全文获取类型
收费全文 | 265篇 |
免费 | 10篇 |
国内免费 | 4篇 |
专业分类
电工技术 | 5篇 |
综合类 | 1篇 |
化学工业 | 64篇 |
金属工艺 | 10篇 |
机械仪表 | 4篇 |
建筑科学 | 8篇 |
能源动力 | 12篇 |
轻工业 | 22篇 |
水利工程 | 1篇 |
无线电 | 61篇 |
一般工业技术 | 33篇 |
冶金工业 | 9篇 |
原子能技术 | 1篇 |
自动化技术 | 48篇 |
出版年
2024年 | 1篇 |
2023年 | 5篇 |
2022年 | 12篇 |
2021年 | 10篇 |
2020年 | 10篇 |
2019年 | 11篇 |
2018年 | 16篇 |
2017年 | 10篇 |
2016年 | 10篇 |
2015年 | 12篇 |
2014年 | 11篇 |
2013年 | 22篇 |
2012年 | 15篇 |
2011年 | 13篇 |
2010年 | 11篇 |
2009年 | 17篇 |
2008年 | 13篇 |
2007年 | 11篇 |
2006年 | 6篇 |
2005年 | 1篇 |
2004年 | 6篇 |
2003年 | 5篇 |
2002年 | 7篇 |
2001年 | 5篇 |
2000年 | 1篇 |
1999年 | 4篇 |
1998年 | 3篇 |
1997年 | 2篇 |
1996年 | 4篇 |
1995年 | 6篇 |
1994年 | 3篇 |
1993年 | 5篇 |
1992年 | 1篇 |
1991年 | 1篇 |
1989年 | 1篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1983年 | 1篇 |
1981年 | 1篇 |
1979年 | 2篇 |
1975年 | 1篇 |
1974年 | 1篇 |
排序方式: 共有279条查询结果,搜索用时 15 毫秒
71.
Mongia Hosni Samir Farhat Mounir Ben Amar Andrei Kanaev Noureddine Jouini Ivaylo Hinkov 《American Institute of Chemical Engineers》2015,61(5):1708-1721
We report on the effect of mixing on the morphology of ultrafine zinc oxide nanoparticles synthesized via a polyol process using zinc acetate and water in a diethylene glycol medium. Three mixing strategies were considered: stirred batch, T‐mixer, and impinging free jets. The particle granulometry was accessed using the transmission electron microscopy and x‐ray diffraction methods. The nanoparticle size and polydispersity decreased with an increase in the local dissipated energy. In particular, the polyol process conducted in the same chemical environment at 353 K did not lead to the observation of nanoparticles in the stirred batch reactor but resulted in unconventionally small 6‐nm particles in the T‐mixer and impinging jet configurations. This result is apparently related to the micromixing eddy geometry described by the Kolmogorov length. The hydrodynamic flow patterns and energy dissipation were obtained from computational ?uid dynamics simulations, which are essential in the design, optimization, and scale‐up of the polyol process. © 2015 American Institute of Chemical Engineers AIChE J, 61: 1708–1721, 2015 相似文献
72.
Mounir El Asmar Wafik Lotfallah Gary Whited Awad S. Hanna 《Canadian Metallurgical Quarterly》2010,136(8):904-912
The use of design/build (DB) contracting by transportation agencies has been steadily increasing as a project delivery system for large complex highway projects. However, moving to DB from traditional design-bid-build procurement can be a challenge. One significant barrier is gaining acceptance of a best-value selection process in which technical aspects of a proposal are considered separately and then combined with price to determine the winning proposal. These technical aspects mostly consist of qualitative criteria, thus making room for human errors or biases. Any perceived presence of bias or influence in the selection process can lead to public mistrust and protests by bidders. It is important that a rigorous quantitative mathematical analysis of the evaluation process be conducted to determine whether bias exists and to eliminate it. The paper discusses two potential sources of bias—evaluators and weighting model—in the DB selection process and presents mathematical models to detect and remove biases should they exist. A score normalization model deals with biases from the evaluators; then a graphical weight-space volume model and a Monte Carlo statistical sampling model are developed to remove biases from the weighting model. The models are then tested and demonstrated using results from the DB bridge replacement project for the collapsed Mississippi River bridge of Interstate 35W in Minneapolis. 相似文献
73.
Meriem Fodil Amine Mounir Mohammed Ameri Hadj Baltache Bachir Bouhafs Y. Al-Douri Ibrahim Ameri 《Materials Science-Poland》2014,32(2):220-227
First-principles calculations of the lattice constants, bulk modulus, pressure derivatives of the bulk modulus and elastic constants of AlN and TiN compounds in rock-salt (B1) and wurtzite (B4) structures are presented. We have used the fullpotential linearized augmented plane wave (FP-LAPW) method within the density functional theory (DFT) in the generalized gradient approximation (GGA) for the exchange-correlation functional. Moreover, the elastic properties of cubic TiN and hexagonal AlN, including elastic constants, bulk and shear moduli are determined and compared with previous experimental and theoretical data. Our results show that the structural transition at 0 K from wurtzite to rock-salt phase occurs at 10 GPa and ?26 GPa for AlN and TiN, respectively. These results are consistent with those of other studies found in the literature. 相似文献
74.
