全文获取类型
| 收费全文 | 440篇 |
| 免费 | 16篇 |
| 国内免费 | 1篇 |
专业分类
| 电工技术 | 5篇 |
| 综合类 | 1篇 |
| 化学工业 | 116篇 |
| 金属工艺 | 7篇 |
| 机械仪表 | 8篇 |
| 建筑科学 | 25篇 |
| 矿业工程 | 3篇 |
| 能源动力 | 17篇 |
| 轻工业 | 47篇 |
| 水利工程 | 1篇 |
| 石油天然气 | 1篇 |
| 无线电 | 28篇 |
| 一般工业技术 | 86篇 |
| 冶金工业 | 18篇 |
| 原子能技术 | 2篇 |
| 自动化技术 | 92篇 |
出版年
| 2024年 | 6篇 |
| 2023年 | 4篇 |
| 2022年 | 15篇 |
| 2021年 | 21篇 |
| 2020年 | 18篇 |
| 2019年 | 11篇 |
| 2018年 | 10篇 |
| 2017年 | 13篇 |
| 2016年 | 17篇 |
| 2015年 | 17篇 |
| 2014年 | 21篇 |
| 2013年 | 37篇 |
| 2012年 | 24篇 |
| 2011年 | 40篇 |
| 2010年 | 26篇 |
| 2009年 | 19篇 |
| 2008年 | 24篇 |
| 2007年 | 24篇 |
| 2006年 | 15篇 |
| 2005年 | 12篇 |
| 2004年 | 12篇 |
| 2003年 | 12篇 |
| 2002年 | 10篇 |
| 2001年 | 4篇 |
| 2000年 | 3篇 |
| 1999年 | 4篇 |
| 1998年 | 7篇 |
| 1997年 | 4篇 |
| 1996年 | 5篇 |
| 1995年 | 4篇 |
| 1994年 | 3篇 |
| 1993年 | 1篇 |
| 1992年 | 1篇 |
| 1991年 | 1篇 |
| 1990年 | 1篇 |
| 1989年 | 1篇 |
| 1988年 | 1篇 |
| 1986年 | 1篇 |
| 1985年 | 2篇 |
| 1984年 | 1篇 |
| 1981年 | 2篇 |
| 1978年 | 1篇 |
| 1977年 | 2篇 |
排序方式： 共有457条查询结果，搜索用时 15 毫秒
431.
432.
Magdalena Ka
mierczak Bartosz Trzaskowski Silvio Osella 《International journal of molecular sciences》2022,23(1)
An artificial leaf is a concept that not only replicates the processes taking place during natural photosynthesis but also provides a source of clean, renewable energy. One important part of such a device are molecules that stabilize the connection between the bioactive side and the electrode, as well as tune the electron transfer between them. In particular, nitrilotriacetic acid (NTA) derivatives used to form a self-assembly monolayer chemisorbed on a graphene monolayer can be seen as a prototypical interface that can be tuned to optimize the electron transfer. In the following work, interfaces with modifications of the metal nature, backbone saturation, and surface coverage density are presented by means of theoretical calculations. Effects of the type of the metal and the surface coverage density on the electronic properties are found to be key to tuning the electron transfer, while only a minor influence of backbone saturation is present. For all of the studied interfaces, the charge transfer flow goes from graphene to the SAM. We suggest that, in light of the strength of electron transfer, Co2+ should be considered as the preferred metal center for efficient charge transfer. 相似文献
433.
