全文获取类型
收费全文 | 446篇 |
免费 | 29篇 |
专业分类
电工技术 | 11篇 |
化学工业 | 108篇 |
金属工艺 | 9篇 |
机械仪表 | 12篇 |
建筑科学 | 7篇 |
矿业工程 | 5篇 |
能源动力 | 33篇 |
轻工业 | 42篇 |
水利工程 | 4篇 |
无线电 | 50篇 |
一般工业技术 | 98篇 |
冶金工业 | 61篇 |
原子能技术 | 4篇 |
自动化技术 | 31篇 |
出版年
2024年 | 2篇 |
2023年 | 5篇 |
2022年 | 11篇 |
2021年 | 18篇 |
2020年 | 14篇 |
2019年 | 13篇 |
2018年 | 19篇 |
2017年 | 14篇 |
2016年 | 18篇 |
2015年 | 18篇 |
2014年 | 22篇 |
2013年 | 36篇 |
2012年 | 19篇 |
2011年 | 17篇 |
2010年 | 15篇 |
2009年 | 10篇 |
2008年 | 19篇 |
2007年 | 15篇 |
2006年 | 7篇 |
2005年 | 12篇 |
2004年 | 8篇 |
2003年 | 10篇 |
2002年 | 8篇 |
2001年 | 4篇 |
2000年 | 6篇 |
1999年 | 10篇 |
1998年 | 14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475条查询结果,搜索用时 31 毫秒
121.
L.J. Moitsheki R.H. Matjie A. Baran O.I. Mooketsi H.H. Schobert 《Minerals Engineering》2010,23(3):258-261
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
122.
A new functional model for determining minimum and maximum detectable deformation gradient resolved by satellite radar interferometry 总被引:2,自引:0,他引:2
Baran I. Stewart M. Claessens S. 《Geoscience and Remote Sensing, IEEE Transactions on》2005,43(4):675-682
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
123.
Murat Karadag Caner Geyik Dilek Odaci Demirkol F. Nil Ertas Suna Timur 《Materials science & engineering. C, Materials for biological applications》2013,33(2):634-640
An electrochemical biosensor mediated by using 6-(Ferrocenyl) hexanethiol (FcSH) was fabricated by construction of gold nanoparticles (AuNPs) on the surface of polyamidoamine dendrimer (PAMAM) modified gold electrode. Glucose oxidase (GOx) was used as a model enzyme and was immobilized onto the gold surface forming a self assembled monolayer via FcSH and cysteamine. Cyclic voltammetry and amperometry were used for the characterization of electrochemical response towards glucose substrate. Following the optimization of medium pH, enzyme loading, AuNP and FcSH amount, the linear range for the glucose was studied and found as 1.0 to 5.0 mM with the detection limit (LOD) of 0.6 mM according to S/N = 3. Finally, the proposed Au/AuNP/(FcSH + Cyst)/PAMAM/GOx biosensor was successfully applied for the glucose analysis in beverages, and the results were compared with those obtained by HPLC. 相似文献
124.
Mainak Mohan Das Mallar Ray Nil Ratan Bandyopadhyay Syed Minhaz Hossain 《Materials Chemistry and Physics》2010
Estimation of electron trap energy (Et), with respect to bulk Si valence band, of oxidized porous silicon (PS) nanostructures is reported. Photoluminescence (PL) spectra of oxidized PS prepared with different formation parameters have been investigated and the room temperature PL characteristics have been successfully explained on the basis of oxide related trap assisted transitions. PL peak energy for the oxidized samples with low porosity exhibited a blue shift with increasing formation current density (J). For the high porosity samples double peaks appeared in the PL spectra. One of these peaks remained constant at ∼730 nm while the other was blue shifted with increase in J. Evolution of PS nanostructure was correlated to the formation parameters using a simple growth mechanism. PS nanostructure was modelled as an array of regular hexagonal pores and the average value of Et was estimated to be 1.67 eV. 相似文献
125.
