全文获取类型
收费全文 | 51711篇 |
免费 | 2213篇 |
国内免费 | 75篇 |
专业分类
电工技术 | 553篇 |
综合类 | 45篇 |
化学工业 | 9848篇 |
金属工艺 | 1033篇 |
机械仪表 | 1101篇 |
建筑科学 | 2808篇 |
矿业工程 | 161篇 |
能源动力 | 1526篇 |
轻工业 | 4359篇 |
水利工程 | 530篇 |
石油天然气 | 149篇 |
武器工业 | 6篇 |
无线电 | 3822篇 |
一般工业技术 | 8909篇 |
冶金工业 | 9513篇 |
原子能技术 | 448篇 |
自动化技术 | 9188篇 |
出版年
2023年 | 337篇 |
2022年 | 244篇 |
2021年 | 932篇 |
2020年 | 794篇 |
2019年 | 960篇 |
2018年 | 1191篇 |
2017年 | 1059篇 |
2016年 | 1297篇 |
2015年 | 1163篇 |
2014年 | 1533篇 |
2013年 | 3403篇 |
2012年 | 2495篇 |
2011年 | 3162篇 |
2010年 | 2385篇 |
2009年 | 2303篇 |
2008年 | 2561篇 |
2007年 | 2452篇 |
2006年 | 2216篇 |
2005年 | 1953篇 |
2004年 | 1602篇 |
2003年 | 1497篇 |
2002年 | 1405篇 |
2001年 | 935篇 |
2000年 | 753篇 |
1999年 | 826篇 |
1998年 | 1194篇 |
1997年 | 959篇 |
1996年 | 838篇 |
1995年 | 827篇 |
1994年 | 767篇 |
1993年 | 748篇 |
1992年 | 656篇 |
1991年 | 424篇 |
1990年 | 540篇 |
1989年 | 516篇 |
1988年 | 436篇 |
1987年 | 459篇 |
1986年 | 412篇 |
1985年 | 549篇 |
1984年 | 537篇 |
1983年 | 428篇 |
1982年 | 378篇 |
1981年 | 377篇 |
1980年 | 347篇 |
1979年 | 357篇 |
1978年 | 329篇 |
1977年 | 334篇 |
1976年 | 340篇 |
1975年 | 268篇 |
1974年 | 240篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
Moustapha Moussa Amudhan Ponrajan Osvaldo H. Campanella Martin R. Okos Mario M. Martinez Bruce R. Hamaker 《International Journal of Food Science & Technology》2022,57(7):4594-4601
Traditional West African pearl millet couscous products are popular; however, their preparation is laborious, time-consuming and energy-demanding, involving agglomeration, steaming, drying and sieving steps. In this study, a process was developed to produce millet couscous using a high pressure, high temperature and low-cost single-screw extruder. The innovation was to directly process the cooked low-moisture extrudate to a couscous product by drying and milling to the appropriate particle size (ranging between 1 and 2 mm). Throughput for the traditional process as prepared for commercial sale is 50 kg per day, but with the same amount of labour, the extrusion process yields ~350 kg per day. A consumer sensory study held in Niamey (Niger) showed that the extruded millet couscous was comparable to traditional couscous, though this was dependent on selection of the proper millet variety. This novel extrusion process could stimulate small- to medium-scale manufacturing of couscous and couscous-type products in West Africa. 相似文献
2.
Christopher J. Marvel Qirong Yang Scott D. Walck Kelvin Y. Xie Kristopher D. Behler Jerry C. LaSalvia Masashi Watanabe Richard A. Haber Martin P. Harmer 《Journal of the American Ceramic Society》2022,105(5):2990-3007
Compositional analysis of boron carbide on nanometer length scales to examine or interpret atomic mechanisms, for example, solid-state amorphization or grain-boundary segregation, is challenging. This work reviews advancements in high-resolution microanalysis to characterize multiple generations of boron carbide. First, ζ-factor microanalysis will be introduced as a powerful (scanning) transmission electron microscopy ((S)TEM) analytical framework to accurately characterize boron carbide. Three case studies involving the application of ζ-factor microanalysis will then be presented: (1) accurate stoichiometry determination of B-doped boron carbide using ζ-factor microanalysis and electron energy loss spectroscopy, (2) normalized quantification of silicon grain-boundary segregation in Si-doped boron carbide, and (3) calibration of a scanning electron microscope X-ray energy-dispersive spectroscopy (XEDS) system to measure compositional homogeneity differences of B/Si-doped arc-melted boron carbides in the as-melted and annealed conditions. Overall, the improvement and application of advanced analytical tools have helped better understand processing–microstructure–property relationships and successfully manufacture high-performance ceramics. 相似文献
3.
Scientometrics - Examining the relationships among scientific disciplines is important today, but existing methods are limited by the contents and structure of their bibliographic databases. We... 相似文献
4.
5.
6.