Avinash P. Ingle Rafael R. Philippini Mahendra Rai Silvio Silvrio da Silva 《IET nanobiotechnology / IET》2020,14(1):40
The present study demonstrated the preparation of three different acid‐functionalised magnetic nanoparticles (MNPs) and evaluation for their catalytic efficacy in hydrolysis of cellobiose. Initially, iron oxide (Fe3 O4)MNPs were synthesised, which further modified by applying silica coating (Fe3 O4 ‐MNPs@Si) and functionalised with alkylsulfonic acid (Fe3 O4 ‐MNPs@Si@AS), butylcarboxylic acid (Fe3 O4 ‐MNPs@Si@BCOOH) and sulphonic acid (Fe3 O4 ‐MNPs@Si@SO3 H) groups. The Fourier transform infrared analysis confirmed the presence of above‐mentioned acid functional groups on MNPs. Similarly, X‐ray diffraction pattern and energy dispersive X‐ray spectroscopy analysis confirmed the crystalline nature and elemental composition of MNPs, respectively. TEM micrographs showed the synthesis of spherical and polydispersed nanoparticles having diameter size in the range of 20–80 nm. Cellobiose hydrolysis was used as a model reaction to evaluate the catalytic efficacy of acid‐functionalised nanoparticles. A maximum 74.8% cellobiose conversion was reported in case of Fe3 O4 ‐MNPs@Si@SO3 H in first cycle of hydrolysis. Moreover, thus used acid‐functionalised MNPs were magnetically separated and reused. In second cycle of hydrolysis, Fe3 O4 ‐MNPs@Si@SO3 H showed 49.8% cellobiose conversion followed by Fe3 O4 ‐MNPs@Si@AS (45%) and Fe3 O4 ‐MNPs@Si@BCOOH (18.3%). However, similar pattern was reported in case of third cycle of hydrolysis. The proposed approach is considered as rapid and convenient. Moreover, reuse of acid‐functionalised MNPs makes the process economically viable.Inspec keywords: scanning electron microscopy, catalysis, magnetic separation, magnetic particles, silicon compounds, iron compounds, nanomagnetics, coatings, X‐ray chemical analysis, nanoparticles, X‐ray diffraction, nanofabrication, Fourier transform infrared spectra, organic compounds, nanocompositesOther keywords: catalytic efficacy, alkylsulfonic acid, butylcarboxylic acid, energy dispersive X‐ray spectroscopy analysis, spherical polydispersed nanoparticles, cellobiose hydrolysis, acid‐functionalised MNPs, acid functional groups, cellobiose conversion, acid‐functionalised magnetic nanoparticle, silica coating, sulphonic acid, Fourier transform infrared analysis, SEM micrograph, X‐ray diffraction pattern, size 20.0 nm to 80.0 nm, Fe3 O4 , Si, SiO2 相似文献
434.
Discrepancies between predicted and in-use building performance are well documented in impact assessments for buildings, such as rating codes. This is a consequence of uncertainties that undermine predictions, which include procedural errors, as well as users’ behaviour and technological change. Debate on impact assessment for buildings predominantly focuses on operational issues and does not question the deterministic model on which assessments are based as a potential, underlying cause of ineffectiveness. This article builds on a non-deterministic urban planning theory and the principles it outlines, which can help manage uncertain factors over time. A rating code model is proposed that merges its typical steps of assessment (i.e. classification, characterisation and valuation) with those principles, applied within the impact assessment of buildings. These are experimentation (of other criteria than those typically appraised), exploration (the process of identifying the long-term vulnerability of such criteria) and inquiry (iterating and critically evaluating the assessment over time). 相似文献
435.
Silvio Figueiredo Gomes Júnior Ana Paula dos Santos Rubem João Carlos Correia Baptista Soares de Mello Lidia Angulo Meza 《International Transactions in Operational Research》2016,23(4):669-689
This paper evaluates the operational performance of airlines using an alternative data envelopment analysis (DEA) approach. We start by calculating the relative efficiency of each firm with the classical DEA. After identifying the set of efficient airlines that could be used as benchmarks for the inefficient firms, we employ a nonradial efficiency measure based on vector concepts that considers each efficient airline as a real target at once. This allows the assessment of efficiency scores using other targets than those automatically derived by the classical DEA, traditionally built on radial measures of efficiency. Although the results indicate a large number of negative efficiency scores, for most inefficient airlines, it was possible to identify at least one real target whose corresponding score was positive. In addition, the methodology herein adopted enriches benchmarking analysis, as it provides a set of alternative targets easily understood and accepted by the managers involved in the decision process. 相似文献
436.
437.
