全文获取类型
收费全文 | 793篇 |
免费 | 2篇 |
国内免费 | 41篇 |
专业分类
电工技术 | 4篇 |
综合类 | 13篇 |
化学工业 | 104篇 |
金属工艺 | 113篇 |
机械仪表 | 69篇 |
建筑科学 | 53篇 |
矿业工程 | 7篇 |
能源动力 | 23篇 |
轻工业 | 12篇 |
水利工程 | 1篇 |
石油天然气 | 30篇 |
无线电 | 25篇 |
一般工业技术 | 258篇 |
冶金工业 | 80篇 |
原子能技术 | 9篇 |
自动化技术 | 35篇 |
出版年
2023年 | 8篇 |
2022年 | 25篇 |
2021年 | 20篇 |
2020年 | 20篇 |
2019年 | 16篇 |
2018年 | 19篇 |
2017年 | 21篇 |
2016年 | 21篇 |
2015年 | 35篇 |
2014年 | 42篇 |
2013年 | 25篇 |
2012年 | 29篇 |
2011年 | 69篇 |
2010年 | 47篇 |
2009年 | 51篇 |
2008年 | 58篇 |
2007年 | 40篇 |
2006年 | 42篇 |
2005年 | 37篇 |
2004年 | 30篇 |
2003年 | 26篇 |
2002年 | 25篇 |
2001年 | 17篇 |
2000年 | 13篇 |
1999年 | 22篇 |
1998年 | 19篇 |
1997年 | 8篇 |
1996年 | 10篇 |
1995年 | 10篇 |
1994年 | 9篇 |
1993年 | 2篇 |
1992年 | 4篇 |
1991年 | 1篇 |
1990年 | 6篇 |
1989年 | 1篇 |
1988年 | 2篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1984年 | 2篇 |
1983年 | 1篇 |
1980年 | 1篇 |
排序方式: 共有836条查询结果,搜索用时 15 毫秒
81.
Localized inhomogeneous plastic deformation phenomenon was experimentally investigated in a structural steel by using the magnetic Barkhausen noise measurements. ANSI 1050 steel plates, throughout oriented in the rolling transversal direction, were selected additionally inducing different strains. Scanning of the magnetic Barkhausen energy (MBNenergy) shows the formation of Lüders bands as well as the displacements in the material deformation zone. The MBNenergy angular dependency on the applied stress and on the anisotropy coefficient were determined as well as the presence of Lüders bands in samples oriented according to the rolling direction. 相似文献
82.
Xiao L.He Y. 《传感技术学报》2018,(8):1181-1186and1200
Orderly polymer composites based on polyvinyl-lidene fluoride(PVDF)assembled with parallel aligned expanded graphite(EG)flakes were fabricated by two-step forming process. This paper analyzed the thermal diffusion features in various directions,thermal conductivity property,and the thermal stability and mechanical property of the PVDF/EG thermal conductivity laminated composite. The thermal diffusion coefficient in the parallel direction was 4.1 times that of the perpendicular direction. When mass frictions of EG are 15wt%,20 wt% and 25%,the thermal conductivities of the composite material will be 1.595 W/(m•K),2.87 W/(m•K)and 3.984 3 W/(m•K),and have a lower "leakage" threshold. Thus,it is interesting to note that the microstructure of parallel arrangement could introduce excellent thermal conductivity with obvious anisotropic thermal behaviors. In addition,as PVDF/EG thermal conductivity orderly composite material has a sound flexibility,the deformation behaviors of PVDF/EG composites were studied and indicated they are more flexible than PVDF. © 2018, The Editorial Office of Chinese Journal of Sensors and Actuators. All right reserved. 相似文献
83.
Wen Shifeng Li Shuai Wei Qingsong Chunze Yan Zhang Sheng Shi Yusheng 《Journal of Materials Processing Technology》2014,214(11):2660-2667
Selective laser melting (SLM) manufactures components through the overlapping of multi-track and multi-layer molten pools of metal powders, resulting in two types of molten pool boundaries (MPBs), “layer–layer” and “track–track” MPBs, remaining in SLM parts. The microstructure of MPBs exhibits a complex and regular spatial topological structure. There is a coarse grain zone below the MPBs and nonmetallic elements (C, O, Si) near the MPBs are in an unstable state. Long and thin columnar grains with the same orientations distribute on two sides of the “layer–layer” MPBs, whereas the columnar grains on both sides of “track–track” MPBs have different orientations. The “track–track” MPBs are short and intersect with “layer–layer” MPBs at some points and form acute angles, where cracks are initiated when applied with external loads. The effect of the MPBs on microscopic slipping, macroscopic ductility and fracture mechanism of the SLM parts made along different directions, which were exerted a tensile loading in the as-built condition without heat treatment, was analyzed and evaluated using slip theory and experiments. The results reveal that the MPBs have a significant impact on the microscopic slipping at the loading, macroscopic plastic behavior and fracture mode, and are one of the main reasons for the obvious anisotropy and low ductility of SLM parts. 相似文献
84.
