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排序方式: 共有1364条查询结果,搜索用时 46 毫秒
41.
Eugene Wai Keong Koh Cheng Hsin Chiu Yao Kun Lim Yong-Wei Zhang Hui Pan 《International Journal of Hydrogen Energy》2012
We investigate the hydrogen adsorption on and diffusion through the MoS2 monolayer based on density-functional theory. We show that the hydrogen atom prefers to bond to the S atom at the monolayer, leading to enhanced conductivity. The hydrogen atom can also adsorb at the middle of the hexagon ring by overcoming an energy barrier of 0.57 eV at a strain of 8%. Also, we show that the MoS2 monolayer is flexible and any mechanical deformation of the monolayer is reversible because the extension of the Mo–S bond is much smaller than the applied strain. The monolayer can block the diffusion of hydrogen molecule from one side to the other due to a high energy barrier (6.56 eV). However, the barrier can be reduced to 1.38 eV at a strain of 30% and even totally removed by creating S vacancies and applying a strain of 15%. The MoS2 monolayer may find applications in sensors to detect hydrogen, and as mechanical valve to control the concentration of hydrogen gas. 相似文献
42.
Commercial process for mass production of synthetic natural gas through the adiabatic reactors: operational characteristics of a 50‐kW pilot‐plant,influence of steam,and CO2
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Suk‐Hwan Kang Jin‐Ho Kim Ki‐Jin Jung Young‐Don Yoo Kwang‐Jun Kim Dong‐Jun Koh Jae‐Hong Ryu 《国际能源研究杂志》2017,41(3):353-364
In synthetic natural gas (SNG) reaction process, the water gas shift (WGS) reaction and methanation reaction take place simultaneously, and an insufficient supply of steam might deactivate the catalyst. In this study, the characteristics of the methanation reaction with a commercial catalyst and using a low [H2]/[CO] mole ratio in SNG synthesis are evaluated. The reaction characteristics at various possible process parameters are evaluated varying different process parameters such as the [H2O]/[CO] mole ratio, [H2]/[CO] mole ratio, flow of different % CO2, and reaction temperature. Temperature profiles on catalyst bed are monitored as a function of the [H2O]/[CO] mole ratio, [H2]/[CO] mole ratio, and flow of different % CO2. Through a lab‐scale optimization process, suitable optimum conditions are selected and in the same condition a 50‐kW pilot‐scale SNG production process through adiabatic reactors is carried out. The pilot scale SNG reaction is stable through overnight and the CO conversion efficiency and CH4 selectivity are 100% and 97.3%, respectively, while the maximum CH4 productivity is 0.654 m3/kgcat · h. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
43.
Application of ultrasound to biological tissues has been identified as a promising cancer treatment technique relying on temporal enhancement of biological membrane permeability via shock wave impact. In the present study, the effects of ultrasonic waves on a 1,2-dipalmitoyl-sn-phosphatidylcholine biological membrane are examined through molecular dynamics simulations. Molecular dynamics methods traditionally employ periodic boundary conditions which, however, restrict the total simulation time to the time required for the shock wave crossing the domain, thus limiting the evaluation of the effects of shock waves on the diffusion properties of the membrane. A novel method that allows capturing both the initial shock wave transit as well as the subsequent longer-timescale diffusion phenomena has been successfully developed, validated and verified via convergence studies. Numerical simulations have been carried out with ultrasonic impulses varying from 0.0 to 0.6 mPa s leading to the conclusion that for impulses ≥0.45 mPa s, no self-recovery of the bilayer is observed and, hence, ultrasound could be applied to the destruction of localized tumor cells. However, for impulses ≤0.3 mPa s, an increase in the transversal diffusivity of the lipids, indicating a consequent enhancement of drug absorption across the membrane, is initially observed followed by a progressive recovery of the initial values, thereby suggesting the advantageous effects of ultrasound on enhancing the chemotherapy efficiency. 相似文献
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45.
Jayven Chee Chuan Yeo Joseph Kinyanjui Muiruri Justin Junqiang Koh Warintorn Thitsartarn Xikui Zhang Junhua Kong Ting Ting Lin Zibiao Li Chaobin He 《Advanced functional materials》2020,30(30)
The future of green electronics possessing great strength and toughness proves to be a promising area of research in this technologically advanced society. This work develops the first fully bendable and malleable toughened polylactic acid (PLA) green composite by incorporating a multifunctional polyhydroxybutyrate rubber copolymer filler that acts as an effective nucleating agent to accelerate PLA crystallization and performs as a dynamic plasticizer to generate massive polymer chain movement. The resultant biocomposite exhibits a 24‐fold and 15‐fold increment in both elongation and toughness, respectively, while retaining its elastic modulus at >3 GPa. Mechanism studies show the toughening effect is due to an amalgamation of massive shear yielding, crazing, and nanocavitation in the highly dense PLA matrix. Uniquely distinguished from the typical flexible polymer that stretches and recovers, this biocomposite is the first report of PLA that can be “bend, twist, turn, and fold” at room temperature and exhibit excellent mechanical robustness even after a 180° bend, attributes to the highly interconnected polymer network of innumerable nanocavitation complemented with an extensively unified fibrillar bridge. This unique trait certainly opens up a new horizon to future sustainable green electronics development. 相似文献
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This article considers an inbound ordering and outbound dispatching problem for a single product in a third-party warehouse, where the demands are dynamic over a discrete and finite time horizon, and moreover, each demand has a time window in which it must be satisfied. Replenishing orders are shipped in containers and the freight cost is proportional to the number of containers used. The problem is classified into two cases, i.e. non-split demand case and split demand case, and a mathematical model for each case is presented. An in-depth analysis of the models shows that they are very complicated and difficult to find optimal solutions as the problem size becomes large. Therefore, genetic algorithm (GA) based heuristic approaches are designed to solve the problems in a reasonable time. To validate and evaluate the algorithms, finally, some computational experiments are conducted. 相似文献
49.
Fernanda B. R. D. Iorio Ana M. A. Liberatore Ivan H. J. Koh Choyu Otani 《臭氧:科学与工程》2016,38(4):253-260
The ozonation of vegetable oils has been studied, since the produced ointments have antibacterial and fungicidal activities. However, the ozonation of mineral oils has not been reported in the literature yet, opening an interesting field for examination. In this work, we have shown the ozonation of a commercial mineral oil (Nujol). The main goal was to produce oils containing free ozone, so that this gas could act as antimicrobial agent. It was found that in Nujol, ozone remains for at least 40 days and in the sample ozonized for 15 h its concentration was 7.5 mg mL?1. Neat Nujol showed no antimicrobial activity against the tested microorganisms, however, when ozonated it showed antimicrobial activity against Enterococcus faecalis, Staphylococcus aureus and Escherichia coli. 相似文献
50.
Mild functionalization of carbon nanotubes filled epoxy composites: Effect on electromagnetic interferences shielding effectiveness
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The effect of nitric acid mild functionalized multiwalled carbon nanotubes (MWCNTs) on electromagnetic interference (EMI) shielding effectiveness (SE) of epoxy composites was examined. MWCNTs were oxidized by concentrated nitric acid under reflux conditions, with different reaction times. The dispersion of MWCNTs after functionalization was improved due to the presence of oxygen functional groups on the nanotubes surface. Functionalization at 2 h exhibits the highest EMI SE and electrical conductivity of MWCNTs filled epoxy composites. However, EMI shielding performance of MWCNTs filled epoxy composite declined when the functionalization reaction time was prolonged. This was due to extensive damage on the MWCNT structure, as verified by a Raman spectroscope. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42557. 相似文献