全文获取类型
| 收费全文 | 4156篇 |
| 免费 | 81篇 |
| 国内免费 | 2篇 |
专业分类
| 电工技术 | 47篇 |
| 综合类 | 5篇 |
| 化学工业 | 906篇 |
| 金属工艺 | 73篇 |
| 机械仪表 | 55篇 |
| 建筑科学 | 181篇 |
| 矿业工程 | 5篇 |
| 能源动力 | 149篇 |
| 轻工业 | 280篇 |
| 水利工程 | 53篇 |
| 石油天然气 | 15篇 |
| 无线电 | 327篇 |
| 一般工业技术 | 861篇 |
| 冶金工业 | 610篇 |
| 原子能技术 | 29篇 |
| 自动化技术 | 643篇 |
出版年
| 2024年 | 91篇 |
| 2023年 | 75篇 |
| 2022年 | 105篇 |
| 2021年 | 182篇 |
| 2020年 | 142篇 |
| 2019年 | 144篇 |
| 2018年 | 140篇 |
| 2017年 | 128篇 |
| 2016年 | 151篇 |
| 2015年 | 119篇 |
| 2014年 | 189篇 |
| 2013年 | 261篇 |
| 2012年 | 231篇 |
| 2011年 | 291篇 |
| 2010年 | 194篇 |
| 2009年 | 179篇 |
| 2008年 | 186篇 |
| 2007年 | 169篇 |
| 2006年 | 149篇 |
| 2005年 | 95篇 |
| 2004年 | 107篇 |
| 2003年 | 69篇 |
| 2002年 | 78篇 |
| 2001年 | 32篇 |
| 2000年 | 26篇 |
| 1999年 | 44篇 |
| 1998年 | 64篇 |
| 1997年 | 46篇 |
| 1996年 | 28篇 |
| 1995年 | 34篇 |
| 1994年 | 26篇 |
| 1993年 | 27篇 |
| 1992年 | 17篇 |
| 1990年 | 19篇 |
| 1989年 | 17篇 |
| 1987年 | 12篇 |
| 1986年 | 12篇 |
| 1985年 | 23篇 |
| 1984年 | 19篇 |
| 1983年 | 17篇 |
| 1982年 | 22篇 |
| 1981年 | 26篇 |
| 1980年 | 13篇 |
| 1979年 | 25篇 |
| 1978年 | 19篇 |
| 1977年 | 17篇 |
| 1976年 | 23篇 |
| 1975年 | 18篇 |
| 1974年 | 18篇 |
| 1971年 | 12篇 |
排序方式： 共有4239条查询结果，搜索用时 15 毫秒
101.
Benjamin C. Krummacher Stefan Nowy Jörg Frischeisen Markus Klein Wolfgang Brütting 《Organic Electronics》2009,10(3):478-485
In spite of huge progress in improving the internal quantum efficiency of organic light-emitting diodes (OLEDs), these devices still suffer from poor light out-coupling. Loss mechanisms are for example waveguiding in the organic layers and the substrate as well as the excitation of surface plasmons at metallic electrodes. Their relative strength and the mutual dependence on the OLED structure have been studied both experimentally and by numerical simulation. Here, we consider the impact of the radiative quantum efficiency of the emitter material on predictions of light extraction from OLEDs. Competing processes resulting in non-radiative recombination of charge carriers usually reduce the emitter quantum efficiency in a real device. We show that optical simulation leads to erroneous conclusions when neglecting these competing processes. Furthermore, we demonstrate a method, which allows determining both the radiative quantum efficiency and the charge recombination factor via simulation based analysis of experimental data. This analysis of device efficiency is applied on a set of red-emitting electrophosphorescent devices. 相似文献
102.
Sébastien Fritz Chris Hoze Emmanuelle Rebours Anne Barbat Méline Bizard Amanda Chamberlain Clémentine Escouflaire Christy Vander Jagt Mekki Boussaha Cécile Grohs Aurélie Allais-Bonnet Maëlle Philippe Amélie Vallée Yves Amigues Benjamin J. Hayes Didier Boichard Aurélien Capitan 《Journal of dairy science》2018,101(7):6220-6231
103.
Jonathan Thomas Fabarius;Carsten Pietzka;Dhananjai Pangotra;Benjamin Wriedt;Luciana Vieira;Carina Sagstetter;Melanie Speck;Athanassios Ziogas;Nils Baumgarten;Hans-Joachim Kost;Patrick Löb;Katja Patzsch;Catherine Bernau;Sarah Boeringer;Davide Pico;Antje Lieske;Marcus Vater;Ulrich Wendler;Arne Roth; 《化学，工程师，技术》2024,96(5):698-712
Production processes based on CO2 as raw material offer high scalability and sustainability. Here, a novel process cascade is introduced, combining the advantages of electrochemical CO2 conversion with the synthetic potential of industrial biotechnology: CO2 is electrocatalytically reduced to formic acid as substrate for the metabolically engineered bacterium Methylorubrum extorquens that produces l-lysine as precursor of the polymer building block 1,5-diaminopentane (cadaverine). Cadaverine is purified through targeted downstream processing and finally used in a polycondensation process to produce polyamide materials. 相似文献
104.
