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   101篇
  免费   3篇
电工技术   1篇
化学工业   15篇
金属工艺   4篇
建筑科学   5篇
能源动力   9篇
轻工业   12篇
无线电   31篇
一般工业技术   10篇
冶金工业   6篇
原子能技术   1篇
自动化技术   10篇
  2022年   1篇
  2021年   1篇
  2020年   3篇
  2019年   3篇
  2018年   4篇
  2017年   4篇
  2016年   4篇
  2013年   3篇
  2012年   2篇
  2011年   5篇
  2010年   4篇
  2009年   8篇
  2008年   6篇
  2007年   7篇
  2006年   3篇
  2004年   9篇
  2003年   1篇
  2002年   3篇
  2001年   4篇
  2000年   2篇
  1998年   4篇
  1997年   7篇
  1996年   2篇
  1995年   1篇
  1993年   1篇
  1992年   2篇
  1991年   1篇
  1984年   1篇
  1983年   1篇
  1976年   2篇
  1974年   1篇
  1973年   2篇
  1972年   2篇
排序方式: 共有104条查询结果,搜索用时 31 毫秒
1.
Unsupervised Multiway Data Analysis: A Literature Survey   总被引:1,自引:0,他引:1  
Two-way arrays or matrices are often not enough to represent all the information in the data and standard two-way analysis techniques commonly applied on matrices may fail to find the underlying structures in multi-modal datasets. Multiway data analysis has recently become popular as an exploratory analysis tool in discovering the structures in higher-order datasets, where data have more than two modes. We provide a review of significant contributions in the literature on multiway models, algorithms as well as their applications in diverse disciplines including chemometrics, neuroscience, social network analysis, text mining and computer vision.  相似文献   
2.
The high temperature fatigue crack growth behaviour of the nickel base superalloys Alloy 718 and Rene 95 (specimen thickness=4.1 mm) were investigated and compared with each other. Fatigue crack propagation (FCP) tests were carried out in laboratory air at room temperature and 600°C by using C-T (compact tension) type specimen that were fatigue precracked at room temperature.Alloy 718 was found to provide the higher resistance to crack propagation under the present testing conditions.At 600°C, in Alloy 718, the fracture path was of mixed type at low and transgranular at high K (stress intensity factor range) values, while it remained intergranular in Rene 95 throughout the whole K range tested. The difference in the crack growth rates of Alloy 718 with different thicknesses (4.1 mm and 13.0 mm) was related to their different fracture modes.The striation spacings, both at room temperature and 600°C, of Alloy 718 were found to be proportional to the empirical equation proposed by Bates and Clark [2] but with a constant of 9.5 instead of 6. However, although the correlation between the microscopic FCP rate obtained from fatigue striation measurements – and hence the empirical equation – and the macroscopic FCP rate was pretty good at room temperature, it was found to be poor at 600°C, indicating that, at 600°C, striation formation alone did not control the fatigue resistance of Alloy 718 which is thought to account for the insufficiency of the COD (crack opening displacement) approach to correctly correlate the macroscopic FCP rates of Alloy 718 at these two test temperatures. © 1998 Chapman & Hall  相似文献   
3.
Circular microfluidic channels are in great demand since they are more realistic in mimicking physiological flow systems, generating axis-symmetrical flow, and achieving uniform shear stress. A typical microchannel with rectangular cross section can induce non-physiological gradients of shear rate, pressure, and velocity. This paper presents a novel method of fabricating microfluidic channels with circular and elliptical cross sections through grayscale dual-projection lithography. Our method utilizes two projecting systems to expose grayscale image face-to-face and simultaneously polymerize the photocurable material. The cross-sectional profiles of the fabricated microchannels are consistent with mathematical predictions and, therefore, demonstrate the capability of controlling the channel shapes precisely. Customized circular microchannels can be generated with complex features such as junctions, bifurcations, hierarchies, and gradually changed diameters. This method is capable of fabricating circular channels with a wide range of diameters (39 μm–2 mm) as well as elliptical channels with a major-to-minor axis ratio up to 600%. Microfluidic devices with circular cross sections suitable for particle analysis were made as a demonstrative application in nanoparticle binding and distribution within a mimetic blood vessel. A ready-to-use microfluidic device with customized circular channels can be fabricated within 1 h without the need of clean room or expensive photolithography devices.  相似文献   
4.
