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排序方式: 共有1343条查询结果,搜索用时 15 毫秒
121.
Kei Nishikawa Yasuhiro Fukunaka Tetsuo Sakka Yukio Ogata J. Robert Selman 《Journal of power sources》2007
The charging (lithiation) and discharging (delithiation) of a Ni–Sn alloy electrode was examined by means of holographic interferometry and laser scanning confocal microscopy (LSCM). The developing concentration profile of Li+ ion during discharging (delithiation) of the Ni–Sn alloy electrode agreed reasonably well with the prediction based on transient diffusion theory, indicating that the cell configuration successfully suppressed natural convection due to the electrochemical reaction. The morphological variation of Ni–Sn alloy electrode during charge/discharge cycle could be observed very clearly by in situ LSCM. It was found that the contraction of active material during the discharge (delithiation) initiates cracks in the Ni–Sn alloy electrode. 相似文献
122.
Hyun Tae KimJong Suk Yoo Han-Ik Joh Heeyeon KimSang Heup Moon 《International Journal of Hydrogen Energy》2011,36(2):1606-1612
Sn-promoted Pt-based catalysts were prepared by the chemical vapor deposition (CVD) of Sn on commercial Pt/C and PtRu/C catalysts using Sn(CH3)4 as an Sn precursor. The prepared catalysts showed higher CO tolerance than those prepared by adding Sn using an impregnation (IMP) method. This result was obtained because Sn added by CVD was selectively deposited on the Pt and Ru surfaces, instead of on a carbon support, such that the interfacial contact between Pt and Sn was greater in the Sn-CVD catalyst than in the others, as confirmed by in-situ infrared and X-ray photoelectron spectroscopic observations of the catalysts. 相似文献
123.
利用扫描电子显微镜(SEM)和透射电子显微镜(TEM)研究了Sn3.8Ag0.7Cu(Sn37Pb)/Cu焊点在时效过程中的界面金属间化合物(IMC)形貌和成份。结果表明:150℃高温时效50、100、200、500h后,Sn3.8Ag0.7Cu(Sn37Pb)/Cu焊点界面IMC尺寸和厚度增加明显,IMC颗粒间的沟槽越来越小。50h时效后界面出现双层IMC结构,靠近焊料的上层为Cu6Sn5,邻近基板的下层为Cu3Sn。之后利用透射电镜观察了Sn37Pb/Ni和Sn3.8Ag0.7Cu/Ni样品焊点界面,结果显示,焊点界面清晰,IMC晶粒明显。 相似文献
124.
For development of a lead-free composite solder for advance electrical components, lead-free Sn3.5Ag0.5Cu solder was produced by mechanically mixing 0.5 wt.% TiO2 nanopowder with Sn3.5Ag0.5Cu solder. The morphology and growth kinetics of the intermetallic compounds that formed during the soldering reactions between Sn3.5Ag0.5Cu solder with intermixed TiO2 nanopowder and Cu substrates at various temperatures ranging from 250 to 325 °C were investigated. A scanning electron microscope (SEM) was used to quantify the interfacial microstructure at each processing condition. The thickness of interfacial intermetallic layers was quantitatively evaluated from SEM micrographs using imaging software. Experimental results show that a discontinuous layer of scallop-shaped Cu-Sn intermetallic compounds formed during the soldering. Kinetics analysis shows that the growth of such interfacial Cu-Sn intermetallic compounds is diffusion controlled with an activation energy of 67.72 kJ/mol. 相似文献
125.