《Intermetallics》2014
Structural modification in a Zr-based metallic glass caused by irradiation with 7 MeV Xe26+ ions was investigated. Needle-like nanocrystalline structures, formed under ion irradiation, consist of Cu10Zr7 phase (primary) and/or minor (NixCu1−x)10Zr7 phase. The formation of needle-like nanocrystals suggested an anisotropic atomic diffusion caused by ion irradiation. 相似文献
85.
《Intermetallics》2016
We report a correlation between magnetoresistivity Δρmag and magnetic entropy change ΔSmag for specified crystallographic directions of a HoAl2 single crystal. This ferromagnetic compound shows differentiated behavior among the members of the RAl2 series due to the presence of spontaneous spin reorientation. We discussed this effect in order to establish a relationship between the two quantities studied. The calculations were performed using a self-consistent model based on a Hamiltonian containing exchange, Zeeman and crystal field terms. We found that the normalized relation {Δρmag} = (T/TC)m{ΔSmag}, with m = 0.1 for the [100] and [110] directions matches satisfactorily the two quantities. 相似文献
86.
Toshihiko Kuwabara Kazuma Hashimoto Eiji Iizuka 《Journal of Materials Processing Technology》2011,211(3):475-481
The deformation behavior of 780 MPa grade dual-phase steel sheet subjected to hole expansion is investigated both experimentally and analytically to clarify the effect of the material model (anisotropic yield function) on the predictive accuracy of finite element analysis of hole expansion. Biaxial tensile tests of the material were conducted; contours of plastic work and the directions of plastic strain rates are precisely measured and are in good agreement with those predicted from the Yld2000-2d yield function with an exponent of 4 ( [Barlat et al., 2003] and [Yoon et al., 2004]). Finite element and experimental analyses on the hole expansion of the material were conducted. The Yld2000-2d yield function with an exponent of 4 provides closer agreement with the experimental results than other yield functions. Consequently, the anisotropic yield functions significantly affect the predictive accuracy of the deformation behavior of the steel sheet subjected to hole expansion, and the biaxial tensile test is effective for identification of the appropriate anisotropic yield function to be used for hole expansion simulation. 相似文献
87.
88.
《Intermetallics》2015
The non-equiatomic FeCoNiAlSi alloy is prepared by the Bridgman solidification (BS) technique at different withdrawal velocities (V = 30, 100, and 200 μm/s). Various characterization techniques have been used to study the microstructure and crystal orientation. The morphological evolutions accompanying the crystal growth of the alloy prepared at different withdrawal velocities are nearly the same, from equiaxed grains to columnar crystals. The transition of coercivity is closely related to the local microstructure, while the saturation magnetization changes little at different sites. The coercivity can be significantly reduced from the equiaxed grain area to the columnar crystal area when the applied magnetic field direction is parallel to the crystal growth direction, no matter what is the withdrawal velocity. In addition, the alloy possesses magnetic anisotropy when the applied magnetic field is in different directions. 相似文献
89.
Yusuf Özçatalbaş 《Machining Science and Technology》2013,17(4):626-637
□ In conventional metal cutting process, materials are assumed to be homogeneous and isotropic structure. However, some materials with a single crystal or coarse elongated polycrystalline demonstrate strong anisotropic behavior in physical and mechanical properties in machining of some superalloy materials. The anisotropic structure always leads to variation at machinability properties of the material. In this study, machinability properties of ferritic superalloy PM2000, which had elongated a few coarse grains, were investigated. These properties were determined by investigation of chip formation, cutting forces and surface roughness. Machinability was assessed by single-point turning on a CNC lathe and turning forces were measured by using a Kistler Lathe Dynamometer. The chip formation mechanisms in machining of PM2000 at various cutting speeds were determined by using a quick-stop device (QSD). Chip roots and machined surfaces were analyzed by means of scanning electron microscopy (SEM). The results indicated that the machinability properties of the PM2000 were changed by orientated coarse grain structure. Three types chip formation mechanism were determined at the same cutting conditions. Also, surface roughness on the machined each grain changed with changing the grain to be cut. Surface roughness and force fluctuations decreased with increasing the cutting speed; however, tool wearing increased. 相似文献
90.
M. Merklein 《CIRP Annals》2008,57(1):269-274
The enhancement of material modeling in fields of sheet metal forming is essential for finite element-based designing of processes and dimensioning of parts. Since new lightweight materials, e.g. aluminum and magnesium wrought alloys show anisotropic and temperature-dependent forming behavior adequate testing methods and evaluation strategies have to be developed to obtain the reliable material data. For that purpose an experimental setup has been designed at the Chair of Manufacturing Technology which enables biaxial tensile testing of sheet metal at elevated temperatures. In this paper, the setup is introduced and the obtained results, i.e. experimentally determined yield loci and subsequent yield loci as a function of temperature are given for the well-known aluminum alloy AA6016 as well as the magnesium alloy AZ31. 相似文献