全文获取类型
收费全文 | 196篇 |
免费 | 16篇 |
专业分类
电工技术 | 5篇 |
化学工业 | 44篇 |
金属工艺 | 7篇 |
机械仪表 | 3篇 |
建筑科学 | 5篇 |
矿业工程 | 5篇 |
能源动力 | 2篇 |
轻工业 | 26篇 |
水利工程 | 3篇 |
石油天然气 | 3篇 |
无线电 | 11篇 |
一般工业技术 | 32篇 |
冶金工业 | 26篇 |
原子能技术 | 3篇 |
自动化技术 | 37篇 |
出版年
2022年 | 3篇 |
2021年 | 4篇 |
2020年 | 4篇 |
2019年 | 5篇 |
2018年 | 7篇 |
2017年 | 12篇 |
2016年 | 9篇 |
2015年 | 7篇 |
2014年 | 6篇 |
2013年 | 24篇 |
2012年 | 8篇 |
2011年 | 15篇 |
2010年 | 10篇 |
2009年 | 16篇 |
2008年 | 6篇 |
2007年 | 5篇 |
2006年 | 6篇 |
2005年 | 5篇 |
2004年 | 4篇 |
2003年 | 2篇 |
2002年 | 3篇 |
2001年 | 7篇 |
2000年 | 3篇 |
1999年 | 3篇 |
1998年 | 5篇 |
1997年 | 5篇 |
1996年 | 6篇 |
1995年 | 4篇 |
1994年 | 1篇 |
1993年 | 3篇 |
1992年 | 3篇 |
1989年 | 1篇 |
1988年 | 1篇 |
1986年 | 1篇 |
1985年 | 4篇 |
1976年 | 2篇 |
1968年 | 1篇 |
1967年 | 1篇 |
排序方式: 共有212条查询结果,搜索用时 15 毫秒
101.
L. F. Peres J. A. Sobrino R. Libonati J. C. Jiménez‐Muñoz C. C. Dacamara M. Romaguera 《International journal of remote sensing》2013,34(24):7251-7268
This paper presents an assessment of the performance of a hybrid method that allows a simultaneous retrieval of land‐surface temperature (LST) and emissivity (LSE) from remotely‐sensed data. The proposed method is based on a synergistic usage of the split‐window (SW) algorithm and the two‐temperature method (TTM) and combines the advantages of both procedures while mitigating their drawbacks. The method was implemented for thermal channels 76 (10.56 µm) and 78 (11.72 µm) of the Airborne Hyperspectral Scanner (AHS), which was flown over the Barrax test site (Albacete, Spain) in the second week of July 2005, within the framework of the Sentinel‐2 and Fluorescence Experiment (SEN2FLEX) field campaign. A set of radiometric measurements was performed in the thermal infrared region in coincidence with aircraft overpasses for different surface types, e.g. bare soil, water body, corn, wheat, grass. The hybrid method was tested and compared with a standard SW algorithm and the results obtained show that the hybrid method is able to provide better estimates of LST, with values of bias (RMSE) of the order of 0.8 K (1.9 K), i.e. about one third (one half) of the corresponding values of 2.7 K (3.4 K) that were obtained for bias (RMSE) when using the SW algorithm. These figures provide a sound indication that the developed hybrid method is particularly useful for surface and atmospheric conditions where SW algorithms cannot be accurately applied. 相似文献
102.
Maurício C. de Oliveira Ricardo C.L.F. Oliveira Pedro L.D. Peres 《International journal of control》2013,86(10):2181-2192
This article is concerned with robust stability of uncertain discrete-time linear systems. The matrix defining the linear system (system matrix) is assumed to depend affinely on a set of time-invariant unknown parameters lying on a known polytope. Robust stability is investigated by checking whether a certain integer power κ of the uncertain system matrix has spectral norm less than one. This peculiar stability test is shown to be equivalent to the positivity analysis of a homogeneous symmetric matrix polynomial with precisely known coefficients and degree indexed by κ. A unique feature is that no extra variables need to be added to the problems being solved. Numerical experiments reveal that the value of κ needed to test robust stability is mostly independent of the system dimension but grows sharply as the eigenvalues of the uncertain system approach the unit circle. By identifying the proposed stability test with a particular choice of a parameter-dependent Lyapunov function, extra variables can be introduced, yielding linear matrix inequalities optimisation problems of improved convergence. 相似文献
103.