Y. Cai F. Phillipp A. Zimmermann L. Zhou F. Aldinger M. Rühle 《Acta Materialia》2003,51(20):6429-6436
The superstructure of an antiferroelectric Pb0.97La0.02(Zr0.66Sn0.25Ti0.09)O3 phase, whose composition is near the morphotropic-phase boundary, was characterized. Systematic selected-area diffraction revealed that there were two kinds of superlattice reflections in the pseudocubic reciprocal lattice, i.e.
superlattice reflections (h, k, l all odd), and
one-dimensional incommensurate superlattice reflections, where g denotes the vectors of fundamental or
superlattice reflections. Convergent-beam electron diffraction disclosed that the average structure of the phase was rhombohedral with space group of
. Based on the rhombohedral reciprocal lattice, the
reflections were no longer superlattice but fundamental reflections, and the reciprocal vector of the one-dimensional incommensurate reflections was re-expressed as , where h, k, l are integers and (−h + k + l) = 3n. In the light of the average structure and the reflection condition, the superspace Bravais class of the phase with one-dimensional incommensurate structure was determined to be
in a (3 + 1)-dimensional space. In addition, the origins of the superlattice reflections were also examined and discussed. 相似文献
126.
J. S. Kang R. A. Gagliano G. Ghosh M. E. Fine 《Journal of Electronic Materials》2002,31(11):1238-1243
Isothermal solidification of conventional Cu/Sn diffusional couples was performed to form thin (30 μm) joints consisting of
Cu-Sn intermetallics. During initial stages of isothermal solidification, both Cu6Sn5 and Cu3Sn phases grow, even though the former is the dominant. After consumption of all available Sn, the Cu3Sn phase grows reactively at the expense of Cu and Cu6Sn5. Finally, we obtain solder joints that consist of only Cu3Sn. Indentation fracture-toughness measurements show that Cu3Sn is superior to Cu6Sn5. Furthermore, indentations of Cu3Sn exhibit the presence of shear bands, which are not observed in Cu6Sn5, implying that the former is more ductile than the latter. Ductile intermetallic-based joints formed by isothermal solidification
are promising candidates to form thin (as thin as 5–10 μm or less) solder joints, as they are thermally and thermodynamically
stable compared to conventional solder joints. Excess copper in the interconnect provides ductility to the interconnect. 相似文献
127.
128.
The solid state reaction between tin and copper(I) chloride powders was studied by means of thermogravimetry under vacuum using non-isothermal and isothermal method of analysis. It is established that the kinetics in the temperature range 150 to 210 °C is governed by a diffusion-controlled process in terms of the Jander equation with an apparent activation energy of 110 KJ mol−1. In the first stage, the rate determined step is the best described by an interfacial reaction. Two intermetallic compounds η-Cu6Sn5 and ε-Cu3Sn predicted from the phase diagram have been identified in the reaction products and the presence of tin whiskers on the surface on the grains has been observed. 相似文献
129.
(Zr0.7Sn0.3)TiO4陶瓷介电性能与工艺参数关系的回归分析 总被引:2,自引:0,他引:2
用回归分析方法得到了(Zr0.7Sn0.3)TiO4陶瓷的介电性能ε和δ与其工艺参数(CuO、ZnO)和玻璃的添加量(分别为x1、x2、x3 wt%)及预烧和烧结温度(分别为x4×103和x5×103℃)之间的定量关系ε=10.9731-1.4559x1+9.9154x2+1.9776x3-3.3160x22-0.2286x23-200.1697x24-161.9102x25+375.1160x4x5;lg(tanδ)=-38.5876-0.6452x2+0.1235x3+31.2221x4+30.3861x5+0.1100x21+0.2077x22-0.0106x23-27.4317x4x5.能对给定工艺参数下的介电性能进行预测,并能确定满足特定介电性能的工艺参数,有助于加快电子陶瓷材料的研究. 相似文献
130.
A theoretical model of a beam of unidirectional composites—based on the homogenisation theory and a refined kinematical hypothesis—is used for the analysis of the influence of the helicoidal geometry of a superconducting strand triplet on its strain state. The triplet is the first cabling stage of the superconducting cables used to wind the coils of ITER fusion reactor. The multiscale modelling strategy is presented, for which a finite element code has been developed. A triplet of Nb3Sn based strands subjected to an axial stretch is analysed, and the resulting complete 3D strain state in the Nb3Sn filament is recovered. An “extra” strain is found due to the helicoidal geometry of the triplet. Discussion of the results concludes the paper. 相似文献