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101.
Hyunjo Jeong Seung-Hoon Nahm Kyung-Young Jhang Young-Hyun Nam 《Journal of Mechanical Science and Technology》2002,16(2):147-154
The objective of this paper is to develop a nondestructive method for estimating the fracture toughness (K IC) of CrMoV steels used as the rotor material of steam turbines in power plants. To achieve this objective, a number of CrMoV steel samples were heat-treated, and the fracture appearance transition temperature (FATT) was determined as a function of aging time. Nonlinear ultrasonics was employed as the theoretical basis to explain the harmonic generation in a damaged material, and the nonlinearity parameter of the second harmonic wave was the experimental measure used to be correlated to the fracture toughness of the rotor steel. The nondestructive procedure for estimating theK IC consists of two steps. First, the correlations between the nonlinearity parameter and the FATT are sought. The FATT values are then used to estimateK IC, using theK IC versus excess temperature (i.e.,T-FATT) correlation that is available in the literature for CrMoV rotor steel. 相似文献
102.
An advanced x-ray imaging crystal spectrometer (XICS) for KSTAR tokamak has been developed by utilizing a segmented two dimensional (2D) position-sensitive multiwire proportional counter. The XICS for the KSTAR tokamak provides time-resolved measurements of the radial ion and electron temperature profiles, toroidal plasma rotation velocity, and ionization equilibrium. The segmented 2D detector with delay-line readout and supporting electronics has been adopted to improve the photon count rate capability. The current fabrication status of the XICS for the KSTAR tokamak and the first performance test results of the prototype segmented 2D detector are presented. 相似文献
103.
Ha Taewook Kang Yerim Kim Nam Seok Park So Hee Lee Sang Han Kim Dong Kyu Ryou Hong Sun 《Journal of Mechanical Science and Technology》2021,35(1):407-415
Journal of Mechanical Science and Technology - The cooling effect of oil cooling method on electric vehicle motors with hairpin winding is analyzed. A 160 kW motor being developed by a commercial... 相似文献
104.
Gaseous Nanocarving‐Mediated Carbon Framework with Spontaneous Metal Assembly for Structure‐Tunable Metal/Carbon Nanofibers
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Dae‐Hyun Nam Sungwoo Lee Young‐Joo Lee Jun‐Hyun Jo Euijoon Yoon Kyung‐Woo Yi Gun‐Do Lee Young‐Chang Joo 《Advanced materials (Deerfield Beach, Fla.)》2017,29(38)
Vapor phase carbon (C)‐reduction‐based syntheses of C nanotubes and graphene, which are highly functional solid C nanomaterials, have received extensive attention in the field of materials science. This study suggests a revolutionary method for precisely controlling the C structures by oxidizing solid C nanomaterials into gaseous products in the opposite manner of the conventional approach. This gaseous nanocarving enables the modulation of inherent metal assembly in metal/C hybrid nanomaterials because of the promoted C oxidation at the metal/C interface, which produces inner pores inside C nanomaterials. This phenomenon is revealed by investigating the aspects of structure formation with selective C oxidation in the metal/C nanofibers, and density functional theory calculation. Interestingly, the tendency of C oxidation and calculated oxygen binding energy at the metal surface plane is coincident with the order Co > Ni > Cu > Pt. The customizable control of the structural factors of metal/C nanomaterials through thermodynamic‐calculation‐derived processing parameters is reported for the first time in this work. This approach can open a new class of gas–solid reaction‐based synthetic routes that dramatically broaden the structure‐design range of metal/C hybrid nanomaterials. It represents an advancement toward overcoming the limitations of intrinsic activities in various applications. 相似文献
105.
Kyoungo Nam Hyunki Park Kihak Im Dongjin Kim Heejae Ahn Jaehyuk Lee Jaewhan Moon Emma Watson Robert Shaw 《Fusion Engineering and Design》2013,88(6-8):701-704
The purpose-built, ITER tokamak assembly tools, which are to be provided by Korea, should be designed to meet: the assembly plan, space reservations, safety standards, simple operations, efficient maintenance, and so on. It is very important that the ITER assembly tools are able to lift and transfer ITER components or their sub-assemblies to their assembled position safely. Furthermore, the lifting tools will lift and handle very heavy loads that can be more than 1200 tonnes sometimes. Therefore, the ITER lifting tools must be designed to endure these heavy load conditions with regard to their structural integrity. Also, these designs should be verified through an appropriate method. The preliminary design of the sector lifting tool and associated lifting attachments are introduced in this paper. The sector lifting tool was designed especially to lift and handle various ITER components by adjusting the lifting centre. The structural analysis results using ANSYS are described considering the heaviest load condition. The results of the analysis show that; all stresses applied on the lifting tool are lower than the allowable stress of the applied material. 相似文献
106.