Xinbo Yang Yuanbao Lin Jiang Liu Wenzhu Liu Qunyu Bi Xin Song Jingxuan Kang Fuzong Xu Lujia Xu Mohamed N. Hedhili Derya Baran Xiaohong Zhang Thomas D. Anthopoulos Stefaan De Wolf 《Advanced materials (Deerfield Beach, Fla.)》2020,32(32):2002608
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
126.
This paper shows that the current an inverter interfaced distributed generator (IIDG) contributes to a fault varies considerably, due mainly to fast response of its controller. This paper proposes a method to extend the conventional fault analysis methods so that IIDG contribution can be estimated in the fault analysis. The proposed method gives rms profiles of the fault currents of interest (IIDG contribution and the fault currents the protective device will see). Test results, based on a prototype feeder, show that the proposed approach can estimate the fault current's contributions under both balanced and unbalanced fault conditions. 相似文献
127.
Yizhou Zhong Anil Koklu Diego Rosas Villalva Yongcao Zhang Luis Huerta Hernandez Maximilian Moser Rawad K. Hallani Iain McCulloch Derya Baran Sahika Inal 《Advanced functional materials》2023,33(6):2211479
The organic photodiode (OPD) is a promising building block for solution-processable, flexible, lightweight, and miniaturized photodetectors, ideal for wearable applications. Despite the advances in materials used in OPDs, their photocurrent and light responsivity are limited, and alternative methods are required to boost the signal response. Herein, a miniaturized organic electrochemical transistor (OECT) is integrated with an OPD module to unlock the potential of OPDs to acquire physiological signals. In this integrated photodetector (IPD) system, the light intensity regulates the OPD voltage output that modulates the OECT channel current. The high transconductance of the OECT provides efficient voltage-to-current conversion, enhancing the signal-to-noise ratio on the sensing site. A microscale, p-type enhancement-mode OECT with high gm and fast switching speed performs better in this application than depletion-mode OECT of the same geometry. The IPD achieves a photocurrent and responsivity 318 and 140 times higher than the standalone OPD, respectively. It is shown that with the IPD, the amplitude of the photoplethysmogram signals detected by the OPD is enhanced by a factor of 2.9 × 103, highlighting its potential as a wearable biosensor and to detect weak, often uncaptured, light-based signals from living systems. 相似文献
128.
Microporous poly(2-hydroxyethyl methacrylate) (PHEMA) membranes were prepared by UV-initiated photopolymerization of HEMA in the presence of an initiator (α,α′-azobisisobutyronitrile, AIBN). An affinity dye Cibacron Blue F3GA (CB) was attached covalently and then Fe3+ ions incorporated. The PHEMA-CB and PHEMA-CB-Fe3+ membranes derived were used for adsorption of glucose oxidase (GOD). The adsorption capacities of these membranes were determined under conditions of different pH and with different concentrations of the adsorbate in the medium. The adsorption phenomena appeared to follow a typical Langmuir isotherm. The glucose oxidase adsorption capacity of the Fe3+ incorporated membrane (87μgcm-2) was greater than that of the dye-derived membrane (66μgcm-2). Non-specific adsorption of the glucose oxidase on the PHEMA membranes was negligible. The Km values for both immobilized glucose oxidase PHEMA-CB-GOD (8·3) and PHEMA-CB-Fe3+-GOD (7·6) were higher than that of the free enzyme (6·2mM). Optimum reaction pH was 5·5 for the free and 6·0 for both immobilized preparations. The optimum reaction temperature of the adsorbed enzymes was 5°C higher than that of the free enzyme and was significantly broader. After 15 successive uses the retained activity of the adsorbed enzyme was 87%. It was observed that enzymes could be repeatedly adsorbed and desorbed on the derived PHEMA membranes without significant loss in adsorption capacity or enzymic activity. © 1998 SCI. 相似文献
129.
130.
Baran Onal-Ulusoy Pamela White Earl Hammond 《Journal of the American Oil Chemists' Society》2007,84(2):157-163
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