全文获取类型
收费全文 | 2003篇 |
免费 | 117篇 |
国内免费 | 4篇 |
专业分类
电工技术 | 35篇 |
化学工业 | 479篇 |
金属工艺 | 33篇 |
机械仪表 | 43篇 |
建筑科学 | 71篇 |
矿业工程 | 2篇 |
能源动力 | 97篇 |
轻工业 | 262篇 |
水利工程 | 17篇 |
石油天然气 | 2篇 |
无线电 | 180篇 |
一般工业技术 | 370篇 |
冶金工业 | 100篇 |
原子能技术 | 4篇 |
自动化技术 | 429篇 |
出版年
2024年 | 7篇 |
2023年 | 26篇 |
2022年 | 54篇 |
2021年 | 73篇 |
2020年 | 30篇 |
2019年 | 59篇 |
2018年 | 58篇 |
2017年 | 66篇 |
2016年 | 73篇 |
2015年 | 56篇 |
2014年 | 105篇 |
2013年 | 150篇 |
2012年 | 151篇 |
2011年 | 171篇 |
2010年 | 114篇 |
2009年 | 139篇 |
2008年 | 137篇 |
2007年 | 106篇 |
2006年 | 85篇 |
2005年 | 53篇 |
2004年 | 69篇 |
2003年 | 51篇 |
2002年 | 42篇 |
2001年 | 31篇 |
2000年 | 21篇 |
1999年 | 23篇 |
1998年 | 39篇 |
1997年 | 36篇 |
1996年 | 18篇 |
1995年 | 21篇 |
1994年 | 11篇 |
1993年 | 11篇 |
1992年 | 4篇 |
1991年 | 3篇 |
1990年 | 7篇 |
1989年 | 2篇 |
1988年 | 4篇 |
1987年 | 3篇 |
1986年 | 2篇 |
1985年 | 3篇 |
1984年 | 2篇 |
1983年 | 3篇 |
1982年 | 2篇 |
1980年 | 2篇 |
1976年 | 1篇 |
排序方式: 共有2124条查询结果,搜索用时 15 毫秒
991.
We studied the enhancement of lignin reactivity in an alkaline medium, using sodium hydroxide in a microreactor set. The chemical composition and structural characterization of the reacted lignosulfonate in terms of the phenolic hydroxyl groups, aromatic protons, weight‐average molecular weight, number‐average molecular weight, and lignosulfonate content of all reacted lignins were determined. The techniques that we used were ultraviolet spectroscopy, proton nuclear magnetic resonance spectroscopy, and aqueous gel permeation chromatography. Using response surface methodology, we studied how the temperature and reaction time affected the lignin properties. The reaction conditions were temperatures between 116 and 180°C and reaction times between 18 and 103 min. Modeled response surfaces showed that the two factors affected the lignin properties within the studied ranges. The phenolic hydroxyl groups, aro matic protons, and lignosulfonate content increased when the severity of the treatment increased. The weight‐average molecular weight, number‐average molecular weight, and solid yield (%) decreased when the severity of the treatment increased. The reactivity of the modified lignins was studied with a formaldehyde reactivity test: more severe conditions produced greater improvements in the formaldehyde reactivity. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3286–3292, 2006 相似文献
992.
993.
For many years, applications of the TNDE (Thermographic NonDestructive Evaluation) technique has been limited due to the complex non-linearity nature of related inversion problems such as defect depth estimation. Artificial neural networks have recently obtained success in revealing and providing quantitative information concerning defects in TNDE. In this paper, a three dimensional thermal model for non-homogenous materials such as carbon fiber reinforced plastic (CFRP) is first given. The modeling results are compared with the analytical solution based on Duhamel's theorem. Two back propagation neural networks (NN) as defect detector and depth estimator are then presented. Finally, simulated and experimental results are presented and discussed. 相似文献
994.
Doussineau T Bao CY Clavier C Dagany X Kerleroux M Antoine R Dugourd P 《The Review of scientific instruments》2011,82(8):084104
This work presents the implementation of tandem mass spectrometry for experiments on single electrosprayed ions from compounds of megadalton (MDa) molecular weight, using two charge detection devices. The first mass spectrometry stage (first charge detection device) combined with an ion gate allows both mass-to-charge ratio and charge selections of the megadalton ion of interest. The second stage is based on an electrostatic ion trap and consists of an image charge detection tube mounted between two ion mirrors. Single MDa ions can be stored for several dozen milliseconds. During the trapping time, single ions can be irradiated by a continuous wavelength CO(2) laser. We observe stepwise changes in the charge of a single trapped ion owing to multiphoton activation. Illustration of infrared multiphoton dissociation tandem mass spectrometry are given for single megadalton ions of poly(ethylene oxide)s and DNAs. 相似文献
995.
Photodynamic Therapy: Porous Porphyrin‐Based Organosilica Nanoparticles for NIR Two‐Photon Photodynamic Therapy and Gene Delivery in Zebrafish (Adv. Funct. Mater. 21/2018) 下载免费PDF全文
Chiara Mauriello Jimenez Dina Aggad Jonas G. Croissant Karen Tresfield Danielle Laurencin Dorothée Berthomieu Nicolas Cubedo Mireille Rossel Shahad Alsaiari Dalaver H. Anjum Rachid Sougrat Manuel A. Roldan‐Gutierrez Sébastien Richeter Erwan Oliviero Laurence Raehm Clarence Charnay Xavier Cattoën Sébastien Clément Michel Wong Chi Man Marie Maynadier Vincent Chaleix Vincent Sol Marcel Garcia Magali Gary‐Bobo Niveen M. Khashab Nadir Bettache Jean‐Olivier Durand 《Advanced functional materials》2018,28(21)
996.
Barakat S Garth C Tricoche X 《IEEE transactions on visualization and computer graphics》2012,18(8):1368-1380
In this paper, we present a novel technique that allows for the coupled computation and visualization of salient flow structures at interactive frame rates. Our approach is built upon a hierarchical representation of the Finite-time Lyapunov Exponent (FTLE) field, which is adaptively sampled and rendered to meet the need of the current visual setting. The performance of our method allows the user to explore large and complex data sets across scales and to inspect their features at arbitrary resolution. The paper discusses an efficient implementation of this strategy on graphics hardware and provides results for an analytical flow and several CFD simulation data sets. 相似文献
997.
998.
999.
1000.
Naci Balkan Engin Tiras Ayse Erol Mustafa Gunes Sukru Ardali MCetin Arikan Dalphine Lagarde Helene Carrère Xavier Marie Cebrail Gumus 《Nanoscale research letters》2012,7(1):574
We report on the Mg-doped, indium-rich GaxIn1−xN (x < 30). In the undoped material, the intrinsic electron density is very high and as a result there is no detectable photoconductivity (PC) signal within the range of temperatures of 30 <T < 300 K. In the Mg-doped material however, where the conductivity is reduced, there is a strong PC spectrum with two prominent low-energy peaks at 0.65 and 1.0 eV and one broad high-energy peak at around 1.35 eV. The temperature dependence of the spectral photoconductivity under constant illumination intensity, at T > 150 K, is determined by the longitudinal-optical phonon scattering together with the thermal regeneration of non-equilibrium minority carriers from traps with an average depth of 103 ± 15 meV. This value is close to the Mg binding energy in GaInN. The complementary measurements of transient photoluminescence at liquid He temperatures give the e-A0 binding energy of approximately 100 meV. Furthermore, Hall measurements in the Mg-doped material also indicate an activated behaviour with an acceptor binding energy of 108 ± 20 meV. 相似文献