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1.
Camera distortion self-calibration using the plumb-line constraint and minimal Hough entropy 总被引:1,自引:0,他引:1
In this paper, we present a simple and robust method for self-correction of camera distortion using single images of scenes
which contain straight lines. Since the most common distortion can be modelled as radial distortion, we illustrate the method
using the Harris radial distortion model, but the method is applicable to any distortion model. The method is based on transforming
the edgels of the distorted image to a 1-D angular Hough space, and optimizing the distortion correction parameters which
minimize the entropy of the corresponding normalized histogram. Properly corrected imagery will have fewer curved lines, and
therefore less spread in Hough space. Since the method does not rely on any image structure beyond the existence of edgels
sharing some common orientations and does not use edge fitting, it is applicable to a wide variety of image types. For instance,
it can be applied equally well to images of texture with weak but dominant orientations, or images with strong vanishing points.
Finally, the method is performed on both synthetic and real data revealing that it is particularly robust to noise. 相似文献
2.
Venkatesh Rajagopalan Author Vitae Author Vitae Rohan Samsi Jeffrey Mayer 《Pattern recognition》2007,40(11):2897-2907
This paper presents symbolic time series analysis (STSA) of multi-dimensional measurement data for pattern identification in dynamical systems. The proposed methodology is built upon concepts derived from Information Theory and Automata Theory. The objective is not merely to classify the time series patterns but also to identify the variations therein. To achieve this goal, a symbol alphabet is constructed from raw data through partitioning of the data space. The maximum entropy method of partitioning is extended to multi-dimensional space. The resulting symbol sequences, generated from time series data, are used to model the dynamical information as finite state automata and the patterns are represented by the stationary state probability distributions. A novel procedure for determining the structure of the finite state automata, based on entropy rate, is introduced. The diversity among the observed patterns is quantified by a suitable measure. The efficacy of the STSA technique for pattern identification is demonstrated via laboratory experimentation on nonlinear systems. 相似文献
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Luis M. Montao Bettina Sommer Juan C. Gomez-Verjan Genaro S. Morales-Paoli Gema Lizbeth Ramírez-Salinas Hctor Solís-Chagoyn Zuly A. Sanchez-Florentino Eduardo Calixto Gloria E. Prez-Figueroa Rohan Carter Ruth Jaimez-Melgoza Bianca S. Romero-Martínez Edgar Flores-Soto 《International journal of molecular sciences》2022,23(8)
Theophylline (3-methyxanthine) is a historically prominent drug used to treat respiratory diseases, alone or in combination with other drugs. The rapid onset of the COVID-19 pandemic urged the development of effective pharmacological treatments to directly attack the development of new variants of the SARS-CoV-2 virus and possess a therapeutical battery of compounds that could improve the current management of the disease worldwide. In this context, theophylline, through bronchodilatory, immunomodulatory, and potentially antiviral mechanisms, is an interesting proposal as an adjuvant in the treatment of COVID-19 patients. Nevertheless, it is essential to understand how this compound could behave against such a disease, not only at a pharmacodynamic but also at a pharmacokinetic level. In this sense, the quickest approach in drug discovery is through different computational methods, either from network pharmacology or from quantitative systems pharmacology approaches. In the present review, we explore the possibility of using theophylline in the treatment of COVID-19 patients since it seems to be a relevant candidate by aiming at several immunological targets involved in the pathophysiology of the disease. Theophylline down-regulates the inflammatory processes activated by SARS-CoV-2 through various mechanisms, and herein, they are discussed by reviewing computational simulation studies and their different applications and effects. 相似文献
7.
Rohan Walker Buddhima Indraratna Nagaratnam Sivakugan 《Canadian Metallurgical Quarterly》2009,135(5):657-663
A new, easy to implement, solution to the consolidation of multilayered soil based on the spectral method is presented. Combined vertical and radial drainage under instantaneous or single ramp loading is considered, ignoring well resistance. Flow in the vertical direction is based on the average hydraulic gradient at a particular depth which allows smear effects to be included. The excess pore-water pressure profile across all soil layers is described by a single expression calculated with common matrix operations. Average excess pore pressures within or across any number of layers are easily calculated from the single expression. The new model is verified against other solutions from the current literature indicating that the more general spectral method model can replace the separate solutions developed for specific problems. 相似文献
8.
Clark Mertice M.; Robertson Rohan K.; Galef Bennett G. Jr. 《Canadian Metallurgical Quarterly》1996,110(2):413
When assuming their species-typical tripodal stance. male Mongolian gerbils (Meriones unguiculatus) use their right forepaw for support more frequently than do females. This experiment determined whether. as N. Geschwind and A. M. Galaburda (1987) have proposed, the direction of such sexualIy dimorphic lateral asymmetry of forelimb use is affected by perinatal exposure to testosterone (TP). It was found that male gerbils injected with TP when 4 days old were significantly less likely to rest on their right forepaw when in a tripodal stance than were their oil-injected siblings. Female gerbils injected with TP when 6 days old were more likely than oil-injected controls to use their right forepaws for support. The findings demonstrate effects of perinatal exposure to TP on handedness in gerbils and suggest that the relationship between TP exposure and asymmetrical forelimb use is not always as direct as Geschwind and Galaburda's model suggests. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
9.
Arsenic binding mechanisms on natural red earth: a potential substrate for pollution control 总被引:1,自引:0,他引:1
Vithanage M Senevirathna W Chandrajith R Weerasooriya R 《The Science of the total environment》2007,379(2-3):244-248
Natural red earth (hereafter NRE) was used as a novel adsorbent to examine its retention behaviour in different inorganic arsenic species (As (III) and As (V)) that are abundant in natural water. Adsorption isotherms were constructed at pH approximately 5.5 for As(III) and As(V) in 0.01 M NaNO(3) at 298K for 5 g/L NRE system. The initial arsenic [As(III) or As(V)] concentrations varied between approximately 10(-5) and approximately 10(-4) M. The experimental data were quantified using single site or stepwise Langmuir models. Sorption maximum, was observed at approximately 0.173 mM of As(V). To reach the maximum surface coverage of red earth at pH approximately 5.5 As(III) requires approximately 0.308 mM of initial loading. When compared to As (III), As(V) shows strong affinity for NRE surface sites. This study suggests the potential of NRE as a starting material in decontaminating water polluted with As species. 相似文献
10.
Ateek Shah Yashwant Kumar S. Rohan Amrita B. Hazra 《Chembiochem : a European journal of chemical biology》2023,24(11):e202300055
Flavin adenine dinucleotide (FAD) is an essential redox cofactor in cellular metabolism. The organic synthesis of FAD typically involves coupling flavin mononucleotide (FMN) with adenosine monophosphate, however, existing synthesis routes present limitations such as multiple steps, low yields, and/or difficult-to-obtain starting materials. In this study, we report the synthesis of FAD nucleobase analogues with guanine/cytosine/uracil in place of adenine and deoxyadenosine in place of adenosine using chemical and enzymatic approaches with readily available starting materials, achieved in 1–3 steps with moderate yields (10–57 %). We find that the enzymatic route using Methanocaldococcus jannaschii FMN adenylyltransferase (MjFMNAT) is versatile and can produce these FAD analogues in high yields. Further, we demonstrate that Escherichia coli glutathione reductase is capable of binding and using these analogues as cofactors. Finally, we show that FAD nucleobase analogues can be synthesized inside a cell from cellular substrates FMN and nucleoside triphosphates by the heterologous expression of MjFMNAT. This lays the foundation for their use in studying the molecular role of FAD in cellular metabolism and as biorthogonal reagents in biotechnology and synthetic biology. 相似文献