全文获取类型
收费全文 | 237篇 |
免费 | 19篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 1篇 |
综合类 | 2篇 |
化学工业 | 49篇 |
金属工艺 | 4篇 |
机械仪表 | 8篇 |
建筑科学 | 17篇 |
能源动力 | 1篇 |
轻工业 | 18篇 |
水利工程 | 10篇 |
无线电 | 42篇 |
一般工业技术 | 39篇 |
冶金工业 | 17篇 |
原子能技术 | 1篇 |
自动化技术 | 48篇 |
出版年
2023年 | 6篇 |
2022年 | 12篇 |
2021年 | 21篇 |
2020年 | 11篇 |
2019年 | 17篇 |
2018年 | 5篇 |
2017年 | 9篇 |
2016年 | 19篇 |
2015年 | 10篇 |
2014年 | 8篇 |
2013年 | 21篇 |
2012年 | 14篇 |
2011年 | 19篇 |
2010年 | 12篇 |
2009年 | 7篇 |
2008年 | 8篇 |
2007年 | 13篇 |
2006年 | 7篇 |
2005年 | 3篇 |
2004年 | 1篇 |
2003年 | 3篇 |
2002年 | 1篇 |
2001年 | 1篇 |
2000年 | 3篇 |
1999年 | 3篇 |
1998年 | 5篇 |
1997年 | 8篇 |
1996年 | 2篇 |
1995年 | 2篇 |
1994年 | 1篇 |
1993年 | 1篇 |
1988年 | 1篇 |
1984年 | 1篇 |
1981年 | 1篇 |
1967年 | 1篇 |
排序方式: 共有257条查询结果,搜索用时 15 毫秒
161.
162.
163.
M.-Q. Thai F. Schmidt G. Dusserre A. Cantarel L. Silva 《International Journal of Material Forming》2017,10(4):567-580
Liquid composite molding (LCM) includes all composite-manufacturing methods, where the liquid state resin is forced into the dry preformed reinforcement. In this study, numerical simulation of the resin infusion is presented based on a coupled approach involving Boundary Element Method (BEM) and Level Set Method. The method developed can handle stationary and transient flows by solving the Stokes equations. The numerical results on a square packed set of fibers show excellent agreement with the analytical model. The comparison between experimental and simulation results of flow front patterns revealed a fair accordance. 相似文献
164.
This study focused on the development of three-dimensional (3D) polymer composite filament made of disposable chopstick (DC) and post-consumer polypropylene (PPP). The PPP/DC composite parts were printed via fused filament fabrication (FFF) process. The effect of the printing temperature and different DC fiber content on the properties of the 3D printed parts were investigated. The printing temperature of 200–220°C was suitable for these filaments because the printing temperature did not show any thermal degradation, as proven by thermogravimetric analysis. Furthermore, the thermal stability of the 3D filament increased with DC content. The chemical modification with sodium hydroxide (NaOH) was carried out on DC to remove the unwanted organic components by showing changes in peak intensity in the Fourier transform infrared analysis. Moreover, the melt flow index of the composite filaments decreased with increasing of the DC content and caused the composites' viscosity increased. The results show that the optimum printing temperature of 210°C would reduce the warping and gave better tensile properties to the 3D printed parts. Nevertheless, the tensile strength and elongation at break of the 3D printed PPP/DC parts reduced as the DC content increased because the presence of some air gap and fiber pull out on the fracture surface of 3D printed parts, which are in line with the results observed from scanning electron microscopy. However, the tensile strength and elongation at break percentage of all 3D printed PPP/DC composite parts were higher in comparison with the 3D parts printed by commercial wood plastic composite filament. 相似文献
165.
Nonlinear inelastic analysis of space frames 总被引:1,自引:0,他引:1
Huu-Tai Thai Seung-Eock Kim 《Journal of Constructional Steel Research》2011,67(4):585-592
In this paper, a fiber beam-column element which considers both geometric and material nonlinearities is presented. The geometric nonlinearities are captured using stability functions obtained from the exact stability solution of a beam-column subjected to axial force and bending moments. The material nonlinearities are included by tracing the uniaxial stress-strain relationship of each fiber on the cross sections. The nonlinear equilibrium equations are solved using an incremental iterative scheme based on the generalized displacement control method. Using only one element per member in structure modeling, the nonlinear responses predicted by the proposed element compare well with those given by commercial finite element packages and other available results. Numerical examples are presented to verify the accuracy and efficiency of the proposed element. 相似文献
166.
