全文获取类型
收费全文 | 297篇 |
免费 | 5篇 |
专业分类
电工技术 | 1篇 |
化学工业 | 35篇 |
金属工艺 | 4篇 |
机械仪表 | 7篇 |
建筑科学 | 26篇 |
能源动力 | 13篇 |
轻工业 | 34篇 |
水利工程 | 1篇 |
无线电 | 31篇 |
一般工业技术 | 25篇 |
冶金工业 | 12篇 |
自动化技术 | 113篇 |
出版年
2023年 | 3篇 |
2022年 | 3篇 |
2021年 | 1篇 |
2020年 | 2篇 |
2019年 | 4篇 |
2018年 | 10篇 |
2017年 | 6篇 |
2016年 | 8篇 |
2015年 | 8篇 |
2014年 | 8篇 |
2013年 | 21篇 |
2012年 | 12篇 |
2011年 | 27篇 |
2010年 | 8篇 |
2009年 | 20篇 |
2008年 | 14篇 |
2007年 | 20篇 |
2006年 | 16篇 |
2005年 | 11篇 |
2004年 | 10篇 |
2003年 | 7篇 |
2002年 | 12篇 |
2001年 | 7篇 |
2000年 | 9篇 |
1999年 | 4篇 |
1998年 | 5篇 |
1997年 | 3篇 |
1996年 | 6篇 |
1995年 | 5篇 |
1994年 | 4篇 |
1993年 | 2篇 |
1992年 | 2篇 |
1991年 | 2篇 |
1990年 | 6篇 |
1989年 | 3篇 |
1988年 | 2篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1976年 | 1篇 |
1960年 | 2篇 |
1926年 | 2篇 |
1924年 | 3篇 |
排序方式: 共有302条查询结果,搜索用时 15 毫秒
31.
The feasibility of using a constructed wetland for treatment of nitrate-contaminated groundwater resulting from the land application of biosolids was investigated for a site in the southeastern United States. Biosolids degradation led to the release of ammonia, which upon oxidation resulted in nitrate concentrations in the upper aquifer in the range of 65-400 mg N/L. A laboratory-scale system was constructed in support of a pilot-scale project to investigate the effect of temperature, hydraulic retention time (HRT) and nitrate and carbon loading on denitrification using soil and groundwater from the biosolids application site. The maximum specific reduction rates (MSRR), measured in batch assays conducted with an open to the atmosphere reactor at four initial nitrate concentrations from 70 to 400 mg N/L, showed that the nitrate reduction rate was not affected by the initial nitrate concentration. The MSRR values at 22 °C for nitrate and nitrite were 1.2 ± 0.2 and 0.7 ± 0.1 mg N/mg VSSCOD-day, respectively. MSRR values were also measured at 5, 10, 15 and 22 °C and the temperature coefficient for nitrate reduction was estimated at 1.13. Based on the performance of laboratory-scale continuous-flow reactors and model simulations, wetland performance can be maintained at high nitrogen removal efficiency (>90%) with an HRT of 3 days or higher and at temperature values as low as 5 °C, as long as there is sufficient biodegradable carbon available to achieve complete denitrification. The results of this study show that based on the climate in the southeastern United States, a constructed wetland can be used for the treatment of nitrate-contaminated groundwater to low, acceptable nitrate levels. 相似文献
32.
J. Bajaj S. J. C. Irvine H. O. Sankur Spyros A. Svoronos 《Journal of Electronic Materials》1993,22(8):899-906
An effective way to in situ monitor the metalorganic chemical vapor deposition (MOCVD) of HgCdTe/CdTe/ZnTe on GaAs or GaAs/Si
substrates is presented. Specular He-Ne laser reflectance was used to in situ monitor the growth rates, layer thickness, and
morphology for each layer in the grown multilayer structure. In situ monitoring has enabled precise measurements of ZnTe nucleation
and CdTe buffer layer thicknesses. Monitoring the constancy of reflectance during the thicker CdTe buffer growth where absorption
in the CdTe reduces reflectance to just the surface component has led to optimum buffer growth ensuring good quality of subsequently
grown HgCdTe. During the interdiffused multilayer process (IMP) HgCdTe growth, because multiple interfaces are present within
the absorption length, a periodic reflectance signal is maintained throughout this growth cycle. A theoretical model was developed
to extract IMP layer thicknesses from in situ recorded experimental data. For structures that required the growth of a larger
band gap HgCdTe cap layer on top of a smaller band gap active layer, in situ monitored reflectance data allowed determination
of alloy composition in the cap layer as well. Continuous monitoring of IMP parameters established the stability of growth
conditions, translating into depth uniformity of the grown material, and allowed diagnosis of growth rate instabilities in
terms of changes in the HgTe and CdTe parts of the IMP cycle. A unique advantage of in situ laser monitoring is the opportunity
to perform “interactive” crystal growth, a development that is a key to real time MOCVD HgCdTe feedback growth control. 相似文献
33.
