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   210篇
  免费   7篇
  国内免费   1篇
电工技术   1篇
化学工业   51篇
金属工艺   8篇
机械仪表   7篇
建筑科学   4篇
矿业工程   2篇
能源动力   28篇
轻工业   14篇
石油天然气   4篇
无线电   17篇
一般工业技术   46篇
冶金工业   14篇
自动化技术   22篇
  2023年   1篇
  2022年   2篇
  2021年   3篇
  2020年   10篇
  2019年   14篇
  2018年   14篇
  2017年   11篇
  2016年   16篇
  2015年   4篇
  2014年   18篇
  2013年   24篇
  2012年   18篇
  2011年   22篇
  2010年   11篇
  2009年   5篇
  2008年   6篇
  2007年   6篇
  2006年   3篇
  2005年   2篇
  2004年   1篇
  2003年   1篇
  2001年   1篇
  2000年   2篇
  1999年   4篇
  1997年   4篇
  1996年   3篇
  1995年   3篇
  1994年   4篇
  1993年   1篇
  1992年   1篇
  1981年   1篇
  1979年   1篇
  1974年   1篇
排序方式: 共有218条查询结果,搜索用时 15 毫秒
81.
82.
Wireless Personal Communications - Wireless networks on chip (WiNoC) are considered to be a novel approach for designing efficient and scalable systems. The rationale behind this new approach is to...  相似文献   
83.
In this paper, the nonlinear free axisymmetric vibration of a thin circular functionally graded plate in thermal environment is formulated in terms of von-Karman's dynamic equations, and a semi-analytical approach is developed. The plate thickness is constant and the material properties of the functionally graded plate are assumed to vary continuously through the thickness, according to a power-law distribution of the volume fraction of the constituents. For harmonic vibrations, by using assumed-time-mode method and Kantorovich time averaging technique, governing equations are solved. The nonlinear frequencies and associated stresses are determined at large amplitudes of vibration. Effects of material compositions and thermal loads on the vibration characteristics and stresses are examined. The numerical results obtained here are compared with available published results, based on various approaches.  相似文献   
84.
Poly-ortho-aminophenol (PoAP) and multi-walled carbon nanotubes (MWCNTs) were deposited on the platinum electrode using cyclic voltammetry technique to form the Pt/PoAP/MWCNTs nanosensor for the electrochemical determination of oxytetracycline as analyte. This electrochemical nanosensor with good uniformity and high surface area was prepared in the presence of an ionic surfactant (sodium dodecyl sulfate) as electrolyte to suspend carbon nanotubes within the PoAP and improve the stability and electroactivity of the composite film. The surface morphology of the prepared nanosensor was characterized by scanning electron microscopy and showed a three-dimensional network structure. The influence of several parameters such as number of potential cycles, scan rate and pH of the solution on the electrochemical response of the resultant electrode was investigated. The prepared electrode functioned as a selective recognition element for oxytetracycline determination. It showed excellent electrochemical response to oxytetracycline at low oxidative potential in buffer solution of pH 2.0, with good stability and sensitivity. Under the optimal experimental conditions, the electrochemical response of the sensor was linear with respect to the concentration of oxytetracycline in a dynamic range of 0.2 μM–0.25 mM. The detection limit of the fabricated nanosensor was calculated as 0.10 μM (signal/noise = 3). This sensor was used successfully for the oxytetracycline determination in real samples with recoveries of 96.9–103.5 %.  相似文献   
85.
Identifying a simplified model for heavy duty gas turbine   总被引:2,自引:0,他引:2  
A dynamic model was developed for long-term simulation of a heavy duty gas turbine. The model includes the essential control algorithm of the gas turbine as well as the most common outputs and other important intermediate variables. Control algorithm details, such as wind up protection and load limiter algorithm which have large effect on gas turbine transient behavior, are included. The model parameters are identified by applying genetic algorithm and least squares algorithm on regular operational data from a real plant to better match the model response to the real plant. The simulation results have been validated with real plant data and shown to have valid accuracy for many engineering applications.  相似文献   
86.
