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   134篇
  免费   9篇
  国内免费   2篇
化学工业   40篇
金属工艺   1篇
机械仪表   4篇
建筑科学   7篇
能源动力   6篇
轻工业   12篇
水利工程   2篇
无线电   15篇
一般工业技术   32篇
冶金工业   3篇
自动化技术   23篇
  2023年   2篇
  2022年   2篇
  2021年   6篇
  2020年   4篇
  2019年   5篇
  2018年   9篇
  2017年   8篇
  2016年   12篇
  2015年   10篇
  2014年   9篇
  2013年   10篇
  2012年   20篇
  2011年   11篇
  2010年   3篇
  2009年   5篇
  2008年   4篇
  2007年   9篇
  2006年   2篇
  2005年   3篇
  2003年   1篇
  2001年   1篇
  2000年   3篇
  1999年   2篇
  1998年   1篇
  1996年   1篇
  1978年   1篇
  1943年   1篇
排序方式: 共有145条查询结果,搜索用时 78 毫秒
61.
Although the cognitive disorder of multiple sclerosis (MS) is well characterized, little is known about personality changes that may occur in this disease. There are reliable personality tests available for research in neurological disease, based on the well-known Five Factor Model. Preliminary research suggests that cognitively impaired MS patients exhibit elevation in Neuroticism, and diminution in Extraversion, Agreeableness, and Conscientiousness, as do patients with Alzheimer's disease. We predicted that these characteristics would be associated with lower neocortical volume. We studied 44 patients using brain MRI and the NEO Five-Factor Inventory. Regression models controlling for T2 lesion volume, depression, and cognitive dysfunction revealed significant correlation between cortical atrophy and reduction in Extraversion and Conscientiousness. Discrepancies between patient- and informant-reports were found, and overreporting of high Openness and Conscientiousness among patients was associated with lower neocortical volume. A final regression model accounting for depression, cognitive function, and personality accounted for 38% of the variance in neocortical volume. These findings suggest that cortical atrophy in MS is associated with adverse impact on personality, although longitudinal research is needed to test this hypothesis. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
62.
Simple and reliable immobilization techniques that preserve the activity of enzymes are of interest in many technologies based on catalysis. Here, two redox enzymes, glucose oxidase from Aspergillus niger and horseradish peroxidase, were immobilized by physisorption on glassy carbon electrodes coated with Schizophyllum commune hydrophobin. Hydrophobins are small, interfacially active proteins that have the remarkable property of adhering to almost any surface. We showed recently that these proteins can be used to immobilize small, electroactive molecules. The results obtained in this work show a way to easily manufacture stable, enzyme-based catalytic surfaces for applications in biosensing.  相似文献   
63.
Conifer trees resist pest and pathogen attacks by complex defense responses involving different classes of defense compounds. However, it is unknown whether prior infection by biotrophic pathogens can lead to subsequent resistance to necrotrophic pathogens in conifers. We used the infection of jack pine, Pinus banksiana, by a common biotrophic pathogen dwarf mistletoe, Arceuthobium americanum, to investigate induced resistance to a necrotrophic fungus, Grosmannia clavigera, associated with the mountain pine beetle, Dendroctonus ponderosae. Dwarf mistletoe infection had a non-linear, systemic effect on monoterpene production, with increasing concentrations at moderate infection levels and decreasing concentrations at high infection levels. Inoculation with G. clavigera resulted in 33 times higher monoterpene concentrations and half the level of phenolics in the necrotic lesions compared to uninoculated control trees. Monoterpene production following dwarf mistletoe infection seemed to result in systemic induced resistance, as trees with moderate disease severity were most resistant to G. clavigera, as evident from shorter lesion lengths. Furthermore, trees with moderate disease severity had the highest systemic but lowest local induction of α-pinene after G. clavigera inoculation, suggesting a possible tradeoff between systemically- and locally-induced defenses. The opposing effects to inoculation by G. clavigera on monoterpene and phenolic levels may indicate the potential for biosynthetic tradeoffs by the tree between these two major defense classes. Our results demonstrate that interactions between a biotrophic parasitic plant and a necrotrophic fungus may impact mountain pine beetle establishment in novel jack pine forests through systemic effects mediated by the coordination of jack pine defense chemicals.  相似文献   
64.
