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41.
Baozeng Li Qing Wang Yingmin Wang Chunyan Li Jianbing Qiang Chunjun Ji Chuang Dong 《Metallurgical and Materials Transactions A》2012,43(2):544-554
Copper is a good corrosion resisting element, but due to its immiscibility with Fe, it is only used as a minor-alloying element
in stainless steels. In this work, we introduced a double-cluster structure model [CuNi12][NiFe12]
m
for stable solid solutions in Cu-containing Fe-Ni corrosion-resistant invar alloys. Our model takes into account all of the
enthalpies between the element pairs by assuming Fe-Ni and Ni-Cu nearest neighbors and by avoiding Fe-Cu ones, so that the
ideally stabilized structures are described by mixing two cuboctahedral clusters in the fcc lattice, NiFe12 and CuNi12. Two alloy series were designed by varying the relative proportions of the two clusters and the Cu contents. It was proved
that the alloys with Cu contents below those prescribed by this model could easily be solutionized and water-quenched to a
monolithic fcc solid solution, and resultant alloys possessed good corrosion-resisting properties in 3.5 wt pct NaCl solution. 相似文献
42.
Bogdana Simionescu Irina-Elena Bordianu Magdalena Aflori Florica Doroftei Mihai Mares Xenia Patras Alina Nicolescu Mihaela Olaru 《Materials Chemistry and Physics》2012
The paper reports the first study on hierarchical assemblies (nanofibrillar micelles confined within semi-cylindrical shells) with silsesquioxane and quaternary ammonium units obtained through polymer blending intended for antimicrobial/antifungal stone coatings. The formation of hierarchical structures on solid surfaces is due to the multiple intermolecular ionic interactions, intermolecular Van der Waals and hydrophobic interactions acting among the component molecules. Their antimicrobial/antifungal properties toward the Gram-negative bacteria, Escherichia coli, Gram-positive bacteria, Staphylococcus aureus, and Candida albicans fungus were determined in aqueous solution and were found to be strongly dependent of the topographical features of the coating. 相似文献
43.
Diffusivity of interstitial oxygen (O) in bcc iron (Fe) with and without the effect of vacancy has been investigated in terms of first-principles calculations within the framework of transition state theory. Examination of migration pathway and phonon results indicates that O in octahedral interstice is always energetically favorable (minimum energy) with and without vacancy. It is found that vacancy possesses an extremely high affinity for O in bcc Fe, increasing dramatically the energy barrier (∼80%) for O migration, and in turn, making the predicted diffusion coefficient of O in bcc Fe in favorable accord with experiments. 相似文献
44.
《Fusion Engineering and Design》2014,89(7-8):1019-1023
The generation and diffusion of runaway electrons (REs) during major disruptions in the HL-2A tokamak has been studied numerically. The diffusion caused by the magnetic perturbation is especially addressed. The simulation results show that the strong magnetic perturbation (δB/B ∼ 1.0 × 10−3) can cause a significant loss of REs due to the radial diffusion and restrain the RE avalanche effectively. The results also indicate that the REs are generated initially in the plasma core during disruptions, and that the toroidal electric field does not exhibit a centrally hollow phenomenon. In addition, it is found that the toroidal effects have little impact on the generation of RE and the evolution of toroidal electric field. 相似文献
45.
《Intermetallics》2014
The crystal and electronic structures of D8l-V5SiB2 and D88-V5Si3B ternary compounds have been investigated by means of first principle calculations. The calculated structural parameters are in very good agreement with the experimental data. The calculated values of the enthalpies of formation at T = 0 K of the D8l-V5SiB2 and D88-V5Si3B ternary compounds are −67.1 and −62.1 kJ/mol of atoms respectively. The total and partial electronic densities of states show a strong hybridization between the B p states and V d states. The defect enthalpies of formation as well as the mixing enthalpies have been computed. These data are essential for the modeling of the D8l and D88 phases in the V–Si–B ternary system. A partial V–VSi2–VB isothermal section at 298 K is proposed. 相似文献
46.
47.
Spatially-resolved cathodoluminescence spectroscopy has contributed significant new information to our understanding of native point defects in ZnO micro- and nanoscale structures. This paper aims to review representative examples of this work and the new perspectives gained from spatially resolving these defects both laterally and depth-wise. Results obtained from many groups worldwide include studies of Schottky diodes, polycrystalline ceramics, nanostructures, and microwires. The nature and spatial distribution of native point defects in these materials together with their strong dependence on growth and processing suggest new avenues for their control in transport and optoelectronic device structures. 相似文献
48.
49.
Paul Mullowney Ming-Chieh LinKevin Paul Cory AhrensMichael Loh R.J. CooperD.C. Radford Ethan Hull 《Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment》2012,662(1):33-44
In the crystal bulk of group IV covalent semiconductors such as germanium (Ge), simple analytic models for the valence band structure can provide fast, accurate computations of hole mobility for moderate energy ranges up to a few eV. On the surfaces of these materials, such as on Ge-vacuum or Ge-GeO2 interfaces, the transport rates differ significantly from the bulk. This can be problematic for both point contact and segmented Ge gamma ray detectors, that require accurate carrier drift rates for computing signal basis sets, which themselves are necessary for the precise determination of gamma-ray induced compton scattering events. While several techniques exist for computing surface hole mobilities, more often than not, these methods are complex to implement, require significant computational resources, and lack the simplicity of bulk models for interpreting results. This paper presents a new technique for computing Ge surface hole mobility that can give a first estimate for the surface transport rates after tuning a physically based computational parameter. This model is used in conjunction with particle-in-cell (PIC) simulations for modeling hole-dynamics inside a Ge p-type point contact detector. The results of our calculations agree with experimental data gathered from Ge p-type point contact detectors at Oak Ridge National Laboratory. 相似文献
50.
Cosmin Popa 《Microelectronics Journal》2012,43(8):515-520
An original realization of a CMOS Gaussian function generator is presented. The proposed method is based on a new approximation function that is able to fourth-order match the Gaussian function. The current-mode operation of the circuit strongly reduces the technological-caused errors and the errors introduced by temperature variations, with the result of an important increasing of the accuracy for the squaring circuit that represents the functional core of the Gaussian generator (0.1%). Additionally, the bandwidth of the generator is increased as a result of its current-mode operation. Because of the utilization of the new fourth-order approximation function, the deviation from the ideal Gaussian function is smaller than 1 dB for an extended range of the input variable. The circuit is designed for implementing in 0.18 μm CMOS technology, its proposed architecture being compatible with a low-voltage operation (VDD=1 V). The proposed Gaussian function generator based on the new approximation function allows to extend its capability of generating any continuous mathematical functions, this feature being obtained by changing the approximation function coefficients. 相似文献