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   174篇
  免费   3篇
  国内免费   2篇
妇产科学   2篇
基础医学   33篇
口腔科学   2篇
临床医学   9篇
内科学   38篇
皮肤病学   3篇
神经病学   10篇
特种医学   1篇
外科学   26篇
预防医学   21篇
眼科学   1篇
药学   11篇
中国医学   1篇
肿瘤学   21篇
  2023年   1篇
  2022年   12篇
  2021年   21篇
  2020年   3篇
  2019年   13篇
  2018年   2篇
  2017年   3篇
  2016年   4篇
  2015年   6篇
  2014年   9篇
  2013年   9篇
  2012年   15篇
  2011年   16篇
  2010年   10篇
  2009年   6篇
  2008年   8篇
  2007年   5篇
  2006年   5篇
  2005年   9篇
  2004年   9篇
  2003年   6篇
  2002年   5篇
  1982年   1篇
  1970年   1篇
排序方式: 共有179条查询结果,搜索用时 15 毫秒
1.
Background There is limited information about the clinical characteristics, treatment and outcome of maintenance hemodialysis patients with COVID-19. Moreover, regional differences are also conceivable since the extend and severity of outbreaks varied among countries.Methods In this retrospective, observational, single-center study, we analyzed the clinical course and outcomes of 37 maintenance hemodialysis patients (median age 64 years, 51% men) hospitalized with COVID-19 from 24 March to 22 May 2020 as confirmed by real-time PCR.Results The most common symptoms at admission were fatigue (51%), fever (43%), dyspnea (38%) and cough (35%). There were 59% mild/moderate patients and 41% severe/critical patients. Patients in the severe/critical group had a significantly higher atherosclerotic burden since diabetic kidney disease and vascular nephropathies were the most common primary kidney diseases and eighty percent of them had coronary heart disease. Also, Charlson comorbidity score was higher in this group. At admission chest X-ray, 46% had ground-glass abnormalities. Overall, 60% patients received hydroxychloroquine, 22% lopinavir–ritonavir, 11% tocilizumab, 24% systemic glucocorticoids, and 54% received prophylactic anticoagulation. Seven (19%) patients died during hospitalization and 30 were discharged. The main causes of death were cardiovascular (5 patients) and respiratory distress syndrome (2 patients). In Cox regression analysis, lower oxygen saturation, anemia and hypoalbuminemia at admission were associated with increased mortality.Conclusions In conclusion, we observed a high mortality rate among maintenance hemodialysis patients hospitalized for COVID-19. Anemia, lower serum albumin and lower basal oxygen saturation at admission were factors associated with poor prognosis.  相似文献   
2.
The aim of this study was to determine the effects of main factors and interactions on the color removal performance from dye solutions using the electrocoagulation process enhanced by adsorption on Granular Activated Carbon (GAC). In this study, a mathematical approach was conducted using a two-level fractional factorial design (FFD) for a given dye solution. Three textile dyes: Acid Blue 74, Basic Red 1, and Reactive Black 5 were used. Experimental factors used and their respective levels were: current density (2.73 or 27.32 A/m2), initial pH of aqueous dye solution (3 or 9), electrocoagulation time (20 or 180 min), GAC dose (0.1 or 0.5 g/L), support electrolyte (2 or 50 mM), initial dye concentration (0.05 or 0.25 g/L) and current type (Direct Current—DC or Alternative Pulsed Current—APC). GAC-enhanced electrocoagulation performance was analyzed statistically in terms of removal efficiency, electrical energy, and electrode material consumptions, using modeling polynomial equations. The statistical significance of GAC dose level on the performance of GAC enhanced electrocoagulation and the experimental conditions that favor the process operation of electrocoagulation in APC regime were determined. The local optimal experimental conditions were established using a multi-objective desirability function method.  相似文献   
3.
The aim of this cross-sectional study was to examine the association of supernatural beliefs and sense of coherence with death anxiety and death depression in a Romanian sample of cancer patients. We found support for the terror management theory worldview defence hypothesis postulating the presence of a curvilinear relation between death anxiety and supernatural beliefs among cancer patients. Results conformed to an inverted U-shape quadratic regression, indicating that cancer patients who scored moderately on supernatural beliefs were afraid of death the most, while death anxiety was lowest for the extreme atheists and extreme believers in supernatural entities.  相似文献   
4.
While high levels of activity and exercise training have been associated with improvements in sleep quality, minimum levels of activity likely to improve sleep outcomes have not been explored. A two‐armed parallel randomized controlled trial (N=41; 30 females) was designed to assess whether increasing physical activity to the level recommended in public health guidelines can improve sleep quality among inactive adults meeting research diagnostic criteria for insomnia. The intervention consisted of a monitored program of ≥150 min of moderate‐ to vigorous‐intensity physical activity per week, for 6 months. The principal end‐point was the Insomnia Severity Index at 6 months post‐baseline. Secondary outcomes included measures of mood, fatigue and daytime sleepiness. Activity and light exposure were monitored throughout the trial using accelerometry and actigraphy. At 6 months post‐baseline, the physical activity group showed significantly reduced insomnia symptom severity (F8,26 = 5.16, = 0.03), with an average reduction of four points on the Insomnia Severity Index; and significantly reduced depression and anxiety scores (F6,28 = 5.61, P = 0.02; and F6,28 = 4.41, P = 0.05, respectively). All of the changes were independent of daily light exposure. Daytime fatigue showed no significant effect of the intervention (F8,26 = 1.84, P = 0.18). Adherence and retention were high. Internationally recommended minimum levels of physical activity improve daytime and night‐time symptoms of chronic insomnia independent of daily light exposure levels.  相似文献   
5.
6.
In this research work, silica nanoparticles and silica-gentamicin nanostructured solution were synthesized by using the microwave-assisted synthesis, in basic medium, using two silane precursors (tetraethylorthosilicate and octyltriethoxysilane) and the antibiotic (gentamicin sulfate). The prepared materials were characterized through Fourier transform infrared (FTIR) spectroscopy, TGA analysis, transmission electron microscopy (TEM), and atomic force microscopy (AFM) to investigate the morphology and structure. Antimicrobial studies of the silica-gentamicin nanostructured solution versus silica nanoparticles were performed against Pseudomonas aeruginosa, Staphylococcus aureus, and Escherichia coli. FTIR spectra showed that the gentamicin has been loaded to the silica nanoparticles. AFM analysis showed that the morphology of the silica-gentamicin nanostructured solution has changed, and agglomerations of particles are present at the surface. Antimicrobial testing, performed using the diffusion method through spot inoculation, indicates that the silica-gentamicin nanostructured solution exhibited activity against the resistant strain. The obtained silica-gentamicin solution can be used as biochemical agent for the prevention and treatment of microorganisms which are deposited on different surfaces (e.g., glass, plastic, ceramic).  相似文献   
7.
The effect of carbon ion radiotherapy on hypoxic tumors has recently been questioned because of low linear energy transfer (LET) values in the spread-out Bragg peak (SOBP). The aim of this study was to investigate the role of hypoxia and local oxygenation changes (LOCs) in fractionated carbon ion radiotherapy. Three-dimensional tumors with hypoxic subvolumes were simulated assuming interfraction LOCs. Different fractionations were applied using a clinically relevant treatment plan with a known LET distribution. The surviving fraction was calculated, taking oxygen tension, dose and LET into account, using the repairable–conditionally repairable (RCR) damage model with parameters for human salivary gland tumor cells. The clinical oxygen enhancement ratio (OER) was defined as the ratio of doses required for a tumor control probability of 50% for hypoxic and well-oxygenated tumors. The resulting OER was well above unity for all fractionations. For the hypoxic tumor, the tumor control probability was considerably higher if LOCs were assumed, rather than static oxygenation. The beneficial effect of LOCs increased with the number of fractions. However, for very low fraction doses, the improvement related to LOCs did not compensate for the increase in total dose required for tumor control. In conclusion, our results suggest that hypoxia can influence the outcome of carbon ion radiotherapy because of the non-negligible oxygen effect at the low LETs in the SOBP. However, if LOCs occur, a relatively high level of tumor control probability is achievable with a large range of fractionation schedules for tumors with hypoxic subvolumes, but both hyperfractionation and hypofractionation should be pursued with caution.  相似文献   
8.

