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   331篇
  免费   27篇
  国内免费   1篇
耳鼻咽喉   1篇
儿科学   1篇
妇产科学   6篇
基础医学   46篇
口腔科学   3篇
临床医学   23篇
内科学   123篇
皮肤病学   2篇
神经病学   32篇
特种医学   21篇
外科学   49篇
综合类   3篇
预防医学   10篇
眼科学   3篇
药学   16篇
肿瘤学   20篇
  2024年   1篇
  2023年   14篇
  2022年   10篇
  2021年   15篇
  2020年   11篇
  2019年   13篇
  2018年   21篇
  2017年   10篇
  2016年   13篇
  2015年   12篇
  2014年   16篇
  2013年   21篇
  2012年   32篇
  2011年   38篇
  2010年   13篇
  2009年   7篇
  2008年   12篇
  2007年   13篇
  2006年   14篇
  2005年   15篇
  2004年   15篇
  2003年   13篇
  2002年   8篇
  2001年   4篇
  2000年   3篇
  1999年   2篇
  1998年   1篇
  1997年   7篇
  1993年   1篇
  1991年   1篇
  1987年   1篇
  1969年   1篇
  1967年   1篇
排序方式: 共有359条查询结果,搜索用时 15 毫秒
1.
INTRODUCTION. This report describes the current status of nephrology and renal replacement therapy (RRT) in Romania, a country with previously limited facilities, highlighting national changes in the European context. METHODS: Trends in RRT development were analysed in 2003, on a national basis, using the same questionnaires as in previous surveys (1991, 1995). Survival data and prognostic risk factors were calculated retrospectively from a large representative sample of 2284 patients starting RRT between January 1, 1995 and December 31, 2001 (44% of the total RRT population investigated). RESULTS: In 2003, RRT incidence [128 per million population (p.m.p.)] and prevalence (250 p.m.p.) were six and five times higher, respectively, than in 1995. The annual rate of increase in the stock of RRT patients (11%) was supported mainly by an exponential development of the continuous ambulatory peritoneal dialysis (CAPD) population (+600%), while the haemodialysis (HD) growth rate was stable (+33%) and renal transplantation made a marginal contribution. Renal care infrastructure followed the same trend: nephrology departments (+100%) and nephrologists (+205%). The characteristics of RRT incident patients changed accordingly to current European epidemiology (increasing age and prevalence of diabetes and nephroangiosclerosis). The estimated overall survival of RRT patients in Romania was 90.6% at 1 year [confidence interval (CI) 89.4-91.8] and 62.2% at 5 years (CI 59.4-65.0). Patients' survival was negatively influenced (Cox regression analysis) by age >65 years (P < 0.001), lack of pre-dialysis monitoring by a nephrologist [P = 0.01, hazards ratio (HR) = 0.8], severe anaemia, lack of erythropoetin treatment (P < 0.001, HR = 0.6), and co-morbidity, e.g. cardiovascular diseases (P < 0.001, HR = 1.8) and diabetes mellitus (P < 0.001, HR = 2.2). CONCLUSIONS: Although the rate of increase in RRT patient stock in 1996-2003 in Romania was the highest in Europe, the prevalence remained below the European mean. As CAPD had the greatest expansion, followed by HD, an effective transplantation programme must be set up to overcome the imbalance. The quality of RRT appears to be good and survival was similar to that in other registries. Further evolution implies strategies of prevention, based on national surveys, supported by the Romanian Renal Registry.  相似文献   
2.
In this paper we describe the development of a computationally efficient computer-aided detection (CAD) algorithm based on the evaluation of the surface morphology that is employed for the detection of colonic polyps in computed tomography (CT) colonography. Initial polyp candidate voxels were detected using the surface normal intersection values. These candidate voxels were clustered using the normal direction, convexity test, region growing and Gaussian distribution. The local colonic surface was classified as polyp or fold using a feature normalized nearest neighborhood classifier. The main merit of this paper is the methodology applied to select the robust features derived from the colon surface that have a high discriminative power for polyp/fold classification. The devised polyp detection scheme entails a low computational overhead (typically takes 2.20 min per dataset) and shows 100% sensitivity for phantom polyps greater than 5 mm. It also shows 100% sensitivity for real polyps larger than 10 mm and 91.67% sensitivity for polyps between 5 to 10 mm with an average of 4.5 false positives per dataset. The experimental data indicates that the proposed CAD polyp detection scheme outperforms other techniques that identify the polyps using features that sample the colon surface curvature especially when applied to low-dose datasets.  相似文献   
3.
