全文获取类型
收费全文 | 812篇 |
免费 | 68篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 6篇 |
综合类 | 1篇 |
化学工业 | 246篇 |
金属工艺 | 18篇 |
机械仪表 | 29篇 |
建筑科学 | 26篇 |
矿业工程 | 7篇 |
能源动力 | 51篇 |
轻工业 | 123篇 |
水利工程 | 10篇 |
石油天然气 | 8篇 |
无线电 | 40篇 |
一般工业技术 | 109篇 |
冶金工业 | 55篇 |
原子能技术 | 2篇 |
自动化技术 | 151篇 |
出版年
2024年 | 5篇 |
2023年 | 17篇 |
2022年 | 46篇 |
2021年 | 66篇 |
2020年 | 26篇 |
2019年 | 38篇 |
2018年 | 53篇 |
2017年 | 54篇 |
2016年 | 44篇 |
2015年 | 29篇 |
2014年 | 28篇 |
2013年 | 76篇 |
2012年 | 60篇 |
2011年 | 70篇 |
2010年 | 34篇 |
2009年 | 40篇 |
2008年 | 30篇 |
2007年 | 36篇 |
2006年 | 14篇 |
2005年 | 15篇 |
2004年 | 9篇 |
2003年 | 8篇 |
2002年 | 13篇 |
2001年 | 5篇 |
2000年 | 7篇 |
1999年 | 3篇 |
1998年 | 7篇 |
1997年 | 10篇 |
1996年 | 5篇 |
1995年 | 4篇 |
1994年 | 3篇 |
1993年 | 3篇 |
1992年 | 4篇 |
1991年 | 2篇 |
1990年 | 1篇 |
1989年 | 2篇 |
1988年 | 1篇 |
1987年 | 2篇 |
1986年 | 2篇 |
1985年 | 2篇 |
1984年 | 1篇 |
1981年 | 1篇 |
1980年 | 2篇 |
1978年 | 1篇 |
1975年 | 1篇 |
1971年 | 1篇 |
1963年 | 1篇 |
排序方式: 共有882条查询结果,搜索用时 15 毫秒
21.
22.
Luis Felipe Ramírez-Verduzco Javier Esteban Rodríguez-Rodríguez Alicia del Rayo Jaramillo-Jacob 《Fuel》2012,91(1):102-111
Biodiesel is a renewable bio-fuel derived from natural fats or vegetable oils, and it is considered as a promising alternative to substitute diesel fuels. Cetane number, viscosity, density, and higher heating value are important properties to affect the utilization of biodiesel fuels, because they are involved in the definition of fuel quality and are required as input data for predictive engine combustion models. This work presents the characterization of two biodiesel samples made from beef tallow and soybean oil through their fatty acid methyl esters (FAMEs) profile. Empirical equations were developed to estimate four physical properties of methyl esters; and an average absolute deviation (AAD) of 5.95%, 2.57%, 0.11% and 0.21% for the cetane number, kinematic viscosity, density, and higher heating value were founded. Cetane number, viscosity, and higher heating value increases because of the increase of molecular weight and these physical properties decrease as the number of double bonds increases. Unlike that of above properties, density decreases as molecular weight increases and density increases as the degree of unsaturation increases. Two general mixing rules and five biodiesel samples were used to study the influence of FAMEs over the physical properties of biodiesel. The prediction of the cetane number, kinematic viscosity, density and higher heating value of biodiesel is very close to the experimental values. 相似文献
23.
Fernando Valdés Roberto Iglesias Felipe Espinosa Miguel A. Rodríguez 《Applied Intelligence》2012,37(2):267-279
This paper describes an innovative routing strategy for intelligent transportation units willing to perform merging manoeuvres with a moving convoy. In particular, we consider a transportation unit located inside a city (pursuer unit), and which wishes to join a convoy that is constantly moving around the city. We first describe a solution that considers idealistic conditions, i.e., the traveling time along each street is constant. We then go on to improve our first approach to deal with the realistic random nature of the traveling times experienced by the pursuer and by the convoy leader. Our search strategy applies Dynamic Programming to achieve a meeting point that is optimal in two ways: on one hand, the optimal destination is the one closest to the current pursuer??s position; on the other hand, the optimal meeting point must minimize the time that elapses until the pursuer meets the convoy (considering that the pursuer must always arrive first). Calculating the optimal path to every possible destination is highly inefficient, error prone and time consuming. On the contrary, we propose an efficient search strategy that will achieve the meeting point and the path to it, both optimally and in a very short time. This enables the real-time application of our approach either for finding new solutions or for re-planning old ones owing to unexpected real-conditions. 相似文献
24.
