全文获取类型
收费全文 | 398篇 |
免费 | 14篇 |
专业分类
化学工业 | 154篇 |
金属工艺 | 3篇 |
机械仪表 | 8篇 |
建筑科学 | 11篇 |
矿业工程 | 1篇 |
能源动力 | 11篇 |
轻工业 | 92篇 |
水利工程 | 3篇 |
石油天然气 | 3篇 |
无线电 | 24篇 |
一般工业技术 | 56篇 |
冶金工业 | 13篇 |
原子能技术 | 1篇 |
自动化技术 | 32篇 |
出版年
2023年 | 4篇 |
2022年 | 39篇 |
2021年 | 38篇 |
2020年 | 8篇 |
2019年 | 12篇 |
2018年 | 10篇 |
2017年 | 9篇 |
2016年 | 9篇 |
2015年 | 8篇 |
2014年 | 16篇 |
2013年 | 28篇 |
2012年 | 21篇 |
2011年 | 30篇 |
2010年 | 22篇 |
2009年 | 23篇 |
2008年 | 20篇 |
2007年 | 26篇 |
2006年 | 11篇 |
2005年 | 10篇 |
2004年 | 4篇 |
2003年 | 11篇 |
2002年 | 5篇 |
2001年 | 1篇 |
2000年 | 4篇 |
1999年 | 3篇 |
1998年 | 4篇 |
1997年 | 3篇 |
1996年 | 2篇 |
1995年 | 2篇 |
1994年 | 1篇 |
1993年 | 1篇 |
1992年 | 4篇 |
1989年 | 2篇 |
1988年 | 4篇 |
1987年 | 2篇 |
1986年 | 2篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1977年 | 1篇 |
1975年 | 1篇 |
1972年 | 1篇 |
1968年 | 1篇 |
1958年 | 1篇 |
1956年 | 1篇 |
1955年 | 1篇 |
1954年 | 1篇 |
排序方式: 共有412条查询结果,搜索用时 0 毫秒
81.
Arantxa de Zarraga Sara Villanueva Maria Eugenia Muoz Rafael Obeso Juan Jos Pea Beln Pascual Anton Santamaría 《大分子材料与工程》2004,289(7):648-652
Summary: Binary and ternary blends of PVC mixed with α‐methylstyrene/acrylonitrile‐butadiene‐styrene copolymer (AMS‐ABS) and ethylene/vinyl acetate/carbon monoxide terpolymer (EVA‐CO) are investigated, with the aim to obtain a new PVC based material with an improved heat distortion temperature and good processability. Dynamic Mechanical Thermal Analysis (DMTA) reveals that ternary PVC/AMS‐ABS/EVA‐CO blends exhibit two glass transition temperatures: the lower Tg corresponds to a PVC/EVA‐CO phase and the higher one to a PVC/AMS‐ABS phase. An analysis of PVC respective interactions with AMS‐ABS and EVA‐CO leads to assert that the distribution of PVC in the ternary PVC/AMS‐ABS/EVA‐CO system is basically controlled by the binary immiscible blend composition, taken as Φ AMS‐ABS/Φ EVA‐CO ratio. The inclusion of AMS‐ABS and EVA‐CO to form ternary blends based on PVC, allows to improve heat distortion temperature (owed to the presence of AMS‐ABS), maintaining a low viscosity in the molten state, due to the plasticizing effect of EVA‐CO.
82.
Apparent mass transfer coefficients for solid dissolution in a liquid with and without a chemical reaction were experimentally determined in a fixed bed three phases reactor with downward cocurrent gas and liquid flows. The chemical system selected was benzoic acid, sodium hydroxide in aqueous solution, and atmospheric air. Continuous gas, pulse and dispersed bubble regimes were studied and the results were correlated obtaining apparent mass transfer coefficient as a function of liquid and fluid volumetric flow. It was found that gas flow effect on mass transfer coefficient was small over continuous gas and dispersed bubble regimes, but appreciable over pulse regime. Additionally, it was found that the mathematical model that best described the mass transfer process under pulse regime, by using the increment factor due to the instantaneous chemical reaction, is the film theory 相似文献
83.
Thin liquid layers of polymer solutions, oligomers and monomers, and oligomer–monomer bilayers were used as model systems to explore the mechanism of formation of surface textures in solid coatings and films. It was shown that under particular conditions vertical temperature gradients imposed on these fluid layers induce in them various types of convection. We demonstrated that hexagonal patterns with a high degree of order and symmetry are generated in fluid films undergoing surface tension-driven convection. Various non-equilibrium textures have been trapped in the solid state either by vitrification induced by solvent evaporation from the fluid layer, or by carefully performed polymerization of monomers and oligomers. Finally, we demonstrated that convection patterns can be replicated in convection-passive fluids by bringing them in contact with a fluid layer undergoing convection. 相似文献
84.
This paper describes the method of determining the force constant and displacement sensitivity of piezoresistive Wheatstone bridge cantilevers applied in scanning probe microscopy (SPM). In the procedure presented here, the force constant for beams with various geometry is determined based on resonance frequency measurement. The displacement sensitivity is measured by the deflection of the cantilever with the calibrated piezoactuator stage. Preliminary results show that our method is capable of measuring the force constant of Wheatstone bridge cantilevers with an accuracy of better than 5% and this is used as feedback for improvement of sensor micromachining process. 相似文献
85.
