全文获取类型
收费全文 | 126320篇 |
免费 | 12815篇 |
国内免费 | 6495篇 |
专业分类
电工技术 | 8223篇 |
综合类 | 9426篇 |
化学工业 | 19216篇 |
金属工艺 | 6580篇 |
机械仪表 | 6474篇 |
建筑科学 | 7094篇 |
矿业工程 | 3826篇 |
能源动力 | 3397篇 |
轻工业 | 17449篇 |
水利工程 | 3363篇 |
石油天然气 | 3187篇 |
武器工业 | 1567篇 |
无线电 | 9354篇 |
一般工业技术 | 12116篇 |
冶金工业 | 16484篇 |
原子能技术 | 1578篇 |
自动化技术 | 16296篇 |
出版年
2024年 | 581篇 |
2023年 | 1787篇 |
2022年 | 4385篇 |
2021年 | 5779篇 |
2020年 | 4093篇 |
2019年 | 3120篇 |
2018年 | 3795篇 |
2017年 | 3958篇 |
2016年 | 3845篇 |
2015年 | 4956篇 |
2014年 | 6259篇 |
2013年 | 8581篇 |
2012年 | 9595篇 |
2011年 | 9793篇 |
2010年 | 9011篇 |
2009年 | 8216篇 |
2008年 | 8233篇 |
2007年 | 7851篇 |
2006年 | 6576篇 |
2005年 | 5127篇 |
2004年 | 3939篇 |
2003年 | 2920篇 |
2002年 | 2512篇 |
2001年 | 2255篇 |
2000年 | 1838篇 |
1999年 | 1176篇 |
1998年 | 4724篇 |
1997年 | 2848篇 |
1996年 | 1832篇 |
1995年 | 1042篇 |
1994年 | 863篇 |
1993年 | 908篇 |
1992年 | 249篇 |
1991年 | 219篇 |
1990年 | 200篇 |
1989年 | 205篇 |
1988年 | 199篇 |
1987年 | 185篇 |
1986年 | 152篇 |
1985年 | 144篇 |
1984年 | 89篇 |
1983年 | 69篇 |
1982年 | 89篇 |
1981年 | 111篇 |
1980年 | 149篇 |
1979年 | 55篇 |
1978年 | 49篇 |
1977年 | 273篇 |
1976年 | 508篇 |
1975年 | 51篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
3.
4.
5.
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
6.
7.
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
8.
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
9.
Raquel Cano Jos L. Prez Liss Angarita Dvila ngel Ortega Yosselin Gmez Nereida Josefina Valero-Cedeo Heliana Parra Alexander Manzano Teresa Isabel Vliz Castro María P. Díaz Albornoz Gabriel Cano Joselyn Rojas-Quintero Maricarmen Chacín Valmore Bermúdez 《International journal of molecular sciences》2021,22(9)
Non-alcoholic fatty liver disease (NAFLD) is considered the most common liver disorder, affecting around 25% of the population worldwide. It is a complex disease spectrum, closely linked with other conditions such as obesity, insulin resistance, type 2 diabetes mellitus, and metabolic syndrome, which may increase liver-related mortality. In light of this, numerous efforts have been carried out in recent years in order to clarify its pathogenesis and create new prevention strategies. Currently, the essential role of environmental pollutants in NAFLD development is recognized. Particularly, endocrine-disrupting chemicals (EDCs) have a notable influence. EDCs can be classified as natural (phytoestrogens, genistein, and coumestrol) or synthetic, and the latter ones can be further subdivided into industrial (dioxins, polychlorinated biphenyls, and alkylphenols), agricultural (pesticides, insecticides, herbicides, and fungicides), residential (phthalates, polybrominated biphenyls, and bisphenol A), and pharmaceutical (parabens). Several experimental models have proposed a mechanism involving this group of substances with the disruption of hepatic metabolism, which promotes NAFLD. These include an imbalance between lipid influx/efflux in the liver, mitochondrial dysfunction, liver inflammation, and epigenetic reprogramming. It can be concluded that exposure to EDCs might play a crucial role in NAFLD initiation and evolution. However, further investigations supporting these effects in humans are required. 相似文献
10.
Ramiro Palazn-García Ana María Benavente-Valdepeas 《International journal of molecular sciences》2021,22(9)
Botulism has been known for about three centuries, and since its discovery, botulinum toxin has been considered one of the most powerful toxins. However, throughout the 20th century, several medical applications have been discovered, among which the treatment of spasticity stands out. Botulinum toxin is the only pharmacological treatment recommended for spasticity of strokes and cerebral palsy. Although its use as an adjuvant treatment against spasticity in spinal cord injuries is not even approved, botulinum toxin is being used against such injuries. This article describes the advances that have been made throughout history leading to the therapeutic use of botulinum toxin and, in particular, its application to the treatment of spasticity in spinal cord injury. 相似文献