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   495篇
  免费   26篇
  国内免费   1篇
电工技术   11篇
综合类   1篇
化学工业   120篇
金属工艺   17篇
机械仪表   13篇
建筑科学   19篇
能源动力   25篇
轻工业   52篇
水利工程   5篇
石油天然气   1篇
无线电   34篇
一般工业技术   71篇
冶金工业   19篇
原子能技术   4篇
自动化技术   130篇
  2024年   1篇
  2023年   6篇
  2022年   35篇
  2021年   35篇
  2020年   14篇
  2019年   19篇
  2018年   16篇
  2017年   18篇
  2016年   12篇
  2015年   13篇
  2014年   18篇
  2013年   49篇
  2012年   32篇
  2011年   32篇
  2010年   29篇
  2009年   27篇
  2008年   16篇
  2007年   23篇
  2006年   24篇
  2005年   18篇
  2004年   12篇
  2003年   11篇
  2002年   7篇
  2001年   9篇
  2000年   3篇
  1999年   4篇
  1998年   6篇
  1997年   3篇
  1996年   5篇
  1995年   5篇
  1994年   4篇
  1993年   1篇
  1992年   3篇
  1990年   1篇
  1988年   2篇
  1985年   3篇
  1983年   1篇
  1981年   2篇
  1979年   1篇
  1977年   1篇
  1974年   1篇
排序方式: 共有522条查询结果,搜索用时 15 毫秒
141.
The collapse behavior of cylindrical shells pressurized from outside is examined. Attention is focused on tubes of moderate thickness, as required by very deep water pipelines or some innovative nuclear power plant proposals. Their collapse is expected to be dominated by yielding but, because of the decreasing nature of the post-collapse evolution, interaction with instability is likely to be significant enough to demand consideration. At present, no quantitative assessment of such effect is available, because little study has been devoted to tubes in this thickness range.Plasticity–instability interaction is activated by imperfections and to assess their influence on a systematic numerical study is undertaken. Computations produce a meaningful measure of the collapse pressure and it is proposed that the allowable pressure be determined on its basis, by introducing a suitable safety factor. This is chosen so that results reproduce those provided by presently accepted procedures in the well explored and reliable range of medium-thin tubes. When the same factor is applied to thicker tubes, the resulting allowable pressure is significantly higher than the values suggested by codes, which apparently react to the present lack of knowledge by assuming an extremely conservative attitude.  相似文献   
142.
Osteoarthritis (OA) is a degenerative bone disease that involved micro and macro-environment of joints. To date, there are no radical curative treatments for OA and novel therapies are mandatory. Recent evidence suggests the role of miRNAs in OA progression. In our previous studies, we demonstrated the role of miR-31-5p and miR-33a families in different bone regeneration signaling. Here, we investigated the role of miR-31-5p and miR-33a-5p in OA progression. A different expression of miR-31-5p and miR-33a-5p into osteoblasts and chondrocytes isolated from joint tissues of OA patients classified in based on different Kellgren and Lawrence (KL) grading was highlighted; and through a bioinformatic approach the common miRNAs target Specificity proteins (Sp1) were identified. Sp1 regulates the expression of gap junction protein Connexin43 (Cx43), which in OA drives the modification of (i) osteoblasts and chondrocytes genes expression, (ii) joint inflammation cytokines releases and (iii) cell functions. Concerning this, thanks to gain and loss of function studies, the possible role of Sp1 as a modulator of CX43 expression through miR-31-5p and miR-33a-5p action was also evaluated. Finally, we hypothesize that both miRNAs cooperate to modulate the expression of SP1 in osteoblasts and chondrocytes and interfering, consequently, with CX43 expression, and they might be further investigated as new possible biomarkers for OA.  相似文献   
143.
144.
