全文获取类型
收费全文 | 118351篇 |
免费 | 12397篇 |
国内免费 | 6466篇 |
专业分类
电工技术 | 8157篇 |
综合类 | 9315篇 |
化学工业 | 16674篇 |
金属工艺 | 6347篇 |
机械仪表 | 6320篇 |
建筑科学 | 6841篇 |
矿业工程 | 3793篇 |
能源动力 | 3094篇 |
轻工业 | 15889篇 |
水利工程 | 3310篇 |
石油天然气 | 3087篇 |
武器工业 | 1566篇 |
无线电 | 8974篇 |
一般工业技术 | 11145篇 |
冶金工业 | 15951篇 |
原子能技术 | 1510篇 |
自动化技术 | 15241篇 |
出版年
2024年 | 564篇 |
2023年 | 1744篇 |
2022年 | 3873篇 |
2021年 | 5277篇 |
2020年 | 3885篇 |
2019年 | 2871篇 |
2018年 | 3600篇 |
2017年 | 3741篇 |
2016年 | 3615篇 |
2015年 | 4839篇 |
2014年 | 5945篇 |
2013年 | 8044篇 |
2012年 | 9072篇 |
2011年 | 9145篇 |
2010年 | 8513篇 |
2009年 | 7748篇 |
2008年 | 7884篇 |
2007年 | 7590篇 |
2006年 | 6279篇 |
2005年 | 4901篇 |
2004年 | 3756篇 |
2003年 | 2706篇 |
2002年 | 2391篇 |
2001年 | 2130篇 |
2000年 | 1734篇 |
1999年 | 1062篇 |
1998年 | 4502篇 |
1997年 | 2688篇 |
1996年 | 1700篇 |
1995年 | 953篇 |
1994年 | 784篇 |
1993年 | 854篇 |
1992年 | 200篇 |
1991年 | 189篇 |
1990年 | 180篇 |
1989年 | 172篇 |
1988年 | 175篇 |
1987年 | 156篇 |
1986年 | 135篇 |
1985年 | 123篇 |
1984年 | 68篇 |
1983年 | 51篇 |
1982年 | 75篇 |
1981年 | 100篇 |
1980年 | 130篇 |
1979年 | 45篇 |
1977年 | 260篇 |
1976年 | 489篇 |
1975年 | 46篇 |
1973年 | 41篇 |
排序方式: 共有10000条查询结果,搜索用时 234 毫秒
2.
3.
4.
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
5.
6.
以蚕丝蛋白为模板,在相对温和的条件下通过生物矿化的手段形成具有特殊形貌的α-GaOOH颗粒,并通过在不同温度下煅烧α-GaOOH得到α-Ga2O3和β-Ga2O3.采用扫描电镜(SEM)、透射电镜(TEM)、X射线衍射仪(XRD)和荧光分光光度计(PL)等手段研究了丝素蛋白多肽和矿化时间对颗粒的影响,对其生物矿化机理进行了初步探讨.结果表明,所制备的β-Ga2O3具有优良的发光特性,丝素蛋白多肽模板以无定形的结构与产物结合在一起,并且经过高温烧结后仍以碳膜的形式包覆在材料的表面.这种碳膜结构对于提高材料的生物学性能起着重要的作用. 相似文献
7.
Claudia Paredes Francisco J. Martínez-Vázquez Hamada Elsayed Paolo Colombo Antonia Pajares Pedro Miranda 《Journal of the European Ceramic Society》2021,41(1):892-900
Bioactive ceramic scaffolds for bone regeneration consisting of a three-dimensional mesh of interpenetrating struts with square section were fabricated via Digital Light Processing (DLP). The ability of the technique to manufacture 3D porous structures from β-tricalcium phosphate (β-TCP) powders with different dimensions of struts and pores was evaluated, identifying the possibilities and limitations of the manufacturing process. Small pore sizes were found to seriously complicate the elimination of excess slurry from the scaffold’s innermost pores. The effect of the strut/pore size on the mechanical performance of the scaffolds under compressive stresses was also evaluated, but no significant influence was found. Under compressive stresses, the structures resulted weaker when tested perpendicularly to the printing plane due to interlayer shear failure. Interlayer superficial grooves are proposed as potential failure-controlling defects, which could also explain the lack of a Weibull size effect on the mechanical strength of the fabricated DLP scaffolds. 相似文献
8.
Patricia Seoane-Collazo Amparo Romero-Pic Eva Rial-Pensado Laura Liares-Pose nxela Estvez-Salguero Johan Fern Rubn Nogueiras Carlos Diguez Miguel Lpez 《International journal of molecular sciences》2021,22(4)
Several studies have reported that nicotine, the main bioactive component of tobacco, exerts a marked negative energy balance. Apart from its anorectic action, nicotine also modulates energy expenditure, by regulating brown adipose tissue (BAT) thermogenesis and white adipose tissue (WAT) browning. These effects are mainly controlled at the central level by modulation of hypothalamic neuropeptide systems and energy sensors, such as AMP-activated protein kinase (AMPK). In this study, we aimed to investigate the kappa opioid receptor (κOR)/dynorphin signaling in the modulation of nicotine’s effects on energy balance. We found that body weight loss after nicotine treatment is associated with a down-regulation of the κOR endogenous ligand dynorphin precursor and with a marked reduction in κOR signaling and the p70 S6 kinase/ribosomal protein S6 (S6K/rpS6) pathway in the lateral hypothalamic area (LHA). The inhibition of these pathways by nicotine was completely blunted in κOR deficient mice, after central pharmacological blockade of κOR, and in rodents where κOR was genetically knocked down specifically in the LHA. Moreover, κOR-mediated nicotine effects on body weight do not depend on orexin. These data unravel a new central regulatory pathway modulating nicotine’s effects on energy balance. 相似文献
9.
Juan José Burbano He/him Darío Marcelino Cabezas María Jimena Correa 《International Journal of Food Science & Technology》2022,57(8):4772-4781
Walnut flour (WF), a by-product of walnut oil production, is characterised by high polyunsaturated fatty acids, proteins, and fibre contents and presents suitability for bakery products. However, when using non-traditional ingredients, it is essential to evaluate the effect on the quality properties of the final product. So, this work aimed to assess the impact of WF on the technological, physicochemical, and sensory properties of gluten-free (GF) cakes. WF was added at a flour blend (cassava (CS) and maize (MS) starches and rice flour) at 0, 10%, 15%, and 20%. The results showed that WF modified starch gelatinisation, increased amylose–lipid complex (ALC) content, and made crumbs easier to chew. Besides, the total dietary fibre (TDF) and protein content significantly increased. Cakes with 15% WF presented the highest specific volume (SV) and no differences in overall acceptability with respect to control. Hence, WF is a suitable ingredient for gluten-free bakery products. 相似文献
10.