全文获取类型
收费全文 | 175篇 |
免费 | 7篇 |
专业分类
电工技术 | 2篇 |
化学工业 | 27篇 |
金属工艺 | 1篇 |
机械仪表 | 4篇 |
建筑科学 | 12篇 |
能源动力 | 18篇 |
轻工业 | 48篇 |
水利工程 | 2篇 |
无线电 | 17篇 |
一般工业技术 | 25篇 |
冶金工业 | 5篇 |
自动化技术 | 21篇 |
出版年
2023年 | 1篇 |
2022年 | 2篇 |
2021年 | 4篇 |
2020年 | 3篇 |
2019年 | 3篇 |
2018年 | 5篇 |
2017年 | 11篇 |
2016年 | 10篇 |
2015年 | 4篇 |
2014年 | 8篇 |
2013年 | 18篇 |
2012年 | 15篇 |
2011年 | 21篇 |
2010年 | 12篇 |
2009年 | 15篇 |
2008年 | 13篇 |
2007年 | 5篇 |
2006年 | 5篇 |
2005年 | 2篇 |
2004年 | 6篇 |
2003年 | 3篇 |
2002年 | 3篇 |
1999年 | 1篇 |
1998年 | 3篇 |
1995年 | 4篇 |
1994年 | 1篇 |
1993年 | 1篇 |
1992年 | 3篇 |
排序方式: 共有182条查询结果,搜索用时 15 毫秒
1.
Microfibre reinforced cement composites reinforced with high volume fractions of carbon, steel and polypropylene fibres were tested in uniaxial tension. Composites investigated included those with only one type of fibre (mono-fibre composites) and those with two or more types of fibres (hybrid-fibre composites) in the same mix. Considerable strengthening, toughening and stiffening of the host matrix due to microfibre reinforcement were observed. In the hybrid-fibre composites, different fibres appear to act as additive phases; i.e., they maintain their individual reinforcing capabilities. The composites were also impact tested in uniaxial tension using a newly designed instrumented impact machine. When compared with static test results, considerable sensitivity to stress rate was noted; composites were found to be stronger and tougher under impact and the improvements were more pronounced at higher fibre volume fractions. The potential of these composites for use in thin sheet products and other similar applications is recognized, and the need for continued research is stressed. 相似文献
2.
Esin Guldogan Thomas Olsson Else Lagerstam Moncef Gabbouj 《Multimedia Tools and Applications》2014,71(3):1087-1104
It is important to adapt and personalize image browsing and retrieval systems based on users’ preferences for improved user experience and satisfaction. In this paper, we present a novel instance based personalized multi-form image representation with implicit relevance feedback and adaptive weighting approach for image browsing and retrieval systems. In the proposed system, images are grouped into forms, which represent different information on images such as location, content etc. We conducted user interviews on image browsing, sharing and retrieval systems for understanding image browsing and searching behaviors of users. Based on the insights gained from the user interview study we propose an adaptive weighting method and implicit relevance feedback for multi-form structures that aim to improve the efficiency and accuracy of the system. Statistics of the past actions are considered for modeling the target of the users. Thus, on each iteration weights of the forms are updated adaptively. Moreover, retrieval results are modified according to the users’ preferences on iterations in order to improve personalized user experience. The proposed method has been evaluated and results are illustrated in the paper. It is shown that, satisfactory improvements can be achieved with proposed approaches in the multi-form scheme. 相似文献
3.
Effects of frequency dimming electronic ballast on a high‐pressure mercury thallium iodide discharge
下载免费PDF全文
![点击此处可从《Journal of the Society for Information Display》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Abdeljelil Chammam Walid Nsibi Mohamed Nejib Nehdi Brahim Mrabet Anis Sellami 《Journal of the Society for Information Display》2016,24(3):154-158
This study focuses on the behavior of a cylindrical metal halide discharge lamp powered by frequency‐controlled electronic ballast. Half‐bridge electronic ballast was designed and achieved. 相似文献
4.
