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31.
Processing of High‐Density Magnesia Spinel Electro‐Conducting Ceramic Composite and its Oxidation at 1400°C 下载免费PDF全文
Zaki Zaki Nasser Mostafa Yasser Ahmed Emad Ewais Mohamed Rashad 《International Journal of Applied Ceramic Technology》2016,13(4):662-669
Dense conductive ceramic composites of MgAl2O4 and MoSi2 were processed using combustion synthesis under‐load methodology. The starting reactants were blends of MoO3, SiO2, MgO, and Al powders. The study revealed that to obtain dense composite with homogeneous microstructure, 30 wt. % of MoSi2, 18.5 μm Al average particle size, and 175 MPa load are required. The produced dense composite was found to have a low apparent porosity (<1.0 vol. %), moderate density 4.61 g/cm3, and low electrical resistivity 0.3 Ωcm. The dense composite exhibited excellent thermodynamic stability between its phases at 1400°C in open atmosphere. 相似文献
32.
铌基超高温合金表面Si-Al包埋共渗抗氧化涂层的组织形成 总被引:2,自引:0,他引:2
通过1000~1150℃Si-Al包埋共渗8h的方法在铌基超高温合金表面制备Al改性硅化物抗氧化涂层,结果表明:实验温度下制备的涂层均具有多层复合结构;不同温度下共渗涂层外层的相组成不同,但最内层均由(Nb,Ti)Al3和(Cr,Al)2(Nb,Ti)组成。1050℃、8hSi-Al共渗在合金表面形成了Al改性的硅化物涂层,其最外层主要为Nb3Si5Al2,依次往内为(Nb,X)(Si,Al)2(X代表Ti,Cr和Hf元素)层、(Nb,X)5Si3层以及最内层;而在1000℃、8h条件下Si-Al共渗形成的涂层以(Nb,Ti)Al3为主,其中含有少量的(Nb,X)5Si3,没有形成以硅化物为主的涂层;在1100℃、8h和1150℃、8h条件下Si-Al共渗形成的涂层外层以(Nb,X)(Si,Al)2为主,但其中Al含量(摩尔分数)仅为2.35%,没有形成Nb-Si-Al三元化合物层。 相似文献
33.
目的提高钼合金表面红外辐射性能与高温抗氧化性能。方法将40%Si、20%Cr、5%Ti、5%SiC、30%Mn O_2五种粉末与酒精、粘结剂按比例混合,经高能球磨6 h后制得均匀悬浮的料浆。采用浸涂工艺对预处理的钼合金试样进行料浆涂覆,在1450℃真空烧结0.5 h后制得黑色涂层试样。通过1550℃高温静态氧化试验和高温粒子薄片红外光谱综合实验系统,分别评价涂层抗氧化性能和红外辐射性能,并通过扫描电镜(SEM)、能谱分析(EDS)、X射线衍射仪(XRD)对涂层氧化前后的形貌与组织结构进行分析。结果钼合金Si-Cr-Ti-SiC-Mn O_2涂层在700、900℃的法向发射率分别达0.85、0.88,在1550℃高温有氧环境下的静态抗氧化寿命达7 h。原始涂层呈四层复合梯度结构,由外到内分别为SiO_2+Mn3O_4+M5Si3(M指Mo、Cr、Ti)、M5Si3+Mo Si2+SiC+Mn3O_4、Mo Si2、Mo5Si3。高温氧化后,涂层四层复合结构由外到内转变为SiO_2+(Cr,Ti)5Si3+Mn Cr2O_4+Mn3O_4、M5Si3+SiC+Mn Cr2O_4+Mn3O_4、Mo Si2、M5Si3。高温氧化过程中,MSi2高硅化物层逐渐转变为M5Si3低硅化物层,涂层表面形成含Mn Cr2O_4尖晶石相和复合硅化物的致密SiO_2玻璃膜。结论 Si-Cr-Ti-SiC-Mn O_2涂层可有效提高钼合金基体的红外辐射性能和高温抗氧化性能,复合硅化物与硅锰复杂氧化物具有良好的抗氧化性能、高辐射性能和自愈合性能。 相似文献
34.