104.
105.
Renata C. B. Madeo Clodoaldo A. M. Lima Sarajane M. Peres 《Language Resources and Evaluation》2017,51(2):547-579
This paper presents an overview of studies on automated hand gesture analysis, which is mainly concerned with recognition and segmentation issues related to functional types and gesture phases. The issues selected for discussion have been arranged in a way that takes account of problems within the Theory of Gestures that each study seeks to address. Their principal computational factors that were involved in conducting the analysis of automated hand gesture have been examined, and an analysis of open research issues has been carried out for each application dealt with in the studies. 相似文献
106.
Electron Microscopic Investigation of Ointment Structure I: Investigation of Vaselines The structure of fibril-lattices of vaseline is studied with the help of a freeze-etching technique. From the electron microscopic pictures it can be concluded that vaseline represents a colloidal fibrilary system and that the fibrils comprise of fibrous threadlike bundles. 相似文献
107.
Lima Clodoaldo A. M. Coelho André L. V. Madeo Renata C. B. Peres Sarajane M. 《Neural computing & applications》2016,27(3):791-804
Neural Computing and Applications - Surface electromyography (EMG) signals have been studied extensively in the last years aiming at the automatic classification of hand gestures and movements as... 相似文献
108.
In this paper, a less conservative condition for the robust stability of uncertain discrete-time linear systems is proposed. The uncertain parameters, assumed to be time-invariant, are supposed to belong to convex bounded domains (polytope type uncertainty). The stability condition is formulated in terms of a set of linear matrix inequalities involving only the vertices of the polytope domain. A simple and numerically efficient feasibility test provides a set of Lyapunov matrices whose convex combination can be used to assess the stability of any dynamic matrix inside the uncertainty domain. Examples illustrate the results. 相似文献
109.
Luís G. Dias Ana C.A. Veloso Daniela M. Correia Orlando Rocha Duarte Torres Isabel Rocha Lígia R. Rodrigues António M. Peres 《Food chemistry》2009
Monitoring the industrial production of galacto-oligosaccharides (GOS) requires a fast and accurate methodology able to quantify, in real time, the substrate level and the product yield. In this work, a simple, fast and inexpensive UV spectrophotometric method, together with partial least squares regression (PLS) and artificial neural networks (ANN), was applied to simultaneously estimate the products (GOS) and the substrate (lactose) concentrations in fermentation samples. The selected multiple models were trained and their prediction abilities evaluated by cross-validation and external validation being the results obtained compared with HPLC measurements. ANN models, generated from absorbance spectra data of the fermentation samples, gave, in general, the best performance being able to accurately and precisely predict lactose and total GOS levels, with standard error of prediction lower than 13 g kg−1 and coefficient of determination for the external validation set of 0.93–0.94, showing residual predictive deviations higher than five, whereas lower precision was obtained with the multiple model generated with PLS. The results obtained show that UV spectrophotometry allowed an accurate and non-destructive determination of sugars in fermentation samples and could be used as a fast alternative method for monitoring GOS production. 相似文献
110.
Rafael L. Quirino André P. Tavares Antônio C. Peres Joel C. Rubim Paulo A. Z. Suarez 《Journal of the American Oil Chemists' Society》2009,86(2):167-172
The pyrolysis of vegetable oils consists of cracking triglycerides to produce smaller molecules. A mixture of hydrocarbons
and oxygenated compounds, such as carboxylic acids and aldehydes, is obtained as the product and which can be separated by
fractional distillation. When the reaction is carried out in the absence of catalysts (thermal cracking), a great quantity
of these oxygenated compounds is obtained. Thus, the presence of those oxygenated compounds in the products results in a high
level of acidity, which can be a problem when using them as fuels in combustion engines. The aim of this work was to study
the composition of the products obtained by cracking of vegetable oils assisted by γ-alumina doped with zinc and tin oxides.
The products were analyzed by FT-IR, GC-MS and GC-FID and the acid number was determined by titration with alcoholic KOH solution.
The acid number, infrared spectra and chromatograms of the resulting hydrocarbon mixtures indicated a significant reduction
in oxygenated compounds when compared with the mixtures obtained by the thermal cracking process, thus decreasing the acidity
of the mixture. 相似文献