全文获取类型
收费全文 | 1316篇 |
免费 | 64篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 13篇 |
综合类 | 1篇 |
化学工业 | 305篇 |
金属工艺 | 15篇 |
机械仪表 | 33篇 |
建筑科学 | 98篇 |
矿业工程 | 2篇 |
能源动力 | 24篇 |
轻工业 | 205篇 |
水利工程 | 11篇 |
石油天然气 | 1篇 |
无线电 | 69篇 |
一般工业技术 | 213篇 |
冶金工业 | 169篇 |
原子能技术 | 3篇 |
自动化技术 | 220篇 |
出版年
2023年 | 14篇 |
2022年 | 20篇 |
2021年 | 32篇 |
2020年 | 19篇 |
2019年 | 35篇 |
2018年 | 30篇 |
2017年 | 35篇 |
2016年 | 41篇 |
2015年 | 36篇 |
2014年 | 44篇 |
2013年 | 73篇 |
2012年 | 61篇 |
2011年 | 62篇 |
2010年 | 54篇 |
2009年 | 49篇 |
2008年 | 67篇 |
2007年 | 61篇 |
2006年 | 37篇 |
2005年 | 41篇 |
2004年 | 41篇 |
2003年 | 27篇 |
2002年 | 35篇 |
2001年 | 23篇 |
2000年 | 31篇 |
1999年 | 26篇 |
1998年 | 78篇 |
1997年 | 46篇 |
1996年 | 26篇 |
1995年 | 19篇 |
1994年 | 19篇 |
1993年 | 19篇 |
1992年 | 11篇 |
1991年 | 8篇 |
1989年 | 7篇 |
1988年 | 9篇 |
1986年 | 8篇 |
1984年 | 5篇 |
1983年 | 11篇 |
1982年 | 6篇 |
1981年 | 5篇 |
1980年 | 6篇 |
1979年 | 6篇 |
1978年 | 6篇 |
1977年 | 7篇 |
1976年 | 11篇 |
1975年 | 9篇 |
1973年 | 8篇 |
1971年 | 10篇 |
1969年 | 8篇 |
1968年 | 5篇 |
排序方式: 共有1382条查询结果,搜索用时 15 毫秒
71.
Joachim Mittendorf Prof. Dr. Stefan Weigand Dr. Cristina Alonso‐Alija Dr. Erwin Bischoff Dr. Achim Feurer Dr. Michael Gerisch Dr. Armin Kern Dr. Andreas Knorr Dr. Dieter Lang Dr. Klaus Muenter Dr. Martin Radtke Dr. Hartmut Schirok Dr. Karl‐Heinz Schlemmer Dr. Elke Stahl Dr. Alexander Straub Dr. Frank Wunder Dr. Johannes‐Peter Stasch Dr. 《ChemMedChem》2009,4(5):693-693
72.
Falling films exhibit very complex wavy patterns, which depend on the properties of the liquid, the Reynolds number, the wall inclination angle, and the distance from the film inlet. The film hydrodynamics governs the heat and mass transfer in the liquid films. Our vision is to control and enhance heat and mass transport by using walls with specific microscale topographies that influence the falling film flow, stability, and wavy pattern. In this work, long-wave theory and integral boundary layer approximation are used for modeling the falling film flow on walls with three-dimensional periodic microstructures. The wall topography is periodic both in the main flow direction and in the transverse direction. Examples of such microstructures are longitudinal grooves with sinusoidal path (or meandering grooves) and herringbone structures. The effects of the Reynolds number, the wall inclination angle, and the longitudinal and transverse periods of the structure on the shape of liquid–gas interface are investigated. It is shown that, as opposed to straight grooves in longitudinal direction, grooves with meandering paths may lead to significant interface deformations. 相似文献
73.
Yeon-Suk Jang Michael Jank Verena Maier Karsten Durst Nahum Travitzky Cordt Zollfrank 《Journal of the European Ceramic Society》2010,30(13):2773-2779
Micropatterned SiC ceramics were fabricated from polycarbosilanes applying a softlithographic replication technique. A polydimethylsiloxane mould replicated from a photolithographic microstructured silicon wafer was used as master structure. The polydimethylsiloxane mould was coated with a solution containing a mixture of two different polycarbosilanes in n-octane. After treatment at 200–400 °C the cross-linked polycarbosilane films were debonded and pyrolysed at 900 °C in nitrogen and subsequently crystallised at temperatures up to 1500 °C in argon. The cross-linking and thermal degradation behaviour of the polycarbosilanes was investigated by Fourier-transform infrared spectroscopy, differential scanning calorimetry and thermogravimetric analysis. X-ray diffractrometry showed the expected development of a nanocrystalline β-SiC (3 nm) as the main phase with increasing temperature. However, traces of α-SiO2 derived from the polycarbosilane precursors were also detected by X-ray analysis. Removal of the α-SiO2 dioxide with hydrofluoric acid in the pyrolysed samples and subsequent increased the crystallite size to 7 nm. The Young's modulus determined by nanoindentation was increased from 3 GPa after cross-linking to 110 GPa after crystallisation. Scanning electron microscopy revealed, that the initial micropatterns were fully retained in the pyrolysed and crystallised SiC ceramics. The micropatterned cross-linked and crystallised β-SiC based substrates exhibited light scattering characteristics, which qualify them as promising candidates for diffractive optical elements in microoptical applications. 相似文献
74.
