全文获取类型
收费全文 | 1071篇 |
免费 | 63篇 |
国内免费 | 14篇 |
专业分类
电工技术 | 17篇 |
综合类 | 2篇 |
化学工业 | 242篇 |
金属工艺 | 25篇 |
机械仪表 | 30篇 |
建筑科学 | 52篇 |
矿业工程 | 1篇 |
能源动力 | 78篇 |
轻工业 | 122篇 |
水利工程 | 9篇 |
石油天然气 | 9篇 |
无线电 | 126篇 |
一般工业技术 | 166篇 |
冶金工业 | 87篇 |
原子能技术 | 9篇 |
自动化技术 | 173篇 |
出版年
2024年 | 6篇 |
2023年 | 17篇 |
2022年 | 35篇 |
2021年 | 41篇 |
2020年 | 46篇 |
2019年 | 51篇 |
2018年 | 46篇 |
2017年 | 71篇 |
2016年 | 48篇 |
2015年 | 34篇 |
2014年 | 40篇 |
2013年 | 107篇 |
2012年 | 49篇 |
2011年 | 49篇 |
2010年 | 45篇 |
2009年 | 47篇 |
2008年 | 44篇 |
2007年 | 25篇 |
2006年 | 28篇 |
2005年 | 23篇 |
2004年 | 16篇 |
2003年 | 15篇 |
2002年 | 7篇 |
2001年 | 7篇 |
2000年 | 12篇 |
1999年 | 8篇 |
1998年 | 32篇 |
1997年 | 20篇 |
1996年 | 18篇 |
1995年 | 20篇 |
1994年 | 11篇 |
1993年 | 14篇 |
1992年 | 11篇 |
1991年 | 8篇 |
1990年 | 6篇 |
1989年 | 10篇 |
1988年 | 9篇 |
1987年 | 6篇 |
1986年 | 3篇 |
1985年 | 10篇 |
1984年 | 11篇 |
1983年 | 7篇 |
1982年 | 10篇 |
1981年 | 4篇 |
1980年 | 4篇 |
1977年 | 2篇 |
1976年 | 4篇 |
1974年 | 2篇 |
1973年 | 3篇 |
1966年 | 1篇 |
排序方式: 共有1148条查询结果,搜索用时 15 毫秒
131.
Ramadan SS Heyn C Mackenzie LT Chambers AF Rutt BK Foster PJ 《Magma (New York, N.Y.)》2008,21(4):251-259
INTRODUCTION: The use of MRI with iron-based magnetic nanoparticles for imaging cells is a rapidly growing field of research. We have recently reported that single iron-labeled cells could be detected, as signal voids, in vivo in mouse brains using a balanced steady-state free precession imaging sequence (b-SSFP) and a customized microimaging system at 1.5 T. METHODS: In the current study we assess the benefits, and challenges, of using a higher magnetic field strength for imaging iron-labeled cells with b-SSFP, using ex vivo mouse brain specimens imaged with near identical systems at 1.5 and 3.0 T. RESULTS: The substantial banding artifact that appears in 3 T b-SSFP images was readily minimized with RF phase cycling, allowing for banding-free b-SSFP images to be compared between the two field strengths. This study revealed that with an optimal 3 T b-SSFP imaging protocol, more than twice as many signal voids were detected as with 1.5 T. CONCLUSION: There are several factors that contributed to this important result. First, a greater-than-linear SNR gain was achieved in mouse brain images at 3 T. Second, a reduction in the bandwidth, and the associated increase in repetition time and SNR, produced a dramatic increase in the contrast generated by iron-labeled cells. 相似文献
132.
Said Barkati Lotfi Baghli El Madjid Berkouk Mohamed-Seghir Boucherit 《Electric Power Systems Research》2008
This paper describes two evolutionary algorithms for the optimized harmonic stepped–waveform technique. Genetic algorithms and particle swarm optimization are applied to compute the switching angles in a three-phase seven-level inverter to produce the required fundamental voltage while, at the same time, specified harmonics are eliminated. Furthermore, these algorithms are also used to solve the starting point problem of the Newton-Raphson conventional method. This combination provides a very effective method for the harmonic elimination technique. This strategy is useful for different structures of seven-level inverters. The diode-clamped topology is considered in this study. 相似文献
133.
This work concerns the steady‐state and dynamic analysis of misaligned compliant journal bearings considering the effects of couple stresses arising from the lubricant blended with polymer additives. Based on the Stokes micro‐continuum theory, a modified form of the Reynolds equation is derived. The displacement field at the fluid film–bearing liner interface due to pressure forces is determined using the elastic thin liner model. The effects of the misalignment and the couple stress parameters on static and dynamic performances such as pressure distribution, load‐carrying capacity, power loss, side leakage flow, misalignment moment, critical mass and whirl frequency are presented and discussed. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
134.