Enio Henrique Pires Da Silva;Silvio De Barros;Pascal Casari;Marcelo Leite Ribeiro; 《Polymer Engineering and Science》2024,64(6):2778-2794
The objective of this study is to assess, characterize, and forecast the aging effects on the mechanical properties of a vegetable-based polyurethane foam (PUF) derived from castor oil under elevated relative humidity conditions and at two distinct load orientations (aligned with the expansion direction and perpendicular to it). Ten specimens were subjected to temperatures of 60, 75, and 90°C, along with a relative humidity of 90%, for a duration of up to 60 days. Compression tests, following ASTM D1621-16 standards and supplemented by 3D digital image correlation, revealed nearly isotropic behavior with marginally lower compression strength in the expansion direction. On the other hand, the strength of the foams at 90°C was higher in that direction. This led to a smaller activation energy (Ea) in this property, which ended up showing a shorter lifespan prediction considering the strength retention in this direction. The stiffness values were proportionally more similar in both directions than the strength ones and this was observed in the Ea for those curves. In contrast to several other foams and polyurethanes, the one examined in this study exhibited consistently higher Ea values for its mechanical properties, particularly in the transverse direction to expansion, surpassing 94 kJ/mol. This indicates a robust diffusion and chemical stability, suggesting its potential for prolonged utilization compared to conventional oil-based foams. A prediction was made that this foam would lose 50% of its stiffness and strength in around 9.8 and 9.5 years at 20°C, respectively, considering the directions more sensitive to the aging process. This research offers valuable insights for predicting lifespan based on operating temperatures and property retention needs, contributing to the advancement of sustainable materials in structural applications. 相似文献
438.
Silvio Pappadà Per Gren Kourosh Tatar Tord Gustafson Rocco Rametta Ettore Rossini Alfonso Maffezzoli 《Journal of Materials Engineering and Performance》2009,18(5-6):531-537
Currently, there is a great interest in the study of shape memory alloy (SMA) composites, since SMA wires with a small diameter have become commercially available. Many potential uses have been found for SMA composites in shape control, vibration control, and for the realization of structures with improved damage tolerance. In this work, two types of SMA-hybridized composites are presented for investigating the mechanical and vibration characteristics. The first one contains unidirectional superelastic SMA wires, while the other has been realized with embedded knitted SMA layers. The samples from these laminates have been tested according to “Charpy method” (ASTM D256) and static flexural test method (ASTM D790) to evaluate the influence of the integration of thin superelastic SMA wires on the impact behavior and the mechanical properties of the hybrid composites. Moreover, since the SMA wires are expected to give damping capacity, by measuring the vibration mode of a clamped cantilever using laser vibrometry, the influence of both SMA arrangements on the vibration characteristics has been investigated. Finally, further tests have been carried out on composite panels realized by embedding unidirectional steel wires to distinguish the influence of the martensitic transformation from the pure introduction of a metallic wire into the polymeric matrix. 相似文献
439.
Afonso R. G. de Azevedo Markssuel Teixeira Marvila Leandro Barbosa de Oliveira Weslley Macario Ferreira Henry Colorado Silvio Rainho Teixeira Carlos Mauricio Fontes Vieira 《International Journal of Applied Ceramic Technology》2021,18(6):1891-1900
The development of new building materials based on alkaline activation technology is very promising, mainly linked to products that need significant technological properties and durability due to their adverse service conditions and environmental exposure. The objective of this research was to evaluate the development of a circular economy within the scope of durability of ceramic pieces incorporating glass polishing waste aimed at the production of roof tiles, obtained by the geopolymerization process. Two methodologies to evaluate the sample's durability were studied: wetting and drying cycles; and exposure to salt spray; both simulating conditions that tiles typically face in normal conditions. Prismatic specimens were made with an alkaline solution/(metakaolin + waste) ratio = 0.26; a SiO2/Al2O3 molar ratio = 3.5, 4, and 4.5; and with ambient and thermal cure at 7 days. Samples were evaluated in their mechanical strength, mass loss, and water absorption. Results showed that the SiO2/Al2O3 = 4.0 ratio with thermal curing had the best behavior in aggressive conditions, and therefore, this formulation can be used for the production of tiles. 相似文献
440.
Antonia Elaine Frutuoso Lima Patrícia Lopes Andrade Telma Leda Gomes de Lemos Daniel Esdras de Andrade Uchoa Marcos Cirineu Aguiar Siqueira Antonio Silvio do Egito Renata Chastinet Braga Juliana Nascimento da Costa Daniele Maria Alves Teixeira Sá 《Journal of Food Processing and Preservation》2021,45(1):e15091