The aim of this study was the identification of specific proteomic profiles, related to a restored cystic fibrosis transmembrane conductance regulator (CFTR) activity in cystic fibrosis (CF) leukocytes before and after ex vivo treatment with the potentiator VX770. We used leukocytes, isolated from CF patients carrying residual function mutations and eligible for Ivacaftor therapy, and performed CFTR activity together with proteomic analyses through micro-LC–MS. Bioinformatic analyses of the results obtained revealed the downregulation of proteins belonging to the leukocyte transendothelial migration and regulation of actin cytoskeleton pathways when CFTR activity was rescued by VX770 treatment. In particular, we focused our attention on matrix metalloproteinase 9 (MMP9), because the high expression of this protease potentially contributes to parenchyma lung destruction and dysfunction in CF. Thus, the downregulation of MMP9 could represent one of the possible positive effects of VX770 in decreasing the disease progression, and a potential biomarker for the prediction of the efficacy of therapies targeting the defect of Cl transport in CF.  相似文献   
145.
International Journal of Computer Vision - In this paper, a unified three-layer hierarchical approach for solving tracking problem in a multiple non-overlapping cameras setting is proposed. Given a...  相似文献   
146.
In this article we question the utility of the distinction between conceptual and nonconceptual content in cognitive science, and in particular, in the empirical study of visual perception. First, we individuate some difficulties in characterizing the notion of “concept” itself both in the philosophy of mind and cognitive science. Then we stress the heterogeneous nature of the notion of nonconceptual content and outline the complex and ambiguous relations that exist between the conceptual/nonconceptual duality and other pairs of notions, such as top–down/bottom-up and modular/nonmodular. Finally we look in greater detail at the proposal developed by Jacob and Jeannerod (Ways of seeing. The scopes and limits of visual cognition. Oxford, UK: Oxford University Press, 2003), who apply the notion of nonconceptual content to empirical research on visual perception. After reconstructing their point of view on concepts, we try to reject their major arguments in support of the conceptual/nonconceptual distinction, i.e. the compositionality of thought and the fineness of grain of percepts.  相似文献   
147.
148.
PET radiotracer development to target in vivo P‐glycoprotein (P‐gp) could be an important strategy for the early diagnosis of neurodegenerative disorders such as Alzheimer’s disease (AD). Indeed, as a dysfunction of P‐gp is responsible for the accumulation of β‐amyloid plaques (a hallmark of AD) in brain parenchyma, P‐gp is the cause of AD onset. P‐gp substrates and inhibitors are useful for imaging the activity or expression of this protein, respectively; herein we discuss the in vivo evaluation of some 11C radiotracers with P‐gp‐inhibitory activity, such as [11C]MC18 and [11C]MC113, as well as P‐gp substrates [11C]MC266 and [11C]MC80. Moreover, the radiosynthesis of all these P‐gp probes is reported.  相似文献   
149.
The growing dispersion of ICs’ parameters poses relevant uncertainties on gate output conductances and logic thresholds which play a main role in bridging fault detection. In this evolving context, the quality of fault simulation and test generation tools making use of nominal parameters should be verified. To analyze this problem we have studied bridging fault detection in combinational ICs in the presence of growing variations of IC’s parameters. Results show that a single test is not sufficient to ensure acceptable escape probabilities. Conversely, the minimal number of test vectors required to provide a null escape probability is upper bounded with respect to variations in the standard deviation of IC’s parameters. This result has been verified by means of Monte Carlo electrical level simulation. We propose a method to derive these minimal test sets in the case of low frequency tests. A fault simulator and a test generator have been developed supporting the search of minimal test sets targeting a null escape probability. These tools have been applied to a set of combinational benchmarks.
Michele FavalliEmail:

Michele Favalli   received the Dr. Eng. degree in Electronic Engineering from the University of Bologna in 1987 and the Ph. D. in Electronic Engineering and Computer Science in 1993. From 1993 he has worked at the Department of Electronics at the University of Bologna as a Researcher. From 1998 he is Associate Professor of Computer Science at the University of Ferrara. His research interests are in the area of digital IC’s design and testing. They include fault modeling, fault simulation, test generation, on-line testing and fault tolerant circuits. Marcello Dalpasso   received the B.S. degree (summa cum laude) in electrical engineering, in 1990, and the Ph.D. degree in computer science, in 1994, from the University of Bologna, Italy. Since 2004, he has been an Associate Professor at the University of Padova, Italy, where he teaches computer science. His research interests include the areas of fault modeling and simulation for digital IC design and CAD frameworks and tools for intellectual-property protection in EDA.  相似文献   
150.
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