The primary effect of the field continuously capted by aGpr is the production of a class which limits the contrast of the reflections on the targets. The target response becomes illegible sight the influence of certain disturbances which are due to the reflections caused by certain parasitic elements which are randomly distributed in the soil and the dispersion phenomenon. We present in this paper an approach based on a μ-wave modulation which allowed stage this problem. The technique suggested makes it possible to do a classification of capted signals. It will be shown that the frequency of modulation fm must be higher than a cut-off frequency fc which depends on the electric parameters of the ground. In a second part of this paper, we show how to improve quality of the radargram of a systemGpr by a simple convolution between the collected signal and a wavelet with a defined parameters. 相似文献
75.
This survey paper aims to show methods to analyze and classify field satellite images using deep learning and machine learning algorithms. Users of deep learning-based Convolutional Neural Network (CNN) technology to harvest fields from satellite images or generate zones of interest were among the planned application scenarios (ROI). Using machine learning, the satellite image is placed on the input image, segmented, and then tagged. In contemporary categorization, field size ratio, Local Binary Pattern (LBP) histograms, and color data are taken into account. Field satellite image localization has several practical applications, including pest management, scene analysis, and field tracking. The relationship between satellite images in a specific area, or contextual information, is essential to comprehending the field in its whole. 相似文献
76.
Deepu J. Babu Guangwei He Jian Hao Mohammad Tohidi Vahdat Pascal Alexander Schouwink Mounir Mensi Kumar Varoon Agrawal 《Advanced materials (Deerfield Beach, Fla.)》2019,31(28)
Although polycrystalline metal‐organic framework (MOF) membranes offer several advantages over other nanoporous membranes, thus far they have not yielded good CO2 separation performance, crucial for energy‐efficient carbon capture. ZIF‐8, one of the most popular MOFs, has a crystallographically determined pore aperture of 0.34 nm, ideal for CO2/N2 and CO2/CH4 separation; however, its flexible lattice restricts the corresponding separation selectivities to below 5. A novel postsynthetic rapid heat treatment (RHT), implemented in a few seconds at 360 °C, which drastically improves the carbon capture performance of the ZIF‐8 membranes, is reported. Lattice stiffening is confirmed by the appearance of a temperature‐activated transport, attributed to a stronger interaction of gas molecules with the pore aperture, with activation energy increasing with the molecular size (CH4 > CO2 > H2). Unprecedented CO2/CH4, CO2/N2, and H2/CH4 selectivities exceeding 30, 30, and 175, respectively, and complete blockage of C3H6, are achieved. Spectroscopic and X‐ray diffraction studies confirm that while the coordination environment and crystallinity are unaffected, lattice distortion and strain are incorporated in the ZIF‐8 lattice, increasing the lattice stiffness. Overall, RHT treatment is a facile and versatile technique that can vastly improve the gas‐separation performance of the MOF membranes. 相似文献
77.
Kulishov M Daxhelet X Gaidi M Chaker M 《Journal of the Optical Society of America. A, Optics, image science, and vision》2002,19(8):1632-1648
The perturbation to the refractive index induced by a periodic electric field from two systems of interdigitated electrodes with the electrode-finger period l is analyzed for a waveguide with an electro-optically (EO) active core-cladding. It is shown that the electric field induces two superimposed transmissive refractive-index gratings with different symmetries of their cross-section distributions. One of these gratings has a constant component of an EO-induced refractive index along with its variable component with periodicity l, whereas the second grating possesses only a variable component with periodicity 2l. With the proper waveguide design, the gratings provide interaction between a guided fundamental core mode and two guided cladding modes. Through the externally applied electric potential, these gratings can be independently switched ON and OFF, or they can be activated simultaneously with electronically controlled weighting factors. Coupling coefficients of both gratings are analyzed in terms of their dependence on the electrode duty ratio and dielectric permittivities of the core and cladding. The coupled-wave equations for the superimposed gratings are written and solved. The spectral characteristics are investigated by numerical simulation. It is found that the spectral characteristics are described by a dual-dip transmission spectrum with individual electronic control of the dip depths and positions. Within the concept, a new external potential application scheme is described in which the symmetry of the cross-sectional distribution of the refractive index provides coupling only between the core mode and the cladding modes, preventing interaction of the cladding modes with each another. This simple concept opens opportunities for developing a number of tunable devices for integrated optics by use of the proposed design as a building block. 相似文献
78.
79.
Laifa Israa Hajji Mounir Farhat Nèjia Elkhouni Amine Smaoui Abderrazak M’nif Adel Hamzaoui Ahmed Hichem Savouré Arnould Abdelly Chedly Zorrig Walid 《SILICON》2021,13(12):4501-4517
Silicon - Silicon (Si) plays an important role in providing beneficial effects on plant growth and yield, especially under stressful environments such as salinity. The objective of this work is to... 相似文献
80.