全文获取类型
收费全文 | 952篇 |
免费 | 72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 | 230篇 |
金属工艺 | 12篇 |
机械仪表 | 40篇 |
建筑科学 | 26篇 |
矿业工程 | 4篇 |
能源动力 | 26篇 |
轻工业 | 152篇 |
水利工程 | 6篇 |
石油天然气 | 8篇 |
无线电 | 78篇 |
一般工业技术 | 141篇 |
冶金工业 | 80篇 |
原子能技术 | 4篇 |
自动化技术 | 212篇 |
出版年
2024年 | 3篇 |
2023年 | 15篇 |
2022年 | 23篇 |
2021年 | 35篇 |
2020年 | 34篇 |
2019年 | 25篇 |
2018年 | 43篇 |
2017年 | 44篇 |
2016年 | 42篇 |
2015年 | 34篇 |
2014年 | 42篇 |
2013年 | 84篇 |
2012年 | 68篇 |
2011年 | 69篇 |
2010年 | 45篇 |
2009年 | 49篇 |
2008年 | 39篇 |
2007年 | 33篇 |
2006年 | 46篇 |
2005年 | 37篇 |
2004年 | 24篇 |
2003年 | 19篇 |
2002年 | 19篇 |
2001年 | 12篇 |
2000年 | 13篇 |
1999年 | 5篇 |
1998年 | 34篇 |
1997年 | 15篇 |
1996年 | 19篇 |
1995年 | 9篇 |
1994年 | 6篇 |
1993年 | 10篇 |
1992年 | 3篇 |
1991年 | 3篇 |
1990年 | 7篇 |
1989年 | 2篇 |
1988年 | 1篇 |
1987年 | 2篇 |
1986年 | 2篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1982年 | 2篇 |
1977年 | 3篇 |
1976年 | 2篇 |
1972年 | 1篇 |
排序方式: 共有1025条查询结果,搜索用时 15 毫秒
41.
Ana B. Bautista‐Ortín Naiara Busse‐Valverde Jose M. López‐Roca Rocío Gil‐Muñoz Encarna Gómez‐Plaza 《International Journal of Food Science & Technology》2014,49(1):34-41
Winemakers are interested in wines with low bitterness and astringency, and therefore, there is a preference for a higher presence of skin proanthocyanidins in wines. However, the information regarding the effect of reducing or eliminating seed proanthocyanidins from the must or fermenting wine on the characteristics of finished wines is scarce. For this reason, we elaborated a wine using Monastrell grapes from which the seeds had been removed and compared it with a control wine (CW) made from intact grapes. The anthocyanin and proanthocyanidin concentration and profile, and the chromatic and sensory characteristics were studied. The absence of seed proanthocyanidins did not affect anthocyanin concentration, although the proanthocyanidin concentration was 40% lower than in the CW. The copigmentation (CA) study showed that both wines had a similar extent of CA phenomena although colour intensity was higher when seed proanthocyanidins were present. The panellist evaluated the wines elaborated without seeds as being fruitier, less astringent and with an overall higher quality. 相似文献
42.
Tactic planning or master production scheduling focuses on time and spatial decomposition of the aggregate planning targets and forecasts, as well as, forecast and provision of needed resources. This process becomes extremely hard and time consuming with the increase of number of products, resources and periods considered. In face of such obstacles, this work shows a study of an Artificial Intelligence technique called Simulated Annealing applied to the optimization of production planning problem, more specifically, Master Production Scheduling. This work reviews some of the fundamental theory of simulated annealing, the methodology for master production scheduling calculation, the applicability of simulating annealing to planning problems, most important results and suggestions for further studies. 相似文献
43.
44.
A new multisensory system that aims at fostering the interaction of people with cerebral palsy is presented. This article describes the strategies and technologies used to provide people who have moderate to severe cerebral palsy with playful and fun activities designed according to their abilities. These activities are based on interactive systems that use computer vision and generate graphics and sounds in real time. The well-being that is achieved through the use of these activities is the result of gaining a significant degree of autonomy by the users. The presented system was first developed in the Cerebral Palsy Centre of Tarragona, Spain. Its motivation came from the low rate of users able to interact with computers. Although several assistive technology gadgets and special software applications (e.g., cause–effect and educational activities, simple navigation environments, etc.) were used, most users simply did not understand the interaction mechanisms. It was thought that a highly interactive activity (reinforced with sounds and images closely related with gestures) would be more accessible to most users in spite of their sensory, motor, and cognitive impairments. Tests with impaired users show that the proposal promotes participation, engagement, and play. In this article, the experimental methodology, the used and developed tools, and the results that were obtained are explained. 相似文献
45.
46.
Fuzzy frequency response: definition and analysis for uncertain dynamic systems is proposed in this paper. In terms of transfer function, the uncertain dynamic system is partitioned into several linear sub‐models and organized according to Takagi–Sugeno fuzzy representation. The main contribution of this paper is to demonstrate through the proposal of a Theorem that fuzzy frequency response is a boundary in the magnitude and phase Bode plots. Low‐ and high‐frequency analysis of fuzzy dynamic model is obtained by varying the frequency ω from zero to infinity. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
47.
