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   287篇
  免费   27篇
  国内免费   1篇
耳鼻咽喉   1篇
妇产科学   1篇
基础医学   44篇
口腔科学   3篇
临床医学   21篇
内科学   126篇
皮肤病学   1篇
神经病学   31篇
特种医学   20篇
外科学   17篇
综合类   3篇
预防医学   11篇
眼科学   3篇
药学   14篇
肿瘤学   19篇
  2024年   1篇
  2023年   14篇
  2022年   19篇
  2021年   15篇
  2020年   11篇
  2019年   12篇
  2018年   21篇
  2017年   10篇
  2016年   12篇
  2015年   10篇
  2014年   14篇
  2013年   21篇
  2012年   31篇
  2011年   35篇
  2010年   12篇
  2009年   5篇
  2008年   10篇
  2007年   11篇
  2006年   12篇
  2005年   13篇
  2004年   9篇
  2003年   7篇
  2002年   5篇
  2001年   2篇
  1997年   1篇
  1977年   1篇
  1967年   1篇
排序方式: 共有315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.
Aging is a risk factor for many chronic noncommunicable diseases, including chronic obstructive pulmonary disease (COPD), which is often associated with cardiovascular disease (CVD). Moreover, aging is associated with a mild form of systemic inflammation. The aim of our study was to analyze the relationship between age, systemic and vascular inflammation, and the presence of CVD comorbidities in a stable COPD population. Forty COPD patients were divided into 2 age groups (<65 and ≥65 years of age), from which we collected the following inflammatory biomarkers: C-reactive protein, tumor necrosis factor alpha (TNF-α), interleukin-6 (IL-6), and endothelin-1 (ET-1). Elderly COPD patients had more frequent exacerbation events per year (2 vs 1, P = .06), a higher prevalence of CVD (3 vs 2, P = .04), more limited exercise tolerance (6-minute walking test distance, 343 [283–403] vs 434 [384–484]; P = .02), and mild systemic inflammation (TNF-α, 9.02 [7.08–10.96] vs 6.48 [5.21–7.76]; P = .03; ET-1, 2.24 [1.76–2.71] vs 1.67 [1.36–1.98] pg/mL; P = .04). A weak correlation between age and ET-1 (r = 0.32, P = .04) was observed. Mild systemic inflammation, characterized by a slightly increased level of TNF-α, and endothelial dysfunction, marked by elevated ET-1, could be liaisons between aging, COPD, and CVD comorbidities.  相似文献   
5.
This paper presents the usage of spark plasma sintering (SPS) as a method to obtain aluminum-expanded perlite syntactic foams with high porosity. In the test samples, fine aluminum powder with flaky shape particles was used as matrix material and natural, inorganic, granular, expanded perlite was used as a space holder to ensure high porosity (35–57%) and uniform structure. SPS was used to consolidate the specimens. The structures were characterized by scanning electron microscopy and compression tests. Energy absorption (W~7.49 MJ/m3) and energy absorption efficiency (EW < 90%) were also determined.  相似文献   
6.
This paper addressed the issues of both direct and indirect synthesis of Ni aluminides by pack cementation (pure Ni and IN 718 superalloy). On the Al-Ni diffusion twosome under pressure, at temperatures below and above the Al melting temperature, the appearance and evolution of diffusion porosity because of the Kirkendall–Frenkel effect manifestation was highlighted. It has been confirmed that, as the temperature rises above the Al melting temperature, the porosity decreases. Nickel-based superalloys, and in particular IN 718, significantly increase their performance by increasing the aluminides proportion in the top diffusion coating. This is made possible by changing the value of the Al and Ni weight percentage ratio in this area (noted as Al/Ni). In the case of the diffusion twosome between IN 718 and pack aluminizing mixtures, having in their composition as active components Al powder, Ferroaluminum (FeAl40) or mixtures of Al and Fe powders, at processing temperatures above the Al melting temperature, by modifying the active component of the mixture, substantial changes in the Al/Ni values were observed, as well as in the maximum %Al in the diffusion coating and of its thickness. It was found that, when switching from Al to FeAl40 or powder mixture (Al + Fe), the Al/Ni value changes between 3.43 and 1.01, from initial subunit values. The experiments confirmed that the highest %Al in the top aluminized diffusion coating, for IN 718, was obtained if the powder mixture contained 66.34 wt.% Al.  相似文献   
7.
