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排序方式: 共有332条查询结果,搜索用时 15 毫秒
1.
Multishell Carrier Transport in Multiwalled Carbon Nanotubes 总被引:1,自引:0,他引:1
Agrawal S. Raghuveer M.S. Ramprasad R. Ramanath G. 《Nanotechnology, IEEE Transactions on》2007,6(6):722-726
Understanding carrier transport in carbon nanotubes (CNTs) and their networks is important for harnessing CNTs for device applications. Here, we report multishell carrier transport in individual multiwalled CNTs, and films of randomly dispersed multiwalled CNTs, as a function of electric field and temperature. Electrical measurements and first-principles density functional theory calculations indicate transport across CNT shells. Intershell conduction occurs across an energy barrier range of 60-250 meV in individual CNTs, and ~ 60 meV in CNT networks. In both cases, the conductance behavior can be explained based upon field-enhanced carrier injection and defect-enhanced transport, as described by the Poole-Frenkel model. 相似文献
2.
3.
Hugo E. Delgado Ph.D. Ramanath I. Ramakrishnan M.S. Timothy E. Howson D.E.S. 《JOM Journal of the Minerals, Metals and Materials Society》1994,46(9):21-23
Computer-aided engineering tools are routinely used to simulate forging and heat-treatment operations and to perform thermal and stress analyses. This review gives a few examples of the current uses of process modeling tools and outlines some developing capabilities and near-term applications. 相似文献
4.
Furnace grown gate oxynitride using nitric oxide (NO) 总被引:4,自引:0,他引:4
Okada Y. Tobin P.J. Reid K.G. Hegde R.I. Maiti B. Ajuria S.A. 《Electron Devices, IEEE Transactions on》1994,41(9):1608-1613
Gate oxynitride was grown in NO for the first time. This approach can provide a tight N accumulation near the Si/SiO2 interface. Much lower thermal budget is required for an NO process than for an N2O process to produce an oxynitride with useful properties. Submicron MOSFET's with NO oxynitride showed superior current drive characteristics and comparable hot carrier immunity to those with N2O oxynitride 相似文献
5.
Spontaneous regression of AK-5, a histiocytic tumor, is mediated by CD3-, CD8+ NK cells through ADCC. The onset of AK-5 regression is associated with the induction of humoral immune response and the augmentation of effector function. The mechanism of tumor cell death involves both necrosis and apoptosis. Interleukin-12, a 75-kDa heterodimeric cytokine, has multiple effects on T and NK cells. We have investigated the role of IL-12 in the NK cell-mediated AK-5 tumor regression process. Subcutaneous transplantation of AK-5 tumor induced the expression of IL-12 (p35 and p40) message by Day 6-8 in the splenocytes of syngenic rats. Similarly, analysis of serum samples from tumor-bearing animals showed the presence of circulating IL-12 around the same time. Interaction of immune cells with antibody-tagged AK-5 cells in vitro also triggered the expression of IL-12 message and protein by 3 hr. The circulating IL-12 in the sera of tumor-rejecting animals, as well as rIL-12, stimulated NK cell proliferation, expression of CD16 and CD25, and the activation of NK cells function. These observations suggest that the ability of the AK-5 tumor to induce the endogenous production of IL-12 may be responsible for keeping the NK cells constantly in an activated state, thus demonstrating an efficient mechanism for the complete regression of the tumor. 相似文献
6.
Ceria-supported Au catalyst has been synthesized by the solution combustion method for the first time and characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). Au is dispersed as Au0 as well as Au3+ states on CeO2 surface of 20-30 nm crystallites. On heating the as-prepared 1% Au/CeO2 in air, the concentration of Au3+ ions on CeO2 increases at the expense of Au0. Catalytic activities for CO and hydrocarbon oxidation and NO reduction over the as-prepared and the heat-treated 1% Au/CeO2 have been carried out using a temperature-programmed reaction technique in a packed bed tubular reactor. The results are compared with nano-sized Au metal particles dispersed on -Al2O2 substrate prepared by the same method. All the reactions over heat-treated Au/CeO2 occur at lower temperature in comparison with the as-prepared Au/CeO2 and Au/Al2O2. The rate of NO + CO reaction over as-prepared and heat-treated 1% Au/CeO2 are 28.3 and 54.0 mol g-1 s-1 at 250 and 300 °C respectively. Activation energy (E
a) values are 106 and 90 kJ mol-1 for CO + O2 reaction respectively over as-prepared and heat-treated 1% Au/CeO2 respectively. 相似文献
7.
