全文获取类型
收费全文 | 8993篇 |
免费 | 603篇 |
国内免费 | 15篇 |
专业分类
电工技术 | 98篇 |
综合类 | 8篇 |
化学工业 | 2324篇 |
金属工艺 | 143篇 |
机械仪表 | 187篇 |
建筑科学 | 424篇 |
矿业工程 | 20篇 |
能源动力 | 278篇 |
轻工业 | 793篇 |
水利工程 | 59篇 |
石油天然气 | 20篇 |
无线电 | 1045篇 |
一般工业技术 | 1587篇 |
冶金工业 | 1118篇 |
原子能技术 | 106篇 |
自动化技术 | 1401篇 |
出版年
2022年 | 35篇 |
2021年 | 114篇 |
2020年 | 105篇 |
2019年 | 160篇 |
2018年 | 198篇 |
2017年 | 214篇 |
2016年 | 281篇 |
2015年 | 214篇 |
2014年 | 304篇 |
2013年 | 551篇 |
2012年 | 422篇 |
2011年 | 497篇 |
2010年 | 423篇 |
2009年 | 427篇 |
2008年 | 438篇 |
2007年 | 387篇 |
2006年 | 395篇 |
2005年 | 308篇 |
2004年 | 305篇 |
2003年 | 267篇 |
2002年 | 246篇 |
2001年 | 180篇 |
2000年 | 148篇 |
1999年 | 127篇 |
1998年 | 214篇 |
1997年 | 180篇 |
1996年 | 161篇 |
1995年 | 159篇 |
1994年 | 165篇 |
1993年 | 138篇 |
1992年 | 106篇 |
1991年 | 76篇 |
1990年 | 103篇 |
1989年 | 91篇 |
1988年 | 76篇 |
1987年 | 80篇 |
1986年 | 59篇 |
1985年 | 119篇 |
1984年 | 105篇 |
1983年 | 93篇 |
1982年 | 84篇 |
1981年 | 114篇 |
1980年 | 75篇 |
1979年 | 88篇 |
1978年 | 34篇 |
1977年 | 74篇 |
1976年 | 75篇 |
1975年 | 61篇 |
1974年 | 49篇 |
1973年 | 49篇 |
排序方式: 共有9611条查询结果,搜索用时 218 毫秒
101.
The Density of States and the Transport Effective Mass in a Highly Oriented Semiconducting Polymer: Electronic Delocalization in 1D 下载免费PDF全文
102.
Plasmonic Absorbers: A Switchable Mid‐Infrared Plasmonic Perfect Absorber with Multispectral Thermal Imaging Capability (Adv. Mater. 31/2015) 下载免费PDF全文
103.
Laurent Bédouet Florentina Pascale Michel Bonneau Alexandre Laurent 《Drug development and industrial pharmacy》2015,41(1):85-94
Intra-articular drug delivery systems (DDSs) are envisaged as interesting alternative to locally release non-steroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen to reduce pain in patients with osteoarthritis. The present study examines the efficacy of S-(+)-ibuprofen on cartilage degradation as drug candidate for DDS loading. Humeral cartilage and joint capsule explants were collected from healthy sheep shoulder joints and they were cultured in mono- or in co-culture for 13?days with LPS in combination with S-(+)-ibuprofen at 50?µM and 1?mM. S-(+)-ibuprofen (50?µM) blocked prostaglandins production in LPS-activated explants but did not reduce cartilage degradation. By contrast, 1?mM S-(+)-ibuprofen treatment of cartilage explants reduced nitric oxide synthesis by 51% (p?=?0.0072), proteoglycans degradation by 35% (p?=?0.0114) and expression of serum amyloid protein – the main protein induced upon LPS challenge – by 44% (p?0.0001). On contrary, in presence of synovial membrane, the protective effects of S-(+)-ibuprofen on cartilage damages were significantly diminished. At 1mM, S-(+)-ibuprofen reduced the cell lysis during culture of cartilage and joint capsule either in mono- or in co-culture. This study performed on sheep explants shows that 1?mM S-(+)-ibuprofen inhibited cartilage degradation via a mechanism independent of cyclooxygenase inhibition. Reduction of prostaglandins synthesis at 50?µM in all treatment groups and reduction of cartilage degradation observed at 1?mM suggest that S-(+)-ibuprofen could be considered as a promising drug candidate for the loading of intra-articular DDS. 相似文献
104.
