全文获取类型
收费全文 | 8731篇 |
免费 | 478篇 |
国内免费 | 11篇 |
专业分类
电工技术 | 117篇 |
综合类 | 38篇 |
化学工业 | 2206篇 |
金属工艺 | 245篇 |
机械仪表 | 184篇 |
建筑科学 | 604篇 |
矿业工程 | 20篇 |
能源动力 | 281篇 |
轻工业 | 838篇 |
水利工程 | 86篇 |
石油天然气 | 43篇 |
武器工业 | 1篇 |
无线电 | 658篇 |
一般工业技术 | 1463篇 |
冶金工业 | 559篇 |
原子能技术 | 58篇 |
自动化技术 | 1819篇 |
出版年
2023年 | 75篇 |
2022年 | 154篇 |
2021年 | 332篇 |
2020年 | 185篇 |
2019年 | 200篇 |
2018年 | 270篇 |
2017年 | 233篇 |
2016年 | 316篇 |
2015年 | 235篇 |
2014年 | 338篇 |
2013年 | 629篇 |
2012年 | 482篇 |
2011年 | 616篇 |
2010年 | 427篇 |
2009年 | 492篇 |
2008年 | 453篇 |
2007年 | 410篇 |
2006年 | 344篇 |
2005年 | 292篇 |
2004年 | 270篇 |
2003年 | 258篇 |
2002年 | 190篇 |
2001年 | 138篇 |
2000年 | 137篇 |
1999年 | 114篇 |
1998年 | 130篇 |
1997年 | 131篇 |
1996年 | 99篇 |
1995年 | 80篇 |
1994年 | 82篇 |
1993年 | 86篇 |
1992年 | 63篇 |
1991年 | 62篇 |
1990年 | 63篇 |
1989年 | 70篇 |
1988年 | 53篇 |
1987年 | 48篇 |
1986年 | 50篇 |
1985年 | 54篇 |
1984年 | 66篇 |
1983年 | 45篇 |
1982年 | 38篇 |
1981年 | 38篇 |
1980年 | 40篇 |
1979年 | 32篇 |
1978年 | 34篇 |
1977年 | 35篇 |
1976年 | 40篇 |
1975年 | 42篇 |
1973年 | 36篇 |
排序方式: 共有9220条查询结果,搜索用时 171 毫秒
911.
Bert Blocken Jan Carmeliet 《Journal of Wind Engineering & Industrial Aerodynamics》2005,93(12):905-928
With the specific intention to provide experimental data for model development and model validation, a new measurement setup for wind, rain and wind-driven rain (WDR) has been designed and installed at the Laboratory of Building Physics (Katholieke Universiteit Leuven). This paper focuses on the new measurement setup and on the obtained measurement results. The CFD-based design and the installation of the measurement setup are outlined and samples of the database containing the wind, rain and high-resolution WDR measurements are provided and discussed. This paper also provides the link to a website from which the experimental WDR database can be downloaded. Finally, the use of these data to determine WDR coefficients and their use in WDR assessment are briefly addressed. 相似文献
912.
Development of software product families relies heavily on the use of variability to manage the differences between products by delaying design decisions to later stages of the development and usage of the constructed software systems. Implementation of variability is not a trivial task, and is governed by a number of factors. In this paper, we describe the factors that are relevant in determining how to implement variability, and present a taxonomy of variability realization techniques. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
913.
Karun Mehta Jan Fong Jue Anil V. Virkar 《Journal of the American Ceramic Society》1990,73(6):1777-1779
Ceria- and yttria-doped tetragonal polycrystalline zirconia ceramics were ground at temperatures as high as 1100°C. X-ray diffraction revealed that the intensity ratio I (002) / I (200) increased (to as high as ∼4.5) compared with that from the as-sintered surfaces (∼0.55). The enhancement in I (002) / I (200) at temperatures well above the m → t transition temperature shows that it is not related to transformation, reversible or otherwise, but can be explained by ferroelastic domain switching. 相似文献
914.
Energy savings certificates (ESCs) are potentially a major tool that can be used by regulators and policy makers in reducing greenhouse gas (GHG) emissions. In this paper, we present our findings on the experience to date with ESCs, outline potential program opportunities in the US, and conclude with our perspective on how to proceed with the use of ESCs, particularly as a component of GHG reduction programs. 相似文献
915.