Conventional pile materials such as steel, concrete, and timber are prone to deterioration for many reasons. Fiber-reinforced polymer (FRP) concrete composites represent an alternative construction material for deep foundations that can eliminate many of the performance disadvantages of traditional piling materials. However, FRP composites present several difficulties related to constructability, and the lack of design tools for their implementation as a foundation element. This paper describes the results of an experimental study on frictional FRP/dense sand interface characteristics and the constructability of FRP–concrete composite piles. An innovative toe driving technique is developed to install the empty FRP shells in the soil and self-consolidating concrete is subsequently cast in them. The experimental program involves interface shear tests on small FRP samples and uplift load tests on large-scale model piles. Two different FRP pile materials with different roughness and a reference steel pile are examined. Static uplift load tests are conducted on different piles installed in soil samples subjected to different confining pressures in the pressure chamber. The results showed that the interface friction for FRP materials compared favorably with conventional steel material. It was shown that toe driving is suitable for installation of FRP piles in dense soils. 相似文献
5.
The use of FRP as reinforcement in concrete structures has been growing rapidly. A potential application of FRP reinforcement
is in reinforced concrete (RC) frames. However, due to FRP's predominantly elastic behaviour, FRP-RC members exhibit low ductility
and energy dissipation. Hybrid steel-FRP reinforcement can be a viable solution to the lack of ductility of FRP-RC members.
Using two layers of reinforcement in a section, FRP rebars can be placed in the outer layer and steel rebars in the inner
layer away from the effects of carbonation and chloride intrusion. Combined with the use of FRP stirrups, this approach can
enhance the corrosion resistance of RC members. However, current design standards and detailing criteria for FRP-RC structures
do not provide detailed seismic provisions. In particular, the design and detailing of beam-column joints is a key issue in
seismic design. During recent earthquakes, many structural collapses were initiated or caused by beam-column joint failures.
Thus, research is needed to gain a better understanding of the behaviour of FRP and hybrid FRP-steel-RC under seismic loading.
In this study, three full-scale beam-column joint specimens reinforced with steel, GFRP and a hybrid GFRP-steel configuration,
respectively were tested in order to investigate their performance in the event of an earthquake.
Résumé L'utilisation de barres en polymères renforcés de fibres (PRF) comme armature dans les structures en béton est en train d'augmenter rapidement. Une application prometteuse des armatures en PRF est dans les structures en cadres de béton armé à multi-étages. Cependant, à cause de leur comportement élastique, les membres renforcés avec des armatures en PRF démontrent une ductilité limitée et une faible capacité de dissipation d'énergie. Les systèmes hybrides (combinaison d'armatures en acier et en polymères renforcés de fibres de verre (PRFV) se présentent comme une solution pratique pour remédier aux inconvénients des systèmes renforcés uniquement avec PRFV. En utilisant deux couches d'armatures, les barres en PRFV peuvent être placées à l'extérieur et ceux en acier à l'intérieur, loin des effets de la carbonatation et l'intrusion des ions chlores. En plus, l'utilisation des étriers en PRFV peut améliorer la durabilité de ces structures. Cependant, les normes de conception actuelles pour PRF n'offrent pas assez de détails sur les provisions sismiques, en particulaier sur la conception des joints de poutres-colonnes. De récents tremblements de terre ont démontré sans équivoque que les joints de poutres-colonnes sont critiques pour assurer l'intégrité structurale. Alors, il est important d'étudier le comportement de tels assemblages utilisant des armatures en PRFV ou des armatures hybrides (acier-PRFV). Dans cette étude, trois assemblages poutrecolonne en grandeur nature renforcés avec des armatures en acier, PRFV, et hybride (acier-PRFV) ont été construits et testés sous charges cycliques pour examiner leur comportement durant des tremblements de terre.相似文献
6.
