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   220篇
  免费   14篇
  国内免费   4篇
电工技术   2篇
化学工业   28篇
金属工艺   8篇
机械仪表   7篇
建筑科学   20篇
能源动力   28篇
轻工业   26篇
水利工程   5篇
石油天然气   1篇
无线电   17篇
一般工业技术   57篇
冶金工业   20篇
自动化技术   19篇
  2024年   2篇
  2023年   8篇
  2022年   4篇
  2021年   12篇
  2020年   5篇
  2019年   11篇
  2018年   15篇
  2017年   13篇
  2016年   12篇
  2015年   9篇
  2014年   11篇
  2013年   23篇
  2012年   10篇
  2011年   14篇
  2010年   9篇
  2009年   11篇
  2008年   8篇
  2007年   4篇
  2006年   4篇
  2005年   3篇
  2004年   4篇
  2003年   1篇
  2002年   4篇
  2001年   3篇
  2000年   3篇
  1999年   3篇
  1998年   3篇
  1997年   5篇
  1996年   1篇
  1995年   4篇
  1994年   1篇
  1991年   2篇
  1990年   2篇
  1989年   2篇
  1986年   3篇
  1985年   2篇
  1984年   1篇
  1983年   1篇
  1982年   1篇
  1980年   1篇
  1979年   1篇
  1977年   1篇
  1974年   1篇
排序方式: 共有238条查询结果,搜索用时 0 毫秒
1.
The role of myelin basic protein (MBP) T cell recognition in the induction of experimental allergic encephalomyelitis (EAE) has been well established in mice and rats. A remarkable restriction has been observed in T cell receptor (TCR) genes utilized by encephalitogenic T cell lines (TCLs) specific for immunodominant epitopes in these species. Pathological similarities between this animal model and multiple sclerosis (MS) has led to consider MBP as a major candidate autoantigen in this human disorder. Unlike in inbred strains of animals, the T cell response to MBP in humans is quite heterogenous with regard to fine epitope specificity. The existence of V alpha and/or V beta restriction in MBP-specific T cells, from MS patients and healthy controls, is still a matter of debate. In this study we generated 77 MBP-specific TCLs from nine healthy donors and showed that peptide 7-27 is one of the most frequently recognized epitopes. 37% of all epitope-specific TCLs recognized this peptide and p7-27 specific TCLs were generated from seven out of the nine subjects studied. A high level of in vivo clonal expansion was observed in p7-27-specific TCLs in several subjects, which however is not specific of this epitope since this phenomenon was also observed in p85-104- and 149-162-specific TCLs.  相似文献   
2.
3.
To evade signature-based detection, metamorphic viruses transform their code before each new infection. Software similarity measures are a potentially useful means of detecting such malware. We can compare a given file to a known sample of metamorphic malware and compute their similarity—if they are sufficiently similar, we classify the file as malware of the same family. In this paper, we analyze an opcode-based software similarity measure inspired by simple substitution cipher cryptanalysis. We show that the technique provides a useful means of classifying metamorphic malware.  相似文献   
4.
In this article, new probabilistic health-informatics indices connecting probabilities: Pr(A),Pr(B),Pr(A IB) and P r(A ]B-) are discovered, where .4 and B denote respectively the "ability of a hospital to treat anthrax patients" and "whether a hospital drilled to be prepared to deal with an adverse bioterrorism". These probabilistic informatics are not seen in any textbooks or journal articles and yet, they are too valuable to be unnoticed to comprehend the hospitals' preparedness to treat anthrax patients in an outbreak of bioterrorism. A demonstration of this new probabilistic informatics is made in this article with the data in the U.S. Government's General Accounting Office's report GA0-03-924. Via this example, this article advocates the importance of the above mentioned probabilistic-informatics for health professionals to understand and act swiftly to deal with public health emergencies.  相似文献   
5.