Mehdi Qasim Jinan Al‐Dabbagh Naser Mahmoud Ahmed V.G. Chigrinov Gurumurthy Hegde 《Journal of the Society for Information Display》2014,22(4):187-190
Indium tin oxide‐coated thin films (200 nm) are deposited on glass substrates by using R.f. sputtering technique. Here, we investigate the influence of new technique of treatment, which is called as “oil thermal annealing” on the nano‐structured indium tin oxide thin films at fixed temperature (150 °C) which improves adhesion strength, electrical conductivity and optical properties (transmittance) of the films. Oil thermal annealing is used to reduce inherent defects that may be introduced during the prepared thin film and cooling processes. Proposed technique is highly suitable for liquid crystal displays, solar cells and organic light emitting diodes, and many other display‐related applications. 相似文献
8.
High-throughput drilling of titanium alloys 总被引:3,自引:1,他引:3
Rui Li Parag Hegde Albert J. Shih 《International Journal of Machine Tools and Manufacture》2007,47(1):63-74
Experiments of high-throughput drilling of Ti–6Al–4V at 183 m/min cutting speed and 156 mm3/s material removal rate (MRR) using a 4 mm diameter WC–Co spiral point drill were conducted. The tool material and geometry and drilling process parameters, including cutting speed, feed, and fluid supply, were studied to evaluate the effect on drill life, thrust force, torque, energy, and burr formation. The tool wear mechanism, hole surface roughness, and chip light emission and morphology for high-throughput drilling were investigated. Supplying the cutting fluid via through-the-drill holes has proven to be a critical factor for drill life, which can be increased by 10 times compared to that of dry drilling at 183 m/min cutting speed and 0.051 mm/rev feed. Under the same MRR of 156 mm3/s with a doubled feed of 0.102 mm/rev (91 m/min cutting speed), over 200 holes can be drilled. The balance of cutting speed and feed is essential to achieve long drill life and good hole surface roughness. This study demonstrates that, using proper drilling process parameters, spiral point drill geometry, and fine-grained WC–Co tool material, the high-throughput drilling of Ti alloy is technically feasible. 相似文献
9.
We report the stress relaxation behavior of arc-evaporated TiCxN1−x thin films during isothermal annealing between 350 and 900°C. Films with x=0, 0.15, and 0.45, each having an initial compressive intrinsic stress σint=−5.4 GPa, were deposited by varying the substrate bias Vs and the gas composition. Annealing above the deposition temperature leads to a steep decrease in the magnitude of σint to a saturation stress value, which is a function of the annealing temperature. The corresponding apparent activation energies for stress relaxation are Ea=2.4, 2.9, and 3.1 eV, for x=0, 0.15, and 0.45, respectively. TiC0.45N0.55 films with a lower initial stress σint=−3 GPa, obtained using a high substrate bias, show a higher activation energy Ea=4.2 eV. In all the films, stress relaxation is accompanied by a decrease in defect density indicated by the decreased width of X-ray diffraction peaks and decreased strain contrast in transmission electron micrographs. Correlation of these results with film hardness and microstructure measurements indicates that the stress relaxation is a result of point-defect annihilation taking place both during short-lived metal-ion surface collision cascades during deposition, and during post-deposition annealing by thermally activated processes. The difference in Ea for the films of the same composition deposited at different Vs suggests the existence of different types of point-defect configurations and recombination mechanisms. 相似文献
10.
Eugene Pozhidaev Vladimir Chigrinov Gurumurthy Hegde Peizhi Xu 《Journal of the Society for Information Display》2009,17(1):53-59
Abstract— Multistable electro‐optical modes exist under certain conditions in ferroelectric liquid‐crystal (FLC) cells, which means that any light‐transmission level can be memorized after the driving voltage is switched off. The multistability is responsible for three new electro‐optical modes with different shapes of the gray‐scale curve that can be either S‐shaped (double or single dependent upon the applied‐voltage pulse sequence and boundary conditions) or V‐shaped dependent upon boundary conditions and FLC cell parameters. The origin of these modes will be described. 相似文献