首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   381篇
  免费   27篇
电工技术   10篇
化学工业   92篇
金属工艺   8篇
机械仪表   10篇
建筑科学   3篇
矿业工程   5篇
能源动力   31篇
轻工业   23篇
水利工程   4篇
无线电   46篇
一般工业技术   88篇
冶金工业   58篇
原子能技术   2篇
自动化技术   28篇
  2023年   4篇
  2022年   11篇
  2021年   16篇
  2020年   12篇
  2019年   12篇
  2018年   15篇
  2017年   12篇
  2016年   16篇
  2015年   16篇
  2014年   21篇
  2013年   32篇
  2012年   16篇
  2011年   11篇
  2010年   10篇
  2009年   7篇
  2008年   12篇
  2007年   8篇
  2006年   5篇
  2005年   9篇
  2004年   6篇
  2003年   9篇
  2002年   7篇
  2001年   3篇
  2000年   6篇
  1999年   9篇
  1998年   12篇
  1997年   13篇
  1996年   14篇
  1995年   7篇
  1994年   7篇
  1993年   7篇
  1992年   3篇
  1991年   3篇
  1990年   7篇
  1989年   6篇
  1988年   7篇
  1987年   2篇
  1986年   3篇
  1985年   3篇
  1984年   3篇
  1983年   1篇
  1981年   2篇
  1980年   2篇
  1978年   1篇
  1977年   4篇
  1976年   9篇
  1975年   3篇
  1973年   4篇
排序方式: 共有408条查询结果,搜索用时 15 毫秒
91.
Bread pieces were fried at 180 °C in soybean oil (SBO) containing no additives (control), 0.1% linalyl oleate (LO), or 10 ppm methyl silicone (MS). After 2 h of heating, the MS-containing oil was the most stable, followed by the oil with LO and the control, based on conjugated dienoic acid percentage (CD) and the ratio of linoleate%/palmitate%. Oil extracted from the fresh fried bread showed similar, but not significant, trends for CD and PV. Fresh and stored (60 °C, 2 days) bread fried in LO-containing oil had less hexanal than the other two treatments, and the stored LO bread had less t,c- and t,t-2,4-heptadienal than the control. Fresh bread fried in LO-containing oil had a less rancid flavor than did the other two treatments, and the LO treatment had less fishy flavor than the control. In stored bread, the MS treatment was less rancid than the control. In oil extracted from the stored bread, the amounts of t,c-2,4-heptadienal and 2-decenal correlated (p ≤ 0.05) with the amounts of individual unsaturated fatty acids and with CD, but only t,c-2,4-heptadienal correlated with the PV. The t,c-2,4-heptadienal correlated with individual Polyunsaturated fatty acids (PUFA) in freshly fried bread. In general, oil and fried bread had improved flavor quality and/or oil stability when they contained MS or LO.  相似文献   
92.
93.
This paper reports a study of fullerite-Sn films containing 4, 6, 8, 10, 12, or 20 at % Sn grown by thermal evaporation in vacuum using a combined atomic-molecular flow. The influence of metal content and thermal annealing on the surface topography, structure, and elemental and phase compositions of the fullerite-Sn films has been studied by atomic force microscopy, X-ray and electron diffraction, scanning electron microscopy, and X-ray microanalysis. The results demonstrate that films grown by codeposition of Sn atoms and fullerene molecules on oxidized single-crystal silicon substrates have a granular structure. The phase composition of the fullerite-Sn films varies widely, depending on the percentage of Sn: from an intercalated structure to a mixed-phase composite containing a hexagonal fullerite phase, tetragonal Sn, and fullerite-like structures containing Sn nanoparticles. Thermal annealing of the fullerite-Sn films leads to the formation of a new phase.  相似文献   
94.
A new polyphenol (poly‐2‐[(4‐methylbenzylidene)amino]phenol) (P(2‐MBAP)) containing an azomethine group was synthesized by oxidative polycondensation reaction of 2‐[(4‐methylbenzylidene)amino]phenol (2‐MBAP) with NaOCl, H2O2, and O2 oxidants in an aqueous alkaline medium. The structures of 2‐MBAP and P(2‐MBAP) were characterized by UV‐vis, FT‐IR, and 1H NMR spectra. While the monomer decomposed completely up to 350°C and 57.2% of the polymer decomposed up to 1000°C. The thermal degradation of P(2‐MBAP) was also supported by the Thermo‐IR spectra recorded in the temperature range of 25–800°C. Electrical conductivity of the polymer was observed to increase 108 fold after doping with I2. Antimicrobial activities of the P(2‐MBAP) and 2‐MBAP against Sarcina lutea, Enterobacter aerogenes, Escherichia coli, Enterococcus feacalis, Klebsiella pneumoniae, Bacillus subtilis, Candida albicans, and Saccharomyces cerevisiae were also investigated. The number average molecular weight (Mn), weight average molecular weight (Mw) and polydispersity index (PDI) of the polymers were determined by gel permeation chromatography (GPC). © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41758.  相似文献   
95.