Evelyn VillagraLeonardo S. Santos Boniek Gontijo VazMarcos N. Eberlin V. Felipe Laurie 《Food chemistry》2012,131(2):692-697
A simple, direct injection, electrospray ionization Fourier transform mass spectrometry (ESI FT-MS) method, in combination with multivariate statistics, was used for the characterization and sorting of Chilean wines. 47 commercial red wines labelled as Cabernet Sauvignon, Carménère, Syrah, and Pinot noir, and 25 white wines of the varieties Chardonnay and Sauvignon blanc were diluted, directly infused into the mass spectrometer, and analyzed in negative ion mode. The signature ions used for statistical analyses were manually filtered out from the signals with m/z ratios over 10%. The results of principal component analysis allowed a good sorting of white wines, but not so in the case of reds. The main three principal components explained 96.82% and 85.65% of the variance for white and red wines, respectively. Instead, linear discriminant analysis, allowed the correct discrimination of 100.00% of white and 95.74% of red samples. The validation of these results using the leave-one-out cross-validation method gave lower percentages of correct classification (76.00% and 61.70% of white and red samples respectively), suggesting that some of the wine samples analyzed might have been blends of more than one variety. Consequently, ESI FT-MS direct injection analysis of wines can be used for sample discrimination, but requires a stronger mathematical model built with spectral information of pure and blended samples before improving the percentages of classification. 相似文献
25.
An adaptive color similarity function suitable for image segmentation and its numerical evaluation
下载免费PDF全文
![点击此处可从《Color research and application》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Rodolfo Alvarado‐Cervantes Edgardo M. Felipe‐Riverón Vladislav Khartchenko Oleksiy Pogrebnyak 《Color research and application》2017,42(2):156-172
In this article, we present an adaptive color similarity function defined in a modified hue‐saturation‐intensity color space, which can be used directly as a metric to obtain pixel‐wise segmentation of color images among other applications. The color information of every pixel is integrated as a unit by an adaptive similarity function thus avoiding color information scattering. As a direct application we present an efficient interactive, supervised color segmentation method with linear complexity respect to the number of pixels of the input image. The process has three steps: (1) Manual selection of few pixels in a sample of the color to be segmented. (2) Automatic generation of the so called color similarity image (CSI), which is a gray level image with all the gray level tonalities associated with the selected color. (3) Automatic threshold of the CSI to obtain the final segmentation. The proposed technique is direct, simple and computationally inexpensive. The evaluation of the efficiency of the color segmentation method is presented showing good performance in all cases of study. A comparative study is made between the behavior of the proposed method and two comparable segmentation techniques in color images using (1) the Euclidean metric of the a* and b* color channels rejecting L* and (2) a probabilistic approach on a* and b* in the CIE L*a*b* color space. Our testing system can be used either to explore the behavior of a similarity function (or metric) in different color spaces or to explore different metrics (or similarity functions) in the same color space. It was obtained from the results that the color parameters a* and b* are not independent of the luminance parameter L* as one might initially assume in the CIE L*a*b* color space. We show that our solution improves the quality of the proposed color segmentation technique and its quick result is significant with respect to other solutions found in the literature. The method also gives a good performance in low chromaticity, gray level and low contrast images. © 2016 Wiley Periodicals, Inc. Col Res Appl, 42, 156–172, 2017 相似文献
26.
Felipe Sánchez Carrillo Linda Saucier Cristina Ratti 《International Journal of Food Properties》2017,20(3):573-584
Thermal properties of duck fatty liver (foie gras), foie gras emulsion and fatty liver fat, as well as regular duck fat, were determined as a function of temperature. Density of foie gras and foie gras fat and emulsion at 20°C was measured as 947, 836, and 928 kg/m3, respectively. Differential scanning calorimetry thermograms for foie gras fat resulted in melting points ranging from –20 to 40°C. Values for the specific heat at 65°C for the fatty liver, its emulsion and fat, and duck fat were 1.79, 2.38, 1.71, and 2.48 J/g°C, respectively. Thermal conductivity of foie gras (organ) and its emulsion at 40°C was determined as 0.330 and 0.428 W/m°C, respectively. Mathematical models based on composition and temperature were developed for all the thermal properties obtained in this work. 相似文献
27.
28.
Russian Engineering Research - Work standardization at Russian high-tech enterprises is considered, in the digital era. The new possibilities created by the digital economy permit increased... 相似文献
29.
Cleveland Pablo Rios Sebastian A. Aguilera Felipe Graña Manuel 《Neural computing & applications》2022,34(19):16717-16738
Neural Computing and Applications - Understanding at microscopic level the generation of contents in an online social network (OSN) is highly desirable for an improved management of the OSN and the... 相似文献
30.
Borrego Gilberto Morán Alberto L. Meza Victoria Orihuela-Espina Felipe Sucar Luis Enrique 《Universal Access in the Information Society》2021,20(4):767-783
Universal Access in the Information Society - In this work, the results of usability and user experience (UX) evaluation of a serious video game for the cognitive stimulation and motor... 相似文献