Xiangfeng Lai;Seong Hoong Chow;Anton P. Le Brun;Benjamin W. Muir;Phillip J. Bergen;Jacinta White;Heidi H. Yu;Jiping Wang;Jill Danne;Jhih-hang Jiang;Francesca L. Short;Mei-Ling Han;Richard A. Strugnell;Jiangning Song;Neil R. Cameron;Anton Y. Peleg;Jian Li;Hsin-Hui Shen; 《Small (Weinheim an der Bergstrasse, Germany)》2024,20(6):2305052
The rapid increase and spread of Gram-negative bacteria resistant to many or all existing treatments threaten a return to the preantibiotic era. The presence of bacterial polysaccharides that impede the penetration of many antimicrobials and protect them from the innate immune system contributes to resistance and pathogenicity. No currently approved antibiotics target the polysaccharide regions of microbes. Here, describe monolaurin-based niosomes, the first lipid nanoparticles that can eliminate bacterial polysaccharides from hypervirulent Klebsiella pneumoniae, are described. Their combination with polymyxin B shows no cytotoxicity in vitro and is highly effective in combating K. pneumoniae infection in vivo. Comprehensive mechanistic studies have revealed that antimicrobial activity proceeds via a multimodal mechanism. Initially, lipid nanoparticles disrupt polysaccharides, then outer and inner membranes are destabilized and destroyed by polymyxin B, resulting in synergistic cell lysis. This novel lipidic nanoparticle system shows tremendous promise as a highly effective antimicrobial treatment targeting multidrug-resistant Gram-negative pathogens. 相似文献
105.
Benjamin Poole;Alex Marsh;David Lunt;Chris Hardie;Mike Gorley;Cory Hamelin;Allan Harte; 《Strain》2024,60(5):e12472
The high source stability and brightness of field emission gun equipped scanning electron microscopes (SEM) makes them ideal for high-resolution digital image correlation (HRDIC). However, their high initial capital cost can be prohibitive for research organisations and groups. Conventional thermionic SEMs using either a tungsten hairpin or LaB6 filament are far more widespread due to their lower cost. Whilst it is understood that overall performance and ultimate resolution are lower than field emission SEMs, we propose that there is no fundamental reason why these instruments are unsuitable for HRDIC. We investigate the use of a LaB6 SEM as a viable tool for HRDIC. We detail the subtleties of performing HRDIC using a LaB6 thermionic source SEM, providing technical recommendations for best practices in using these instruments for strain mapping. The effects of instrument parameters on strain measurement noise are examined, with a focus on parameters of key relevance to in situ and ex situ mechanical testing. Errors in focus and image pixel size are found to be the primary contributors to the strain noise floor values, with stage accuracy being of secondary importance. We present a case study in oxygen-free high-conductivity copper, OFHC-Cu, which is used in the designs of nuclear fusion components as a heat sink interlayer. Heterogeneous strain patterns are observed in this material, with high levels of strain localisation at grain boundaries. Active slip systems are identified using the relative displacement ratio method, demonstrating the quality of these data and the suitability of LaB6 instruments for HRDIC strain mapping, achieving performance approaching that expected of a field emission SEM. 相似文献
106.
Design of masonry window parapets considering flexural tensile strength Parapet masonry is often neglected in design. However, if verification is explicitly necessary, this is often economically feasible only on the basis of flexural tensile strength. For this application, two design methods are presented with which parapet masonry can be designed as a freestanding wall considering the flexural tensile strength. In addition to a general method based on linear‐elastic stress‐strain relationship of the masonry, which is applicable to both fully and partially supported slabs, a second approach is presented, which takes into account an existing slab edge shell and thus applies especially for parapet masonry with reduced bearing length. Both methods can also be used to design freestanding walls with minor adjustments. Finally, the permissible height of a parapet made of brickwork is determined exemplarily for various applications and indicated in tabular form depending on the acting wind load. 相似文献
107.
