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排序方式: 共有252条查询结果,搜索用时 750 毫秒
1.
A. Simon Z. Kntor 《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》2002,190(1-4):351-356
The formation and deposition of particulates by pulsed laser deposition of Si1−xGex semiconductor alloy thin films are discussed. Using Rutherford backscattering spectrometry with micrometer lateral resolution (micro-RBS) the film composition was measured with high accuracy, even in the presence of particulates with a high areal density of 20,000–30,000 particulates per mm2. We show that on impact of a particulate, the part of the thin film which is already deposited probably melts and its Ge content segregates to the surface. 相似文献
2.
M. Fujita J. Tajima T. Nakagawa S. Abo A. Kinomura F. Pszti M. Takai R. Schork L. Frey H. Ryssel 《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》2002,190(1-4):26-33
A rapid shrinkage in the minimum feature size of integrated circuits requires analysis of dopants in their shallow source–drain and their extensions with an enhanced depth resolution. Rutherford backscattering spectroscopy (RBS) combining a medium-energy He ion beam with a detector of improved energy resolution should meet the requirement of a depth resolution better than 5 nm at a depth of 10–20 nm in the next 10 years. A toroidal electrostatic analyzer of 4×10−3 energy resolution has been used to detect the scattered ions of a medium-energy He ion beam. Five keV As+ implanted Si or SiO2 samples were measured. Depth profiling results using the above technique are compared with those of glancing-angle RBS by MeV energy He ions. Limitations in the energy resolution due to various energy-spread contributions have been clarified. 相似文献
3.
考虑塑性铰外移的钢框架梁柱连接设计 总被引:16,自引:0,他引:16
介绍美国联邦突发事件管理局 (FEMA)对 1 994年北岭地震中焊接钢框架节点破坏原因的正式解释 ,说明塑性铰外移的必要性。此外 ,还介绍了塑性铰外移的两种基本形式以及狗骨式 (RBS)连接的有关设计规定和适用条件 ,其设计方法可供我国工程设计人员参考。 相似文献
4.
In view of the importance for CoxOy,-MoO3/-Al2O3 hydrodesulphurization (HDS) catalysts, the reactivity of cobalt oxide layers towards cobalt aluminate formation was investigated on both MoO3-covered and bare -Al2O3 substrates. Co3O4/MoO3/-Al2O3 and Co3O4/-Al2O3 systems were prepared by vapour-deposition of MoO3 (12 × 1015 Mo atoms/cm2) and Co (400 × 1015 Co atoms/cm2) layers onto a -Al2O3 substrate, followed by oxidation of the Co layer to Co3O4. After annealing at 800°C for 40 h, the interfacial reaction to cobalt aluminate was assessed using Rutherford backscattering spectrometry. The presence of molybdenum oxide appeared to enhance cobalt aluminate formation. The Mo atoms, which spread out over the entire cobalt-containing layer, presumably caused a high defect density, which explains the observed higher reaction rate. The amount of MoO3 was much too low to stabilize all cobalt atoms by cobalt molybdate formation. 相似文献
5.
É. Vázsonyi G. Battistig Z.E. Horváth M. Fried G. Kádár F. Pászti J.L. Cantin D. Vanhaeren L. Stalmans J. Poortmans 《Journal of Porous Materials》2000,7(1-3):57-61
A comparative study is presented on the pore propagation directions of porous silicon layers (PSL) formed on p+-type substrates of different orientations. PSLs were formed on plain (0 0 1) and (1 1 1) silicon wafers as well as on structured (0 0 1) wafers containing facets of various orientations. During anodization, regular pores follow the 0 0 1 direction on the (0 0 1) planes. While on the (1 1 1) planes fewer regular pores develop and seemingly propagate closely to the 1 1 1 direction. These results indicate that the pores propagate perpendicular to the surface i.e. along the field lines when the surface orientation is either (0 0 1) or (1 1 1).When the silicon surface provided (1 1 0) orientation (Chuang, Collins, and Smith, 1989), or its position is in between the (0 0 1) and (1 1 1) planes then the pores do not propagate perpendicular to the surface but along the 0 0 1 direction.All the phenomena exhibited might be explained by presuming that during formation, the pores propagate along the 1 0 0 directions, and that those 1 0 0 directions are preferred which are closely to the field lines. In PSLs formed on (0 0 1) surfaces the field lines and the 0 0 1 crystallographic direction are coincident. However, in the (1 1 1) oriented wafer where three equally probable 1 0 0 directions exist around the field lines, more irregular structure of PSLs will develop. 相似文献
6.
