全文获取类型
收费全文 | 2370篇 |
免费 | 164篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 43篇 |
综合类 | 2篇 |
化学工业 | 672篇 |
金属工艺 | 71篇 |
机械仪表 | 74篇 |
建筑科学 | 55篇 |
矿业工程 | 3篇 |
能源动力 | 85篇 |
轻工业 | 490篇 |
水利工程 | 13篇 |
石油天然气 | 30篇 |
无线电 | 146篇 |
一般工业技术 | 303篇 |
冶金工业 | 216篇 |
原子能技术 | 13篇 |
自动化技术 | 320篇 |
出版年
2024年 | 17篇 |
2023年 | 27篇 |
2022年 | 86篇 |
2021年 | 132篇 |
2020年 | 78篇 |
2019年 | 98篇 |
2018年 | 126篇 |
2017年 | 121篇 |
2016年 | 99篇 |
2015年 | 66篇 |
2014年 | 93篇 |
2013年 | 191篇 |
2012年 | 145篇 |
2011年 | 145篇 |
2010年 | 134篇 |
2009年 | 125篇 |
2008年 | 105篇 |
2007年 | 75篇 |
2006年 | 63篇 |
2005年 | 59篇 |
2004年 | 44篇 |
2003年 | 37篇 |
2002年 | 31篇 |
2001年 | 22篇 |
2000年 | 35篇 |
1999年 | 35篇 |
1998年 | 62篇 |
1997年 | 51篇 |
1996年 | 38篇 |
1995年 | 31篇 |
1994年 | 18篇 |
1993年 | 32篇 |
1992年 | 11篇 |
1991年 | 15篇 |
1990年 | 8篇 |
1989年 | 9篇 |
1988年 | 11篇 |
1987年 | 7篇 |
1986年 | 5篇 |
1985年 | 7篇 |
1984年 | 5篇 |
1982年 | 5篇 |
1980年 | 2篇 |
1979年 | 3篇 |
1978年 | 2篇 |
1977年 | 2篇 |
1976年 | 11篇 |
1975年 | 5篇 |
1974年 | 2篇 |
1973年 | 2篇 |
排序方式: 共有2536条查询结果,搜索用时 8 毫秒
61.
Danielle F.M. OliveiraPaulo S. Batista Paulo S. Muller Jr.Valdemir Velani Marcela D. FrançaDanilo R. de Souza Antonio E.H. Machado 《Dyes and Pigments》2012,92(1):563-572
The performance of different titanium dioxide (TiO2) catalysts and a composite based on the association between TiO2 P25 and Zinc Phthalocyanine (TiO2/ZnPc 1.6%) was evaluated in the photocatalytic degradation of the dye Ponceau 4R (C.I. 16255). The results show that the composite presents a better performance than the other, reaching about 50% mineralization of the dye in 120 min of reaction, around three times higher than that observed under the action of pure TiO2 P25, although this catalyst presents a quantum yield of hydroxyl radical generation about three times higher than that estimated for the composite. This result seems to be a consequence of the synergism between the electronically excited ZnPc aggregates and the TiO2 surface.A parallel study, based on methods from quantum mechanics also suggested the most feasible routes for the photodegradation of the dye in the absence of the catalyst. 相似文献
62.
63.
Magnetic polystyrene–palygorskite nanocomposite obtained by heterogeneous phase polymerization to apply in the treatment of oily waters 下载免费PDF全文
Antonieta Middea Luciana Spinelli Fernando Gomes de Souza Junior Reiner Neumann Thais Fernandes Fabiano Richard Leite Faulstich Otavio Gomes 《应用聚合物科学杂志》2018,135(15)
Water contaminated by oil poses challenges to the management of water resources. Magnetic nanoparticles has been issue of different potential applications including remotion oil from water. Magnetic polystyrene–palygorskite nanocomposites were prepared by a heterogeneous phase polymerization for the removal of organic contaminants from water. The organo‐Fe3O4‐palygorskite nanoparticles were coated with polystyrene, forming water repellent and oil absorbing surfaces to promote the removal of oil from the surfaces of nanocomposites by applying an external magnetic field. X‐ray fluorescence, X‐ray diffraction, scanning electron microscopy, zeta potential and size distribution measurement, surface area determination by BET, density measurement by He pycnometry, carbon grade determination, thermogravimetric analysis, Fourier‐transform infrared spectroscopy, Raman spectroscopy, and evaluation of hydrophobicity by contact angle were used to characterize the nanoparticles. The magnetic nanocomposite obtained showed excellent hydrophobicity, around 78° contact angle. In addition, oil removal capability tests were also performed, according to which the preliminary results indicated removal of approximately 98% of oil in synthetic oily water samples. The oil–water separation using this magnetic nanocomposite provides a promising alternative strategy for water treatment. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46162. 相似文献
64.
