全文获取类型
收费全文 | 2214篇 |
免费 | 117篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 29篇 |
综合类 | 1篇 |
化学工业 | 566篇 |
金属工艺 | 50篇 |
机械仪表 | 44篇 |
建筑科学 | 76篇 |
矿业工程 | 21篇 |
能源动力 | 47篇 |
轻工业 | 204篇 |
水利工程 | 5篇 |
石油天然气 | 38篇 |
无线电 | 141篇 |
一般工业技术 | 438篇 |
冶金工业 | 301篇 |
原子能技术 | 28篇 |
自动化技术 | 344篇 |
出版年
2023年 | 19篇 |
2022年 | 44篇 |
2021年 | 80篇 |
2020年 | 38篇 |
2019年 | 40篇 |
2018年 | 73篇 |
2017年 | 66篇 |
2016年 | 87篇 |
2015年 | 53篇 |
2014年 | 81篇 |
2013年 | 150篇 |
2012年 | 137篇 |
2011年 | 158篇 |
2010年 | 89篇 |
2009年 | 120篇 |
2008年 | 115篇 |
2007年 | 108篇 |
2006年 | 87篇 |
2005年 | 55篇 |
2004年 | 59篇 |
2003年 | 55篇 |
2002年 | 43篇 |
2001年 | 34篇 |
2000年 | 32篇 |
1999年 | 24篇 |
1998年 | 48篇 |
1997年 | 34篇 |
1996年 | 42篇 |
1995年 | 30篇 |
1994年 | 27篇 |
1993年 | 13篇 |
1992年 | 16篇 |
1991年 | 11篇 |
1990年 | 16篇 |
1989年 | 15篇 |
1988年 | 10篇 |
1987年 | 19篇 |
1986年 | 8篇 |
1985年 | 22篇 |
1984年 | 11篇 |
1983年 | 20篇 |
1982年 | 12篇 |
1981年 | 11篇 |
1979年 | 8篇 |
1978年 | 8篇 |
1977年 | 13篇 |
1976年 | 14篇 |
1975年 | 9篇 |
1970年 | 7篇 |
1969年 | 8篇 |
排序方式: 共有2333条查询结果,搜索用时 260 毫秒
111.
Microstructure Variation and Hardness Diminution During Low Cycle Fatigue of 55NiCrMoV7 Steel 总被引:1,自引:0,他引:1
The influence of temperature and hardness level on the cyclic behavior of 55NiCrMoV7 steel, and the microstructure variation and hardness diminution during low cycle fatigue behavior were investigated. By means of SEM and XRD, the modality of carbides and the full width half maximum (FWHM) of martensite (211) [M(211)] of X ray diffraction spectrum in fatigue specimen were studied. The results showed that the cyclic stress response behavior generally showed an initial exponential softening for the first few cycles, followed by a gradual softening without cyclic softening saturation. The fatigue behavior of the steel is closely related to the hardness level. The hardness diminution and the variation of half width M(211) are remarkably influenced by the interaction between the cyclic plastic deformation and the thermal loading when the fatigue temperature exceeds the tempering temperature of the steel. 相似文献
112.
Few commercially available membranes can be used for organic solvent nanofiltration (OSN). Applying OSN in chemical industries is nevertheless of high interest to cut with energy consumption linked to solvent recycling and soluble catalysts recovery. A commercial membrane, PERVAP4060, was used to investigate the retention of dilute solutes in toluene feeds and to mimic metathesis medium. The studied solutes were R-BINAP a neutral polyaromatic molecule used in metathesis chemistry, tetraoctylammonium bromide (ToABr), a charged molecule used as a homogeneous catalyst and n-hexadecane. Retention of polar ToABr (95%) was higher than that of neutral R-BINAP (80%). The transfer mechanism, either pore flow or solution-diffusion, was discussed. All the results obtained suggested that the transport is governed by the solution-diffusion mechanism. The measured retentions could be explained in terms of solubility affinities and diffusion coefficients. The stability and performances of PERVAP4060 were well established, showing the strong potential for industrial applications. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48359. 相似文献
113.
Lubricant films containing colloidal overbased calcium salts have particular effects on detergency and on the wear process. The mechanical properties of such boundary films are very dependent on the process conditions, and are essentially a result of physico-chemical transformations of the colloid. Three types of films were compared: a film obtained by the drying of the base solvent, a film due to the compaction of the colloid between two steel surfaces, and a friction film obtained with this type of lubricant. Adsorption, compaction, and shear transformations induce a solid film. The pressure effect on the frictional behaviour of these colloidal films has been investigated using a surface force apparatus for low contact pressure (104 to 106 Pa), and using tribometers supporting heavy loads for the analysis of the high pressure domain. Above a critical pressure, evaluated at 106 Pa, the colloidal film does not flow, but forms a compacted mattress sliding on the surface plane and squeezing a molecular layer of lubricant. 相似文献
114.
