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排序方式: 共有705条查询结果,搜索用时 15 毫秒
31.
32.
研究了高硅铝硅合金(45wt% Si)熔体电磁分离过程中,Sb添加量、下拉速率、温度等对分离效果的影响,对Sb在高硅铝硅合金电磁分离过程中的变质机理进行了分析。结果表明,在1500℃、下拉速率为10 μm/s时,过共晶铝硅合金熔体中加入Sb进行定向凝固后,合金部分硅铝比从11.53%降至11.21%,初晶硅富集区的硅含量从86wt%增至90wt%;当1500℃、下拉速率为40 μm/s时,合金部分硅铝比从12.56%降至12.13%,初晶硅富集区的硅含量从81wt%增至86.5wt%;加入变质剂后合金部分共晶硅相在α-Al基体中分布均匀且连续,形貌有所细化。 相似文献
33.
采用十溴二苯乙烷(DBDPE)协同三氧化二锑(Sb2O3)组成复合阻燃剂DBDPE–Sb2O3(D–S)阻燃长玻纤增强聚丙烯(LGFPP),并采用热烘箱老化法研究了140℃条件下不同热氧老化时间对复合材料热氧老化性能的影响。结果表明,随着热氧老化时间的延长,LGFPP/D–S阻燃体系的氧指数值呈现出先升高后下降的趋势,垂直燃烧等级始终保持FV–0级的阻燃级别,复合材料的结晶度减小,力学性能逐渐下降。PP基体分子链的断裂以及玻纤与PP基体间发生界面脱粘是导致LGFPP/D–S复合材料宏观力学性能下降的主要原因。红外光谱表明,随着热氧老化时间的延长,试样表面会产生更多的生色基团使材料发生黄变,说明PP基体分子链的断裂加剧。 相似文献
34.
Wenhui Xue You Yu Yuna Zhao HuiLei Han Tao Gao 《Computational Materials Science》2009,45(4):1025-1030
We have investigated the electronic, dynamical, and thermodynamic properties of the rocksalt ScX (X = N, P, As, Sb) using a plane-wave pseudopotential method within the generalized gradient approximation in the frame of density functional perturbation theory. The calculated lattice constants are found to differ by less than 0.56% from the available experimental values. These materials have the indirect Γ–X band gaps and a wide and direct band gap at the X-point in band structure, which are closer to experimental results than the previous calculations. A linear-response approach is used to calculate the phonon frequencies, the phonon density of states and LO–TO splitting. The obtained phonon frequencies at the zone-center (Γ-point) for the Raman-active and infrared-active modes are analyzed. We also calculate the thermodynamic functions using the phonon density of states, and the calculated values are in nearly perfect agreement with experimental data. 相似文献
35.
H.A. Abd El‐Rahman S.A. Salih A. M. Abd El‐Wahab 《Materialwissenschaft und Werkstofftechnik》2011,42(9):784-791
Effect of phosphoric acid on the performance of Pb‐1.7%Sb grid of lead‐acid cell is studied in 5 M H2SO4 by cyclic galvanostatic polarization and impedance spectroscopy. An increase in capacitance to a maximum is recorded during the initial stages of the electro‐reduction of PbO2 into Pb(II) compounds and attributed to concurrent compositional and dimensional changes. These changes include removal of O2 bubbles, insertion of large amounts of H2SO4 and H2O. Efficiency of PbO2 formation decreases, while its rate of self‐discharge increases with increasing the charging current and in the presence of H3PO4. The charge capacity increases with increasing the discharging current due to the decrease in the self‐discharge. The charge capacity is lower in the presence of H3PO4. On increasing the cycle number, the corrodibility of the grid increases, because more layers of the surface Pb are involved in the self‐discharge. H3PO4 significantly retards the effect of cycle number. 相似文献
36.
Sn−5wt.%Sb alloy is used for the soldering of ceramic devices. Reaction couples, dissolution, and differential scanning calorimetry
experiments are conducted to examine the interfacial reactions and dissolution of Ag substrates with the molten Sn−5wt.%Sb
solder. One intermetallic compound, Ag3Sn, is formed at 260°C at the Sn−5wt.%Sb/Ag contact. With the intake of Ag from the substrate, the binary Sn−5wt.%Sb alloy
becomes a ternary (Sn−5wt.%Sb)100−xAgx melt. It is found that a small amount of Ag addition significantly lowers the melting point of the Sn−5wt.%Sb alloy. This
phenomenon is illustrated with the (Sn−5wt.%Sb)100−xAgx isoplethal section. 相似文献
37.
重点研究了由CdO-SnO2-WO3系列(简称Cd-Sn-W)和CdO-Sb2O3-WO3系列(简称Cd-Sb-W)及由它们共同组成的双基体三相(Cd2Sb2O7,CdSnO3,CdWO4)结构线性敏感陶瓷的制备方法。给出了上述半导体陶瓷的电子转移式;分析了半导相Cd2Sb2O7和CdSnO3的导电机理和电阻-温度(R-T)曲线呈线性的机理,并对其他相关特性进行了分析和研究。独立地设计了用化学共沉淀方法制备上述NTC(负温度系数)陶瓷微粉的化学反应方程式,并对聚乙二醇和无水乙醇在制备纳米微粉时所起的防止颗粒发生团聚现象的作用进行了分析。由于大分子量的聚乙二醇几乎是无毒的,对人体基本无毒害作用,因而有广泛的推广价值。 相似文献
38.
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40.
M. F. Grattont R. G. Goodchild L. Y. Juravel J. C. Woolley 《Journal of Electronic Materials》1979,8(1):25-29
Measurements have been made to determine accurately the solidus curve of the pseudobinary section GaAsySb1−y, by annealing samples to equilibrium and determining compositions by x-ray powder photography. It is found that the equilibriui
diagram shows a peritectic form with a peritectic temperature of 745 ± 1‡C and a miscibility gap at that temperature extending
from y = 0.38 to y = 0.68. It is also shown that as the temperature is lowered the miscibility gap widens rapidly, being from
y = 0.30 to y = 0.95 at 700‡C. The form of these phase boundaries is important when growth of GaAsySb1−y alloys by liquid phase epitaxy or similar techniques is considered. 相似文献