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   9305篇
  免费   474篇
  国内免费   24篇
耳鼻咽喉   115篇
儿科学   784篇
妇产科学   399篇
基础医学   993篇
口腔科学   168篇
临床医学   470篇
内科学   1723篇
皮肤病学   188篇
神经病学   347篇
特种医学   213篇
外科学   1805篇
综合类   271篇
一般理论   3篇
预防医学   382篇
眼科学   602篇
药学   528篇
中国医学   25篇
肿瘤学   787篇
  2023年   75篇
  2022年   173篇
  2021年   325篇
  2020年   159篇
  2019年   230篇
  2018年   317篇
  2017年   204篇
  2016年   274篇
  2015年   246篇
  2014年   369篇
  2013年   403篇
  2012年   609篇
  2011年   616篇
  2010年   395篇
  2009年   291篇
  2008年   479篇
  2007年   506篇
  2006年   472篇
  2005年   387篇
  2004年   295篇
  2003年   303篇
  2002年   257篇
  2001年   221篇
  2000年   218篇
  1999年   195篇
  1998年   87篇
  1997年   59篇
  1996年   49篇
  1995年   42篇
  1992年   94篇
  1991年   95篇
  1990年   71篇
  1989年   69篇
  1988年   71篇
  1987年   74篇
  1986年   80篇
  1985年   104篇
  1984年   56篇
  1983年   56篇
  1982年   39篇
  1981年   35篇
  1980年   34篇
  1979年   80篇
  1978年   45篇
  1977年   47篇
  1976年   39篇
  1975年   35篇
  1974年   42篇
  1973年   48篇
  1972年   46篇
排序方式: 共有9803条查询结果,搜索用时 31 毫秒
991.
Heart failure is prevalent in those with type 2 diabetes and chronic kidney disease, and is associated with significant mortality and morbidity. In the CREDENCE trial, canagliflozin reduced the risk of hospitalization for heart failure (HHF) or cardiovascular (CV) death by 31%. In the current analysis we sought to determine whether the effect of canagliflozin on HHF/CV death differed in subgroups defined by key baseline participant characteristics. Cox regression models were used to estimate hazard ratios and 95% confidence intervals. Canagliflozin was associated with a reduction in the relative risk of HHF/CV death regardless of age, sex, history of heart failure or CV disease, and the use of loop diuretics or glucagon-like peptide-1 receptor agonists (all pinteraction > .114). The absolute benefit of canagliflozin was greater in those at highest baseline risk, such as those with CV disease (50 fewer events/1000 patients treated over 2.5 years vs. 20 fewer events in those without CV disease) or advanced kidney disease (estimated glomerular filtration rate [eGFR] 30–45 mL/min/1.73m2: 61 events prevented/1000 patients treated over 2.5 years vs. 23 events in eGFR 60–90 mL/min/1.73m2). Canagliflozin consistently reduces the proportional risk of HHF/CV death across a broad range of subgroups with greater absolute benefits in those at highest baseline risk.  相似文献   
992.
993.
Aplastic anemia (AA) is an immune-mediated disorder in which hematopoietic stem and progenitor cells are targeted by a number of cellular and molecular pathways. This case control study aims to investigate the association of interleukin-1beta (IL-1β) gene polymorphisms, (IL-1β-31, IL-1β-511 and IL-1β-3954) and their plasma levels with acquired AA. Genotyping was done by Restricted Fragment Length Polymorphism (PCR–RFLP) method and IL-1β plasma levels were evaluated in peripheral blood using ELISA. Increased level of IL-1β was reported to be significant in cases as compared to controls. The susceptibility of developing AA was higher in the cases for IL-1β-3954 genotype. IL-1β-511 genotype showed significant association with the severity groups of AA. No significant association was noticed in responder versus non-responder group. Plasma level of IL-1β gene was found to be significantly higher in severe and very-severe group of AA versus control group. Our findings suggest that IL-1β gene and its genotypes might be involved in the pathophysiology of AA and play a central role in the etiopathogenesis of AA.  相似文献   
994.
Endothelium plays a crucial role in the maintenance of vascular tone and structure. Endothelial dysfunction is known to precede overt coronary artery disease. A number of cardiovascular risk factors, as well as metabolic diseases and systemic or local inflammation cause endothelial dysfunction. Nitric oxide (NO) is one of the major endothelium derived vaso-active substances whose role is of prime importance in maintaining endothelial homeostasis. Low levels of NO are associated with impaired endothelial function. Asymmetric dimethylarginine (ADMA), an analogue of L-arginine, is a naturally occurring product of metabolism found in human circulation. Elevated levels of ADMA inhibit NO synthesis and therefore impair endothelial function and thus promote atherosclerosis. ADMA levels are increased in people with hypercholesterolemia, atherosclerosis, hypertension, chronic heart failure, diabetes mellitus and chronic renal failure. A number of studies have reported ADMA as a novel risk marker of cardiovascular disease. Increased levels of ADMA have been shown to be the strongest risk predictor, beyond traditional risk factors, of cardiovascular events and all-cause and cardiovascular mortality in people with coronary artery disease. Interventions such as treatment with L-arginine have been shown to improve endothelium-mediated vasodilatation in people with high ADMA levels. However the clinical utility of modifying circulating ADMA levels remains uncertain.  相似文献   
995.
A risk score for atrial fibrillation (AF) has been developed by the Framingham Heart Study; however, the applicability of this risk score, derived using data from white patients, to predict new-onset AF in nonwhites is uncertain. Therefore, we developed a 10-year risk score for new-onset AF from risk factors commonly measured in clinical practice using 14,546 subjects from the Atherosclerosis Risk In Communities (ARIC) study, a prospective community-based cohort of blacks and whites in the United States. During 10 years of follow-up, 515 incident AF events occurred. The following variables were included in the AF risk score: age, race, height, smoking status, systolic blood pressure, hypertension medication use, precordial murmur, left ventricular hypertrophy, left atrial enlargement, diabetes, coronary heart disease, and heart failure. The area under the receiver operating characteristics curve (AUC) of a Cox regression model that included the previous variables was 0.78, suggesting moderately good discrimination. The point-based score developed from the coefficients in the Cox model had an AUC of 0.76. This clinical risk score for AF in the Atherosclerosis Risk In Communities cohort compared favorably with the Framingham Heart Study's AF (AUC 0.68), coronary heart disease (CHD) (AUC 0.63), and hard CHD (AUC 0.59) risk scores and the Atherosclerosis Risk In Communities CHD risk score (AUC 0.58). In conclusion, we have developed a risk score for AF and have shown that the different pathophysiologies of AF and CHD limit the usefulness of a CHD risk score in identifying subjects at greater risk of AF.  相似文献   
996.
997.
998.