Zuzana Jehliková Jana Hajlová Jan Poustka Frantiek Pudil Jii Davidek 《Zeitschrift für Lebensmitteluntersuchung und -Forschung A》1990,190(5):436-440
Summary A reproducible and sensitive gas Chromatographic method has been developed for the trace analysis of fluazifop-butyl, haloxyfop-ethoxyethyl and quizalofop-ethyl as well as their main metabolites (corresponding acids analysed after conversion to methyl esters) in some fruits and vegetables treated with herbicidal sprays. Comparable detection limits (0.01 mg/kg) were achieved when mass fragmentography and/or the electron capture detector were employed. However, in the latter case, bromination of fluazifop esters had to be carried out prior to GC analysis. By means of the nitrogen-phosphorus detector, determination of residues at a level of 0.05 mg/kg was possible. The residue values found in strawberries, cabbages, cauliflowers and carrots were used to discuss the degree of metabolic hydrolysis of parent esters, i.e. active ingredients of herbicides.
Bestimmung von Aryloxyphenoxypropionsäure-Derivaten in mit Herbicidsprays behandelten Produkten
Zusammenfassung Es wurde eine gaschromatographische Methode zur quantitativen und selektiven Bestimmung von Fluazifop-butyl, Haloxyfop-ethoxyethyl und Quizalofop-ethyl sowie von ihren Hauptmetaboliten (den entsprechenden Säuren, die zu Methylestern umgesetzt werden müssen) in mit Herbiciden behandelten Obst- und Gemüseproben entwickelt. Eine Nachweisgrenze von 0,01 mg/kg wurde durch Elektroneneinfanggaschromatographie oder durch Massenfragmentographie erzielt. Um die gleiche Empfindlichkeit des EC-Detektors bei Fluazifop zu erreichen, wurden die beiden Ester mit Brom umgesetzt. Mit Hilfe des NP-Detektors konnte eine Nachweisgrenze von 0,05 mg/kg erreicht werden. Die festgestellten Rückstandsgehalte in Erdbeeren, Kohl, Blumenkohl und Möhren wurden gleichzeitig zur Beurteilung der metabolischen Hydrolyse der diskutierten Ester (der Wirkstoffe der Herbicide) herangezogen.相似文献
916.
Joint investigation of concrete at high rates of loading 总被引:2,自引:0,他引:2
Uniaxial tensile tests have been carried out on a micro-concrete with strain rates between 0.5 and 1.25 s−1. The investigation is described and the results are discussed with respect to the influence of water content on the strain-rate
sensitivity. 相似文献
917.
James E. Oliver John W. Neal Jr. William R. Lusby Jeffrey R. Aldrich Jan P. Kochansky 《Journal of chemical ecology》1985,11(9):1223-1228
The azalea lace bug secretes a clear fluid from secretory setae on the antennae and globulated spines on the dorsal and lateral aspects of the abdomen. The secretion contains 2-alkyl-5-hydroxychromones, the corresponding chromanones and diketones, and straight-chain aldehydes and ketones. 相似文献
918.
919.
Jan?van den?Broek Jennifer?L.?M.?RuppEmail author Semih?AfyonEmail author 《Journal of Electroceramics》2017,38(2-4):182-188
All-solid-state batteries based on fast Li+ conducting solid electrolytes such as Li7La3Zr2O12 (LLZO) give perspective on safe, non-inflammable, and temperature tolerant energy storage. Despite the promise, ceramic processing of whole battery assemblies reaching close to theoretical capacities and finding optimal strategies to process large-scale and low cost battery cells remains a challenge. Here, we tackle these issues and report on a solid-state battery cell composed of Li4Ti5O12 / c-Li6.25Al0.25La3Zr2O12 / metallic Li delivering capacities around 70–75 Ah/kg with reversible cycling at a rate of 8 A/kg (for 2.5–1.0 V, 95 °C). A key aspect towards the increase in capacity and Li+ transfer at the solid electrolyte-electrode interface is found to be the intimate embedding of grains and their connectivity, which can be implemented by the isostatic pressing of cells during their preparation. We suggest that simple adaption of ceramic processing, such as the applied pressure during processing, strongly alters the electrochemical performance by assuring good grain contacts at the electrolyte-electrode interface. Among the garnet-type all-solid-state ceramic battery assemblies in the field, considerably improved capacities and cycling properties are demonstrated for Li4Ti5O12 / c-Li6.25Al0.25La3Zr2O12 / metallic Li pressed cells, giving new perspectives on cheap ceramic processing and up-scalable garnet-based all-solid-state batteries. 相似文献
920.