Proposition of a New Severity Analysis Based on ‘Shake’ Detection: Example of the Vatry Airport Tarmac 下载免费PDF全文
Victor Huart Jean‐Charles Candore Jean‐Baptiste Nolot Nicolas Krajka Jérôme Pellot Serge Odof Damien Erre 《Packaging Technology and Science》2015,28(6):529-544
In packaging science, the study of transport is important in determining the viability of a package/product pair. Many load breaks occur (e.g. handling and storage) along a supply chain. Transport also generates various physical stresses (e.g. shocks, shakes and vibrations). These physical phenomena can be recorded using a variety of customized sensors (e.g. tri‐axial accelerometers, temperature sensors and pressure sensors). This study focuses on a transport phase that has not been studied in depth to date. Transportation operations on tarmacs include many handling and transportation machines, which are characterized by typical constraints that are often more stringent than airlift phase constraints. For comparison, acceleration distributions were estimated and analysed for the tarmac phase and road phase. Severity indicators were calculated based on existing methods. The second part of this study addresses the study of shakes. The shake distributions at 90 and 95% were another indicator of the shakes' severity and probability of occurrence. These elements allow us to characterize the impact of the tarmac area during air transport. 相似文献
105.
Stéphane Mathieu Lionel Aranda Léo Portebois Sandrine Mathieu Michel Vilasi 《Oxidation of Metals》2018,90(1-2):43-63
The short-term oxidation behaviour of RA 602CA, Inconel 693, Manaurite 40XO and Sumitomo 696, which are four alloys recommended for hydrocarbon processing, was studied both in air and in Ar–H2O to determine the conditions of pre-oxidation treatments. Regardless of the considered material, the oxidation rate at 950 °C was systematically higher in Ar–H2O than in dry air. Surface examination of the Al-containing alloys indicated that they were not uniformly oxidized all over the surface. All Al-containing alloys (from 1.6 to 3.2% wt) formed an external protective alumina scale and behaved as alumina-forming alloys in dry air at 950 °C. In contrast, these alloys developed a rate-controlling chromia scale and severe internal oxidation in a H2O-containing atmosphere. Compared with their oxidation behaviour in air + H2O, the phenomenon was significantly enhanced in the atmosphere that coupled water vapour with a low oxygen pressure. Consequently, the Al-containing alloys should not be pre-oxidized in a water vapour atmosphere prior to long exposure to a corrosive atmosphere. In contrast, the chromia-forming Al-free 696 alloy exhibited identical oxidation behaviour in both atmospheres, demonstrating that the degradation of this alloy was not significantly affected by water vapour. 相似文献
106.
A new kind of high electrical conductive epoxy coating with low filler rate was investigated for lightning strike protection (LSP) of carbon fiber reinforced polymer (CFRP). The coating without CFRP substrate was firstly studied. The influence of silver submicronic wires (AgSWs) with a high aspect ratio on the electrical behavior is observed; that is, the electrical resistivity evolution, the current density value, and the electrical conduction mechanisms as function of temperature. The preponderant electrical conduction mechanism is an Ohmic behavior. The higher level of conductivity obtained is 5.5 × 105 S m−1 for 9% vol of AgSWs. Lightning strike tests were carried out on an epoxy/AgSWs coating filled with 8% in volume (74 gsm) and deposited on a CFRP. The ultrasonic testing after lightning strike on coated CFRP shows no structural delamination and demonstrates the interest of this new route for an efficient LSP. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 137, 48700. 相似文献
107.