We have previously shown that flutamide (specific antagonist of the androgen receptor) has antihypertensive effects. In the present study we examined the mechanisms of flutamide action in the vasculature. The vascular effects of flutamide were assayed in aortae isolated from male or female Sprague-Dawley rats and from rats or mice lacking a functional androgen receptor ( tfm, testicular feminization mutation). The effect of flutamide on coronary flow was tested in isolated hearts. In addition, male hypertensive rats with tfm mutation were treated with flutamide, and blood pressure was monitored. Flutamide induced a relaxation of rat aortae from all the strains used (maximum relaxation at 10 microM: 51.3+/-5.2% of phenylephrine contraction) and increased the coronary flow. The aortic relaxation to flutamide was abolished by endothelium removal, or by inhibition of nitric oxide synthase, guanylyl cyclase, and tyrosine kinase but not by calmodulin inhibition. Flutamide treatment attenuated the development of hypertension in mouse renin transgenic rats with the tfm mutation. Flutamide produces direct vasodilation by inducing release of NO from the endothelium and causes subsequent activation of soluble guanylyl cyclase in an active androgen receptor independent manner. This response may contribute to the observed antihypertensive actions of flutamide.  相似文献   
4.
Chronic myocardial ischemia is the leading cause of disturbances in myocardial contractility (myocardial infarction) or hemodynamic overload upon the left ventricle. The heart reactions consist in a series of adaptative mechanisms in order to maintain its pump function: Frank-Starling mechanism, myocardial hypertrophy and neurohumoral activation. In heart failure, the cardiac output is maintained by an increase of the preload which enhances the contractility (Frank-Starling law). Myocardial ischemia influences the systolic and diastolic function. The decrease of cardiac output leads to neurohumoral responses which, in the initial stages of cardiac failure are compensatory; along with the progression of the disease, they exert adverse effects. Increased activity of the sympathetic nervous system induces high cardiac rates, chronotropic incompetence. Activation of the renin-angiotensin system held to myocardial and vascular hypertrophy, vasoconstriction, fluid retention. Endothelin is the most powerful vasoconstrictor; its plasmatic concentrations correlate with the severity of the disease. Vasodilator mediators released in cardiac failure are the natriuretic peptide, nitric oxide, dopamine, prostacicline, bradikinin.  相似文献   
5.
Actually the old age is not considered a contra-indication of cardiac rehabilitation, although it influences the prognosis of patients with chronic myocardial infarction. The objective of the paper is the study of age as a limiting factor of the cardiac performance and exercise capacity at patients with myocardial infarction at the admission in rehabilitation programmes. METHODS: Among the patients admitted in the Department of Internal Medicine of Rehabilitation Hospital of Iasi there were selected 132 with chronic myocardial infarction; they were divided into two groups: group A of 56 patients more than 55 years old and group B of 76 under 55. There were analysed the clinical features (risk factors, symptoms), the cardiac performance (by echographic study of the regional and global abnormalities of myocardial contractility) and the functional capacity (by exercise testing at the ergometric bicycle). RESULTS: Both groups were similar by the point of view of the prevalence of the risk factors and location of the infarction. The ejection fraction, although smaller at the group A (45% vs 50%), did not reach the statistical significance. The exercise testing revealed a lower capacity of the group A, marked by higher levels of the cardiac rate and time-tension index at similar levels of exercise. The metabolic equivalent (MET) and VO2max were significantly lower (p = 0.001 respectively 0.002). There can be concluded that the age diminishes the exercise capacity of the patients with myocardial infarction without a marked influence of the cardiac performance. The last one depends on the infarction size and the myocardial status while the lowering of the functional capacity is influenced by noncardiac factors as well.  相似文献   
6.
7.
