全文获取类型
收费全文 | 370篇 |
免费 | 5篇 |
专业分类
电工技术 | 15篇 |
化学工业 | 103篇 |
金属工艺 | 15篇 |
机械仪表 | 10篇 |
建筑科学 | 3篇 |
能源动力 | 18篇 |
轻工业 | 21篇 |
无线电 | 28篇 |
一般工业技术 | 40篇 |
冶金工业 | 103篇 |
原子能技术 | 5篇 |
自动化技术 | 14篇 |
出版年
2022年 | 3篇 |
2021年 | 5篇 |
2020年 | 5篇 |
2019年 | 2篇 |
2018年 | 2篇 |
2016年 | 6篇 |
2014年 | 4篇 |
2013年 | 13篇 |
2012年 | 9篇 |
2011年 | 12篇 |
2010年 | 8篇 |
2009年 | 11篇 |
2008年 | 6篇 |
2007年 | 13篇 |
2006年 | 8篇 |
2005年 | 7篇 |
2004年 | 7篇 |
2003年 | 9篇 |
2002年 | 6篇 |
2001年 | 14篇 |
2000年 | 9篇 |
1999年 | 4篇 |
1998年 | 37篇 |
1997年 | 18篇 |
1996年 | 20篇 |
1995年 | 12篇 |
1994年 | 13篇 |
1993年 | 8篇 |
1992年 | 6篇 |
1990年 | 4篇 |
1989年 | 3篇 |
1988年 | 3篇 |
1987年 | 2篇 |
1986年 | 5篇 |
1985年 | 6篇 |
1984年 | 8篇 |
1983年 | 8篇 |
1982年 | 6篇 |
1980年 | 3篇 |
1979年 | 5篇 |
1977年 | 7篇 |
1976年 | 11篇 |
1975年 | 3篇 |
1974年 | 3篇 |
1973年 | 3篇 |
1972年 | 2篇 |
1971年 | 2篇 |
1970年 | 2篇 |
1969年 | 2篇 |
1968年 | 2篇 |
排序方式: 共有375条查询结果,搜索用时 15 毫秒
21.
Kataoka K. Itoh T. Okumura K. Suga T. 《Electronics Packaging Manufacturing, IEEE Transactions on》2007,30(3):194-199
A contact process between large-scale integration (LSI) pads and test probes at low contact force is a key to developing a probe card with smaller pitch and higher pin count. In this paper, we report on the characteristics of low-force contact methods on Cu electrodes. One is the fritting process, in which an electric breakdown is utilized to break the surface oxide, and the other is the heating treatment in hydrogen gas aimed at deoxidizing the surface Cu oxide. Conventional tungsten needle probes were used as testing probes, and contact resistances at low contact force of 1-5 mN were measured. Contact resistances smaller than 1 Omega were obtained by the fritting processes, in which the voltage and the current were 10 V and 280-320 mA, respectively. A deoxidization process at over 260degC was found to be effective for decreasing the contact resistance. The X-ray photoelectron spectroscopy (XPS) was utilized to investigate the surface state of hydrogen-treated Cu, and the deoxidization of Cu2O to Cu was observed in samples treated at 260degC, while no change was found in that at 150degC. 相似文献
22.
Numerical evaluations of grid erosions in ion engines are required to estimate the lifetimes of long-term space missions. In this study, to investigate the characteristics of ions colliding with neutrals and impacting the accel grid surface, including ions that collide with neutrals more than once, three-dimensional particle analyses using a full-PIC (Particle in Cell) code were performed. The distributions of erosion by charge-exchanged ions show periodic patterns. The multiple-collided ion constitutes 7 and 8% of the accel grid current to the inner and downstream surfaces, respectively. The energy of the multiple-collided ion impacting the downstream surface has a broader distribution than that of the charge-exchanged ion. These results suggest the importance of investigating multiple-collided ions in high-accuracy quantitative evaluations of grid erosion. 相似文献
23.
24.
Y Katakura T Kumamoto Y Iwai Y Kurokawa T Omasa K Suga 《Canadian Metallurgical Quarterly》1997,34(10):731-734
The interaction between a single-chain Fv (sFv) of the monoclonal antibody 3A21 and its antigen, bovine pancreatic ribonuclease A (RNase A), was studied by site-directed mutagenesis of the hypervariable regions and fluorescence polarization analysis. The affinity constants of wild-type sFv and a mutant sFv D31A (Asp31 of heavy chain was replaced by Ala) for RNase A were found to be 2.7 x 10(7) and 4.7 x 10(6) M-1 in PBS at pH 7.2 and 37 degrees C, respectively. While the affinity constant of D31A is not affected by NaCl concentration, that of wild-type sFv is almost the same as that of D31A in the presence of more than 1 M NaCl. These results demonstrate that Asp31 of the heavy chain interacts electrostatically with a positively charged amino acid residue of RNase A. 相似文献
25.
A fuel cell system using yttria-stabilized zirconia as a solid electrolyte was applied to the oxidative coupling of methane. The most active and selective catalyst was BaCO3 deposited on Au-electrode (anode). Optimum conditions for the reaction were examined. The pressure of methane at the anode and that of oxygen at the cathode should be high as much as possible. The optimum temperature was 1073 K. Several advantages of the method are described. 相似文献
26.