The use of FRP as reinforcement in concrete structures has been growing rapidly due to its advantages over conventional steel reinforcement (e.g., corrosion resistance, light weight, magnetic neutrality). A potential application of FRP reinforcement is in structural concrete frames. However, current seismic design standards and detailing criteria for beam-column joints were established for steel reinforcement and may be unsuitable for FRP reinforcement due to its different mechanical properties. During recent earthquakes, many structural collapses were initiated or caused by beam-column joint failures. Since there are no detailed specifications for the application of FRP reinforcement in seismic zones, research is needed to gain a better understanding of the behaviour of FRP-reinforced concrete under seismic loading. In this study, two full-scale beam-column joint specimens reinforced with steel and GFRP, respectively, were tested in order to investigate their performance in the event of an earthquake. The control steel-reinforced specimen is detailed according to the Canadian Code (CSA A23.3-94) recommendations. The GFRP-reinforced specimen is detailed in a similar scheme but using a GFRP grid. The behaviour of the two specimens under reversed cyclic loading, their load-storey drift envelope relationship and energy dissipation ability were compared. The GFRP-reinforced specimen showed a predominantly elastic behaviour up to failure. While its energy dissipation was low, its performance was acceptable in terms of total storey drift demand. 相似文献
7.
Olfa Ghorbel‐Bellaaj Mourad Jridi Hayet Ben Khaled Kemel Jellouli Moncef Nasri 《International Journal of Food Science & Technology》2012,47(9):1835-1841
The pH, proteolytic activity, extent of demineralisation and deprotenisation of shrimp waste were studied during 7 days of fermentation using Pseudomonas aeruginosa A2. After 3 days, pH dropped from 7.0 to 4.4 and then remained constant. Simultaneously, a demineralisation of 92% was achieved. However, protease activity reached its highest level (1230 U mL?1) after 1 day of incubation, and a protein removal of 90% was achieved. Chitin obtained was converted to chitosan. This chitosan, with 73% deacetylation, was tested for clarification of different fruit juices. It was observed that low concentrations of chitosan (below to 1%) greatly increase the clarity of juices without affecting the nutritional value. The antioxidant activity of the hydrolysates produced during fermentation was tested. Hydrolysate obtained after 3 days showed the strongest scavenging activity (90%), which was comparable to the positive control BHA; however, that obtained after 1 day exhibited the highest ferric‐reducing antioxidant power (OD 700 nm = 1.7). 相似文献
8.
9.
Aida Lazzez Stefania Vichi Naziha Grati Kammoun Mohamed Néji Arous Mohcen Khlif Agusti Romero Moncef Cossentini 《European Journal of Lipid Science and Technology》2011,113(6):796-807
Due to the importance of the stage of maturity on several olive pomological parameters and oil quality indices, and to the interest that Tunisian olive oil production has recently received, the optimal harvesting period for the main Tunisian olive cultivar, Chemlali, was assessed. For the first time, a four‐season crops study, carried out in three representative geographical areas, was focused on both olive fruit pomological parameters and oil chemical composition at different stages of maturity. The stage of maturity was the factor showing the highest influence on the major part of these parameters, followed by the crop year. To guarantee a reasonable fat content and a good chemical quality of oil, in particular a harmonious acidic composition, acceptable UV absorbance, and a content high of antioxidants, unsaponifiable matter and sterols, the optimal harvesting period for Chemlali olives would appears to be between the end of November to the middle of December, which corresponds to a maturity index between 2.5 and 3.5. 相似文献
10.
The effects of physical refining on the formation of 3-monochloropropane-1,2-diol esters in relation to palm oil minor components 总被引:2,自引:0,他引:2
The formation of 3-monochloropropane-1,2-diol (3-MCPD) esters in refined palm oil during deodorisation is attributed to the intrinsic composition of crude palm oil. Utilising D-optimal design, the effects of the degumming and bleaching processes on the reduction in 3-MCPD ester formation in refined palm oil from poor-quality crude palm oil were studied relative to the palm oil minor components that are likely to be their precursors. Water degumming remarkably reduced 3-MCPD ester formation by up to 84%, from 9.79 mg/kg to 1.55 mg/kg. Bleaching with synthetic magnesium silicate caused a further 10% reduction, to 0.487 mg/kg. The reduction in 3-MCPD ester formation could be due to the removal of related precursors prior to the deodorisation step. The phosphorus content of bleached palm oil showed a significant correlation with 3-MCPD ester formation. 相似文献