A facile and efficient covalent functionalization of single‐walled carbon nanotubes (SWCNTs) via peroxide‐mediated free radical covalent attachment and polymerization of zirconium acrylate is reported. The resulting covalently functionalized SWCNTs exhibit improved solubility in organic solvents. The covalently functionalized SWCNTs are characterized by cross polarization magic angle spinning 13C NMR, differential scanning calorimetry, thermogravimetric analysis, x‐ray diffraction, Raman, and infrared spectroscopy. Infrared spectroscopy reveals that carboxylate groups of covalently attached ionomers chelate with zirconium ions and the participating carboxylate groups may be from different ionomer chains leading to cross‐linking the chains. The SWCNT topology, ionic clustering, and π‐electron clouds were explored by transmission electron microscopy. © 2014 American Institute of Chemical Engineers AIChE J, 60: 820–828, 2014  相似文献   
96.
This study emphasizes microbial mediated transformation of sunflower oil to an adhesive product and characterization in detail. Marine bacterial isolates Bacillus (MTCC 5514), when grown in mineral medium, releases both hydrolytic enzymes and surface‐active components during the log phase of growth. When this species was grown in the presence of sunflower oil at an optimized concentration of 5% (w/v) under room temperature, enzymatic hydrolysis of oil proceeds with the release of fatty acids and glycerol. Further, on increasing the incubation period, the presence of surface‐active components, lipase and glycerol, influence the dimerization of the fatty acids, which further, transformed to a polymerized product sunflower oil‐based adhesive product with adhesive nature. Liquid chromatography‐mass spectrometry (electrospray ionization) analysis further authenticates the presence of dimeracids. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40555.  相似文献   
97.
This study presents the theoretical frameworks for the thermodynamic quantities namely the heat of adsorption, specific heat capacity, entropy, and enthalpy for the adsorption of methane onto various carbonaceous materials. The proposed theoretical frameworks are developed from the rigor of thermodynamic property surfaces of a single component adsorbate–adsorbent system and by incorporating the micropore filling theory approach, where the effect of adsorbed phase volume is considered. The abovementioned thermodynamic properties are quantitatively evaluated from the experimental uptake data for methane adsorption onto activated carbons such as Maxsorb III at temperatures ranging from 120 to 350 K and pressures up to 25 bar. Employing the proposed thermodynamic approaches, this paper shows the thermodynamic maps of the charge and discharge processes of adsorbed natural gas (ANG) storage system for understanding the behaviors of natural gas in ANG vessel.  相似文献   
98.
Sasol utilizes a low-rank bituminous coal for steam and synthetic gas production. The ash produced is transported by water for further processing. Understanding the chemistry of coal and the resulting ash properties would allow a better understanding of the origin of high pH of water used during ash handling or transport. A main objective of this study was to identify the species responsible for high pH values of the ash transport water, when burning coal from the Sasolburg Mooikraal mine. The coal contained proportions of extraneous carbonates, i.e. CaMg(CO3)2 and CaCO3, that decompose at elevated temperatures to form CaO and MgO. The ash samples in this work contained free CaO, as verified by X-ray diffraction and ethylene glycol leaching. ICP-OES analysis of water leachates of the ash showed calcium dissolution into the water. The high pH values of the leachates were consistent with the expected pH of a saturated water solution of calcium hydroxide. Contact of the ash with water produced Ca(OH)2. For combustion of this coal, the high pH of the water used for ash transport can be attributed to the free CaO in the ash. The methodological approach to this study could be directly applicable to other coals and their ashes, even of different composition than the specific coal and ash used in this study.  相似文献   
99.
In this paper, a functional model for determining the minimum and maximum detectable deformation gradient in terms of coherence for synthetic aperture radar (SAR) sensors is presented. The model is developed based on a new methodology that incorporates both real and simulated data. Sets of representative surface deformation models have been simulated, and the associated phase from these models introduced into real SAR data acquired by European Remote Sensing 1 and 2 satellites. Subsequently, interferograms were derived, and surface deformation was estimated. A number of cases of surface deformation with varying magnitudes and spatial extent have been simulated. In each case, the resultant surface deformation has been compared with the "true" surface deformation as defined by the deformation model. Based on these comparisons, a set of observations that lead to a new functional model has been established. Finally, the proposed model has been validated against external datasets and proven viable. Although the major weakness of the model is its reliance on visual interpretation of interferograms, this model can serve as a decision-support tool to determine whether or not to apply satellite radar interferometry to study a given surface deformation.  相似文献   
100.
High-quality carrier-selective contacts with suitable electronic properties are a prerequisite for photovoltaic devices with high power conversion efficiency (PCE). In this work, an efficient electron-selective contact, titanium oxynitride (TiOxNy), is developed for crystalline silicon (c-Si) and organic photovoltaic devices. Atomic-layer-deposited TiOxNy is demonstrated to be highly conductive with a proper work function (4.3 eV) and a wide bandgap (3.4 eV). Thin TiOxNy films simultaneously provide a moderate surface passivation and enable a low contact resistivity on c-Si surfaces. By implementation of an optimal TiOxNy-based contact, a state-of-the-art PCE of 22.3% is achieved for a c-Si solar cell featuring a full-area dopant-free electron-selective contact. Simultaneously, conductive TiOxNy is proven to be an efficient electron-transport layer for organic photovoltaic (OPV) devices. A remarkably high PCE of 17.02% is achieved for an OPV device with an electron-transport TiOxNy layer, which is superior to conventional ZnO-based devices with a PCE of 16.10%. Atomic-layer-deposited TiOxNy ETL on a large area with a high uniformity may help accelerate the commercialization of emerging solar technologies.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号