Joseph Turnbull Ryan Szukalo Dmitrij Zagidulin Mark Biesinger David Shoesmith 《工业材料与腐蚀》2021,72(1-2):348-360
The strategy for the permanent disposal of high-level nuclear waste in Canada involves sealing it in a copper-coated steel container and burying it in a deep geologic repository. During the early emplacement period, the container could be exposed to warm humid air, which could result in the condensation of nitric acid, produced by the radiolysis of the humid air, on the copper surface. Previous studies have suggested that both nitrate and oxygen reduction will drive copper corrosion, with the nitrate reduction kinetics being dependent on the concentration of soluble copper(I) produced by the anodic dissolution of copper in the reaction with oxygen. This study focused on determining the kinetics of nitrate and oxygen reduction and elucidating the synergistic relationship between the two processes. This was investigated using corrosion potential and polarization measurements in conjunction with scanning electron microscopy and X-ray photoelectron spectroscopy. Oxygen reduction was shown to be the dominant cathodic reaction with the oxidation of copper(I) to copper(II) by nitrate, promoting the catalytic cycle involving the reaction of copper(II) with copper to reproduce copper(I). 相似文献
7.
Coline Grisotto Janice Taïl Cynthia Planesse Nicolas Diotel Marie-Paule Gonthier Olivier Meilhac David Couret 《International journal of molecular sciences》2021,22(9)
Background: Stroke in context of type 2 diabetes (T2D) is associated with a poorer outcome than in non-diabetic conditions. We aimed at creating a new reproducible mouse model of stroke in impaired glucose tolerance conditions induced by high-fat diet. Methods: Adult C57BL6 mice were fed for 2 months with either normal diet (ND) or high-fat diet (HFD). We used a model of Middle Cerebral Artery Occlusion (MCAO) for 90 min. Oral Glucose Tolerance Test (OGTT) and Insulin Tolerance Test (ITT) were used to assess pre-diabetic status. Brain infarct volume, hemorrhagic transformation (HT) as well as systemic and cerebral inflammatory markers were evaluated. Results: HFD was associated with an increased body weight and glycemia following OGTT. The HFD group presented a significant increase in brain infarct volume (38.7 (IQR 30–46.7%) vs. 28.45 (IQR 21–30%); p = 0.016) and HT (HFD: 2 (IQR 1–5) vs. ND: 0 (IQR 0–1); p = 0.012) and higher levels of IL-6 and MCP-1 in infarcted hemisphere compared to the ND group. Conclusion: Two months of HFD in adult mice were sufficient to alter the lipid profile and the control of hyperglycemia. These metabolic perturbations were significantly associated with increased infarct volume and hemorrhagic complications. 相似文献
8.
Golam Haider Krishna Sampathkumar Tim Verhagen Lukáš Nádvorník Farjana J. Sonia Václav Valeš Jan Sýkora Peter Kapusta Petr Němec Martin Hof Otakar Frank Yang-Fang Chen Jana Vejpravová Martin Kalbáč 《Advanced functional materials》2021,31(29):2102196
Recent advancements in isolation and stacking of layered van der Waals materials have created an unprecedented paradigm for demonstrating varieties of 2D quantum materials. Rationally designed van der Waals heterostructures composed of monolayer transition-metal dichalcogenides (TMDs) and few-layer hBN show several unique optoelectronic features driven by correlations. However, entangled superradiant excitonic species in such systems have not been observed before. In this report, it is demonstrated that strong suppression of phonon population at low temperature results in a formation of a coherent excitonic-dipoles ensemble in the heterostructure, and the collective oscillation of those dipoles stimulates a robust phase synchronized ultra-narrow band superradiant emission even at extremely low pumping intensity. Such emitters are in high demand for a multitude of applications, including fundamental research on many-body correlations and other state-of-the-art technologies. This timely demonstration paves the way for further exploration of ultralow-threshold quantum-emitting devices with unmatched design freedom and spectral tunability. 相似文献
9.
Dr. Aline D. de Araujo Huy T. Nguyen Prof. David P. Fairlie 《Chembiochem : a European journal of chemical biology》2021,22(10):1784-1789
The conventional S-alkylation of cysteine relies upon using activated electrophiles. Here we demonstrate high-yielding and selective S-alkylation and S-lipidation of cysteines in unprotected synthetic peptides and proteins by using weak electrophiles and a Zn2+ promoter. Linear or branched iodoalkanes can S-alkylate cysteine in an unprotected 38-residue Myc peptide fragment and in a 91-residue miniprotein Omomyc, thus highlighting selective late-stage synthetic modifications. Metal-assisted cysteine alkylation is also effective for incorporating dehydroalanine into unprotected peptides and for peptide cyclisation via aliphatic thioether crosslinks, including customising macrocycles to stabilise helical peptides for enhanced uptake and delivery to proteins inside cells. Chemoselective and efficient late-stage Zn2+-promoted cysteine alkylation in unprotected peptides and proteins promises many useful applications. 相似文献