悬臂梁段不同拼接方式下延性节点静力性能分析 总被引:1,自引:0,他引:1
为了解决装配式钢结构的抗震问题,提出3种适用于模块化装配式钢框架的带Z字形悬臂梁段拼接的梁柱节点,通过拼接区的滑移或者削弱梁段的塑性变形实现节点良好的延性性能.为减少强震作用对梁柱连接焊缝的破坏,对3种不同的节点提出了各自的抗震设计要求.在对3组试件进行足尺静力试验的基础上,对节点进行了单调加载有限元分析.获得了节点的弯矩-转角曲线以及节点的破坏模式,并和试验结果进行了对比,得到了接触面摩擦力和螺栓拉力的变化规律.通过推导的简化计算公式对节点的初始转动刚度、滑移荷载和屈服荷载进行了计算.结果表明:节点静力加载的破坏模式为靠近拼接区域的悬臂梁下翼缘或者削弱梁段单独或者同时发生较大的局部屈曲变形,节点在破坏前经历了充分的塑性变形,属于延性破坏,3种试件都有良好的延性性能和塑性转动能力.节点简化计算公式得到的结果和试验结果吻合良好. 相似文献
7.
Michael M. Li Brijesh Verma Xiaolong Fan Kevin Tickle 《Neural computing & applications》2008,17(4):391-397
This paper investigates a new method to solve the inverse problem of Rutherford backscattering (RBS) data. The inverse problem
is to determine the sample structure information from measured spectra, which can be defined as a function approximation problem.
We propose using radial basis function (RBF) neural networks to approximate an inverse function. Each RBS spectrum, which
may contain up to 128 data points, is compressed by the principal component analysis, so that the dimensionality of input
data and complexity of the network are reduced significantly. Our theoretical consideration is tested by numerical experiments
with the example of the SiGe thin film sample and corresponding backscattering spectra. A comparison of the RBF method with
multilayer perceptrons reveals that the former has better performance in extracting structural information from spectra. Furthermore,
the proposed method can handle redundancies properly, which are caused by the constraint of output variables. This study is
the first method based on RBF to deal with the inverse RBS data analysis problem. 相似文献
8.
To study the influence of steam on the solid state reaction between MeO (Me = Ni, Co, Cu or Fe) and Al2O3, MeO/-Al2O3 and MeO/-Al2O3 model catalysts were kept in either N2/20% O2 or N2/O2/30% H2O at 500–1000°C. The samples were subsequently analyzed with RBS and FTIR. Surprisingly, nickel, cobalt and copper volatilized when MeO/-Al2O3 or MeAl2U4/-Al2O3 samples were annealed in the presence of 0.3 atm steam at 1000°C. Especially copper was found to volatilize very rapidly in the presence of steam, even at a temperature as low as 800°C. FTIR spectra of steam-treated NiO/-Al2O3 samples showed the incorporation of hydroxyl groups in the nickel oxide layer. This observation and an excellent agreement with thermochemical calculations support our conclusion that the volatile species are metal hydroxides. The solid state reaction of MeO with-Al2O3 was found to proceed at a much higher rate in the presence of 0.3 atm steam at 500–800°C, presumably as a result of an enhanced surface mobility of Me and Al ions along the grain boundaries and the surfaces of the internal pores of the-Al2O3 support, when steam is present. 相似文献
9.
SiGe/Si和SGOI材料的Li离子束RBS分析 总被引:1,自引:0,他引:1
SiGe合金薄膜中的Ge含量度分布对材料的禁带宽度和制作器件的性能有十分重要的影响。本文用Li离子束卢瑟福背散射分析法对SiGe/Si和SiGe-OI材料样品进行了分析。与TEM,SEM、Raman等分析结果进行比较表明,Li离子束RBS分析可同时测量SiGe层厚度,Ge含量度其深度分布,Si过渡层和SiO2层厚度,并有较好的测量精度。 相似文献
10.
Abstract The prerequisite for bioactive glasses to bond to living bone is the formation of biologically active apatites on their surface in the body. Reactions and bioactivity mechanisms between bioactive glasses and bone depend on the glass composition. We study a glass in the SiO2‐Na2O‐CaO‐P2O5‐K2O‐Al2O3‐MgO system. To characterise physicochemical reactions at the materials periphery, we immersed the glass pastilles into biological fluids for periods of 5, 10, and 20 days. The surface changes were studied at the micrometer scale by a Particle Induced X‐ray Emission (PIXE) method associated with Rutherford Backscattering Spectroscopy (RBS). After 20 days of immersion, elemental maps showed the formation of a calcium‐phosphate layer at the surface of the glass pastilles. The thickness of this layer was around 15 µm. Thanks to the PIXE method, we demonstrated the presence of traces of Mg in this layer. The glass doped with MgO leads to the formation of an apatite which incorporates magnesium. Formation of this Ca‐P‐Mg layer represents the bioactive properties of the studied glass. This biologically active layer improves the properties of the glass and will permit a chemical bond between the ceramic and bone. 相似文献