Changing pressure, temperature, and composition cause instability in crude oil and create a problematic issue which is called asphaltene deposition. Asphaltene deposition causes problems in wettability alteration and flow assurance in different parts of petroleum industry so asphaltene deposition becomes a challenging issue in petroleum engineering. Hence, it is necessary to predict asphaltene deposition and investigate parameters which effect on asphaltene deposition. In this contribution, because of similarity between pore throat of reservoir rock and capillary tube, to investigate parameters such as asphaltene content, precipitant ratio, flow rate, and temperature effect on asphaltene deposition, a capillary setup was constructed and a model was developed to relate pressure drop along capillary tube to permeability reduction.  相似文献   
87.
Three copolymers of acrylonitrile-methacrylic acid [P(AN-co-MAA)], acrylonitrile-ammonium salt of methacrylic acid [P(AN-co-AMA)], acrylonitrile-methacrylamide-itaconic acid [P(AN-MAM-IA)] and PAN homopolymer were synthesized by aqueous dispersion polymerization technique. The polymerization conditions were adjusted in such a way to produce polymers with similar composition and molecular weight. The influence of comonomer nature on the viscoelastic behavior and spinnability of copolymer/dimethylsulfoxide (DMSO) solutions were investigated. It was found that incorporation of these comonomers into PAN chains led to intense decrease in zero-shear viscosity to lower value as well as appearance of distinct plateau in comparison with PAN homopolymer. However, comparing the results of complex viscosity and shear viscosity of each PAN polymer showed different shear-thinning behavior, typical deviation from Cox-Merz rule at high deformation rates. Amongst these copolymer solutions, P(AN-co-AMA) exhibited the longest relaxation time (λ) at low and medium frequencies. The lower values of frequency dependence of G′ (n′) and cross over frequency (ωc) of storage modulus (G′) and loss modulus (G″) indicated that P(AN-co-AMA) was more elastic than other PAN copolymer solutions. The log-log plots of tan δ versus ω demonstrated that the comonomer nature affects the sol-gel transition behavior and elastic character of copolymer solutions. On average, based upon the slope of logG? versus logG? data, the incorporation of comonomers inside PAN chains led to ~50 % increase in the homogeneity of solutions compared to PAN homopolymer.  相似文献   
88.
Design is a highly knowledge-intensive and ill-structured problem. Most of the practical problems we face in a design are either too complex or too ill-defined to analyse with conventional approaches. By defining functional requirements as a fuzzy set, one can perform inexact reasoning during the conceptual or creative phase of the design process.In this paper the feasibility of utilising fuzzy associative memory (FAM) in design automation is examined. The FAM paradigm exploits the relationships between functional requirements and physical structures in order to map fuzzy functional requirements to a crisp design.  相似文献   
89.
A H2O2/TiO2 P25 nanoparticle system has been examined and applied towards synthesis of a wide range of 2-substituted benzimidazole and benzothiazole derivatives from oxidative coupling of aromatic 1,2-phenylendiamine and 2-aminothiophenol with aromatic aldehydes bearing different types of substituents.  相似文献   
90.
Links play an important role in hitching of implement to a tractor. They must withstand forces that are transmitted between tractor and implement. In modern heavy duty tractors, some type of lower link mounted force transducer is used to measure draft force. Therefore, the lower link needs to have such dimensions that stresses developed by draft force be well below of its material yield strength to safeguard any permanent set, in the meantime, avoiding high material as well as manufacturing costs might encounter due to the unnecessary large dimensions of the link. In this study, the lower link of a three-point hitch of new heavy duty ITM1500 tractor developed in Iran Tractor Manufacturing Co., was analyzed with regards to both static and dynamic conditions using finite element method. The 3-D link was modeled in Solid Works environment while Cosmos Works software was used for finite element analysis. Finally, optimum dimensions of the lower link was found with respect to available raw material and draft forces involved.  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