This paper presents fault-tolerant protocols for fast packet switch networks withconvergence routing. The objective is to provide fast reconfiguration and continuous host-to-host communication after a link or a node (switch) failure,Convergence routingcan be viewed as a variant ofdeflection routing,which combines, in a dynamic fashion, the on-line routing decision with the traffic load inside the network. Unlike other deflection techniques, convergence routing operates withglobal sense of directionand guarantees that packets will reach or converge to their destinations. Global sense of direction is achieved by embedding of virtual rings to obtain a linear ordering of the nodes. We consider virtual ring embeddings over (i) a single spanning tree, and (ii) over two edge-disjoint spanning trees. Thus, the fault-tolerant solution is based on spanning trees and designed for a switch-based (i.e., arbitrary topology) architecture called MetaNet. In this work, the original MetaNet's convergence routing scheme has been modified in order to facilitate the property that the packet header need not be recomputed after a failure and/or a reconfiguration. This is achieved by having, at the network interface, a translator that maps the unique destination address to a virtual address. It is argued that virtual rings embedded over two-edge disjoint spanning trees increase the fault tolerance for both node and link faults and provides continuous host-to-host communication.  相似文献   
5.
6.
The aim of our study was to evaluate the frequency of fibromyalgia syndrome (FMS) in hemodialysis (HD) patients and to assess whether this syndrome is associated with gender, age, duration of HD, or various laboratory parameters. This study was composed of 221 chronic HD patients (99 females and 122 males), and we recorded each participant's age, gender, causes of kidney failure, HD duration, education level, and symptoms related to FMS, which was diagnosed according to the 2010 American College of Rheumatology criteria. We documented the laboratory parameters for all patients. In addition, patients with FMS filled out the Fibromyalgia Impact Questionnaire. Twenty‐two patients met the diagnostic criteria for FMS (9%), and there were no statistically significant differences related to age, gender, or HD duration between FMS and non‐FMS groups (P > 0.05). In addition, the education levels were lower in patients diagnosed with FMS (P < 0.05), and there were statistically significant differences related to sleep disturbance, fatigue, and cognitive symptoms between the two groups (P < 0.05) as well. However, their laboratory parameters were similar (P > 0.05). There was a higher prevalence of FMS in HD patients than in the general population. Sleep disturbances, fatigue, education level, and cognitive symptoms were associated with FMS, but there was no correlation between the laboratory parameters and this condition.  相似文献   
7.
The present status of efforts to model concrete behavior under projected extreme loadings suitable for finite element formulation is presented. The difficulties in modeling introduced by problems associated with quality control of the concrete mix and dependency of test results on a number of variables are pointed out. A variety of modeling schemes which attempt to take into account such peculiarities of concrete behavior are discussed, and advantages and shortcomings of each scheme are mentioned. Future analytical and experimental research needs are indicated, especially with regard to reinforced concrete element modeling. The present paper constitutes a state-of-the-art report on computer modeling of plain and reinforced concrete behavior and contains appropriate recommendations from the authors.  相似文献   
8.
An exact solution to the equation of transient forced convection for time varying inlet temperature with a general, space dependent boundary condition of an incompressible laminar forced convection heat transfer with fully developed flow between two parallel plates is given. The finite integral transform technique has been used as the method of analysis. Analytical results for laminar and turbulent flow are presented. The results are confirmed experimentally by the frequency response method.  相似文献   
9.
Distance estimation is important to many Internet applications. It can aid a World Wide Web client when selecting among several potential candidate servers or among candidate peer-to-peer servers. It can also aid in building efficient overlay or peer-to-peer networks that react dynamically to changes in the underlying Internet. One of the approaches to distance (i.e., time delay) estimation in the Internet is based on placing tracer stations in key locations and conducting measurements between them. The tracers construct an approximated map of the Internet after processing the information obtained from these measurements. This work presents a novel algorithm, based on algebraic tools, that computes additional distances, which are not explicitly measured. As such, the algorithm extracts more information from the same amount of measurement data. Our algorithm has several practical impacts. First, it can reduce the number of tracers and measurements without sacrificing information. Second, our algorithm is able to compute distance estimates between locations where tracers cannot be placed. To evaluate the algorithm's performance, we tested it both on randomly generated topologies and on real Internet measurements. Our results show that the algorithm computes up to 50%-200% additional distances beyond the basic tracer-to-tracer measurements.  相似文献   
10.
This study aims to find a correlation between winter outdoor design temperature (WDT) and mass of the building envelope. The daily variations of the inside surface temperatures and heat fluxes of the walls under various climatic conditions and different wall constructions have been calculated by a computer program based on the response factor technique, which uses variable outside air temperature and solar radiation and constant inside air temperature values as input climatic data. The analysis of the relation between mass of the walls and inside surface heat fluxes resulted with the correction values for winter design temperature (WDTCV) depending on the mass of the wall and on the direction of facades for different climatic zones.  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