全文获取类型
收费全文 | 193篇 |
免费 | 13篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 2篇 |
化学工业 | 42篇 |
金属工艺 | 18篇 |
机械仪表 | 17篇 |
建筑科学 | 12篇 |
能源动力 | 15篇 |
轻工业 | 4篇 |
水利工程 | 2篇 |
无线电 | 9篇 |
一般工业技术 | 44篇 |
冶金工业 | 11篇 |
自动化技术 | 31篇 |
出版年
2023年 | 2篇 |
2021年 | 5篇 |
2020年 | 7篇 |
2019年 | 7篇 |
2018年 | 12篇 |
2017年 | 7篇 |
2016年 | 4篇 |
2015年 | 11篇 |
2014年 | 13篇 |
2013年 | 12篇 |
2012年 | 19篇 |
2011年 | 16篇 |
2010年 | 17篇 |
2009年 | 14篇 |
2008年 | 6篇 |
2007年 | 8篇 |
2006年 | 9篇 |
2005年 | 4篇 |
2004年 | 4篇 |
2003年 | 4篇 |
2002年 | 5篇 |
2001年 | 2篇 |
2000年 | 1篇 |
1999年 | 5篇 |
1998年 | 5篇 |
1997年 | 4篇 |
1995年 | 1篇 |
1993年 | 1篇 |
1988年 | 1篇 |
1977年 | 1篇 |
排序方式: 共有207条查询结果,搜索用时 0 毫秒
21.
In this paper we discuss the peridynamic analysis of dynamic crack branching in brittle materials and show results of convergence studies under uniform grid refinement (m-convergence) and under decreasing the peridynamic horizon (δ-convergence). Comparisons with experimentally obtained values are made for the crack-tip propagation speed with three different peridynamic horizons. We also analyze the influence of the particular shape of the micro-modulus function and of different materials (Duran 50 glass and soda-lime glass) on the crack propagation behavior. We show that the peridynamic solution for this problem captures all the main features, observed experimentally, of dynamic crack propagation and branching, as well as it obtains crack propagation speeds that compare well, qualitatively and quantitatively, with experimental results published in the literature. The branching patterns also correlate remarkably well with tests published in the literature that show several branching levels at higher stress levels reached when the initial notch starts propagating. We notice the strong influence reflecting stress waves from the boundaries have on the shape and structure of the crack paths in dynamic fracture. All these computational solutions are obtained by using the minimum amount of input information: density, elastic stiffness, and constant fracture energy. No special criteria for crack propagation, crack curving, or crack branching are used: dynamic crack propagation is obtained here as part of the solution. We conclude that peridynamics is a reliable formulation for modeling dynamic crack propagation. 相似文献
22.
Chil-Hoon Doh Chul-Wan Park Hye-Min Shin Dong-Hun Kim Young-Dong Chung Seong-In Moon Bong-Soo Jin Hyun-Soo Kim Angathevar Veluchamy 《Journal of power sources》2008
A new anode composition comprising SiO and graphite(C) is prepared through a high-energy ball milling process. During the first cycle, the anode delivers high discharge and charge capacity values of 1556 and 693 mAh g−1, respectively. The electrode shows a reversible charge capacity value of 688 mAh g−1 at the 30th cycle with 99% Coulombic efficiency. X-ray diffraction analysis reveals that ball milling does not produce any new compound, but only causes a reduction in particle size. The irreversible and reversible capacities appear to be interdependent. 相似文献
23.
24.
Anaerobic digestion improvement can be accomplished by different methods. Besides optimization of the process conditions, pretreatment of input sludge and increase of process temperature is frequently used. The thermophilic process brings a higher solids reduction and biogas production, a high resistance to foaming, no problems with odour, better pathogens destruction and an improvement of the energy balance of the whole treatment plant. Disintegration of excess activated sludge in a lysate centrifuge was proved to cause increase of biogas production in full-scale conditions. The rapid thermal conditioning of digested sludge is an acceptable method of particulate matter disintegration and solubilization. 相似文献
25.
N. Jayaprakash N. Kalaiselvi C. H. Doh Gangulibabu D. Bhuvaneswari 《Journal of Applied Electrochemistry》2010,40(12):2193-2202
A series of LiM1xM2yMn2−x−yO3.8F0.2 (M1 = Cr, M2 = V; x = y = 0.2) cathodes, viz., LiMn2O3.8F0.2, LiCr0.2Mn1.8O3.8F0.2 and LiCr0.2V0.2Mn1.6O3.8F0.2 along with native LiMn2O4 have been synthesized by Citric Acid assisted Modified (CAM) sol–gel method, with a view to understand the effect of synthesis
methodology and the effect of dual category dopants, viz., anion and/or cation upon spinel cathodes individually. An acceptable
capacity retention (94%) observed up to 50 cycles for native LiMn2O4 cathodes is attributed to the significance of CAM sol–gel method. Similarly, the encouraging charge–discharge results of
LiMn2O3.8F0.2 (130 mAh g−1) and LiCr0.2Mn1.8O3.8F0.2 (142 mAh g−1) cathodes revealed a possible augmentation in the reversible capacity behavior of the spinels upon F− substitution at 32e site and the simultaneous substitution of Cr3+ and F− at 16d and 32e sites respectively. 相似文献
26.
