全文获取类型
收费全文 | 2711篇 |
免费 | 201篇 |
国内免费 | 14篇 |
专业分类
电工技术 | 51篇 |
综合类 | 17篇 |
化学工业 | 694篇 |
金属工艺 | 66篇 |
机械仪表 | 45篇 |
建筑科学 | 134篇 |
矿业工程 | 6篇 |
能源动力 | 133篇 |
轻工业 | 140篇 |
水利工程 | 14篇 |
石油天然气 | 7篇 |
无线电 | 259篇 |
一般工业技术 | 592篇 |
冶金工业 | 134篇 |
原子能技术 | 5篇 |
自动化技术 | 629篇 |
出版年
2024年 | 7篇 |
2023年 | 62篇 |
2022年 | 126篇 |
2021年 | 165篇 |
2020年 | 108篇 |
2019年 | 109篇 |
2018年 | 114篇 |
2017年 | 123篇 |
2016年 | 138篇 |
2015年 | 103篇 |
2014年 | 168篇 |
2013年 | 197篇 |
2012年 | 218篇 |
2011年 | 231篇 |
2010年 | 141篇 |
2009年 | 149篇 |
2008年 | 130篇 |
2007年 | 104篇 |
2006年 | 87篇 |
2005年 | 45篇 |
2004年 | 50篇 |
2003年 | 44篇 |
2002年 | 33篇 |
2001年 | 31篇 |
2000年 | 23篇 |
1999年 | 23篇 |
1998年 | 37篇 |
1997年 | 20篇 |
1996年 | 8篇 |
1995年 | 15篇 |
1994年 | 15篇 |
1993年 | 9篇 |
1992年 | 12篇 |
1991年 | 11篇 |
1990年 | 15篇 |
1989年 | 5篇 |
1987年 | 3篇 |
1985年 | 3篇 |
1984年 | 2篇 |
1983年 | 5篇 |
1981年 | 5篇 |
1979年 | 2篇 |
1978年 | 2篇 |
1977年 | 2篇 |
1976年 | 3篇 |
1975年 | 4篇 |
1974年 | 3篇 |
1973年 | 3篇 |
1972年 | 4篇 |
1971年 | 2篇 |
排序方式: 共有2926条查询结果,搜索用时 15 毫秒
961.
Sebastian Braun-Lüdicke 《Informatik-Spektrum》2004,34(9):476-480
FORUM / RISKMANAGEMENT
Riskmanagement und IT-Sicherheit 相似文献962.
Neugebauer S Evans SR Aguilar ZP Mosbach M Fritsch I Schuhmann W 《Analytical chemistry》2004,76(2):458-463
A new approach is reported for analysis of ultrasmall volumes. It takes advantage of the versatile positioning of a dispenser to shoot approximately 150-pL droplets of liquid onto a specific location of a substrate where analysis is performed rapidly, in a fraction of the time that it takes for the droplet to evaporate. In this report, the site where the liquid is dispensed carries out fast-scan cyclic voltammetry (FSCV), although the detection method does not need to be restricted to electrochemistry. The FSCV is performed at a microcavity having individually addressable gold electrodes, where one serves as working electrode and another as counter/pseudoreference electrode. Five or six droplets of 10 mM [Ru(NH(3))(6)]Cl(3) in 0.1 M KCl were dispensed and allowed to dry, followed by redissolution of the redox species and electrolyte with one or five droplets of water and immediate FSCV, demonstrating the ability to easily concentrate a sample and the reproducibility of redissolution, respectively. Because this approach does not integrate detection with microfluidics on the same chip, it simplifies fabrication of devices for analysis of ultrasmall volumes. It may be useful for single-step and multistep sample preparation, analyses, and bioassays in microarray formats if dispensing and changing of solutions are automated. However, care must be taken to avoid factors that affect the aim of the dispenser, such as drafts and clogging of the nozzle. 相似文献
963.
In one type of brain-computer interface (BCI), users self-modulate brain activity as detected by electroencephalography (EEG). To infer user intent, EEG signals are classified by algorithms which typically use only one of the several types of information available in these signals. One such BCI uses slow cortical potential (SCP) measures to classify single trials. We complemented these measures with estimates of high-frequency (gamma-band) activity, which has been associated with attentional and intentional states. Using a simple linear classifier, we obtained significantly greater classification accuracy using both types of information from the same recording epochs compared to using SCPs alone. 相似文献
964.
Sumpf B. Beister G. Erbert G. Fricke J. Knauer A. Pittroff W. Ressel P. Sebastian J. Wenzel H. Trankle G. 《Electronics letters》2001,37(6):351-353
Reliable operation of 735 nm laser diodes based on a tensile-strained GaAsP quantum well embedded in an AlGaAs large optical cavity structure is reported. The 100 μm stripe width laser diodes were aged at a record high output power of 2W for 2000 hours. The degradation rates were 3.6×10-5 h-1 相似文献
965.