Woo‐Il Baek Hem Raj Pant R. Nirmala Ki‐Taek Nam Hyun‐Ju Oh Hak‐Yong Kim 《Polymer International》2012,61(5):844-849
In the present study, the effect of adhesive on the morphology of different electrospun polymeric mats was investigated. The modification of two polymers, poly(methyl methacrylate) and poly(vinyl chloride), was carried out by blending the polymers with different amounts of poly(butyl acrylate) (PBA) adhesive to investigate the effect of different amounts of adhesive with heat hardener in hybrid mats. The introduction of various concentrations of PBA into different polymer solutions led to the formation of point‐bonded electrospun fibrous mats. Scanning electron microscopy images indicated that point‐bonded polymer/adhesive fibers were uniformly distributed throughout the mats. Fourier transform infrared spectrometry, contact angle measurements and thermogravimetric analysis were used to study the different properties of the hybrid mats. The tensile strength of the blended fibrous electrospun mats was increased effectively. This enhancement of the mechanical properties of the mats due to the presence of adhesive increases the number of potential applications of the electrospun mats, especially for mechanically weak polymers. Copyright © 2012 Society of Chemical Industry 相似文献
107.
Sung Hyun Hwang Soon Ki Kim Jun-Tae Nam Jong-Sung Park 《International Journal of Hydrogen Energy》2021,46(1):1076-1084
Composite anodes of nano-sized Ni and Ba(Zr0.85Y0.15)O3-δ (BZY) were fabricated by infiltrating a single precursor solution of BZY and Ni into the BZY scaffold, and decreasing the calcination temperature to 1173 K. This decrease in the fabrication temperature of the Ni-cermet anode prevents the chemical reaction between the electrolyte and nickel, thus preventing a reduction in the conductivity of the electrolyte. By optimizing the amount of Ni in the Ni-cermet and infiltrating additional catalysts such as CeO2 and Pd, the non-ohmic ASR of the Ni-cermet anode could be optimized. This resulted in a smaller non-ohmic ASR of anode than one that was fabricated by the conventional co-sintering method. Consequently, a high power density of 790 mW/cm2 at 973 K can be obtained from electrolyte-supported cells. 相似文献
108.
This review introduces recent changes regarding measurement of preferences brought about by the discovery of false preferences that occur with paired preference testing. Testing protocols are examined critically. False preferences result from a response bias elicited by factors distinct from sensory properties of products being tested that can distort results. Statistical approaches to circumventing this problem are examined. Alternative methods are being developed to eliminate false preferences based on understanding information processing in the brain. This has led to development of disruptive experimental preference testing protocols based on hypothesized use of processing subroutines in the brain to protect the central processing system from overload. These disruptive protocols suppress response bias. Paired preference testing is designed to predict consumer behavior. A paucity of studies addressing whether they do is put into perspective. 相似文献
109.
Nam Seung-Hee Kim Young-Min Walsh Marie K. Yim Sun-Hee Eun Jong-Bang 《Food science and biotechnology》2016,25(1):31-39
This study was performed to characterize pear protease proteolytic activity and investigate the use of pear protease as a meat tenderizer. Pear protease was purified and stabilized by 5% dextrin during lyophilization (dry) or concentration (liquid). Pear protease was further characterized with respect to pH, thermodynamics, and enzyme kinetics. Pear protease was stable at a pH range of 5-8 with an optimum pH of 6.5. From Arrhenius plots, liquid protease showed higher temperature dependency (23.49 kJ/mol) than dry protease (18.62 kJ/mol) due to its higher activation energy. The kcat/Km, catalytic efficiency of enzyme, was similar with 2.9 and 2.7 µM/min with dry and liquid proteases. Pear protease was evaluated for its proteolytic activities with casein and beef myofibrillar proteins by individually and combination with fig and kiwifruit proteases. These result indicated that pear and kiwifruit proteases could be complementary to be a desirable product for meat tenderization. 相似文献
110.