Background

Understanding the relationship between alcohol abuse, a common and theoretically modifiable condition, and the most common cause of death in the world, cardiovascular disease, may inform potential prevention strategies.

Objectives

The study sought to investigate the associations among alcohol abuse and atrial fibrillation (AF), myocardial infarction (MI), and congestive heart failure (CHF).

Methods

Using the Healthcare Cost and Utilization Project database, we performed a longitudinal analysis of California residents ≥21 years of age who received ambulatory surgery, emergency, or inpatient medical care in California between 2005 and 2009. We determined the risk of an alcohol abuse diagnosis on incident AF, MI, and CHF. Patient characteristics modifying the associations and population-attributable risks were determined.

Results

Among 14,727,591 patients, 268,084 (1.8%) had alcohol abuse. After multivariable adjustment, alcohol abuse was associated with an increased risk of incident AF (hazard ratio [HR]: 2.14; 95% confidence interval [CI]: 2.08 to 2.19; p < 0.0001), MI (HR: 1.45; 95% CI: 1.40 to 1.51; p < 0.0001), and CHF (HR: 2.34; 95% CI: 2.29 to 2.39; p < 0.0001). In interaction analyses, individuals without conventional risk factors for cardiovascular disease exhibited a disproportionately enhanced risk of each outcome. The population-attributable risk of alcohol abuse on each outcome was of similar magnitude to other well-recognized modifiable risk factors.

Conclusions

Alcohol abuse increased the risk of AF, MI, and CHF to a similar degree as other well-established risk factors. Those without traditional cardiovascular risk factors are disproportionately prone to these cardiac diseases in the setting of alcohol abuse. Thus, efforts to mitigate alcohol abuse might result in meaningful reductions of cardiovascular disease.  相似文献   
999.
Multiple variations exist in performing a primary percutaneous coronary intervention (pPCI) in ST-segment elevation myocardial infarction (STEMI) among various cardiologists. These variations range from the choice of peripheral access artery (radial vs femoral), performance or time of complete angiography including left ventriculography, and nonculprit vessel angiography before or after intervening on the culprit vessel. The reasons for such variations include emphasis on door-to-balloon time, knowledge of cardiac anatomy before proceeding with pPCI, physician expertise, and the level of comfort with radial approach. Over the last 2 decades, the field of interventional cardiology has changed dynamically leading to marked improvements in the clinical outcomes of patients with STEMI. This includes upstreaming of pPCI along with technical advancements ranging from radial artery catheterization to culprit lesion–guided approach. Increased comfort with use of radial access approach by cardiologists and availability of multiuse guide catheters would both reduce door-to-balloon time and enable complete coronary angiography before performance of percutaneous coronary intervention. There are no clear guidelines or consensus dictating on cardiologists a correct sequence of action during STEMI, or even suggesting what the preferred approach is. Lack of guidelines results in a substantive variation in methodology. This review aims to highlight and to better understand the variations in the current practice, and to emphasize the advantages as well as the disadvantages of each approach. It is also perhaps a call out for guidelines that direct cardiologists to the best practice.  相似文献   
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