Andrey Oliveira de Souza Aur lio Moreira Luiz Ant nio Tavernard Pereira Neto Ant nio Carlos Brandao de Araujo Heleno Bispo da Silva Sidinei Kebler da Silva Jose Jailson Nicacio Alves 《中国化学工程学报》2019,27(1):21-31
This study aimed to describe a Computational Fluid Dynamics(CFD) procedure using the ANSYS CFX software 16.1 and Design of Experiments for the determination of volume and extension of explosive atmospheres due to fugitive emissions of flammable gases.The multidimensional statistical sampling technique Latin Hypercube was used, which defined 100 simulations of random methane gas leak conditions.The CFD model proved to be robust in predicting the extension and volume of the explosive atmosphere for orifice diameters from 0.1 to2.5 mm, pressure from 0.1 MPa to 12 MPa and temperatures from 0 ℃ to 400 ℃.It was found that the calculation domain must be parameterized 8 m in length for each millimeter of the diameter of the source of release to ensure the predictions.In order not to lose precision for very small diameters, the mesh was parameterized with 50 elements along the orifice diameter.It was proved that gravity does not influence the extension and volume of the explosive atmosphere at sonic emissions.The deviation from the ideal gas behavior in the reservoir,achieved by applying the Soave–Redlich–Kwong equation of state, also has not significantly influenced the extension and volume of the explosive atmosphere.The results showed that the size of the explosive atmosphere varies directly with the diameter of the source emission and reservoir pressure, and inversely with the temperature of the reservoir.The diameter of the source is the parameter that has the major effect on the extension of the explosive atmosphere, followed by the pressure and lastly the temperature of the reservoir. 相似文献
65.
Oliveira TW Leandro CG de Jesus Deiró TC dos Santos Perez G da França Silva D Druzian JI Couto RD Barreto-Medeiros JM 《Lipids》2011,46(11):1071-1074
The main goal of the present study was to evaluate the long-term effects of a perinatal palatable high-fat diet on the food
intake and cholesterol profile of adult rats. Male Wistar rats (aged 22 days) were divided into two groups according to their
mother’s diet during gestation and lactation (C
p, n = 10; pups from control mothers; and HLp
n = 10; pups from mothers fed a palatable high-fat diet). At the 76th day, pups were housed individually for 14 days, and daily
food consumption was determined during a period of 6 days. Blood from 100-day-old rats was sampled by cardiac puncture. Fasting
(12 h) serum glucose, total cholesterol, LDL-C, HDL-C, triglycerides (TG), and VLDL-C levels were determined. The measurement
of food intake was higher in the animals submitted to a hyperlipidic diet during the perinatal period. Serum total cholesterol,
LDL-C, HDL-C, TG, VLDL-C and glycemia were increased in the HLp group compared to the control group. Our findings show that an early life environment with a high-fat diet can contribute
to metabolic disease in later life. 相似文献
66.
Aleksándros El Áurens Meira de Souza Leonardo José Lins Maciel Nelson Medeiros de Lima Filho Cesar Augusto Moraes de Abreu 《Catalysis Today》2010,149(3-4):413-417
A nickel catalyst (5.75 wt.%) supported on gamma-alumina was evaluated through autothermal reforming of methane (ATR). The reforming process was pointed to hydrogen production, following thermodynamic and stoichiometric predictions. The catalyst was characterised by several methods including atomic absorption spectroscopy (AAS), B.E.T.-N2, X-ray diffraction (XRD), scanning electron microscope (SEM) and thermal analyses (thermogravimetry, TG; derivate thermogravimetry, DTG; and differential thermal analysis, DTA). Experimental evaluations in a fixed-bed reactor (1023–1123 K, 1.00 bar, 150–400 cm3/min feed) presented methane conversions in the range of 40–65%. The effluent mixtures provided hydrogen yields in the range of 78–84%, carbon monoxide 3–14%, and carbon dioxide 5–18%. High molar H2/CO ratios, ranging from 8 to 90, were obtained. Operating autothermal conditions (excess of steam, 1023–1123 K, 1.00 bar) provided low coke formation and high hydrogen selectivity (81%) for methane reforming. 相似文献
67.
Disposable Australian iron-slurry (AL) and NiO-MoO3-Al2O3 (NiMo) catalysts were used in hydrocracking experiments to convert Marlim vacuum residue (ML-VR) in a slurry-bed continuous flow reactor at temperatures of 440-460 °C, under a hydrogen pressure of 14.7 MPa and an LHSV of 0.5. The degree of conversion ranged from 54 to 83%, depending on the reaction temperature and catalyst used, with AL giving more complete conversion than NiMo. AL also proved more active in the removal of nickel. Hydrogen consumption was linearly correlated with conversion regardless of the catalyst used. 相似文献
68.