Pressure ulcer prevention is an important long‐term care (LTC) quality indicator. While the Braden Scale is a recommended risk assessment tool, there is a paucity of information specifically pertaining to its validity within the LTC setting. We, therefore, undertook a systematic review and meta‐analysis comparing Braden Scale predictive and concurrent validity within this context. We searched the Medline, EMBASE, PsychINFO and PubMed databases from 1985–2014 for studies containing the requisite information to analyze tool validity. Our initial search yielded 3,773 articles. Eleven datasets emanating from nine published studies describing 40,361 residents met all meta‐analysis inclusion criteria and were analyzed using random effects models. Pooled sensitivity, specificity, positive predictive value (PPV), and negative predictive values were 86%, 38%, 28%, and 93%, respectively. Specificity was poorer in concurrent samples as compared with predictive samples (38% vs. 72%), while PPV was low in both sample types (25 and 37%). Though random effects model results showed that the Scale had good overall predictive ability [RR, 4.33; 95% CI, 3.28–5.72], none of the concurrent samples were found to have “optimal” sensitivity and specificity. In conclusion, the appropriateness of the Braden Scale in LTC is questionable given its low specificity and PPV, in particular in concurrent validity studies. Future studies should further explore the extent to which the apparent low validity of the Scale in LTC is due to the choice of cutoff point and/or preventive strategies implemented by LTC staff as a matter of course.  相似文献   
8.
Angiogenesis is a key event during tissue regeneration, but the intimate mechanisms controlling this process are still largely unclear. Therefore, the cellular and molecular interplay along normal tissue regeneration should be carefully unveiled. To this matter, we investigated by xMAP assay the dynamics of some angiogenic factors known to be involved in tissue repair, such as follistatin (FST), Placental Growth Factor‐2 (PLGF‐2), epidermal growth factor (EGF), betacellulin (BTC), and amphiregulin (AREG) using an animal model that mimics acute muscle contusion injuries. In situ immunofluorescence was used for the evaluation and tissue distribution of their cellular sources. Tissue levels of explored factors increased significantly during degeneration and inflammatory stage of regeneration, peaking first week postinjury. However, except for PLGF‐2 and EGF, their levels remained significantly elevated after the inflammatory process started to fade. Serum levels were significantly increased only after 24 h for AREG and EGF. Though, for all factors except FST, the levels in injured samples did not correlate with serum or contralateral tissue levels, excluding the systemic influence. We found significant correlations between the levels of EGF and AREG, BTC, FST and FST and AREG in injured samples. Interstitial cells expressing these factors were highlighted by in situ immunolabeling and their number correlated with measured levels dynamics. Our study provides evidence of a dynamic level variation along the regeneration process and a potential interplay between selected angiogenic factors. They are synthesized, at least partially, by cell populations residing in skeletal muscle interstitium during regeneration after acute muscle trauma. Anat Rec, 298:1864–1879, 2015. © 2015 Wiley Periodicals, Inc.  相似文献   
9.
10.
Cardiogenic shock (CS) is a complex multifactorial clinical syndrome with extremely high mortality, developing as a continuum, and progressing from the initial insult (underlying cause) to the subsequent occurrence of organ failure and death. There is a large spectrum of CS presentations resulting from the interaction between an acute cardiac insult and a patient's underlying cardiac and overall medical condition. Phenotyping patients with CS may have clinical impact on management because classification would support initiation of appropriate therapies. CS management should consider appropriate organization of the health care services, and therapies must be given to the appropriately selected patients, in a timely manner, whilst avoiding iatrogenic harm. Although several consensus‐driven algorithms have been proposed, CS management remains challenging and substantial investments in research and development have not yielded proof of efficacy and safety for most of the therapies tested, and outcome in this condition remains poor. Future studies should consider the identification of the new pathophysiological targets, and high‐quality translational research should facilitate incorporation of more targeted interventions in clinical research protocols, aimed to improve individual patient outcomes. Designing outcome clinical trials in CS remains particularly challenging in this critical and very costly scenario in cardiology, but information from these trials is imperiously needed to better inform the guidelines and clinical practice. The goal of this review is to summarize the current knowledge concerning the definition, epidemiology, underlying causes, pathophysiology and management of CS based on important lessons from clinical trials and registries, with a focus on improving in‐hospital management.  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