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   40篇
  免费   1篇
化学工业   9篇
金属工艺   1篇
建筑科学   1篇
能源动力   1篇
轻工业   4篇
水利工程   2篇
无线电   1篇
一般工业技术   7篇
冶金工业   12篇
自动化技术   3篇
  2022年   2篇
  2021年   2篇
  2020年   4篇
  2019年   1篇
  2018年   3篇
  2017年   2篇
  2016年   2篇
  2014年   1篇
  2012年   2篇
  2011年   2篇
  2010年   1篇
  2006年   1篇
  2005年   4篇
  2001年   1篇
  1999年   1篇
  1998年   5篇
  1997年   5篇
  1996年   1篇
  1995年   1篇
排序方式: 共有41条查询结果,搜索用时 31 毫秒
1.
2.
3.
4.
In order to evaluate satisfaction with, and recollection of, the consent process, we sent a postal questionnaire to 204 patients who had taken part in one of six clinical trials. Three trials were multicentre commercial studies and three were 'in house'. The readability of the different patient information sheets was compared. Seventy-seven per cent of patients responded, of whom 82% remembered having an information sheet. Most (99%) thought this was easy to read and understand. Five patients claimed that they had felt pressurised to take part in the trials. Nearly all patients (97%) realised that participation was voluntary and that other treatment would not be affected; 83% knew they could have changed their minds. There were no differences in the response patterns between the patients taking part in the different trials although the patient information sheets produced by pharmaceutical companies were longer and more complex than the 'in hospital' variety. We conclude that increasing the amount and complexity of information does not alter patient satisfaction. Taken overall, patients were content with the way they were approached when asked for consent for clinical trials.  相似文献   
5.
Nuclear-magnetic-resonance (NMR) profiling of exhaled breath condensate (EBC) provides insights into the pathophysiology of bronchiectasis by identifying specific biomarkers. We evaluated whether NMR-based metabolomics discriminates the EBC-derived metabolic phenotypes (“metabotypes”) of 41 patients with non-cystic fibrosis (nCF) bronchiectasis of various etiology [24 subjects with Primary Ciliary Dyskinesia (PCD); 17 patients with bronchiectasis not associated with PCD (nCF/nPCD)], who were compared to 17 healthy subjects (HS). NMR was used for EBC profiling, and Orthogonal Projections to Latent Structures with partial least-squares discriminant analysis (OPLS-DA) was used as a classifier. The results were validated by using the EBC from 17 PCD patients not included in the primary analysis. Different statistical models were built, which compared nCF/nPCD and HS, PCD and HS, all classes (nCF/nPCD-PCD-HS), and, finally, PCD and nCF/nPCD. In the PCD-nCF/nPCD model, four statistically significant metabolites were able to discriminate between the two groups, with only a minor reduction of the quality parameters. In particular, for nCF/nPCD, acetone/acetoin and methanol increased by 21% and 18%, respectively. In PCD patients, ethanol and lactate increased by 25% and 28%, respectively. They are all related to lung inflammation as methanol is found in the exhaled breath of lung cancer patients, acetone/acetoin produce toxic ROS that damage lung tissue in CF, and lactate is observed in acute inflammation. Interestingly, a high concentration of ethanol hampers cilia beating and can be associated with the genetic defect of PCD. Model validation with 17 PCD samples not included in the primary analysis correctly predicted all samples. Our results indicate that NMR of EBC discriminates nCF/nPCD and PCD bronchiectasis patients from HS, and patients with nCF/nPCD from those with PCD. The metabolites responsible for between-group separation identified specific metabotypes, which characterize bronchiectasis of a different etiology.  相似文献   
6.
