全文获取类型
收费全文 | 2222篇 |
免费 | 53篇 |
国内免费 | 9篇 |
专业分类
电工技术 | 14篇 |
综合类 | 1篇 |
化学工业 | 332篇 |
金属工艺 | 24篇 |
机械仪表 | 47篇 |
建筑科学 | 99篇 |
矿业工程 | 6篇 |
能源动力 | 70篇 |
轻工业 | 250篇 |
水利工程 | 17篇 |
石油天然气 | 11篇 |
无线电 | 221篇 |
一般工业技术 | 308篇 |
冶金工业 | 629篇 |
原子能技术 | 27篇 |
自动化技术 | 228篇 |
出版年
2023年 | 32篇 |
2022年 | 37篇 |
2021年 | 47篇 |
2020年 | 36篇 |
2019年 | 39篇 |
2018年 | 41篇 |
2017年 | 33篇 |
2016年 | 47篇 |
2015年 | 23篇 |
2014年 | 43篇 |
2013年 | 97篇 |
2012年 | 70篇 |
2011年 | 93篇 |
2010年 | 64篇 |
2009年 | 47篇 |
2008年 | 70篇 |
2007年 | 82篇 |
2006年 | 68篇 |
2005年 | 62篇 |
2004年 | 47篇 |
2003年 | 52篇 |
2002年 | 49篇 |
2001年 | 52篇 |
2000年 | 38篇 |
1999年 | 50篇 |
1998年 | 157篇 |
1997年 | 120篇 |
1996年 | 75篇 |
1995年 | 42篇 |
1994年 | 44篇 |
1993年 | 31篇 |
1992年 | 25篇 |
1991年 | 21篇 |
1990年 | 21篇 |
1989年 | 19篇 |
1988年 | 22篇 |
1987年 | 15篇 |
1986年 | 22篇 |
1985年 | 24篇 |
1984年 | 28篇 |
1983年 | 13篇 |
1982年 | 20篇 |
1981年 | 18篇 |
1980年 | 25篇 |
1979年 | 15篇 |
1978年 | 14篇 |
1977年 | 34篇 |
1976年 | 42篇 |
1975年 | 15篇 |
1974年 | 18篇 |
排序方式: 共有2284条查询结果,搜索用时 15 毫秒
81.
Television is not only the most powerful medium of communication that our age has produced; it is also the most flexible. Yet its common role in education is that of a mere substitute, called in to mitigate the effects of the shortage of teachers or (to look at the matter historically) the excess of students. That it can be more than that is shown by two University of Nebraska faculty members, describing an experiment in the creative use of television as a tool in the development of that awareness of the characteristics of space which is among the architect's indispensable qualifications. 相似文献
82.
A novel magnetic nano-sorbent was synthesized by Schiff’s base formation via covalent bonding of gelatin to the surface of nano-magnetite-immobilized-3-aminopropyltrimethoxysilane (Nano-Fe3O4-Si-N=Gelatin). The structure was confirmed by the FT-IR, TGA, and SEM. The maximum capacity of Cd(II) and Pb(II) were identified as 440 and 400 µmol g?1, respectively. The separation characteristics were evaluated in presence of various controlling factors. The sorption processes of Cd(II) and Pb(II) were found to follow the postulates of Langmuir, Brunauer-Emmer-Teller, and Dubinin Radushkevich isotherm models. The potential applications of Nano-Fe3O4-Si-N=Gelatin in water treatment of Cd(II) and Pb(II) were successfully accomplished using a micro-column technique. 相似文献
83.
84.
Fabrication of high aspect ratio and open‐ended TiO2 nanotube photocatalytic arrays through electrochemical anodization
下载免费PDF全文
![点击此处可从《American Institute of Chemical Engineers》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Roong Jien Wong Sanly Liu Yun Hau Ng Rose Amal 《American Institute of Chemical Engineers》2016,62(2):415-420
Well‐aligned, high aspect‐ratio and open‐ended TiO2 nanotube arrays secured within a Ti foil (TiO2 nanotubes cartridge) were successfully prepared through the double‐sided anodization method. With ~210 µm of nanotube length, the anodic growth of TiO2 was accelerated and stabilized by the lactic acid‐containing ethylene glycol electrolyte. In the absence of lactic acid, the anodization led to detachment of nanotubes from the Ti foil after 5–6 h of high voltage (80 V) anodization. Transmission electron microscope image and Raman spectrum revealed that the as‐anodized TiO2 nanotube arrays without annealing treatment were partially crystalline anatase and demonstrated photocatalytic activity in the mineralization of formic acid. © 2015 American Institute of Chemical Engineers AIChE J, 62: 415–420, 2016 相似文献
85.
Mokhtar Adel Boukoussa Bouhadjar Baba Ahmed Abderrazzak Abdelkrim Soumia Djelad Amal Hachemaoui Mohammed Zaoui Farouk Bengueddach Abdelkader Sassi Mohamed 《Journal of Inorganic and Organometallic Polymers and Materials》2022,32(7):2615-2633
Journal of Inorganic and Organometallic Polymers and Materials - The discharge of industrial waste comprising organic pollutants into aquatic environment induces numerous health risks. Crosslinked... 相似文献
86.