Markus Grassl Ivana Ili? Spyros Magliveras Rainer Steinwandt 《Journal of Cryptology》2011,24(1):148-156
At CRYPTO ’94, Tillich and Zémor proposed a family of hash functions, based on computing a suitable matrix product in groups
of the form
SL2(\mathbbF2n)SL_{2}(\mathbb{F}_{2^{n}}). We show how to construct collisions between palindromic bit strings of length 2n+2 for Tillich and Zémor’s construction. The approach also yields collisions for related proposals by Petit et al. from ICECS ’08
and CT-RSA ’09. 相似文献
34.
Rajsekhar AdapaAuthor Vitae Spyros TragoudasAuthor Vitae Maria K. MichaelAuthor Vitae 《Integration, the VLSI Journal》2011,44(3):217-228
Defect diagnosis can benefit from fault dominance relations to reduce the set of defect candidate sites. This paper presents new fault dominance collapsing operators that further reduce the set of candidates considered during the initial phase of diagnosis. In contrast to existing dominance-based methods which operate on pairs of faults, the proposed method operates on sets of faults. Fault-related entities are generated to guide the diagnosis process. The proposed collapsing operators can be used to accelerate effect-cause diagnosis. Experimental results demonstrate that the proposed method achieves a higher collapsing ratio than existing methods. 相似文献
35.
A. Spyros 《应用聚合物科学杂志》2002,83(8):1635-1642
Quantitative 31P‐NMR spectroscopy is used to measure the hydroxyl and carboxyl content of some polyester resins (short‐ and long‐oil alkyds, polyols, polyesters) through derivatization of the —OH protons with 2‐chloro‐4,4,5,5‐tetramethyldioxaphospholane I. This methodology is shown to be superior to titration methods, since it can (a) discriminate between primary and secondary hydroxyl groups, (b) identify individual alcohols and acids present, (c) measure the amount of free fatty acids in oil‐modified alkyds, and (d) provide lower limits for the number‐averaged molecular weight of the resins and exact values for linear polyesters. A major advantage of the technique is that the NMR measurements are made on unmodified resins in their final product form supplied by the manufacturer. The information obtained is important for the characterization of the alkyd resins and affects drastically their physical properties and performance as products. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 1635–1642, 2002 相似文献
36.
The main objective is to improve the control performance during catalyst processing experiments in a furnace heated fluidised bed reactor. A model-based predictive control strategy is implemented for the tight control of the reactor temperature and the overall energy requirements. A detailed dynamic model is developed for the furnace reactor and validated using open-loop experimental data. Dynamic programming techniques are used for the calculation of the optimal sequence of manipulated variables that minimise the difference between the desired and the predicted reactor temperature trajectories. The model predictive control strategy leads to superior performance than the previously installed system that consisted of conventional PID controllers. 相似文献
37.
Adsorption of organophosphates into microporous and mesoporous NaX zeolites and subsequent chemistry
Meng Q Doetschman DC Rizos AK Lee MH Schulte JT Spyros A Kanyi CW 《Environmental science & technology》2011,45(7):3000-3005
Due to the neurotoxicity of organophosphate (OP) pesticides and nerve agents synthesized as military or terror agents, their safe destruction and disposal is of considerable current importance. A representative OP, trimethyl phosphate (TMP), was adsorbed onto NaX zeolite, two mesoporous modifications, and a low-silica X zeolite. The nucleophilic chemical reactions of TMP with the zeolites were investigated by solid-state 13C and 31P nuclear magnetic resonance (NMR) and the solvent extracts by 1H, 13C, and 31P NMR. Nucleophilic substitution and subsequent hydrolysis reaction schemes are proposed. All of the zeolites have similar TMP decomposition yields, supporting the hypothesis that slow or incomplete diffusion of TMP in the microporous zeolite regions limits TMP decomposition. 相似文献
38.
In this paper a switching fuzzy logic controller for mobile robots with a bounded curvature constraint is presented. The controller tracks piece-wise linear paths, which are an approximation of the feasible smooth reference path. The controller is constructed through the use of a map, which transforms the problem to a simpler one; namely the tracking of straight lines. This allows the use of an existing fuzzy tracker deployed in a previous work, and its simplification leading to a 70% rule reduction. Simulation results and a comparison analysis with existing trackers are also presented along with some stability considerations on the impulsive error dynamics which emerge. 相似文献
39.
40.
Lena Costaridou Spyros Stefanou Joy Hirsch Stelios Orphanoudakis 《Journal of Visual Communication and Image Representation》1990,1(2)
The image reconstruction capacity of the actual foveal cone sampling mosaics of an adult monkey and human is investigated through computer simulations. A retinocortical mapping model in which positions are known and disorder is compensated (DC) has been implemented using classical Whittaker-Kotelnikov-Shannon (WKS) reconstruction theory and a two-dimensional hexagonal tessellation technique that maps the cone lattice onto a perfectly hexagonal grid. The DC model has been compared with a retinocortical mapping model in which cone positions are also known but position disorder is uncompensated (DU) in the reconstruction process. A control model has also been implemented using WKS reconstruction based on sampled data obtained with simulated perfectly hexagonal lattices whose Nyquist limits are equivalent to those of the human and monkey lattices. Quantitative comparisons of these models are based on the RMS error per pixel between the original and reconstructed images. Results of these simulations demonstrate a pronounced superiority of the DC over the DU model. The results of these simulations, which use “biologically correct” sampling lattices, document a potential image reconstruction advantage when foveal cone positions are known. 相似文献