Grape pomace and berries represent natural sources of phytochemicals that can increase the quality of life of consumers by contributing to the prevention of chronic diseases; thus, the development of a dietary supplement was necessary. The raw material (r.m.) used for the development of the dietary supplement consisted of dried and powdered bilberries (Vaccinium myrtillus L.), red currants (Ribes rubrum L.), and red fermented pomaces (Vitis vinifera L.) from Feteasca Neagra and Cabernet Sauvignon cultivars. The particle size distribution, powder flow, total phenolic content (TPC), HPLC-DAD phenolic profile assessment, and radical scavenging assay (RSA) were employed for the analysis of the raw material. After encapsulation, the average mass and uniformity of mass, the disintegration, and the uniformity of content for the obtained capsules were performed to obtain a high-quality dietary supplement. All the assays performed complied to the compendial requirements and the TPC was determined at 9.07 ± 0.25 mg gallic acid equivalents/g r.m. and RSA at 48.32 ± 0.74%. The highest quantities of phenolic compounds determined were 333.7 ± 0.50 µg/g r.m. for chlorogenic acid, followed by rutin, ferulic acid, and (+)-catechin with 198.9 ± 1.60 µg/g r.m., 179.8 ± 0.90 µg/g r.m. and 118.7 ± 0.75 µg/g r.m., respectively. The results of this study can be used for the manufacturing and assessing of pilot scale-up capsule batches and thinking of quality assurance, we recommend that the industrial batch extracts should be standardized in polyphenols, and the manufacturing process should be validated.  相似文献   
8.
Androgen insensitivity syndrome (AIS) is an X-linked recessive genetic syndrome that occurs as result of an androgen receptor mutation; it affects the normal masculinization process in chromosomal male patients. More than 900 androgen receptor mutations that can lead to AIS have been identified. The complete androgen insensitivity is characterized by a total lack of response to androgens, usually in patients with 46XY karyotype but with feminine phenotype. Primary amenorrhoea and inguinal swellings in female patients are the main signs that could raise suspicion for this syndrome. Patients with partial androgen insensitivity have ambiguous genitalia at birth and gynecomastia during puberty, whereas those with mild androgen insensitivity present a normal male phenotype but altered spermatogenesis during adulthood and pubertal gynecomastia. The diagnosis of AIS often proves to be a challenge; its management is complex and requires a multidisciplinary approach to meet decision-making challenges in sex assignment, fertility and timing of gonadectomy, psychological outcomes and genetic counselling.  相似文献   
9.
Colorectal cancer (CRC) remains a major cause of cancer-related mortality. Consequently, new diagnostic and therapeutic approaches are being investigated including the serum levels of cytokines and other molecules, although the results are often inconclusive. Thus, the present study aimed to determine whether serum level of cytokines, cell adhesion molecules or matrix metalloproteinases (MMPs), alone or in combination, may contribute to the non-invasive diagnosis of CRC. The serum levels of nine cytokines [ILs; IL-1β, IL-4, IL-6, IL-8, IL-10, IL-17, IL-22 and IL-33, and interferon (IFN)-γ], two cell adhesion molecules (intercellular adhesion molecule-1 and P-selectin) and an MMP-7 were measured by ELISA in 33 patients with CRC and 35 healthy controls. Combined capacity of all molecules to detect the presence of CRC was assessed by logistic regression. Molecules and molecule combinations were tested for all stages and tumor grades. A significant increase was identified for IL-8 in patients compared with healthy controls; IL-10 was found to be significantly decreased. The biomarker potential of each significantly modified molecule was tested: IL-8 had a sensitivity of 0.865, a specificity of 0.600 and an area under the curve (AUC) of 0.777; for IL-10, sensitivity was 0.65, specificity was 0.69, with an AUC of 0.689. Logistic regression determined the best discriminative potential between patients and control groups for the combination IL-4 + IL-6 + IL-8 + IFN-γ, with 0.97 sensitivity and 0.58 specificity. For the early stages of CRC, the combination IL-6 + IL-8 + IL-22 showed good performance. It was concluded that increased IL-8 had potential as single biomarker in CRC. Cytokine combinations are superior to single cytokine analysis in showing the presence of CRC.  相似文献   
10.
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