介绍一种纤维梁柱单元,考虑几何和材料非线性。通过轴力和弯矩作用下构件稳定方程中的稳定函数来表示几何非线性,通过跟踪横截面上各纤维的单轴应力-应变关系来模拟材料非线性。基于广义位移控制方法,采用增量迭代法求解非线性平衡方程。用1个单元模拟1根杆件,该单元的非线性性能与有限元软件分析结果及其他有效结果比较吻合,并举例证明了该单元的准确性和有效性。 相似文献
167.
Quoc‐Thai Pham Jung‐Mu Hsu Jing‐Pin Pan Tsung‐Hsiung Wang Chorng‐Shyan Chern 《应用聚合物科学杂志》2013,130(3):1923-1930
The non‐isothermal degradation kinetics of the cured polymer samples of N,N′‐bismaleimide‐4,4′‐diphenylmethane/barbituric acid [BMI/BTA = 2/1 (mol/mol)] based polymers in the presence of hydroquinone (HQ) and native BMI/BTA was investigated by the thermogravimetric (TG) technique. By adding 5 wt % HQ into the BMI/BTA polymerization, the activation energy (Ea) of the thermal degradation process increased significantly in comparison with native BMI/BTA. Thus, the thermal stability of the cured polymer sample in the presence of HQ was greatly improved. The thermal degradation process exhibits three distinct stages. The key kinetic parameters associated with these stages were attained via the model‐fitting method. For the sample of native BMI/BTA, the thermal degradation process was primarily controlled by nucleation, followed by the multi‐decay law in the first stage. In contrast, the reaction order model adequately described the thermal degradation kinetics in the second stage. As to the last stage, the complex processes were described satisfactorily by the best‐fitted reaction model. For the sample of BMI/BTA/5 wt % HQ, the degradation process was controlled by the nucleation mechanism, followed by the multi‐molecular decay law in the first stage. In contrast, the second stage was controlled by the mixed mode of the competitive reaction order mechanism and 3‐D diffusion mechanism. In the third stage, the complex processes were also adequately described by the best‐fitted reaction model. All the experimental results illustrated that incorporation of 5 wt % HQ into the BMI/BTA based polymer resulted in the best thermal stability. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 1923–1930, 2013 相似文献
168.
Trieu-Tien Thai Bruno Therrien Georg Süss-Fink 《Inorganic chemistry communications》2009,12(8):806-807
The neutral chloro complexes [(η5-C5Me5)M(η2-NC9H6O)Cl] as well as the cationic aqua complexes [(η5-C5Me5)M(η2-NC9H6O)(H2O)]+ (M = Rh, Ir) have been synthesized from the reaction of the dinuclear precursors [(η5-C5Me5)MCl2]2 and 8-hydroxyquinoline. The single crystal X-ray structure analysis of [(η5-C5Me5)Ir(η2-NC9H6O)Cl] reveals for these complexes a piano-stool arrangement with the aromatic ligand, the chelating oxinato ligand and the terminal chloro or aqua ligand surrounding the metal center in a pseudo-tetrahedral fashion. 相似文献
169.
A combination of wireless multicast advantage and hitch-hiking 总被引:1,自引:0,他引:1
In the minimum energy broadcast problem, each node adjusts its transmission power to minimize the total energy consumption while still delivering data to all the nodes in a network. The minimum energy broadcast problem is proved to be NP-complete. The Wireless Multicast Advantage (WMA) is that a single transmission can be received by all the nodes that are within the transmission range of a transmitting node. The Hitch-hiking model introduced recently takes advantage of the physical layer to combine partial signals containing the same data in order to decode a complete message. In this letter, we take advantage of both WMA and Hitch-hiking to design an energy-efficient broadcast tree algorithm with Hitch-hiking (BHH). The approximation ratio of BHH is within a factor of O(logn) where n, is the number of nodes in the network. The simulation results show that BHH reduces the total energy of the broadcast tree greatly. 相似文献
170.
A 47-year-old woman presented with extreme hypercalcaemia due to a parathyroid carcinoma. An electrocardiogram which was recorded when the hypercalcaemia was associated with hypokalaemia showed absence of the ST segment, prolonged T wave, a shortened QTac interval and prominent U waves. 相似文献