全文获取类型
收费全文 | 1279篇 |
免费 | 50篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 7篇 |
化学工业 | 225篇 |
金属工艺 | 120篇 |
机械仪表 | 95篇 |
建筑科学 | 32篇 |
矿业工程 | 1篇 |
能源动力 | 41篇 |
轻工业 | 47篇 |
水利工程 | 3篇 |
无线电 | 156篇 |
一般工业技术 | 211篇 |
冶金工业 | 263篇 |
原子能技术 | 23篇 |
自动化技术 | 107篇 |
出版年
2023年 | 8篇 |
2022年 | 14篇 |
2021年 | 36篇 |
2020年 | 24篇 |
2019年 | 44篇 |
2018年 | 35篇 |
2017年 | 41篇 |
2016年 | 37篇 |
2015年 | 20篇 |
2014年 | 49篇 |
2013年 | 62篇 |
2012年 | 74篇 |
2011年 | 71篇 |
2010年 | 49篇 |
2009年 | 63篇 |
2008年 | 57篇 |
2007年 | 66篇 |
2006年 | 53篇 |
2005年 | 39篇 |
2004年 | 45篇 |
2003年 | 40篇 |
2002年 | 38篇 |
2001年 | 31篇 |
2000年 | 29篇 |
1999年 | 33篇 |
1998年 | 42篇 |
1997年 | 41篇 |
1996年 | 15篇 |
1995年 | 18篇 |
1994年 | 13篇 |
1993年 | 12篇 |
1992年 | 5篇 |
1991年 | 8篇 |
1990年 | 18篇 |
1989年 | 13篇 |
1988年 | 7篇 |
1987年 | 6篇 |
1986年 | 4篇 |
1985年 | 16篇 |
1984年 | 9篇 |
1983年 | 8篇 |
1982年 | 4篇 |
1981年 | 3篇 |
1980年 | 4篇 |
1979年 | 6篇 |
1978年 | 5篇 |
1977年 | 3篇 |
1976年 | 2篇 |
1973年 | 3篇 |
1972年 | 2篇 |
排序方式: 共有1331条查询结果,搜索用时 15 毫秒
991.
Sungyeol Yu Jinhyeon Sohn Sungsoo Park Byung Jun Oh 《Computers & Industrial Engineering》1997,33(3-4):797-800
We consider the operation of a multi-functional surface mounting device(SMD) which mounts various components provided by diverse types of feeders such as cassette, stick, and tray on a printed circuit board(PCB). The problem is to minimize the time needed to assemble a PCB using the SMD. We decompose the problem into two subproblems, which are determining the allocation of component feeders and the mounting sequence of components, respectively. We propose heuristic algorithms to solve the subproblems and discuss the procedure to improve the solution. Computational results on real world problems are presented. 相似文献
992.
Bayesian dynamic forecasting for attribute reliability 总被引:2,自引:0,他引:2
So Young Sohn 《Computers & Industrial Engineering》1997,33(3-4):741-744
In this paper, we consider a Bayesian dynamic forecasting model that utilizes both the engineering knowledge about the product reliability and attributes (success or failure) data gathered from the inspection of the early stage of development or storage. We assume that a prior distribution of reliability follows a beta distribution. The expected reliability is represented as a cumulative logistic function of the length of time that a new product has been under development or a finished item has been stockpiled in storage. As periodic testing produces attribute data, a prior distribution is updated. The expected reliability and forecasting errors are obtained from a posterior distribution that reflects the uncertainty involved in forecasting. The proposed method is applied to predict the expected reliability decay of a gyroscope in a missile stockpile. 相似文献
993.
Yiguang Wang Yongho Sohn Linan An Yi Fan Ligong Zhang 《Journal of Phase Equilibria and Diffusion》2006,27(6):671-675
Oxygen (O) diffusion through pure and aluminum (Al)-doped amorphous silica is investigated by using secondary ion mass spectrometry
to profile the diffusion of an18O tracer. The oxides are formed by the thermal oxidation of polymer-derived SiCN and SiAlCN ceramics. The authors demonstrate
that a small amount of Al dopant can significantly inhibit both the interstitial and network diffusion of O. The activation
energy of O network diffusion for Al-doped silica is two times higher than that for pure silica. The results are discussed
in terms of the modification of Al doping on the network structure of the otherwise pure silica.
