs in STEMI patients.Methods and resultsMulticenter retrospective cohort study of 220 STEMI patients undergoing primary percutaneous coronary intervention within 12 h from the onset of symptoms. Hypoalbuminemia was defined by serum SA <35 g/L. SA. In-hospital AEs were defined as cardiogenic shock, resuscitated cardiac arrest and death. Median SA was 38 (IQR 35.4–41.0) g/L and 37 (16.8%) patients showed hypoalbuminemia (<35 g/L) on admission. Patients with hypoalbuminemia were older, more frequently women and diabetics, prior CAD and HF. Furthermore, they showed lower hemoglobin levels and impaired renal function. At multivariable logistic regression analysis, diabetes (odds ratio [OR]:4.59, 95% confidence interval [CI] 1.71–12.28, p = 0.002) and haemoglobin (OR:0.52, 95%CI 0.37–0.72, p < 0.001) were associated with low SA. In a subgroup of 132 patients, SA inversely correlated with D-Dimer (rS −0.308, p < 0.001). Globally, twenty-eight (14.6%) AEs were recorded. Hypoalbuminemia (OR:3.43, 95%CI 1.30–9.07, p = 0.013), high-sensitive (HS)-Troponin peak above median (OR:5.41, 95%CI 1.99–14.7, p = 0.001), C-reactive protein (CRP) peak above median (OR:6.03, 95%CI 2.02–18.00, p = 0.001), and in-hospital infection (OR:3.61, 95%CI 1.21–10.80, p = 0.022) were associated with AEs.ConclusionLow SA levels are associated with worse in-hospital AEs in STEMI patients, irrespective of HS-troponin and CRP plasma levels. Our findings suggest that low SA may contribute to the pro-thrombotic phenotype of these patients.  相似文献   
993.
OBJECTIVES: (1) Evaluate wall motion and perfusion abnormalities after reperfusion therapy of the culprit lesion, (2) delineate the ability of myocardial contrast echocardiography (MCE) to evaluate the microvasculature after reperfusion, in order to distinguish between stunning and necrosis in the risk area. METHODS: We analyzed 446 segments from 28 patients, 10 normal controls (160 segments), and 18 with a first AMI (286 segments). MCE was obtained with Optison and a two-dimensional echocardiography was performed at 3 months post acute myocardial infarction (AMI). RESULTS: In the group with AMI, we analyzed 286 segments, of which 107 had wall motion abnormalities (WMA) related to the culprit artery. Two subgroups were identified: Group I with WMA and normal perfusion (50 segments, 47%) and Group II with WMA and perfusion defects (57 segments, 53%). According to the 2D echocardiogram at 3 months, they were further subdivided into: Group IA: with wall motion improvement (stunning): 18 segments, 36%, Group IB: without wall motion improvement: 32 segments, 64%, Group IIA: with wall motion improvement: 12 segments, 21%, Group IIB: without wall motion improvement (necrosis): 45 segments, 79%. CONCLUSIONS: (1) The presence of myocardial perfusion in segments with WMA immediately after AMI reperfusion therapy predicts viability in most patients. Conversely, the lack of perfusion is not an absolute indicator of the presence of necrosis. (2) Perfusion defects allow to detect patients with thrombolysis in myocardial infarction (TIMI) 3 flow and "no-reflow" phenomenon who will not show improved wall motion in the 2D echocardiogram. However, some patients with initial no-reflow could have microvascular stunning and their regional contractile function will normalize after a recovery period.  相似文献   
994.
针刺抗心肌缺血机制的实验与临床研究现状   总被引:1,自引:0,他引:1  
冠心病表现为不同的临床类型,共同的病理生理机制为心肌缺血,针刺抗心肌缺血涉及心脏的结构与功能及神经内分泌变化,就针刺抗心肌缺血的机制研究加以综述.  相似文献   
995.
Backround: P‐wave dispersion (P dispersion), defined as the difference between the maximum and the minimum P‐wave duration (P minimum), and maximum P‐wave duration (P maximum) have been used to evaluate the discontinuous propagation of sinus impulse and the prolongation of atrial conduction time respectively. The aim of this study was to investigate whether early assessment of P dispersion predicts paroxysmal atrial fibrillation (AF) in patients with acute anterior wall myocardial infarction (MI). Methods: We prospectively evaluated 147 consecutive patients (45 women, 102 men; aged 55 ± 9 years) with a first acute anterior wall MI. All patients were evaluated by echocardiography to measure the left atrial diameter and left ventricular ejection fraction (LVEF). Electrocardiography was recorded from all patients on admission and every day during hospitalization. Results: AF occurred in 25 patients. In 122 patients, AF did not occur. P maximum was found to be significantly higher in patients with AF than in patients without AF (115 ± 17.3 ms vs 101 ± 14.7 ms, P = 0.001 ). P dispersion also was significantly higher in patients with AF than in patients without AF (50 ± 12.5 ms vs 43 ± 10.1 ms, P = 0.01 ). There was no significant difference between the two groups in P minimum (64 ± 12.5 ms vs 59 ± 11.7 ms, P = 0.057 ). The echocardiographically left atrial diameters were not significantly higher in the patients with AF than those without (25 ± 3.38 mm and 23 ± 3.36 mm , respectively, P = 0.76 ). LVEF was found to be significantly different in the patients who developed AF and in those who did not (37.96 ± 6.18% vs 47.70 ± 6.01%, P = 0.0001 ). Conclusions: Although P maximum and P dispersion are significant predictive factors of AF in patients with acute anterior wall MI in the univariate analysis, on the basis of multivariate analysis, only age and LVEF were independent predictive parameters for AF.  相似文献   
996.