Using biodegradable polypropylene carbonate (PPC) as the polymer matrix and 5 to 25?wt% content of spent coffee bean powder (SCBP) as filler, completely biodegradable composite films of PPC/SCBP were prepared. These composite films were characterized by polarized optical microscopy (POM), Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), thermogravimetric analysis, differential scanning calorimetry (DSC), and tensile tests. The POM images indicated the uniform distribution of the SCBP in the composites. The FTIR spectra indicated that the PPC structure was retained by the composite films. The XRD analysis found that the composite films had lower crystallinity than the PPC due to the presence of amorphous hemicellulose containing SCBP. A significant enhancement in thermal stability of the filler reinforced composite was noticed which was more than 30% of the PPC matrix due to the presence of polyphenols in SCBP. A maximum increase of 35% of tensile strength was observed with the addition of 20?wt% SCBP filled composite films. These biodegradable composite films with higher thermal stability and tensile strength can be considered for packaging applications.  相似文献   
65.
Nadir Patir 《Wear》1978,47(2):263-277
A numerical procedure for randomly generating any general threedimensional surface roughness with prescribed statistical properties is presented. Through the use of linear transformations on random matrices, this procedure is capable of generating Gaussian or non-Gaussian rough surfaces with any given surface autocorrelation function. As an example of the numerical procedure, a Gaussian surface having a predetermined exponential autocorrelation function is generated.  相似文献   
66.
Periodic mesoporous organosilica nanoparticles emerge as promising vectors for nanomedicine applications. Their properties are very different from those of well‐known mesoporous silica nanoparticles as there is no silica source for their synthesis. So far, they have only been synthesized from small bis‐silylated organic precursors. However, no studies employing large stimuli‐responsive precursors have been reported on such hybrid systems yet. Here, the synthesis of porphyrin‐based organosilica nanoparticles from a large octasilylated metalated porphyrin precursor is described for applications in near‐infrared two‐photon‐triggered spatiotemporal theranostics. The nanoparticles display unique interconnected large cavities of 10–80 nm. The framework of the nanoparticles is constituted with J‐aggregates of porphyrins, which endows them with two‐photon sensitivity. The nanoparticle efficiency for intracellular tracking is first demonstrated by the in vitro near‐infrared imaging of breast cancer cells. After functionalization of the nanoparticles with aminopropyltriethoxysilane, two‐photon‐excited photodynamic therapy in zebrafish is successfully achieved. Two‐photon photochemical internalization in cancer cells of the nanoparticles loaded with siRNA is also performed for the first time. Furthermore, siRNA targeting green fluorescent protein complexed with the nanoparticles is delivered in vivo in zebrafish embryos, which demonstrates the versatility of the nanovectors for biomedical applications.  相似文献   
67.
68.
开放标准的肿瘤信息系统在不断发展,以此应对现代肿瘤临床试验带来的挑战。本文提出面向服务的软件范例,用于衍生临床试验信息管理系统,支持多机构协同肿瘤研究。提出的方案将临床试验(元)模型和基于WSRF(Web Services Resource Framework)的面向服务体系结构(Service-Oriented Architecture,SOA)相结合,并且应用早期临床试验进行评估。尽管主要目的是针对肿瘤研究,但也适用于具有相似信息模型的其它领域。  相似文献   
69.
70.
In this paper we study the accessibility by visually impaired people of the learning management system (LMS) Moodle 2. The study is conducted by testing four different visually impaired subjects, with different degrees of disability and performing different tasks connected to different roles in the LMS. A peculiar focus is given to the accessibility of content involving mathematics. At the end of the paper, some recommendations to improve the accessibility of Moodle 2 are given.  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