Multilayered multi‐material interfaces are encountered in an array of fields. Here, enhanced mechanical performance of such multi‐material interfaces is demonstrated, focusing on strength and stiffness, by employing bondlayers with spatially‐tuned elastic properties realized via 3D printing. Compliance of the bondlayer is varied along the bondlength with increased compliance at the ends to relieve stress concentrations. Experimental testing to failure of a tri‐layered assembly in a single‐lap joint configuration, including optical strain mapping, reveals that the stress and strain redistribution of the compliance‐tailored bondlayer increases strength by 100% and toughness by 60%, compared to a constant modulus bondlayer, while maintaining the stiffness of the joint with the homogeneous stiff bondlayer. Analyses show that the stress concentrations for both peel and shear stress in the bondlayer have a global minimum when the compliant bond at the lap end comprises ≈10% of the bondlength, and further that increased multilayer performance also holds for long (relative to critical shear transfer length) bondlengths. Damage and failure resistance of multi‐material interfaces can be improved substantially via the compliance‐tailoring demonstrated here, with immediate relevance in additive manufacturing joining applications, and shows promise for generalized joining applications including adhesive bonding.  相似文献   
6.
Laminar free convection induced by two mutually orthogonal discrete heat-generating baffles in a two-dimensional square cavity is analyzed numerically. The computations were carried out for different locations and combinations of heat source strengths of the baffles for a fixed Grashof number of 106and Prandtl number of 0.71. The coupled governing equations were solved bya finite-difference method using alternating direction implicit technique and successive overrelaxation methods. The obtained results clearly show that the hydrodynamic and thermal fields in the cavity depend on both the location and strength of the heat-generating baffles. Though the flow inhibition is caused by both the baffles, the baffle with higher source strength plays a decisive role in inducing the flow. The locations of baffles with unequal source strengths produce significant changes in the net heat transfer rate. This is further magnified for higher contrast in source strengths. This study provides qualitative suggestions that may improve the thermal design of sealed enclosures, which are encountered frequently in the electronics industry.  相似文献   
7.
Microsystem Technologies - The recent availability of inexpensive digital recording and storage devices have created an environment to obtain, replicate and distribute digital content without any...  相似文献   
8.
Parameter Estimation in Water Distribution Networks   总被引:2,自引:2,他引:0  
Estimation of pipe roughness coefficients is an important task to be carried out before any water distribution network model is used for online applications such as monitoring and control. In this study, a combined state and parameter estimation model for water distribution networks is presented. Typically, estimation of roughness coefficient for each individual pipe is not possible due to non-availability of sufficient number of measurements. In order to address this problem, a formal procedure based on K-means clustering algorithm is proposed for grouping the pipes which are likely to have the same roughness characteristics. Also, graph-theoretic concepts are used to reduce the dimensionality of the problem and thereby achieve significant computational efficiency. The performance of the proposed model is demonstrated on a realistic urban water distribution network.  相似文献   
9.
High-resistance phases of Ni-rich Ni silicide are formed on Si(100) below 400/spl deg/C, while high-resistance phases of Si-rich Ni silicide are formed above 600/spl deg/C. The desired low-resistance NiSi is formed between 400/spl deg/C and 600/spl deg/C. In this paper, the authors report the suppression of high-resistance phases of Ni silicide by passivating the Si(100) surface with a monolayer of Se. A 500-/spl Aring/ Ni on n-type low 10/sup 15/ cm/sup -3/ doped Si(100) wafers, passivated with Se, shows a sheet resistance of /spl sim/2.55 /spl Omega//square upon annealing between 200/spl deg/C and 500/spl deg/C, while the sheet resistance of the 500-/spl Aring/ Ni on identical wafers without Se-passivation jumps to /spl sim/7.92 /spl Omega//square between 300/spl deg/C and 350/spl deg/C. Between 600/spl deg/C and 700/spl deg/C, the sheet resistance of the Se-passivated samples is /spl sim/ 10% lower than that of the control samples. Transmission electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy all confirm that the suppression of high-resistance Ni silicides below 500/spl deg/C is attributed to the suppression of silicidation and above 600/spl deg/C to the delay in Si-rich Ni silicide formation at the Ni/Se-passivated Si(100) interface.  相似文献   
10.
An indirect forced convection and desiccant integrated solar dryer is designed and fabricated to investigate its performance under the hot and humid climatic conditions of Chennai, India. The system consists of a flat plate solar air collector, drying chamber and a desiccant unit. The desiccant unit is designed to hold 75 kg of CaCl2-based solid desiccant consisting of 60% bentonite, 10% calcium chloride, 20% vermiculite and 10% cement. Drying experiments have been performed for green peas at different air flow rate. The equilibrium moisture content Me is reached in 14 h at an air flow rate of 0.03 kg/m2 s. The system pickup efficiency, specific moisture extraction rate, dimensionless mass loss, mass shrinkage ratio and drying rate are discussed in this paper.  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