Magdy El-Hagary Said H. Moustafa Hany Hashem Essam R. Shaaban Mohamed Emam-Ismail 《Journal of the American Ceramic Society》2019,102(8):4737-4747
Mn-doped HgO nanostructured thin films (Hg1-xMnxO) have been prepared using electron beam evaporation technique on Corning glass (1022) substrate at room temperature with different concentrations x = 0, 0.015, 0.05, 0.1, 0.15, and 0.2. The microstructural, morphological, semiconducting, and optoelectronic properties of the films have been investigated. The X-ray diffraction spectra suggest a hexagonal wurtzite type structure with lattice parameters decreased with increasing Mn content. It was found that the average particle size of the films decreases with increasing Mn doping which is confirmed by FE-SEM and AFM micrographs. The optical band gap of the investigated Mn-doped HgO nanocrystalline films is determined from the absorption coefficient and found to increase with the increase of Mn concentration which is attributed to the sp-d exchange interaction and/or the quantum confinement effect. The refractive index and extinction coefficient of the Mn-doped HgO films are also reported. The refractive index dispersion n(λ) is analyzed by single-effective-oscillator dispersion model proposed by the Wemple–DiDomenico (WDD). The oscillator parameters were estimated. The obtained dispersion values are suitable for the design of optoelectronic devices. 相似文献
135.
Noresah Said Hasrinah Hasbullah Muhammad Nidzhom Zainol Abidin Ahmad Fauzi Ismail Pei Sean Goh Mohd Hafiz Dzarfan Othman Siti Hamimah Sheikh Abdul Kadir Fatmawati Kamal Mohd Sohaimi Abdullah Be Cheer Ng 《应用聚合物科学杂志》2019,136(21):47502
Protein existence in wastewater is an important issue in wastewater management because proteins are generally present as contaminants and foulants. Hence, in this study, we focused on designing a polysulfone (PSf) hollow-fiber membrane embedded with hydrophilic iron oxide nanoparticles (IONPs) for protein purification by means of ultrafiltration. Before membrane fabrication, the dispersion stability of the IONPs was enhanced by the addition of a stabilizer, namely, citric acid (CA). Next, PSf–IONP–CA nanocomposite hollow-fiber membranes were prepared via a dry–wet spinning process and then characterized in terms of their hydrophilicity and morphology. Ultrafiltration and adsorption experiments were then conducted with bovine serum albumin as a model protein. The results that an IONP/CA weight ratio of 1:20 contributed to the most stable IONP dispersion. It was also revealed that the membrane incorporated with IONP–CA at a weight ratio of 1:20 exhibited the highest pure water permeability (58.6 L m−2 h−1 bar−1) and protein rejection (98.5%) while maintaining a low protein adsorption (3.3 μg/cm2). The addition of well-dispersed IONPs enhanced the separation features of the PSf hollow-fiber membrane for protein purification. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47502. 相似文献
136.
137.
Khan Lal Said Khan Majid Jamal Sajjad Shaukat Amin Muhammad 《Multimedia Tools and Applications》2022,81(23):33591-33611
Multimedia Tools and Applications - One of the most critical aspects of this technologically progressive era is the propagation of information through an unsecured communication channel. The... 相似文献
138.
Emir Altınok Sefik Kurultay Nevzat Konar Omer Said Toker Berkay Kopuk Recep Gunes Ibrahim Palabiyik 《International Journal of Food Science & Technology》2022,57(7):4119-4128
In this study, grape pomace (mixture of grape seeds and skins) powder (GPP), obtained from grape processing, was used at different concentrations [10.0 (GPP10), 20.0 (GPP10) and 30.0 (GPP10) g/100 g] in white chocolate formulation for the partial replacement of sucrose. The results indicated that GPP addition at a higher concentration (>10.0 g/100 g) significantly affected the particle size, moisture content, texture and flow behaviour of white chocolate samples (P < 0.05). However, using GPP at a concentration of 10.0 g/100 g had advantages for physicochemical and flow properties. As expected, under simulated in vitro digestion conditions, the bioaccessibility of total phenolic compounds in saliva, gastric juice and intestinal juice for GPP10 samples was significantly higher than the control (P < 0.05). In conclusion, results of the study showed that it was possible to partially replace the sucrose with GPP at a concentration of 10.0 g/100 g in white chocolate formulations. 相似文献
139.
Microbial Fuel Cell Application for Azoic Dye Decolorization with Simultaneous Bioenergy Production Using Stenotrophomonas sp.
下载免费PDF全文
![点击此处可从《化学工程与技术》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Said Galai Antonia Pérez de los Ríos Francisco José Hernández‐Fernández Sihem Haj Kacem Francisco Mateo Ramírez Joaquín Quesada‐Medina 《化学工程与技术》2015,38(9):1511-1518
A single‐chamber air‐cathode microbial fuel cell (MFC) was successfully applied for decolorization of the diazoic dye Reactive Black 5 (RB5) with simultaneous production of electricity. An innovative low‐cost medium, the marine water‐glucose‐yeast extract medium (MWGY), was developed which appears as a textile marine effluent in terms of salinity. The anode compartment containing a single bacterial strain of Stenotrophomonas sp. showed almost complete dye decolorization with different RB5 concentrations after seven days of treatment. For the four dye concentrations used, a correlation between dye removal and production of electrical energy was found. The comparison of the decolorization process in the MFC with that in a batch reactor as control experiment highlights the efficiency of the single‐chamber air‐cathode MFC technology which improved the dye removal by the same bacterial strain. 相似文献
140.
Multimedia Tools and Applications - In this paper, we present a novel classification approach based on Extreme Learning Machine (ELM) and Wavelet Neural Networks. We introduce two novel... 相似文献