Jeong CY Lee S Doh JG Lee JU Cha HS Nichols WT Lee DG Kim SS Cho HK Rah SY Ahn J 《Journal of nanoscience and nanotechnology》2011,11(7):5717-5722
The coherent scattering microscopy/in-situ accelerated contamination system (CSM/ICS) is a developmental metrology tool designed to analyze the impact of carbon contamination on the imaging performance. It was installed at 11B EUVL beam-line of the Pohang Accelerator Laboratory (PAL). Monochromatized 13.5 nm wavelength beam with Mo/Si multilayer mirrors and zirconium filters was used. The CSM/ICS is composed of the CSM for measuring imaging properties and the ICS for implementing acceleration of carbon contamination. The CSM has been proposed as an actinic inspection technique that records the coherent diffraction pattern from the EUV mask and reconstructs its aerial image using a phase retrieval algorithm. To improve the CSM measurement accuracy, optical and electrical noises of main chamber were minimized. The background noise level measured by CCD camera was approximately 8.5 counts (3 sigma) when the EUV beam was off. Actinic CD measurement repeatability was <1 A (3 sigma) at 17.5 nm line and space pattern. The influence of carbon contamination on the imaging properties can be analyzed by transferring EUV mask to CSM imaging center position after executing carbon contamination without a fine alignment system. We also installed photodiode and ellipsometry for in-situ reflectivity and thickness measurement. This paper describes optical design and system performance observed during the first phase of integration, including CSM imaging performance and carbon contamination analysis results. 相似文献
27.
Euh Duck Jeong Hyun Ju Han Ok Sang Jung Myoung Gyu Ha Chil Hoon Doh Min Ji Hwang Ho-Soon Yang K.S. Hong 《Materials Research Bulletin》2012,47(10):2847-2850
Pure and metal (Cu, Al, Sn, and V)-doped Li4Ti5O12 powders are prepared with solid-state reaction method. The effects of dopants on the physical and electrochemical properties are characterized by using TGA, XRD, and SEM. Compared with pure Li4Ti5O12, metal-doped Li4Ti5O12 powders show structural stability and enhanced lithium ion diffusivity brought by doped metal ions. Voltage characteristics and initial charge–discharge characteristics according to the C rates in pure and metal-doped Li4Ti5O12 electrode materials are studied. Pure Li4Ti5O12 powder shows a relatively good discharge capacity of 164 mAh/g at a rate 0.2C, and some of metal-doped Li4Ti5O12 powders show higher discharge capacities. Metal-doped Li4Ti5O12 powders are promising candidates as anode materials for lithium-ion batteries. 相似文献
28.
Young-Hee Kim Jae-Yoon Sim Hong June Park Jae-Ik Doh Kun-Woo Park Hyun-Woong Chung Jong-Hoon Oh Choon-Sik Oh Seung-Han Ahn 《Solid-State Circuits, IEEE Journal of》1997,32(1):79-85
The occasional power-on latch-up phenomenon of DRAM modules with a data bus shared by multiple DRAM chips on different modules was investigated and the circuit techniques for latch-up prevention were presented. Through HSPICE simulations and measurements, the latch-up triggering source was identified-to be the excessive voltage drop at the n-well pick-up of the CMOS transmission gate of read data latch circuit due to the short-circuit current which flows when the bus contention occurs during power-on. By extracting the HSPICE Gummel-Poon model parameters of the parasitic bipolar transistors of DRAM chips from the measured I-V and C-V data, HSPICE simulations were performed for the power-on latch-up phenomenon of DRAM chips. Good agreements were achieved between measured and simulated voltage waveforms. In order to prevent the power-on latch-up even when the control signals (RAS, GAS) do not track with the power supply, two circuit techniques were presented to solve the problem. One is to replace the CMOS transmission gate by a CMOS tristate inverter in the DRAM chip design and the other is to start the CAS-BEPORE-RAS (CBR) refresh cycle during power-on and thus disable all the Dout buffers of DRAM chips during the initial power-on period 相似文献
29.
Influence of Shell Thickness on the Performance of Light‐Emitting Devices Based on CdSe/Zn1‐XCdXS Core/Shell Heterostructured Quantum Dots 下载免费PDF全文
30.
In-Jin Shon Dong-Mok LeeJung-Mann Doh Jin-Kook YoonIn-Yong Ko 《Materials Science and Engineering: A》2011,528(3):1212-1215
A dense nanostructured MoSi2-SiC-Si3N4 composite was sintered by the high frequency induction heating method within 2 min from mechanically activated powder of Mo2N, Mo2C and Si. Highly dense MoSi2-SiC-Si3N4 composite was produced under simultaneous application of a 80 MPa pressure and the induced current. Mechanical properties and grain size of the composite were investigated. The average hardness and fracture toughness values obtained were 1420 kg/mm2 and 4.5 MPa m1/2, respectively. 相似文献