The irradiation effects of thinning a sample of a Cu-Zn-Al shape memory alloy to electron transparency by a Ga(+) focused ion beam were investigated. This thinning method was compared with conventional electropolishing and Ar(+) ion milling. No implanted Ga was detected but surface FCC precipitation was found as a result of the focused ion beam sample preparation. Decreasing the irradiation dose by lowering the energy and current of the Ga(+) ions did not lead to a complete disappearance of the FCC structure. The latter could only be removed after gentle Ar(+) ion milling of the sample. It was further concluded that the precipitation of the FCC is independent of the crystallographic orientation of the surface. 相似文献
86.
87.
Susan Essien Etok Eugenia Valsami-Jones Timothy J. Wess Jennifer C. Hiller Clark A. Maxwell Keith D. Rogers David A. C. Manning Margaret L. White Elisa Lopez-Capel Matthew J. Collins Mike Buckley Kirsty E. H. Penkman Stephen L. Woodgate 《Journal of Materials Science》2007,42(23):9807-9816
The thermal behaviour of the animal by-product meat and bone meal (MBM) has been investigated in order to assess how it is
affected structurally and chemically by incineration. Initially composed of intergrown collagen and hydroxyapatite (HAP),
combustion of the organic component is complete by 650 °C, with most mass loss (50–55%) occurring by 500 °C. No original proteins
were detected in samples heated at 400 °C or above. Combustion of collagen is accompanied by an increase in HAP mean crystallite
size at temperatures greater than 400 °C, from 10 nm to a constant value of 120 nm at 800 °C or more. Newly formed crystalline
phases appear beyond 400 °C, and include β-tricalcium phosphate, NaCaPO4, halite (NaCl) and sylvite (KCl). Crystallite thickness as judged by small angle X-ray scattering (SAXS) increases from 2 nm
(25–400 °C) to 8–9 nm very rapidly at 550 °C, and then gradually increases to approximately 10 nm. The original texture of
HAP within a collagen matrix is progressively lost, producing a porous HAP dominated solid at 700 °C, and a very low porosity
sintered HAP product at 900 °C. 相似文献
88.
Eugenia Fagadar-Cosma Corina Enache Gheorghe Fagadar-Cosma Grzegorz Bazylak 《Materials Research Bulletin》2009,44(12):2186-68
The present study is dealing with the obtaining of transparent hybrid silica materials encapsulating 5,10,15,20-tetrakis(3,4-dimethoxyphenyl)-21H,23H-porphyrin designated for advanced optoelectronic devices. The porphyrin was synthesized by three methods: an Adler-type reaction between pyrrole and 3,4-dimethoxybenzaldehyde in propionic acid medium; by Lindsey condensation of pyrrole with 3,4-dimethoxybenzaldehyde in the presence of BF3·OEt2 and by a multicomponent reaction by simultaneously using of pyrrole and two different aldehydes: 3,4-dimethoxybenzaldehyde and 3-hydroxybenzaldehyde. The 3,4-dimethoxyphenyl substituted porphyrin was characterized by HPLC, TLC, UV-vis, FT-IR, 1H NMR and 13C NMR analysis. Excitation and emission spectra were also discussed in terms of pH conditions. The hybrid materials, consisting in the porphyrin encapsulated in silica matrices, have been prepared successfully via the two steps acid-base catalyzed hydrolysis and condensation of tetraethylorthosilicate using different approaches of the sol-gel process: in situ, by impregnation and by sonication. The synthetic conditions and the compositions were monitored and characterized by using spectroscopic methods such as FT-IR, fluorescence and UV-vis. Atomic force microscopy (AFM) has been applied to observe the columnar or pyramidal nanostructures which are formed by the immobilization of porphyrin on the silica matrices. 相似文献
89.
Eugenia Rubín Pilar Rodríguez Roberto Herrero Manuel E. Sastre de Vicente 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2006,81(7):1093-1099
Phenol, 2‐chlorophenol (2‐CP), and 4‐chlorophenol (4‐CP) biosorption on Sargassum muticum, an invasive macroalga in Europe, has been investigated. The efficiency of this biosorbent was studied measuring the equilibrium uptake using the batch technique. A chemical pre‐treatment with CaCl2 has been employed in this study in order to improve the stability as well as the sorption capacity of the algal biomass. The influence of pH on the equilibrium binding and the effect of the algal dose were evaluated. The experimental data at pH = 1 have been analysed using Langmuir and Freundlich isotherms. It was found that the maximum sorption capacity of chlorophenols, qmax = 251 mg g?1 for 4‐CP and qmax = 79 mg g?1 for 2‐CP, as well as that of a binary mixture of both chlorophenols, qmax = 108 mg g?1, is much higher than that of phenol, qmax = 4.6 mg g?1. Moreover, sorption kinetics have been performed and it was observed that the equilibrium was reached in less than 10 h. Kinetic data have been fitted to the first order Lagergren model, from which the rate constant and the sorption capacity were determined. Finally, biosorption of the phenolic compounds examined in the present study on Sargassum muticum biomass was observed to be correlated with the octanol‐water partitioning coefficients of the phenols. This result allows us to postulate that hydrophobic interactions are the main responsible for the sorption equilibrium binding. Copyright © 2006 Society of Chemical Industry 相似文献
90.
Néstor Guerrero María Eugenia Marante Ricardo Picón 《Journal of Constructional Steel Research》2007,63(6):779-790
This paper presents a general formulation for the analysis of steel hollow structural beams subjected to biaxial bending. The model has been developed within the framework of lumped damage mechanics. In this approach, the models are based on methods of continuum damage mechanics and the concept of plastic hinge. The model was implemented in a commercial finite element program. In order to calibrate the model, a set of experimental tests were carried out in the Structural Mechanics Laboratory at the Lisandro Alvarado University. The model was evaluated by the numerical simulation of these tests finding a good agreement between the experimental tests and the numerical simulations. 相似文献