Zusammenfassung OpenSocial definiert eine Menge von Programmierschnittstellen für Anwendungen von Drittanbietern im Kontext sozialer Netzwerke.
Unter der Verwendung von Standardtechnologien wie HTML und JavaScript k?nnen Entwickler interoperable Anwendungen erstellen,
die auf den sozialen Graphen des jeweiligen Netzwerks zugreifen. 相似文献
75.
76.
Volker Willert Julian Eggert Jürgen Adamy Raphael Stahl Edgar K?rner 《IEEE transactions on systems, man, and cybernetics. Part B, Cybernetics》2006,36(5):982-994
This paper proposes a biologically inspired and technically implemented sound localization system to robustly estimate the position of a sound source in the frontal azimuthal half-plane. For localization, binaural cues are extracted using cochleagrams generated by a cochlear model that serve as input to the system. The basic idea of the model is to separately measure interaural time differences and interaural level differences for a number of frequencies and process these measurements as a whole. This leads to two-dimensional frequency versus time-delay representations of binaural cues, so-called activity maps. A probabilistic evaluation is presented to estimate the position of a sound source over time based on these activity maps. Learned reference maps for different azimuthal positions are integrated into the computation to gain time-dependent discrete conditional probabilities. At every timestep these probabilities are combined over frequencies and binaural cues to estimate the sound source position. In addition, they are propagated over time to improve position estimation. This leads to a system that is able to localize audible signals, for example human speech signals, even in reverberating environments. 相似文献
77.
Karsten Schmidt 《International Journal on Software Tools for Technology Transfer (STTT)》2006,8(3):195-203
In the context of Petri nets, we propose an automated construction of a progress measure which is an important pre-requisite for a state space reduction technique called the sweep-line method. Our construction is based on linear-algebraic techniques concerning the transition vectors of the Petri net under consideration.
We further discuss the possible combination of the sweep-line method with other state space reduction techniques (partial
order reduction, the symmetry method). 相似文献
78.
The principle mechanisms of solid‐liquid separation processes are sedimentation and filtration, both including the formation and compression of a liquid‐saturated bulk. The compressive properties of the bulk determine the operating parameters of solid‐liquid separation devices and the achievable separation results. Information about the solids volume fraction of the bulk is essential for a better understanding of the physical mechanisms and precise modeling. A numerical model for the calculation of the local solids volume fraction during formation and compression of filter cakes and sediments was developed. The calculated results are compared with experimental NMR data. 相似文献
79.
BACKGROUND:. In all species examined, GDP-fucose is synthesized from GDP-mannose in a three-step reaction catalyzed by two enzymes, GDP-mannose 4,6 dehydratase and a dual function 3, 5-epimerase-4-reductase named GDP-fucose synthetase. In this latter aspect fucose biosynthesis differs from that of other deoxy and dideoxy sugars, in which the epimerase and reductase activities are present as separate enzymes. Defects in GDP-fucose biosynthesis have been shown to affect nodulation in bacteria, stem development in plants, and are associated with the immune defect leukocyte adhesion deficiency type II in humans. RESULTS:. We have determined the structure of GDP-fucose synthetase from Escherichia coli at 2.2 A resolution. The structure of GDP-fucose synthetase is closely related to that of UDP-galactose 4-epimerase and more distantly to other members of the short-chain dehydrogenase/reductase family. We have also determined the structures of the binary complexes of GDP-fucose synthetase with its substrate NADPH and its product NADP+. The nicotinamide cofactors bind in the syn and anti conformations, respectively. CONCLUSIONS:. GDP-fucose synthetase binds its substrate, NADPH, in the proper orientation (syn) for transferring the 4-pro-S hydride of the nicotinamide. We have observed a single binding site in GDP-fucose synthetase for the second substrate, GDP-4-keto,6-deoxy-mannose. This implies that both the epimerization and reduction reactions occur at the same site in the enzyme. As is the case for all members of the short-chain family of dehydrogenase/reductases, GDP-fucose synthetase retains the Ser-Tyr-Lys catalytic triad. We propose that this catalytic triad functions in a mechanistically equivalent manner in both the epimerization and reduction reactions. Additionally, the X-ray structure has allowed us to identify other residues that are potentially required for substrate binding and catalysis. 相似文献
80.
FW Stahl 《Canadian Metallurgical Quarterly》1998,223(1-2):95-102
Several features of bacteriophage lambda suit it for the study of genetic recombination. Central among them are those that make it possible to correlate inheritance of DNA with the inheritance of information encoded by DNA through density-label equilibrium centrifugation. Such studies have revealed relationships between DNA replication and recombination, have identified roles for double-strand breaks in the initiation of recombination, and have elucidated the role of the recombination-stimulating sequence, chi. 相似文献