Introduction

Breast cancer is the most prevalent cancer in women, with slightly more than ten percent developing the disease in Western countries. Mammography screening is a well established method to detect breast cancer.

Aims

The aim of the position statement is to review critically the advantages and shortcomings of population based mammography screening.

Materials and methods

Literature review and consensus of expert opinion.

Results and conclusion

Mammography screening programmes vary worldwide. Thus there are differences in the age at which screening is started and stopped and in the screening interval. Furthermore differences in screening quality (such as equipment, technique, resolution, single or double reading, recall rates) result in a sensitivity varying from 70% to 94% between studies. Reporting results of screening is subject to different types of bias such as overdiagnosis. Thus because of the limitations of population-based mammography screening programmes an algorithm for individualized screening is proposed.  相似文献   
9.
We describe a case of concomitant erythropoietin allergy and resistance with a possible IgE and IgG‐mediated immune response, in which the local allergic cutaneous symptoms preceded the antibody‐mediated anemia.  相似文献   
10.
One of the strategies employed to increase the sensitivity of the fluorescence-based biosensors is to deposit chromophores on plasmonic metasurfaces which are periodic arrays of resonating nano-antennas that allow the control of the electromagnetic field leading to fluorescence enhancement. While artificially engineered metasurfaces realized by micro/nano-fabrication techniques lead to a precise tailoring of the excitation field and resonant cavity properties, the technological overhead, small areas, and high manufacturing cost renders them unsuitable for mass production. A method to circumvent these challenges is to use random distribution of metallic nanoparticles sustaining plasmonic resonances, which present the properties required to significantly enhance the fluorescence. We investigate metasurfaces composed of random aggregates of metal nanoparticles deposited on a silicon and glass substrates. The finite difference time domain simulations of the interaction of the incident electromagnetic wave with the structures reveals a significant enhancement of the excitation field, which is due to the resonant plasmonic modes sustained by the nanoparticles aggregates. We experimentally investigated the role of these structures in the fluorescent behaviour of Rhodamine 6G dispersed in polymethylmethacrylate finding an enhancement that is 423-fold. This suggests that nanoparticle aggregates have the potential to constitute a suitable platform for low-cost, mass-produced fluorescent biosensors.  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