In single-objective optimization problems, with only one optimal design objective, the absolute optimal solution to maximize/minimize the objective function can be determined. However, in most real design problems, the optimization problems are multi-objective, where two or more independent design objectives must be optimized simultaneously, and no single absolute optimal solution necessarily exists. In these cases, it is helpful for designers to recognize the range of alternative solutions that exist in Pareto-optimal sets and choose an acceptable solution from among them. In this paper, the authors carried out multi-objective optimization using Multiple Objective Genetic Algorithms through a real case study involved in indoor environmental design – the design of outer windows. Then the authors analyzed structure of Pareto-optimal solution sets. Here we present the analysis process as well as the case study details, and show how the method proposed here is effective at finding an acceptable solution for multi-objective optimization problems. 相似文献
27.
Okamoto K Narayama S Katsuo A Shigematsu I Yanase H 《Journal of Bioscience and Bioengineering》2002,93(2):207-210
The white-rot basidiomycete Pleurotus ostreatus produced sweet flavor compounds on a liquid medium. The major and minor compounds identified by GC-MS analysis were p-anisaldehyde (4-methoxybenzaldehyde) and 3-chloro-p-anisaldehyde (3-chloro-4-methoxybenzaldehyde), respectively. p-Anisaldehyde was only produced under static culture conditions. Differences in the type and quantity of flavor compounds produced among wild strains of P. ostreatus were observed. Aryl alcohol oxidase and manganese peroxidase activities increased parallel to the production of p-anisaldehyde. These results indicated that the biosynthesis of p-anisaldehyde is concerned in generating H2O2-activated peroxidase in the lignin-degradation system. Addition of L-tyrosine to the culture led to higher production of p-anisaldehyde. The flavor extract, which contains p-anisaldehyde, exhibited antimicrobial activity against Bacillus subtilis, Pseudomonas aeruginosa, Aspergillus niger and Fusarium oxysporum. 相似文献
28.
Flow characteristics at Re = 660–3000 in a serpentine channel are measured. A scale-up model whose channel hydraulic diameter is 50 times as large as that for a proton exchange membrane fuel cell (PEMFC) is used for the measurements. The flow conditions correspond to operating conditions for PEMFCs of 25–40 cm2 at current density of 1–3 A/cm2 when the fuel utilisation ratio is 0.75 and air is used for the O2 supply. Two different porous media are used to simulate the gas diffusion layer (GDL). The results suggest that although the leakage flow rate is rather insensitive to the total flow rate, it increases significantly depending on the increase of the GDL permeability. Increasing the flow rate or the permeability enhances the sectional secondary flows and is expected to enhance mass transfer on the GDL. It is confirmed that the flow becomes turbulent around the bend even at Re = 660. 相似文献
29.
The effect of nine transition elements on the morphology, distribution and composition of MC carbides (MCs) in a nickel-base
superalloy, IN-100, was investigated by differential thermal analysis (DTA), microstructural observation and X-ray microanalysis.
The doping with tantalum, tungsten and molybdenum caused a significant change in the morphology and distribution of MCs as
well as the profile of DTA curve of IN-100. The compositions of the MC in IN-100 were TiC and (Ti0.80Mo0.17V0.03) C, and the doping with niobium, tantalum and tungsten changed significantly the composition of MC. On the other hand, the
doping with chromium, vanadium, hafnium and zirconium scarcely changed the composition. In addition to TiC and (Ti, Mo, V)
C, zirconium- and hafnium-rich MCs were found in the zirconium- and hafnium-doped alloys, respectively. The effect of the
dopants on the composition of MCs could be explained by a relationship between the metallic radius and the free energy of
formation for the MC. 相似文献
30.
Suga K Mochizuki N Harayama K Yamashita H 《Shokuhin eiseigaku zasshi. Journal of the Food Hygienic Society of Japan》2004,45(6):307-312
A simple method for analysis of trichothecenes [Type A: diacetoxyscirpenol, neosolaniol, HT-2 toxin, and T-2 toxin, Type B: deoxynivalenol, nivalenol, fusarenon-X, 3-acetyldeoxynivalenol, 15-acetyldeoxynivarenol] in barley tea and beer using liquid chromatography tandem mass spectrometry (LC/MS/MS) was developed. Trichothecenes were extracted with ethyl acetate-methanol (19:1). The solvent was evaporated to dryness and the residue was dissolved in water-methanol (3:1) for injection into the LC/MS/MS. The LC separation was performed with an octadecylated silica column at a flow-rate of 0.2 mL/min, using a mobile phase consisting of water, methanol and acetonitrile. MS/MS was used in multiple reaction monitoring, employing electrospray ionization (ESI-MRM). The recoveries of trichothecenes from drinks at 1 microg/L (Type A) and 10 microg/L (Type B) were 52.5-115.2% (barley tea) and 68.1-127.5% (beer). Five barley tea and ten beer samples were analyzed by this method. Trichothecenes were not detected in them. This method may have applications in quality assurance. 相似文献