Diana Boraschi Andi Alijagic Manon Auguste Francesco Barbero Eleonora Ferrari Szabolcs Hernadi Craig Mayall Sara Michelini Natividad I. Navarro Pacheco Alessandra Prinelli Elmer Swart Benjamin J. Swartzwelter Neus G. Bastús Laura Canesi Damjana Drobne Albert Duschl Marie‐Ann Ewart Jutta Horejs‐Hoeck Paola Italiani Birgit Kemmerling Peter Kille Petra Prochazkova Victor F. Puntes David J. Spurgeon Claus Svendsen Colin J. Wilde Annalisa Pinsino 《Small (Weinheim an der Bergstrasse, Germany)》2020,16(21)
The interaction of a living organism with external foreign agents is a central issue for its survival and adaptation to the environment. Nanosafety should be considered within this perspective, and it should be examined that how different organisms interact with engineered nanomaterials (NM) by either mounting a defensive response or by physiologically adapting to them. Herein, the interaction of NM with one of the major biological systems deputed to recognition of and response to foreign challenges, i.e., the immune system, is specifically addressed. The main focus is innate immunity, the only type of immunity in plants, invertebrates, and lower vertebrates, and that coexists with adaptive immunity in higher vertebrates. Because of their presence in the majority of eukaryotic living organisms, innate immune responses can be viewed in a comparative context. In the majority of cases, the interaction of NM with living organisms results in innate immune reactions that eliminate the possible danger with mechanisms that do not lead to damage. While in some cases such interaction may lead to pathological consequences, in some other cases beneficial effects can be identified. 相似文献
108.
Benjamin Winkeljann Maria G. Bauer Matthias Marczynski Theresa Rauh Stephan A. Sieber Oliver Lieleg 《Advanced Materials Interfaces》2020,7(4)
Approximately 10% of all hospital patients contract infections from temporary clinical implants such as urinal and vascular catheters or tracheal tubes. The ensuing complications reach from patient inconvenience and tissue inflammation to severe, life threatening complications such as pneumonia or bacteremia. All these device‐associated nosocomial infections have the same origin: biofouling, i.e., the unwanted deposition of proteins, bacteria, and cells onto the device. To date, most strategies to overcome these problems are device specific, which results in high development efforts and costs. Here, it is demonstrated how one and the same coupling mechanism can be used to create a covalent antifouling coating employing mucin glycoproteins on multiple materials: with this method, a stable mucin layer can be generated on a broad range of polymer materials which are frequently used in medical engineering. It is shown that the mucin coating exhibits excellent stability against mechanical, thermal, and chemical challenges and reduces protein adsorption as well as prokaryotic and eukaryotic cell adhesion. Thus, the coating mechanism described here introduces a promising strategy to overcome biofouling issues on a broad range of medical devices. 相似文献
109.
Majid Rasool Hsien‐Chieh Chiu Benjamin Zank Yan Zeng Jigang Zhou Karim Zaghib Dmitrii F. Perepichka George P. Demopoulos 《Advanced Materials Interfaces》2020,7(13)
Lithium iron silicate (LFS) attracts a lot of attention due to its 330 mAh g−1 theoretical capacity (2 Li+ per formula unit). However, inherently it exhibits poor Li‐ion intercalation kinetics, interfacial reactivity, and complex phase transitions resulting in lower than one Li+ capacity and poor retention. In this work, a core–shell architecture is devised largely overcoming these obstacles. At first, the nanostructure of Pmn21 LFS is annealed via mechanochemical processing enabling the activation of Li‐ion diffusion. Subsequently, the LFS nanocrystals are coated via in situ poly(3,4‐ethylenedioxythiophene) (PEDOT) polymerization involving partial chemical de‐lithiation/re‐lithiation, the latter catalyzed with FeCl3. As a result of the devised mechanochemical/interphasial engineering of the LFS@PEDOT nanocrystals, their Li‐ion storage capacity is augmented to > 1 Li, namely 200 mAh g−1 after 50 cycles or 1.2 Li+ units—the highest capacity reported for the Pmn21 LFS cathode. A key attribute of the new PEDOT coating technique is the generation of a Fe3+‐rich subsurface layer that contributes to structure stabilization via accelerated phase transition to inverse Pmn21 phase, in addition to rendering the nanocrystals electronically conductive and protected against reaction with electrolyte. Such core–shell engineered nanocrystals provide a powerful paradigm in developing viable high energy density cathodes for next‐generation Li‐ion batteries. 相似文献
110.
Pengju Li Hashina Parveen Anwar Ali Wen Cheng Jingyi Yang Benjamin C. K. Tee 《Advanced Materials Technologies》2020,5(3)
Mechanical replacement prosthetics have advanced in both esthetics and mechanical functions, but still require progress in attaining full natural functionality via tactile feedback. Through bioinspiration of the somatosensory system, recent works in the development of materials and technologies at three critical interfaces have shown great advancements: skin‐inspired multifunctionality at the prosthetic level using flexible electronics, artificial transmission of the biosignals between the prosthesis and nervous system, and stimulation and recording of these signals with mechanically compliant, implantable neural interfaces. Herein, a systematic study of the artificial skin sensation pathways for the prosthetic interfaces is discussed together with the current state‐of‐the‐art technologies and prospective strategies to enable the complete sensory feedback loop in prosthetics through the use of biomimetic sensing platforms, artificial synapses, and neural interrogation electronics. 相似文献