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61.
The effective neutron multiplication factor (keff) as a function of burnup for different volume coolant (CoR) and fuel (FR) to cell ratio is presented. Additionally the Conversion Ratio (CR) of Th-232 to U-233, concentration of U-233, fissile and fission products calculation as a function of burnup are presented. The assembly is a critical reactor which makes volumes of coolant and fuel changes possible. In addition, an analytical model of calculation of keff as a function of U-233 and a poison concentration in equilibrium state are presented. One can achieve the criticality of Thorium Breeder Reactor (TBR) for enough high average neutron energy which one can obtain in Fast Breeder Reactor (FBR) only. The maximal value of CR and burnup for case of keff ≥ 1 achieves 1.4 and 360 GWd/MTU, correspondently. The calculations were done with a MCNPX 2.7 code using F2Be, Na and Pb coolants. 相似文献
62.
《Journal of the European Ceramic Society》2014,34(9):2111-2115
Neutron imaging devices employing a scintillator can be used in various fields, and eutectic crystals can be suitable for the imaging with a fine position resolution of a few hundred micrometers. Since LiF and LaF3 have different refractive indexes of 1.41 and 1.64 at 300 nm, respectively, the eutectic crystal is expected to behave as a scintillator with light guiding properties. Thus, the optical properties of Ce-doped LiF/LaF3 eutectic crystal grown by micro-pulling down method were investigated. The light output of LiF/Ce:LaF3 eutectic crystal was relatively small. The emission peaks at 300 nm originating from Ce3+ of 5d–4f transition were observed under excitation by UV photons and 5.5 MeV alpha rays. Moreover, the photo-luminescence decay time of Ce-doped LiF/LaF3 eutectic crystal was estimated to be 17 ± 1 ns. 相似文献
63.
Neutron imaging technique can be used as a means of material Non-Destructive testing. One of common neutron sources for neutron radiography is nuclear research reactor. In this work, several neutron imaging parameters such as aperture distance and the radiography plane location from the neutron source as well as the aperture diameter have been computationally optimized to deliver a proposed neutron beam. According to the results, the aperture diameter of 3.5–4 cm which was located at 55–85 cm from the outer layer of reactor core and the position of image plane at 300–400 cm fulfills delivering of the suitable neutron flux and other required conditions. W, Fe and Pb walls with an identified length formed the convergent-divergent collimator and shielded the neutron and gamma out of beam path. Bi and Fluental filters with an optimal dimension were used to efficiently improve the neutron beam profile at a sample position. 相似文献
64.
H. Fritzsche W.P. Kalisvaart B. Zahiri R. Flacau D. Mitlin 《International Journal of Hydrogen Energy》2012
We examined the deuterium absorption and desorption of 55 nm thick Mg films alloyed with Fe and Cr using in-situ neutron reflectometry. The Mg alloy films were covered with bimetallic catalyst layers and could be fully absorbed at room temperature at a pressure of 8 mbar. The NR experiments revealed a deuterium gradient within the Mg alloy layers during absorption and a large deuterium uptake up to a D/M ratio of about 0.45 before the layer started to expand and form magnesium deuteride (MgD2). Our NR data suggest that the catalytic effect of the Fe–Cr alloy is based on the avoidance of the formation of a blocking MgD2 layer in the early stages of the absorption process leading to a fast hydrogen absorption kinetics. 相似文献
65.
We present a quantum Monte Carlo application for the computation of energy eigenvalues for atoms and ions in strong magnetic fields. The required guiding wave functions are obtained with the Hartree–Fock–Roothaan code described in the accompanying publication (Schimeczek and Wunner, 2014). Our method yields highly accurate results for the binding energies of symmetry subspace ground states and at the same time provides a means for quantifying the quality of the results obtained with the above-mentioned Hartree–Fock–Roothaan method. 相似文献
66.
The integrity of turbine blades is at the heart of every operating aerospace engine or land-based gas turbine. In the most demanding environments, they are cast as single crystals. Whereas traditional neutron imaging is an excellent tool for the non-destructive testing in search of cracks or residual core material, it is insensitive to variations in crystallographic properties. In this work we show that by simultaneous imaging of the diffracted neutrons, one can also probe variations in crystal orientation. In a matter of seconds, different dendritic growth in two industrial turbine blades could be ascertained. 相似文献
67.
AbstractAs new environmentally friendly techniques, hydride materials have been proposed to be introduced to fast reactor (FR) cores in this paper. Hydrogen atoms in metal hydride can efficiently moderate fast neutrons. Based on this fact, some metal hydrides have been investigated for their potential environmentally friendly application as nuclear materials to be used in FR cores. Two types of utilisation of metal hydrides in FR cores are discussed in this paper. One is the application of hafnium hydride as neutron absorber in FR cores. The core design has been carried out to examine its characteristics as well as to evaluate the cost reduction effect. Demonstration of the fabrication of hydride pins has been performed using hydride pellets and stainless steel claddings. The coating technique of the inner cladding surface has also been developed to reduce the permeation of hydrogen through the stainless steel cladding. The physical and chemical properties of the pellet have been measured for the purpose of designing a hafnium hydride pin. Irradiation test of the hydride pins has been performed in the experimental FR, JOYO, Japan Atomic Energy Agency. The other application is the utilisation as a transmutation target of long lived nuclear wastes. Hydride fuel containing 237Np, 241Am and 243Am has been studied for a candidate transmutation target to be used to reduce the radioactivity of long lived nuclides contained in the nuclear wastes, which are obtained after reprocessing spent fuels. 相似文献
68.
We derive a customized solution to the diffusion equation in a heterogeneous slab with an arbitrary contiguous source. While aspects of solution have previously been reported in the literature, its full explicit form as presented here by solving a 3-term recurrence, has not. We conclude with a series of exercises demonstrating the utility of the solution. 相似文献
69.
70.
《Journal of the European Ceramic Society》2014,34(15):4043-4052
New fused cast refractories with a high content of zirconia have been developed to face corrosion in glass furnaces. The controlled cooling process is responsible for thermal gradients. So, thermal mismatches appear between core and edge zones of blocks. Besides, the multiphasic nature of ZrO2 based refractories is associated to thermal mismatches during cooling. Finally, the expansive transformation of ZrO2 can lead to stress generation.This paper is an application of neutron diffraction to study texture generated during the cooling process of zirconia based materials. In fact, it is shown that ZrO2 crystallographic variants have particular crystallographic texture regarding the main direction of the thermal gradient in the block. It was hypothesized that a selection of crystallographic variants could be done depending on the field stress. Tensile-compressive tests at high temperature have been done, to reproduce stress environment during the transformation of zirconia. 相似文献