This article was presented at the Multicomponent-Multiphase Diffusion Symposium in Honor of Mysore A. Dayananda, which was
held during TMS 2006, the 135th Annual Meeting and Exhibition, March 12–16, 2006, in San Antonio, TX. The symposium was organized
by Yongho Sohn of University of Central Florida, Carelyn E. Campbell of National Institute of Standards and Technology, Richard
D. Sisson, Jr., of Worcester Polytechnic Institute, and John E. Morral of Ohio State University. 相似文献
994.
J. W. Byeon J. Liu M. Hopkins W. Fischer N. Garimella K. B. Park M. P. Brady M. Radovic T. El-Raghy Y. H. Sohn 《Oxidation of Metals》2007,68(1-2):97-111
Ti2AlC ternary carbide is being explored for various high temperature applications due to its strength at high temperatures,
excellent thermal-shock resistance, and high electrical conductivity. A potential advantage of Ti2AlC over conventional Al2O3-forming materials is the near-identical coefficient of thermal expansion (CTE) of Ti2AlC and α-Al2O3, which could result in superior spallation resistance and make Ti2AlC a promising option for applications ranging from bondcoats for thermal barrier coatings to furnace heating elements. In
this study, isothermal and cyclic oxidation were performed in air to examine the oxidation behavior of Ti2AlC. Isothermal oxidation was performed at 1000, 1200 and 1400 °C for up to 25 h and cyclic oxidation consisted of 1,000 1-hour
cycles at 1200 °C. Characteristics of the oxide scale developed in air, including mass change, residual stress in the α-Al2O3 scale, phase constituents and microstructure, were examined as functions of time and temperature by thermogravimetry, photostimulated
luminescence, x-ray diffraction, scanning electron microscopy, and transmission electron microscopy via focused ion beam in
situ lift-out. Above a continuous and adherent α-Al2O3 layer, a discontinuous-transient rutile-TiO2 scale was identified in the oxide scale developed at 1000 and 1200 °C, while a discontinuous-transient Al2TiO5 scale was identified at 1400 °C. The continuous α-Al2O3scale thickened to more than 15 μm after 25 h of isothermal oxidation at 1400 °C, and after 1,000 1-hour cycles at 1200 °C,
yet remained adherent and protective. The compressive residual stress determined by photoluminescence for the α-Al2O3 scale remained under 0.65 GPa for the specimens oxidized up to 1400°C for 25 hours. The small magnitude of the compressive
residual stress may be responsible the high spallation-resistance of the protective α-Al2O3 scale developed on Ti2AlC, despite the absence of reactive element additions. 相似文献
995.
The corrosion behavior of an Fe-25Cr alloy was investigated in a N2-0.1 vol.% SO2 atmosphere at 973 K with and without stress. Without stress, the surface scale formed at the very initial stage consisting of Cr oxides and sulfides, which later changed to a Cr2O3-rich scale with the initially formed sulfides remaining. Under relatively low constant stress, +15 and +20 MPa, as well as cyclic stress of ±30 or ±40 MPa, the total strain for 36 ks was less than 0.1% and there was little cracking of the external scale, which consisted of Cr2O3 and (Fe, Cr)3O4 with small amounts of sulfide, growing faster. The external scale here was poorly adhesive. Under high stress, +25 and +35 MPa, cracks formed in the external scale and both oxides and Fe sulfide grew rapidly through the cracks to form nodules. The nodules consisted of an FeS-rich core surrounded by Fe3O4. With increasing strain, the preformed Cr2O3-rich scale changed drastically to a multilayered scale with an alternating oxide layer-sulfide layer structure. 相似文献
996.
Solid-to-solid diffusion couples, β-NiAl (B2) versus various commercial superalloys (i.e., CM247, GTD-111, IN-939, IN-718, and Waspalloy) were examined to quantify the
rate of Al interdiffusion as a function of initial superalloy composition. The diffusion couples were assembled with Invar
steel jig encapsulated in Ar by sealing in quartz capsules and annealed at 1050 °C for 96 h. Concentration profiles measured
by electron probe microanalysis in the single-phase β-NiAl region were used to determine interdiffusion fluxes and effective
interdiffusion coefficients of individual components in the single-phase β-NiAl side of the couple. The values determined
using experimental concentration profiles of the single-phase β-NiAl side of the couple were used to predict effective interdiffusion
coefficients in multiphase superalloy side of the couple based on mass balance and local continuity of interdiffusion fluxes.
Microstructural and compositional stability of protective coatings (e.g., NiCoCrAlY and NiAl) as a function of superalloys
composition are discussed based on effective interdiffusion coefficients predicted from diffusion couple studies.
