全文获取类型
收费全文 | 1784篇 |
免费 | 62篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 10篇 |
综合类 | 3篇 |
化学工业 | 320篇 |
金属工艺 | 38篇 |
机械仪表 | 15篇 |
建筑科学 | 30篇 |
矿业工程 | 3篇 |
能源动力 | 22篇 |
轻工业 | 47篇 |
石油天然气 | 2篇 |
无线电 | 118篇 |
一般工业技术 | 404篇 |
冶金工业 | 741篇 |
原子能技术 | 15篇 |
自动化技术 | 79篇 |
出版年
2023年 | 9篇 |
2022年 | 14篇 |
2021年 | 19篇 |
2020年 | 20篇 |
2019年 | 17篇 |
2018年 | 21篇 |
2017年 | 14篇 |
2016年 | 29篇 |
2015年 | 15篇 |
2014年 | 30篇 |
2013年 | 46篇 |
2012年 | 33篇 |
2011年 | 57篇 |
2010年 | 37篇 |
2009年 | 51篇 |
2008年 | 42篇 |
2007年 | 45篇 |
2006年 | 53篇 |
2005年 | 36篇 |
2004年 | 41篇 |
2003年 | 46篇 |
2002年 | 35篇 |
2001年 | 43篇 |
2000年 | 17篇 |
1999年 | 47篇 |
1998年 | 229篇 |
1997年 | 138篇 |
1996年 | 99篇 |
1995年 | 57篇 |
1994年 | 49篇 |
1993年 | 40篇 |
1992年 | 18篇 |
1991年 | 26篇 |
1990年 | 32篇 |
1989年 | 23篇 |
1988年 | 24篇 |
1987年 | 16篇 |
1986年 | 10篇 |
1985年 | 15篇 |
1984年 | 13篇 |
1983年 | 14篇 |
1982年 | 16篇 |
1981年 | 11篇 |
1980年 | 14篇 |
1979年 | 13篇 |
1978年 | 13篇 |
1977年 | 30篇 |
1976年 | 57篇 |
1974年 | 10篇 |
1969年 | 9篇 |
排序方式: 共有1847条查询结果,搜索用时 265 毫秒
51.
Felix Schubert Steffen Wirth Friederike Zimmermann Johannes Heitmann Thomas Mikolajick 《Science and Technology of Advanced Materials》2016,17(1):239-243
Growth conditions have a tremendous impact on the unintentional background impurity concentration in gallium nitride (GaN) synthesized by molecular beam epitaxy and its resulting chemical and physical properties. In particular for oxygen identified as the dominant background impurity we demonstrate that under optimized growth stoichiometry the growth temperature is the key parameter to control its incorporation and that an increase by 55?°C leads to an oxygen reduction by one order of magnitude. Quantitatively this reduction and the resulting optical and electrical properties are analyzed by secondary ion mass spectroscopy, photoluminescence, capacitance versus voltage measurements, low temperature magneto-transport and parasitic current paths in lateral transistor test structures based on two-dimensional electron gases. At a growth temperature of 665?°C the residual charge carrier concentration is decreased to below 1015 cm?3, resulting in insulating behavior and thus making the material suitable for beyond state-of-the-art device applications. 相似文献
52.
53.
Woo‐Hee Kim Min‐Kyu Kim Il‐Kwon Oh Wan Joo Maeng Taehoon Cheon Soo‐Hyun Kim Atif Noori David Thompson Schubert Chu Hyungjun Kim 《Journal of the American Ceramic Society》2014,97(4):1164-1169
Films of CeO2 were deposited by atomic layer deposition (ALD) using a Ce(mmp)4 [mmp = 1‐methoxy‐2‐methyl‐2‐propanolate] precursor and H2O reactant. The growth characteristics and film properties of ALD CeO2 were investigated. The ALD CeO2 process produced highly pure, stoichiometric films with polycrystalline cubic phases. Using the ALD CeO2 process, the effects of Ce doping into an HfO2 gate dielectric were systematically investigated. Regardless of Ce/(Ce + Hf) composition, all ALD CexHf1?xO2 films exhibited constant growth rates of approximately 1.3 Å/cycle, which is essentially identical to the ALD HfO2 growth rates. After high‐temperature vacuum annealing at 900°C, it was verified, based on X‐ray diffraction and high‐resolution cross‐sectional transmission electron microscopy results, that all samples with various Ce/(Ce + Hf) compositions were transformed from nanocrystalline to stabilized cubic or tetragonal HfO2 phases. In addition, the dielectric constant of the CexHf1?xO2 films significantly increased, depending on the Ce doping content. The maximum dielectric constant value was found to be nearly 39 for the Ce/(Ce + Hf) concentration of ~11%. 相似文献
54.