Vincent Nicolas Fernanda Vanin David Grenier Tiphaine Lucas Christophe Doursat Denis Flick 《American Institute of Chemical Engineers》2016,62(11):3847-3863
A two dimensional model of bread baking was developed including, for the first time, the dependence of dough viscosity on both temperature and moisture content, the carbon dioxide dissolved from liquid water together with gas generation from yeast at the beginning of baking and the shrinkage due to dough drying. Particular attention was paid to experimental validation of both overall and local variables such as local temperature, overall mass loss, and local moisture content, overall CO2 released into the oven, and overall deformation and local expansion or shrinkage. Sensitivity studies on generation of carbon dioxide, gravity, and shrinkage are presented to discuss their influences on bread geometry, porosity (reflecting the alveolar structure) and gas pressure. © 2016 American Institute of Chemical Engineers AIChE J, 62: 3847–3863, 2016 相似文献
115.
Modelling of flocculation using a population balance equation 总被引:1,自引:0,他引:1
Carole Coufort Denis Bouyer Alain Lin Benoît Haut 《Chemical Engineering and Processing: Process Intensification》2007,46(12):1264-1273
In this paper, a model based on a population balance equation (PBE) is developed. It aims at reproducing experimental floc size distributions obtained at steady state in a jar-test. The objective is to develop a simple model, based on physical phenomena, and that does not contain any adjustable parameters. Floc size distributions obtained using a part of a particle image velocimetry (PIV) device and image analysis are used to develop mathematical expressions for the aggregation and breakage kernels. A critical volume beyond which breakage is of significant importance is identified and related to the hydrodynamics. Hydrodynamic sequencing allows the distribution of the daughter particles resulting from a breakage event to be established. The model is finally successfully validated against experimental results. 相似文献
116.
Oleg A. Kazantsev Dmitry V. Orekhov Denis M. Kamorin Maria V. Savinova 《Designed Monomers and Polymers》2017,20(1):136-143
Concentration effects in the base-catalyzed hydrolysis of water-soluble methacrylates (3-(N,N-dimethylaminoethyl) methacrylate (DMAEMA), 2-hydroxyethyl methacrylate (HEMA) and oligo(ethylene glycol) methacrylates (OEGMAs)) have been studied. These monomers are rapidly hydrolyzed in the presence of bases at the room temperature in dilute aqueous solutions, but the reaction rate decreases sharply in highly concentrated solutions. A clear correlation was found between a form of the viscosity isotherm for DMAEMA solutions and the concentration dependence of the autocatalytic hydrolysis rate which indicates the connection of process kinetics with the structure of solutions. These data should be considered when carrying out homo- and copolymerization of the previously mentioned monomers in aqueous solutions. 相似文献
117.
Long Distance Enhancement of Nonlinear Optical Properties Using Low Concentration of Plasmonic Nanostructures in Dye Doped Monolithic Sol–Gel Materials
下载免费PDF全文
![点击此处可从《Advanced functional materials》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Denis Chateau Adrien Liotta Hampus Lundén Frederic Lerouge Frederic Chaput Douglas Krein Thomas Cooper Cesar Lopes Ali A. G. El‐Amay Mikael Lindgren Stephane Parola 《Advanced functional materials》2016,26(33):6005-6014
Monolithic sol–gel silica composites incorporating platinum‐based chromophores and various types of gold nanoparticles (AuNPs) are prepared and polished to high optical quality. Their photophysical properties are investigated. The glass materials show well‐defined localized surface plasmon resonance (SPR) absorbance from the visible to NIR. No redshifts of the AuNP plasmon absorption peaks due to the increase in nanoparticle doping concentration are observed in the glasses, proving that no or very small SPR coupling effects occur between the AuNPs. At 600 nm excitation, but not at 532 nm, the AuNPs improve the nonlinear absorption performance of glasses codoped with 50 × 10?3 m of a Pt‐acetylide chromophore. The glasses doped with lower concentrations of AuNPs (2–5 μm average distance) and 50 × 10?3 m in chromophore, show a marked improvement in nonlinear absorption, with no or only small improvement for the more highly AuNP doped glasses. This study shows the importance of excitation wavelength and nanoparticle concentration for composite systems employing AuNPs to improve two‐photon absorption of chromophores. 相似文献
118.
Staphylococcus epidermidis is a bacterium that is part of the human microbiota. It is most abundant on the skin, in the respiratory system and in the human digestive tract. Also, Staphylococcus aureus contributes to human infections and has a high mortality rate. Both of these bacterial species produce biofilm, a pathogenic factor increasing their resistance to antibiotics. For this reason, we are looking for new substances that can neutralize bacterial cells. One of the best-known substances with such effects are silver nanoparticles. They exhibited antibacterial and antibiofilm formation activity that depended on their size, shape and the concentration used. In this review, we presented the data related to the use of silver nanoparticles in counteracting bacterial growth and biofilm formation published in scientific papers between 2017 and 2021. Based on the review of experimental results, the properties of nanoparticles prompt the expansion of research on their activity. 相似文献
119.
120.