This study aims to investigate interconnectivity and permeability of scCO2-foamed scaffolds and the influence of structural scaffold properties on cell distribution. Supercritical fluid technology was utilized to fabricated scaffolds from 37 kDa, 53 kDa and 109 kDa PLGA (85:15). Pore size, pore size distribution and porosity were quantified by MicroCT, and window sizes were measured using SEM. A novel interconnectivity algorithm allowed the quantification of scaffold interconnectivity in three space dimensions. To determine the permeability of porous materials direct perfusion experiments were performed, where a known flow rate was applied to measure the pressure differential across the scaffolds. The permeability was calculated using Darcy's law. Largest pore sizes, porosities, interconnectivities and permeabilities were obtained for scaffolds fabricated from 37 kDa PLGA. These scaffolds showed a heterogeneous pore structure and distribution, whereas homogeneous pore structure, smallest pore sizes, porosities, interconnectivities and permeabilities were observed for scaffolds fabricated from 109 kDa PLGA. The distribution of 3T3 fibroblasts through scCO2-foamed scaffolds was investigated by MicroCT and MTT staining. Cells were further visualized by fluorescent imaging. Uniform cell distribution was observed on scaffolds fabricated from 109 kDa PLGA and an average of 10% of the total scaffold volume was covered with cells that had adhered onto them. 相似文献
87.
Amal Amin Heba Kandil Mohamed Nader Ismail Nergis Makal Charles N. Moorefield George R. Newkome 《Polymer Engineering and Science》2014,54(11):2669-2675
An adamantane‐based atom transfer radical initiator (Adm‐Br) was prepared by the treatment of 1‐[[N‐[2‐Hydroxy‐l,l‐bis(hydroxymethyl)ethyl]amino]carbonyl]adamantane with bromopropionyl bromide. The resulting initiator was subsequently used in the atom transfer radical polymerization (ATRP) of methyl methacrylate (MMA) to form (Adm‐p‐MMA), which was successfully used, as a macroinitiator, in further ATRP reactions with 3‐O‐methacryloyl‐1,2 5,6‐di‐O‐isopropylidene‐α‐d ‐glucofuranose (gly), a glycomonomer, to afford the Adm‐p‐MMA‐b‐gly polymer. The new Adm‐p‐MMA‐b‐gly polymer subsequently was employed to form a nanocomposite with chitosan‐modified, Nanofil clay (NC). The resulting Adm‐p‐MMA‐b‐gly/NC composite material was progressively hydrolyzed to regenerate the OH groups of the glucose units within the Adm‐p‐MMA‐b‐gly copolymer. The polymer/NC nanocomposites were characterized by X‐ray diffraction, thermal gravimetric analysis, differential scanning calorimetry, and transmission electron microscopy. POLYM. ENG. SCI., 54:2669–2675, 2014. © 2013 Society of Plastics Engineers 相似文献
88.
89.
David W. Niles Xiaonan Li David Albin Doug Rose Timothy Gessert Peter Sheldon 《Progress in Photovoltaics: Research and Applications》1996,4(3):225-229
A commonly used process for forming low-resistance contacts to thin-film p-type CdTe involves the formation of a Te layer by etching the CdTe film in a concentrated mixture of nitric and phosphoric acids. The authors compare evaporated Te back contacts with ‘control’ back contacts formed by the usual etching process, and demonstrate that evaporating Te onto a CdTe thin film is a viable process for forming a low-resistance contact. The best efficiency achieved for a CdTe solar cell made with an evaporated Te back contact is 12.1%, whereas the efficiency of the device made with the control back contact was 11.9%. The evaporation process offers numerous advantages over acid etching, most notably vacuum compatibility amenable to large-scale production of CdTe solar cell modules. 相似文献
90.
Eclesielter Batista Moreira Jair Arrieta Baldovino Juliana Lundgren Rose Ronaldo Luis dos Santos Izzo 《岩石力学与岩土工程学报(英文版)》2019,11(2)
One of the conventional ways to improve the mechanical behavior of soils is to mix them with cementing agents such as cement, lime and fly ash. Recently, introduction to alternative materials or sub-products that can be adopted to improve the soil strength is of paramount importance. Therefore, the present study aims to investigate the effects of porosity (η), dry unit weight (γd) of molding, cement content (C) and porosity/volumetric cement content ratio (η/Civ) or void/cement ratio on the unconfined compressive strength (qu or UCS) of silty soil–roof tile waste (RT) mixtures. Soil samples are molded into four different dry unit weights (i.e. 13 kN/m3, 13.67 kN/m3, 14.33 kN/m3 and 15 kN/m3) using 3%, 6% and 9% cement and 5%, 15% and 30% RT. The results show that with the addition of cement, the strength of the RT–soil mixtures increases in a linear manner. On the other hand, the addition of RT decreases qu of the samples at a constant percentage of cement, and the decrease in porosity can increase qu. A dosage equation is derived from the experimental data using the porosity/volumetric cement content ratio (η/Civ) where the control variables are the moisture content, crushed tile content, cement content and porosity. 相似文献