Fernando G. Souza Jr Marcos T. D. Orlando Ricardo C. Michel José Carlos Pinto Tainá Cosme Geiza E. Oliveira 《应用聚合物科学杂志》2011,119(5):2666-2673
Pressure‐sensitive polymers that simultaneously present reasonable electrical conducting properties, useful thermosetting behavior, and softness are hard to develop. To combine these properties into a single material, a cardanol‐based phenolic resin was prepared and blended in situ with polyaniline (PAni). The final polymer blend was composed of a soft solid material that could not be dissolved in ordinary solvents. Samples were characterized through X‐ray scattering, Fourier transform infrared (FTIR) spectroscopy, and electrical conductivity and pressure sensitivity measurements. FTIR results indicate that the insertion of PAni into the blends did not change the chemical nature of the resin. According to wide‐angle X‐ray scattering results, PAni was dispersed homogeneously in the final polymer samples; this improved the sensitivity of the electrical conductivity to pressure variations, as confirmed through electromechanical tests. Pressure sensitivity and electromechanical analyses indicated that the produced blends could be used as pressure‐sensing materials. Among the tested materials, the blends containing 5 wt % PAni·H2SO4 presented the largest compression sensitivity values. Finally, it was shown for the first time through XRD analyses under pressure that PAni chains were considerably disturbed by compressive stresses. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011 相似文献
69.
João Renato de Jesus Junqueira Jefferson Luiz Gomes Corrêa Kamilla Soares de Mendonça Ronaldo Elias de Mello Júnior Amanda Umbelina de Souza 《Food and Bioprocess Technology》2018,11(10):1863-1875
Pulsed vacuum osmotic dehydration (PVOD) is a widely used technique for reducing moisture content and water activity in biological products. This study aimed to analyze the effect of vacuum application (VA) on PVOD of beetroot, carrot, and eggplant slices, with respect to chemical (moisture, water activity, specific pigments, polyphenols, and sodium content), optical (color), mechanical (shrinkage, maximum stress, and elasticity), and structural (microstructure) properties. PVOD was conducted at three different vacuum pressures (0, 40, and 80 kPa, for 10 min), during a total process time of 300 min. Osmotic processing was performed at 35 °C by using a ternary osmotic solution [40% sucrose +?10% sodium chloride (w/w)]. Eggplant and carrot samples were more sensitive to VA, compared to beetroot. This was related to their porous and less compact structure. In general, VA reduced the moisture content and water activity and preserved the carotenoid content. VA caused loss of betalain and phenolic acid, favored sodium uptake, and induced significant changes in the optical, mechanical, and structural properties, compared to the osmotic processing conducted at atmospheric pressure. 相似文献
70.
Joana T. Martins Ana I. Bourbon Ana C. Pinheiro Bartolomeu W. S. Souza Miguel A. Cerqueira António A. Vicente 《Food and Bioprocess Technology》2013,6(8):2081-2092
The aims of this work were to evaluate the physical and antimicrobial properties of biodegradable films composed of mixtures of κ-carrageenan (κ-car) and locust bean gum (LBG) when organically modified clay Cloisite 30B (C30B) was dispersed in the biopolymer matrix. Film-forming solutions were prepared by adding C30B (ranging from 0 to 16 wt.%) into the κ-car/LBG solution (40/60 wt.%) with 0.3 % (w/v) of glycerol. Barrier properties (water vapour permeability, P vapour; CO2 and O2 permeabilities), mechanical properties (tensile strength, TS, and elongation-at-break, EB) and thermal stability of the resulting films were determined and related with the incorporation of C30B. Also, X-ray diffraction (XRD) was done in order to investigate the effect of C30B in film structure. Antimicrobial effects of these films against Listeria monocytogenes, Escherichia coli and Salmonella enterica were also evaluated. The increase of clay concentration causes a decrease of P vapour (from 5.34?×?10?11 to 3.19?×?10?11 g (m s?Pa)?1) and an increase of the CO2 permeability (from 2.26?×?10?14 to 2.91?×?10?14 g (m s?Pa)?1) and did not changed significantly the O2 permeability for films with 0 and 16 wt.% C30B, respectively. Films with 16 wt.% clay exhibited the highest values of TS (33.82 MPa) and EB (29.82 %). XRD patterns of the films indicated that a degree of exfoliation is attained depending on clay concentration. κ-car/LBG–C30B films exhibited an inhibitory effect only against L. monocytogenes. κ-car/LBG–C30B composite films are a promising alternative to synthetic films in order to improve the shelf life and safety of food products. 相似文献