Alex Gansen Martin Řehoř Clemens Sill Patrycja Polińska Stephan Westermann Jean Dheur Jack S. Hale Jörg Baller 《应用聚合物科学杂志》2020,137(24):48806
An optical method allowing the characterization of melt flow instabilities typically occurring during an extrusion process of polymers and polymer compounds is presented. It is based on a camera-acquired image of the extruded compound with a reference length scale. Application of image processing and transformation of the calibrated image to the frequency domain yields the magnitude spectrum of the instability. The effectiveness of the before mentioned approach is shown on Styrene-butadiene rubber (SBR) compounds, covering a wide range of silica filler content, extruded through a Göttfert capillary rheometer. The results of the image-based analysis are compared with the results from the sharkskin option, a series of highly sensitive pressure transducers installed inside the rheometer. A simplified version of the code used to produce the optical analysis results is included as supplementary material. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48806. 相似文献
108.
A two‐step synthetic procedure is designed for preparing new flame‐retardant methacrylic monomers containing 9,10‐dihydro‐9‐oxa‐10‐phosphaphenanthrene‐10‐oxide (DOPO) as a substituent side group. DOPO and methacrylate moieties are linked by linear aliphatic hydrocarbon spacers (3 to 11 carbon atoms). Copolymerization with methyl methacrylate is carried out leading to copolymers containing between 2 and 10 wt% phosphorus. All homo‐ and copolymers exhibit a unique glass transition temperature (Tg ). A new group contribution for DOPO‐based substituent is extracted that leads to reasonable estimations of Tg s of other published polymers. The Fox equation provides a good estimation of Tg s for most copolymers and for physical blends of poly(methyl methacrylate) (PMMA) and DOPO. When using monomers having three and four carbon atoms in the hydrocarbon spacer, the Tg of copolymers remains close to that of PMMA over a wide range of composition. 相似文献
109.
Maximilian Michel Sandro Cocuzza Martin Biendl Frank Peifer Sebastian Hans Yvonne Methner Friedrich Pehl Werner Back Fritz Jacob Mathias Hutzler 《Journal of the Institute of Brewing》2020,126(4):354-361
Beer spoiling lactic acid bacteria are a major reason for quality complaints in breweries around the world. Spoilage by a variety of these bacteria can result in haze, sediment, slime, off-flavours and acidity. As these bacteria occur frequently in the brewing environment, using certain hop products that inhibit the growth of these spoilers could be a solution to prevent problems. To investigate the impact of seven different hop compounds (α-acids, iso-α-acids, tetrahydro-iso-α-acids, rho-iso-α-acids, xanthohumol, iso-xanthohumol and humulinones) on the growth of six major beer spoilage bacteria (Lactobacillus brevis. L. backi, L. coryniformis, L. lindneri, L. buchneri, Pediococcus damnosous), two concentrations (10 and 25 mg/L) of each hop substance were added to unhopped beer. The potential growth of the spoilage bacteria was investigated over 56 consecutive days. A comparison of the results shows a strong inhibition of growth of all spoilage bacteria at 25 mg/L of tetrahydro-iso-α-acids closely followed by α-acids as the second most inhibitory substance. The results showed a high resistance of L. brevis to all hop compounds as well as an inhibition of L. coryniformis and L. buchneri at low concentrations of most hop components. In comparison with the control sample, L. lindneri showed increased growth in the presence of some hop compounds (rho-iso-α-acids, xanthohumol, iso-xanthohumol, humulinones). © 2020 The Authors. Journal of the Institute of Brewing published by John Wiley & Sons Ltd on behalf of The Institute of Brewing & Distilling 相似文献
110.
Mulders Dounia de Bodt Cyril Bjelland Johannes Pentland Alex Verleysen Michel de Montjoye Yves-Alexandre 《Neural computing & applications》2020,32(24):18023-18043
Neural Computing and Applications - Social networks are known to be assortative with respect to many attributes, such as age, weight, wealth, level of education, ethnicity and gender: Similar... 相似文献