以Ni76Si24(质量百分数)合金粉末为原料,利用激光熔覆技术在A3钢表面制得了组织由条件Ni2Si初生相及少量Ni2Si/Ni3Si2共晶组成的新型金属硅化物合金涂层,分析涂层显微组织并测定其在0.5mol/1 H2SO4水溶液及不同浓度NaCl水溶液中的阳极极化曲线,结果表明激光熔覆Ni2Si/Ni3Si2金属硅化物合金涂层表面平整,组织细小,与基体为完全冶金结合,同时由于涂层的组织组成相Ni3Si2本身均具有极好的耐蚀性并具有快速凝固细小均匀的显微组织,该激光熔覆Ni2Si/Ni3Si2金属硅化物合金涂层在0.5mol/l H2SO4及3.5%NaCl水溶液中均具有优良的耐蚀性能。 相似文献
35.
Ti—Cr—Si硅化物涂层结构及裂纹扩展 总被引:7,自引:0,他引:7
分析研究了C-103铌合金改性Ti-Cr-Si保护涂层氧化过程中结构的变化以及裂纹扩展过程。结果表明,涂层表面玻璃态氧化物性质、涂层主体中硅含量以及低硅化物的生长和其力学性能决定了涂层中裂纹的扩展行为。 相似文献
36.
In this paper, it is shown in which kind the pressure difference across the free surface has to be chosen to obtain a stable convex static meniscus with a prescribed size in the case of a Ge1−XSiX single crystal ribbon growth by E.F.G. technique. The dependence of the pressure difference on the composition X is analyzed. The same tools as for a Ge or Si single crystal ribbon growth are used. The results can be useful in a future experiment planning or manufacturing technology design. 相似文献
37.
John G. Labram Ester Buchaca Domingo Natalie Stingelin Donal D. C. Bradley Thomas D. Anthopoulos 《Advanced functional materials》2011,21(2):356-363
Organic field‐effect transistors (OFETs) are used to investigate the evolution of the solid‐state microstructure of blends of poly(3‐hexylthiophene) (P3HT) and [6,6]‐phenyl C61‐butyric acid methyl ester (PC61BM) upon annealing. Changes in the measured field‐effect mobility of holes and electrons are shown to reveal relevant information about the phase‐segregation in this system, which are in agreement with a eutectic phase behavior. Using dual‐gate OFETs and in‐situ measurements, it is demonstrated that the spatial‐ and time‐dependence of microstructural changes in such polymer:fullerene blend films can also be probed. A percolation‐theory‐based simulation is carried out to illustrate how phase‐segregation in this system is expected to lead to a substantial decrease in the electron conductivity in an OFET channel, in qualitative agreement with experimental results. 相似文献
38.
Henry Berger 《Microelectronic Engineering》1991,10(3-4):259-267
A survey is given of the BOC Group technical research programs, whose purpose is to relate purity in gas processing to ULSI device parameters. Results from the following research programs are presented: how inert gas purity affects the Ti silicide for IGFET metallization; the effects of argon versus nitrogen used in silicon gate oxidation process steps; and preliminary work on a new gas analytical tool, Atmospheric Pressure Ionization Mass Spectrometry (APIMS), which allows measurement of sub ppb impurity levels in processing gases. 相似文献
39.
Relaxation of extrinsic and intrinsic stresses in germanium substrates with silicon films 总被引:1,自引:0,他引:1
Cynthia G. Madras Peter Y. Wong Ioannis N. Miaoulis Lee Goldman Ralph Korenstein 《Thin solid films》1998,320(2):260-263
Si films were deposited on Ge substrates at 400°C by two different Physical Vapor Deposition techniques: (A) ion beam sputtering and (B) magnetron sputtering. The intrinsic stresses in the as-deposited films were measured to be compressive and much greater in samples (A), about −1500 to −2000 MPa than in samples (B), about −300 to −500 MPa. The substrates were subsequently exposed to thermal treatments for varying times at 800°C. In the lower stressed (B) samples, the films had relaxed and reduced the overall curvature of the structure whereas in the high stresses (A) samples, an irreversible large increase in the substrate curvature was found to occur. This indicated that plastic deformation in the Ge substrates itself had occurred. 相似文献
40.
The kinetics of phase redistribution in the (Mo, W)Si2 Nb system at 1500-1800°C was investigated. The kinetic parameters for growth of the lower silicides (Mo, W, Nb) 5Si3 + Nb5Si3 and decrease in the layer thickness of the higher silicide (Mo, W)Si2 as function of the oxidation temperature were determined. It was established that the stability of the multiphase and multicomponent system was more than twice that of the system MoSi2 Nb, and 15-18 times that of MoSi2 Mo. 相似文献