The law of refraction first derived by Snellius and later introduced as the Huygens-Fermat principle, states that the incidence and refracted angles of a light wave at the interface of two different materials are related to the ratio of the refractive indices in each medium. Whereas all natural materials have a positive refractive index and therefore exhibit refraction in the positive direction, artificially engineered negative index metamaterials have been shown capable of bending light waves negatively. Such a negative refractive index is the key to achieving a perfect lens that is capable of imaging well below the diffraction limit. However, negative index metamaterials are typically lossy, narrow band, and require complicated fabrication processes. Recently, an alternative approach to obtain negative refraction from a very thin nonlinear film has been proposed and experimentally demonstrated in the microwave region. However, such approaches use phase conjugation, which makes optical implementations difficult. Here, we report a simple but different scheme to demonstrate experimentally nonlinear negative refraction at optical frequencies using four-wave mixing in nanostructured metal films. The refractive index can be designed at will by simply tuning the wavelengths of the interacting waves, which could have potential impact on many important applications, such as superlens imaging.  相似文献   
7.
8.
ABSTRACT

The present paper presents the development of a thermal energy storage system for application with non-concentrating solar plants using phase change materials (PCMs). The outcomes of an experimental analysis on commercial PCMs and laboratory-grade chemical compounds suitable for latent heat storages in a temperature range of 80–100°C is presented, with main focus on to the enthalpy and the cycle stability of the materials. Particularly, a first evaluation of possible degradation mechanisms in hydrated salts was investigated by means of nuclear magnetic resonance spectroscopy. The best performing materials have been implemented in a numerical model, based on the enthalpy method, used for the design of a thermal storage system. The configuration of the system, starting from a simple shell-and-tube layout, has been optimized by inserting asymmetric fin-and-tubes and the results with two selected materials have been compared. The analysis has shown that the most promising materials are the commercial ones belonging to the classes of paraffinic materials and hydrated salts and that, with the designed configuration, it is possible to store up to 200 kJ/m3 and get a peak power during discharge of about 1.5 kW.  相似文献   
9.
Schimke immuno-osseous dysplasia (SIOD) is a rare multisystemic disorder with a variable clinical expressivity caused by biallelic variants in SMARCAL1. A phenotype–genotype correlation has been attempted and variable expressivity of biallelic SMARCAL1 variants may be associated with environmental and genetic disturbances of gene expression. We describe two siblings born from consanguineous parents with a diagnosis of SIOD revealed by whole exome sequencing (WES). Results: A homozygous missense variant in the SMARCAL1 gene (c.1682G>A; p.Arg561His) was identified in both patients. Despite carrying the same variant, the two patients showed substantial renal and immunological phenotypic differences. We describe features not previously associated with SIOD—both patients had congenital anomalies of the kidneys and of the urinary tract and one of them succumbed to a classical type congenital mesoblastic nephroma. We performed an extensive characterization of the immunophenotype showing combined immunodeficiency characterized by a profound lymphopenia, lack of thymic output, defective IL-7Rα expression, and disturbed B plasma cells differentiation and immunoglobulin production in addition to an altered NK-cell phenotype and function. Conclusions: Overall, our results contribute to extending the phenotypic spectrum of features associated with SMARCAL1 mutations and to better characterizing the underlying immunologic disorder with critical implications for therapeutic and management strategies.  相似文献   
10.
A rare case of adenocarcinoma of the duodenal bulb, arising from adenoma and submitted to Whipple's procedure is presented. A diagnostic delay of about 3 months, according to literature is observed. This delay is generally due to the low incidence of the illness, aspecific symptoms and frequent endoscopic and radiologic false negative, most of all in lesions of the third and fourth duodenal portions. Diagnostic tools for these duodenal tumors are endoscopy and upper gastrointestinal barium studies (UGI). CT is useful to determine preoperatively the stage of the illness and can occasionally show the primary duodenal lesion, as in this case. Surgical approach is still controversial, except in lesions of the second duodenal portion, where Whipple operation is the procedure of choice, if the tumor is resectable, of course. In the other duodenal portions some authors suggest segmental duodenal resections instead of Whipple's procedure.  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