Objectives. To investigate the risk of a first myocardial infarction (MI) and sudden cardiac death (SCD) amongst male snuff users. Design. We used a prospective incident case‐referent study design nested in the population‐based Västerbotten Intervention Program and the Northern Sweden MONICA study. Subjects. Tobacco habits and cardiovascular risk factors were assessed at baseline screening and compared in 525 male MI cases (including 93 SCD cases) and 1798 matched referents. Results. Myocardial infarction occurred on average 4 years and 2 months after the baseline screening. No increased risk for MI was found amongst snuff users without a previous history of smoking compared with nontobacco users after adjustments for body mass index, leisure time physical activity, educational level and cholesterol level (OR 0.82; 95% CI, 0.46–1.43). For snuff users with a previous history of smoking, the adjusted OR was 1.25 (95% CI, 0.80–1.96). Significantly increased risk for MI was found in current smokers with or without current snuff use. For SCD cases with survival time <24 h, the adjusted OR for snuff users without previous history of smoking was 1.18 (95% CI, 0.38–3.70) and for cases with survival time <1 h the OR was 0.38 (95% CI, 0.08–1.89). Conclusions. We found no increased risk for MI amongst snuff users without a previous history of smoking. Amongst snuff users with a previous history of smoking, the tendency towards an increased risk for MI may reflect the residual risk from former smoking. This study does not support the hypothesis that the risk for SCD is increased amongst snuff users.  相似文献   
997.
998.
Three-hundred and ninety-four 68-year-old men, representing 60.3% of a cohort of men born in 1914, were examined with ambulatory ECG during 24 h in 1982-83. Ninety-eight (24.8%) men had one or more episodes of ischaemic type ST segment depression (greater than or equal to 0.10 mV), 79 of whom had no history of previous ischaemic heart disease (IHD). During 63 months follow-up, 17 of the 98 suffered a cardiac event, i.e. fatal or non-fatal myocardial infarction (MI) or death due to chronic IHD. The objective of this study was to assess the influence of psychosocial factors, such as social network and social support, on cardiac event rate in men with ischaemic ST segment depression. A higher risk was found among men with little material and informational support (i.e. access to practical services and material resources and access to guidance, advice and information (crude relative risk 4.8; 95% CI; 1.6-14.8) and men with low availability of emotional support (i.e. opportunity for care, encouragement of personal value and feelings of confidence and trust) (crude relative risk 4.3; 95% CI: 1.4-13.3). This association was independent of history of IHD and other known risk factors for myocardial infarction (MI).  相似文献   
999.
目的:研究氯沙坦对急性心肌梗死后心室重构的影响。方法:符合入选标准的120例急性心肌梗死患者被随机均分为三组:氯沙坦组(A组)。卡托普利组(B组),常规治疗组(C组),分别于治疗前,治疗后6个月进行超声心动图检查。结果:对照组常规治疗后.左室舒张末容积(LVEDV)、左室射血分数(LVEF)、每搏量(SV)均进一步恶化(P<0.05),A、B组的LVEDV、LVEF、SV较C组则无显著恶化(P<0.05~<0.01).A组又好于B组(P<0.05)。结论:氯沙坦能明显改善急性心肌梗死后心室重构。  相似文献   
1000.
目的探讨L-精氨酸(L-Arg)对糖尿病大鼠肝脏、心肌及膈肌线粒体自由基损伤的保护作用. 方法给大鼠腹腔注射四氧嘧啶制备糖尿病模型,随机分为糖尿病组、L-Arg治疗组及正常对照组;用药4 w末测定三组大鼠肝脏、心肌及膈肌细胞线粒体中Mn-SOD、GSH-Px活性和MDA含量及膈肌线粒体内GSH含量.结果糖尿病组较正常组,大鼠肝、心肌、膈肌线粒体内GSH-Px活性显著降低(P<0.01,P<0.05,P<0.001),MDA含量显著升高(P<0.01,P<0.05,P<0.01),肝、膈肌线粒体Mn-SOD活性(均P<0.01)及膈肌线粒体GSH含量(P<0.05)也明显降低;与模型组比较,L-Arg可显著增加糖尿病大鼠肝、心肌、膈肌线粒体GSH-Px活性(P<0.05,P<0.05,P<0.001)及肝、膈肌线粒体Mn-SOD活性(均P<0.001),并使膈肌线粒体MDA含量显著降低(P<0.01),而GSH含量明显升高(P<0.001). 结论糖尿病大鼠肝、心肌、膈肌线粒体内自由基生成增多;L-Arg可通过提高肝、心肌、膈肌细胞线粒体中自由基清除酶的活性来加速自由基的清除,提高机体的抗氧化能力,从而保护机体功能免受氧化损伤.  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