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81.
Circuits and principle of operation of quasioptical power dividers based on two-row periodic structures, formed by grids of metal bars and a dielectric waveguide placed along their longitudinal axis, are described. The experimental studies of power divider prototypes in a frequency range of 60–80 GHz have shown a possibility of regulating the emitted power level in the main divider arm by changing longitudinal and angular coordinates of the two-row periodic structure, which can be used for designing quasioptical attenuators.  相似文献   
82.
Producing of safer products by applying high pressure on biosystem, is a novel non-thermal technology with significant results in maintaining the natural characteristics of the food items. Modeling of the microorganism kinetics inactivation by the high pressure was determined and certificated by an experimental approach. It is established that the basic laws of the joint influence of the factors of high pressure, temperature and process time on microorganisms and vitamin C are reproduced in the framework of the linear kinetics. By choosing the values of the process parameters (pressure, temperature, duration of the process), the averaged thermodynamic characteristics of micro flora can be changed, as well as the value of the activation barrier of the biochemical reaction. Based on these results, working 40 min at the pressure 400 MPa, and temperature 300 K, the microorganism activity is minimum, and the vitamin C contain is preserved about 90 percent.  相似文献   
83.
Oxidized fullerite was obtained by heating a fullerite sample intercalated with oxygen, (O2)0.44C60, up to 300 degrees C. Orientational phase transitions in the oxidized fullerite are studied using differential scanning calorimetry (DSC) and have been found to possess a specific enthalpy whose value is lower by 25% than in the initial (O2)0.44C60 sample. In order to find possible reasons for hindrance to the buckyball rotations, we performed optimizations of defect buckyball fullerenes C60-n with different distributions of vacancies along with the dimers C60-n-C60-n and C60-C60-n for n = 1-4 using density functional theory with generalized gradient approximation. We found that the dimerization energy ranges from 1.07 eV (C58-C58) to 6.56 eV (C56-C56) and from 1.81 eV (C60-C58) to 4.29 eV (C60-C56), respectively. The formation of such dimers, which could in addition interact with defect buckyball cages and form larger aggregates, is to be related to the lowering of the orientational transition enthalpy.  相似文献   
84.
85.
Processes are considered for making materials for medical purposes (filling bone cavities). Methods are surveyed for making materials for osteoplastic treatment such as bioactive glasses, glass ceramics, biological or synthetic hydroxyapatite, and composites based on them.  相似文献   
86.
Using the potentiodynamic polarization curve method, x-ray phase analysis, and Auger electron spectroscopy, we have studied the mechanisms for cathodic and anodic processes occurring in a 30% KOH solution on the surface of the intermetallic compounds Mg2Ni, MgNi2 and the hydride Mg2NiH4. In contrast to MgNi2, we observed hysteresis of the cathodic polarization curve for Mg2Ni due to formation of a surface layer (a mixture of the hydride phases β‐Mg2NiH4 and Mg2NiH3.85) on the sample, as a result of reaction between Mg2Ni and atomic hydrogen. We have shown that the surface of the samples is considerably enriched in magnesium and depleted of nickel, and their corrosion resistance in the indicated electrolyte is determined by active dissolution of nickel and formation of a surface layer (~25 nm) on the electrodes consisting of MgO and Mg(OH)2 in the case of Mg2Ni and Mg2NiH4, and also of MgO, Mg(OH)2, and NiO in the case of MgNi2. The intermetallic compound MgNi2 was the most corrosion-resistant, probably because of the presence of a monolayer of the oxides MgO and NiO on the original surface.  相似文献   
87.

New approaches to the sintering of nanocrystalline powders of refractory compounds are proposed. Titanium nitride-based ceramics with a grain size of 50 nm and nanohardness 28.8 ± 2.47 GPa was obtained by sintering at a controlled rate of densification. Investigation of evolution of the block structure in the material during sintering enabled further optimization of the procedure and reduction of the sintering temperature to 1150°C.

  相似文献   
88.
Features of sintering in argon and structure formation of materials of the systems (TiN, ZrN) – Ni are studied. It is shown that sintering is accompanied by the release of nitrogen from nitrides, reciprocal dissolution of nickel in nitrides and also Ti and Zr in nickel, formation of nickel intermetallics, and an increase in the microhardness of solid phase grains. The main reason for the quite high porosity of sintered TiN – Ni and ZrN – Ni composites are the accumulation of nitrogen released from the nitrides within closed volumes with formation of closed pores. Sintering of materials is accompanied by the growth and faceting of solid phase grains due to dissolution and recrystallization through a liquid phase, and also an increase in metal phase content.  相似文献   
89.
90.
Multicomponent intermetallic absorbers of hydrogen which are used as active materials in secondary current sources have a number of shortcomings: low electrical capacity and excessively high cost, particularly for cobalt containing alloys. A contemporary progressive method to improve the properties of electrode material is optimization of the alloy microstructure. Intermetallic hydrogen absorbers with controlled structural disorder were obtained by powder metallurgy techniques, and the effect of such on the electrochemical properties examined.  相似文献   
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