Sebastian Zoran Ambro Stefan L. Burtscher Veronika Loeffler Johann Kollegger 《Beton- und Stahlbetonbau》2006,101(9):663-669
Pre‐stressed slabs without reinforcing steel The method of pre‐stressing concrete members was developed in the 1930's and the positive effect of pre‐stressing on the reduction of deflections and cracks was recognised at the time. The impressive developments in bridge construction methods in the course of the 20th century could only be achieved by employing pre‐stressing. The advantages of using the pre‐stressing method in building constructions are exploited in a few countries, e. g. Australia and USA but not so much and not to the same extent in European countries. This paper shows, that it is feasible to build post‐tensioned slabs without reinforcing steel and points out a method that makes the construction of concrete slabs more economical. 相似文献
966.
Renovation of the suspended roof of the Olympic Swimming Pool in Munich. The Olympic Swimming Pool being part of the Munich Olympic Facilities was built for the 1972 Olympic Summer Games. After more than 30 years the structural integrity and the thermal behaviour of the suspended membrane ceiling reached a critical stage. The following article describes the history of the suspended roof. It covers architectural, structural and thermal demands in its original state as well as the redesign and execution of the new, recently finished membrane ceiling. 相似文献
967.
Luis E.Villegas-Hernández Vishesh Dubey Mona Nystad Jean-Claude Tinguely David A.Coucheron Firehun T.Dullo Anish Priyadarshi Sebastian Acu?a Azeem Ahmad José M.Mateos Gery Barmettler Urs Ziegler ?sa Birna Birgisdottir Aud-Malin Karlsson Hovd Kristin Andreassen Fenton Ganesh Acharya Krishna Agarwal Balpreet Singh Ahluwalia 《光:科学与应用(英文版)》2022,(3):324-340
Histology involves the observation of structural features in tissues using a microscope. While diffraction-limited optical microscopes are commonly used in hist... 相似文献
968.
Manjunatha Pattabi P. J. Sebastian X. Mathew R. N. Bhattacharya 《Solar Energy Materials & Solar Cells》2000,63(4)
The preparation of copper indium diselenide (CIS) films by electroless deposition technique is reported. The films have been deposited on molybdenum substrates. The deposition bath consisted of aqueous solutions of copper chloride, indium chloride, selenous acid and lithium chloride. The pH of the bath was adjusted to 2.2 by adding dilute HCl. The Mo substrate was short-circuited with the aluminum counter electrode for the electroless deposition. The films have been characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDXA), inductively coupled plasma spectroscopy (ICP), Auger electron spectroscopy (AES) and optical spectroscopy. The results indicate that reasonable quality CIS films can be grown by simple electroless deposition process followed by recrystallization in selenium atmosphere. 相似文献
969.
Natalia Vorontsova Evgenii Vorontsov Dmitrii Antonov Zoya Starikova Kim Butin Stefan Brse Sebastian Hfener Valeria Rozenberg 《Advanced Synthesis \u0026amp; Catalysis》2005,347(1):129-135
Bis‐bifunctional cis‐4,7‐diarylsubstituted‐4,7‐dihydroxy‐4,7‐dihydro[2.2]paracyclophanes 3–6 were synthesized by a highly diastereoselective reaction of ortho‐substituted aryllithium reagents with [2.2]paracyclophane‐4,7‐quinone ( 1 ). Enantiomerically pure diols 3–5 were tested as chiral inductors in the enantioselective addition of diethylzinc to benzaldehyde (up to 93.5% ee). Acid dehydration of cis‐4,7‐di(2‐methoxyphenyl)‐4,7‐dihydroxy‐4,7‐dihydro[2.2]paracyclophane ( 3 ) results in 4,7‐dihydro‐7,8‐di(2‐methoxyphenyl)[2.2]paracyclophane‐4‐one ( 8 ) – a planar chiral cyclohexadienone of the [2.2]paracyclophane series with a para‐semiquinoid substructure. X‐Ray investigations of compounds 3, 4 and 8 were performed. 相似文献
970.
F. Bugge A. Knauer S. Gramlich I. Rechenberg G. Beister J. Sebastian H. Wenzel G. Erbert M. Weyers 《Journal of Electronic Materials》2000,29(1):57-61
GaAs-based diode lasers for emission wavelengths between 800 nm and 1060 nm with AlGaAs-cladding and GaInP-waveguide layers
were grown by MOVPE. For wavelengths above 940 nm broad area devices with InGaAs QWs show state-of-the-art threshold current
densities. Ridge-waveguide lasers fabricated by selective etching achieve 200 mW CW monomode output powers. (In)GaAsP QW-based
diode lasers with an emitting wavelengths around 800 nm suffer from problems at the upper GaInP/AlGaAs interface. Asymmetric
structures with a lower AlGaAs/GaInP and an upper AlGaAs/AlGaAs waveguide not only avoid this interface but also offer better
carrier confinement. Such structures show very high slope efficiencies and a high T0. Maximum output powers of 7 W CW are obtained from 4 mm long devices. 相似文献