This article was presented at the Multicomponent-Multiphase Diffusion Symposium in Honor of Mysore A. Dayananda, which was
held during TMS 2006, 135th Annual Meeting and Exhibition, March 12–16, 2006, in San Antonio, TX. The symposium was organized
by Yongho Sohn of University of Central Florida, Carelyn E. Campbell of National Institute of Standards and Technology, Richard
D. Sisson, Jr., of Worcester Polytechnic Institute, and John E. Morral of Ohio State University. 相似文献
997.
Jung Woo Sohn Juncheol Jeon Minkyu Choi 《Journal of Adhesion Science and Technology》2018,32(4):359-374
In this work, critical operating factors of a jetting dispenser driven by a dual type of the piezostack actuators are experimentally identified. As a first step, geometrical information and working principle of the jetting dispenser are briefly addressed. Subsequently, in order to investigate jetting performance eight important operating (or working) factors of the dispenser such as exciting stroke and frequency are chosen based on two levels for each factor. Then, in order to reduce the number of experiments, one-sixteenth fractional factorial design method is adopted and an experimental apparatus to measure the weight of a single dot is established. After measuring the weight of a single dispensed dot under each test condition, the effect of each operating factor on the jetting performance is analyzed using a statistical program. The main effects and interaction effects on the average and standard deviation of the weight of a single dispensed dot are then analyzed and discussed in details. In addition, the analysis of variance results for average single dot weight is undertaken to determine the specific values of the critical factors which can provide optimal jetting performances. Consequently, critical operating factors for a small amount and small weight variation of a single dot are identified, which directly represent the performances of a non-contact jetting dispenser driven by piezostack actuators such as dotting accuracy and dotting speed. 相似文献
998.
The solidification of a multicomponent stainless steel slag and dust composite has been studied by thermodynamic calculations using Factsage and analyses of samples using EPMA and Rietveld refinement of synchrotron X‐ray powder diffraction after various cooling rates. At an apparent cooling rate of 1 K/min, the content of spinel (10.6 wt%) was less than thermodynamically calculated (16.6 wt%), largely because of difficulties in the diffusion of depleted ions (including Cr, Mn, and Ni) in the liquid with very gradual compositional gradients. Melilite showed a uniform but distorted crystal structure of P21212 and its content (48.9 wt%) was larger than the calculated result (32.3 wt%). At apparent cooling rates of 10 K/min and 50 K/min, a slight decrease in spinel and a significant decrease in melilite were observed, and the spinel was divided into two regions with an identical space group of Fdm but with distinguished composition and lattice parameters. However, the amorphous proportion consistently increased with the cooling rate from 29.4 wt% at 1 K/min to 69.6 and 92.9 wt% at 10 K/min and 50 K/min respectively. 相似文献
999.
Yuan‐Pei Lan Hong Yong Sohn Yousef Mohassab Qingcai Liu Baoqiang Xu 《Journal of the American Ceramic Society》2017,100(5):1863-1875
Nanoceria is an important function material and is widely used in catalytic applications due to its excellent redox properties. Here, we report a simple method to synthesize uniform polyhedral nanoceria powder by the KCl‐LiCl molten salt method. TEM micrographs of the product showed that polyhedral nanoceria particles of 30 nm average size were obtained from cerium carbonate hydroxide when treated at 600°C for 4 hours. Results indicated that the crystal structure broke down to ceria crystal nuclei in the molten salt system at an elevated temperature, and the Ce3+ dissolved in the KCl‐LiCl molten salts provided a cerium source for crystal growth. The crystal and particle sizes increased with treatment temperature. UV‐visible absorption results showed that this nanoceria powder had a significant red shift, and its narrow band gap of 2.7 eV suggests a potential application for photocatalysis. The produced nanoceria had a somewhat lower catalytic activity for CO oxidization than commercial nanoceria, mainly due to smaller specific surface area, but had a higher stability. 相似文献
1000.
This study proposes a method to detect suspicious patterns of stock price manipulation using an unsupervised data mining technique: peer group analysis. This technique detects abnormal behavior of a target by comparing it with its peer group and measuring the deviation of its behavior from that of its peers. Moreover, this study proposes a method to improve the general peer group analysis by incorporating the weight of peer group members into summarizing their behavior, along with the consideration of parameter updates over time. Using real time series data of Korean stock market, this study shows the advantage of the proposed peer group analysis in detecting abnormal stock price change. In addition, we perform sensitivity analysis to examine the effect of the parameters used in the proposed method. 相似文献