Christian Immanuel Müller Thomas Rauscher Andreas Schmidt Thomas Schubert Thomas Weißgärber Bernd Kieback Lars Röntzsch 《International Journal of Hydrogen Energy》2014
In this work different amorphous melt-spun Fe-alloys (Fe82B18, Fe80Si10B10, Fe60Co20Si10B10) were investigated as cathode materials for the alkaline electrolysis of water. In particular, the influence of cobalt as well as the metalloids boron and silicon on the activity for the hydrogen evolution reaction (HER) was studied in 1 M KOH at 298 K using cyclic voltammetric, galvanostatic and polarization techniques. The electrocatalytic activity was evaluated in the view of the overpotential. It was found that cyclic voltammetric techniques can be used to activate the melt-spun Fe-alloys strongly. Different cyclic voltammetric activation procedures are discussed and the influence of the sweep rate and the potential window on the HER activity was elucidated. The experimental data indicate that the addition of metalloids and, most importantly, of cobalt improves the HER activity of the materials. Thus, the overpotential can be reduced by 200 mV compared to polycrystalline Ni. 相似文献
55.
56.
Claudia Voigt Tilo Zienert Pia Schubert Christos G. Aneziris Jana Hubálková 《Journal of the American Ceramic Society》2014,97(7):2046-2053
The aim of this study was to discuss the influence of different filter surface chemistries on the properties of foam filters. For reliable results, it is essential to ensure comparable structural properties (cell size and strut thickness) for all different surface chemistries (Al2O3, MgAl2O4, 3Al2O3·2SiO2, SiO2, and TiO2) possess the same structural properties (cell size and strut thickness). Filters made of 100% of the investigated materials and alumina skeletons coated with the investigated materials were prepared. The coated alumina samples were sintered in one and two steps. The processing route with two sintering steps resulted in improved mechanical properties and comparable shrinkage and strut thickness. The 100% bulk foams possessed different pore sizes due to the differences of the material shrinkage. In this study, a comparison of the experimental investigated properties of the ceramic foam filters and the theoretically calculated values for foam materials derived from the bulk material properties is established. 相似文献
57.
Abstract The influence of optical elements on the statistical properties of the input radiation is analysed by quantum-theoretical means for a representative optical arrangement consisting of beam splitters as well as for various types of grating spectrometers. In particular non-classical light states are studied. Optimum conditions for the maintenance of the signal-to-noise ratio of sub-Poissonian input radiation are derived. 相似文献
58.
Schubert R. Carvalho Ronan Boulic Creto A. Vidal Daniel Thalmann 《The Visual computer》2013,29(3):171-188
We explore an approach to full-body motion editing with linear motion models, prioritized constraint-based optimization and latent-space interpolation. By exploiting the mathematical connections between linear motion models and prioritized inverse kinematics (PIK), we formulate and solve the motion editing problem as an optimization function whose differential structure is rich enough to efficiently optimize user-specified constraints within the latent motion space. Performing motion editing within latent motion spaces has the advantage of handling pose transitions and consequently motion flow by construction from single key-frame editing. To handle motion adjustments from multiple key-frame and trajectory constraints, we developed a latent-space interpolation technique by exploiting spline functions. Such an approach handles per-frame adjustments generating smooth animations, while avoiding the computational expense of joint space interpolations. We demonstrate the usefulness of this approach by editing and generating full-body reaching and walking jump animations in challenging environment scenarios. 相似文献
59.
J. Vogel H.-J. Feige J. Saupe S. Schubert J. Grimm 《Microsystem Technologies》2014,20(10-11):1975-1979
In addition to the development of materials and technologies for smart HARMST applications the analysis of the thermo-mechanical material properties seems to be necessary to describe the photosensitive polymers applied. To do this, a microtensile analysis system has been developed to determine stress–strain curves, Young’s modulus and Poisson’s ratio. The results are compared with those of dynamical mechanical thermal analysis and discussed. 相似文献
60.
AESOP’s 2009 Congress was hosted by the University of Liverpool as part of the centenary celebration of its Department of Civic Design, the world’s oldest university planning school. ‘Why Can’t the Future be More Like the Past?’ was the conference title on all the banners and conference bags – an oddly querulous question, nevertheless it did the trick in getting participants to think historically throughout AESOP 2009. Michael Hebbert and Dirk Schubert ran a planning history track for six of the conference’s seven parallel session slots. Their call for papers elicited 30 abstracts which reduced to 17 papers, a comfortable quantity allowing good time for presentation and discussion. The track had the fortune to be allocated a wood‐panelled Architecture lecture theatre with superb projection facilities – more than one speaker gasped at the glory of their own PowerPoint images. 相似文献