Carlos E.M. Guarido Deborah V. Cesar Mariana M.V.M. Souza Martin Schmal 《Catalysis Today》2009,142(3-4):252
Ethanol reforming and partial oxidation were studied on Cu/Nb2O5 and Ni/Al2O3 catalysts. Compared to the Ni/Al2O3 catalyst, the Cu/Nb2O5 catalyst presents conversion as high as Ni/Al2O3 catalyst, however, for the same level of formation of hydrogen it occurs at much lower temperature on the Cu/Nb2O5 catalyst, 200 °C lower than for the Ni/Al2O3 catalyst, with remarkable little formation of CO, which can be attributed to the strong interaction between copper and niobia. Temperature-programmed desorption (TPD-ethanol) and surface reactions (TPSR) of partial oxidation of ethanol showed formation of ethylene, acetaldehyde, ethane and mainly H2 and CO2 besides little methane. DRIFTS results are in accordance with TPD analysis and the formation of acetate species at room temperature suggests reactivity of the surface and its oxidative dehydrogenation capacity. The adsorption of ethanol gives rise to ethoxide species, which form acetate and acetaldehyde that can be oxidized to CO2 via carbonate. A comparison with reported results for Cu/Al2O3 this catalyst is promising, yielding high level of H2 with little CO production during reforming and partial oxidation reaction. The maximum H2 formation for the partial oxidation of ethanol was 41% at ratio (O2/Et) 0.8, increasing to 50% at ratio 1.5. The H2/CO is around 10 for the partial oxidation and 7 for steam reforming, which is excellent, compared to the Ni/Al2O3 catalyst with a factor 4–8 lower. 相似文献
48.
Electroactive behavior assessment of poly(acrylic acid)‐graphene oxide composite hydrogel in the detection of cadmium 下载免费PDF全文
Areli Bejarano‐Jiménez Vladimir A. Escobar‐Barrios J. Mieke Kleijn Cesar A. Ortíz‐Ledón Luis F. Cházaro‐Ruiz 《应用聚合物科学杂志》2014,131(19)
Super absorbent polymers of acrylic acid‐graphene oxide (PAA‐GO) were synthesized with different percentage of chemical neutralization (0, 10, and 20%) of the acrylic acid monomer before its polymerization. The influence of their swelling and adsorption/desorption capacity of cadmium ions in aqueous solutions were studied and revealed that the GO enables greater mechanical stability in the materials. The PAA hydrogels, with the same degrees of neutralization, were also prepared without GO to compare with the composites. Additionally, carbon paste electrodes (CPE) modified with the composites PAA‐GO were used to asses and compare their adsorption properties with cadmium(II). The anodic stripping voltammetry (ASV) peak, in the differential pulse voltammetry mode, for cadmium oxidation was found to be influenced by the presence of GO into the polymer, and also by their percentage of neutralization. The accumulation of cadmium(II) on the surface of the modified CPEs was performed under open‐circuit conditions taking an account the preconcentration time of the metal cation. The presence of GO enhances the electrical signal of the electrodes in short times of immersion in cadmium(II) solutions. This property contributed to get linear responses of the CPEs modified with the composites, which were influenced by their degrees of neutralization. The PAA‐GO 10N electrode with 10% of neutralization combined the influence of GO and the degree of neutralization in the same matrix, and also showed good performance in terms of its mechanical stability, it was chosen for preliminary studies on the selectivity of the electrode toward Zn(II) and Cu(II). © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40846. 相似文献
49.
Miguel Olvera-Sosa Antonio Guerra-Contreras Cesar F. A. Gómez-Durán Raúl González-García Gabriela Palestino 《应用聚合物科学杂志》2020,137(8):48403
The swelling behavior of poly(acrylic acid-co-itaconic acid)/NaOH hydrogel as well as its ability for iron and copper rust removal was studied and established for the first time. Through an experimental design, the influence of the synthesis parameters on hydrogel response was determined. It was found that pH-responsiveness dependence of hydrogel determines its application. In alkaline media, the hydrogel acted as superabsorbent, while in acidic, the most outstanding property was its pickling capability that allowed to clean carbon steel and copper metallic surfaces. Infrared, thermogravimetry, and scanning electron microscopy were performed to determine copolymer formation, thermal properties, and morphology. Metallic crystallographic phases formed during the corrosion processes were determined by X-ray diffractometer. Hydrogel adhesiveness followed by diffusion and dissolution of metal oxides species was identified as the main steps in the rust removal mechanism. This method offers a new, environmentally friendly perspective to eliminate corrosion from metallic surfaces compared with traditional strategies. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48403. 相似文献
50.
Thamara Thaiane da Silva Gabriel Batista Cesar Carolina Pereira Francisco Guilherme Galerani Mossini Lidiane Vizioli de Castro Hoshino Francielle Sato Eduardo Radovanovic Deuber Lincon da Silva Agostini Wilker Caetano Luzmarina Hernandes Graciette Matioli 《应用聚合物科学杂志》2020,137(9):48415
The application of fibers associated with drugs is a promising alternative to meet the clinical needs of tissue repair. Curcumin exhibits great cicatricial potential because it has numerous pharmacological properties. This research aimed to produce fibers of polycaprolactone and copolymer F-108 associated with curcumin and to evaluate in vivo their action on the process of wound healing. The fibers were produced by electrospinning technique and characterized by scanning electron microscopy (SEM), X-ray diffractometry (XRD), and fluorescence microscopy. They were applied in cutaneous wounds of rats for the analysis of photoacoustic permeation and histological study. The characterization showed that the electrospinning allowed the preparation of homogeneous material with curcumin. The fibers benefited healing of the wounds and allowed the permeation of curcumin at all stages. The use of PCL/F-108 fibers allowed the elaboration of a new curcumin delivery system, improving its bioavailability and action in the healing of excisional wound. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48415. 相似文献