全文获取类型
收费全文 | 918篇 |
免费 | 64篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 5篇 |
化学工业 | 333篇 |
金属工艺 | 21篇 |
机械仪表 | 22篇 |
建筑科学 | 19篇 |
矿业工程 | 1篇 |
能源动力 | 23篇 |
轻工业 | 207篇 |
水利工程 | 4篇 |
石油天然气 | 1篇 |
无线电 | 37篇 |
一般工业技术 | 99篇 |
冶金工业 | 79篇 |
原子能技术 | 20篇 |
自动化技术 | 112篇 |
出版年
2024年 | 4篇 |
2023年 | 14篇 |
2022年 | 82篇 |
2021年 | 89篇 |
2020年 | 31篇 |
2019年 | 23篇 |
2018年 | 31篇 |
2017年 | 35篇 |
2016年 | 39篇 |
2015年 | 28篇 |
2014年 | 37篇 |
2013年 | 56篇 |
2012年 | 46篇 |
2011年 | 53篇 |
2010年 | 51篇 |
2009年 | 36篇 |
2008年 | 47篇 |
2007年 | 38篇 |
2006年 | 29篇 |
2005年 | 18篇 |
2004年 | 19篇 |
2003年 | 26篇 |
2002年 | 19篇 |
2001年 | 13篇 |
2000年 | 18篇 |
1999年 | 12篇 |
1998年 | 19篇 |
1997年 | 15篇 |
1996年 | 6篇 |
1995年 | 3篇 |
1994年 | 6篇 |
1993年 | 14篇 |
1992年 | 1篇 |
1991年 | 5篇 |
1990年 | 2篇 |
1989年 | 3篇 |
1988年 | 3篇 |
1986年 | 1篇 |
1985年 | 3篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1977年 | 3篇 |
1976年 | 1篇 |
1968年 | 1篇 |
1967年 | 1篇 |
排序方式: 共有983条查询结果,搜索用时 15 毫秒
1.
Guglielmina Chimienti Anna Picca Flavio Fracasso Francesco Russo Antonella Orlando Giuseppe Riezzo Christiaan Leeuwenburgh Vito Pesce Angela Maria Serena Lezza 《International journal of molecular sciences》2021,22(4)
Calorie restriction (CR) is the most efficacious treatment to delay the onset of age-related changes such as mitochondrial dysfunction. However, the sensitivity of mitochondrial markers to CR and the age-related boundaries of CR efficacy are not fully elucidated. We used liver samples from ad libitum-fed (AL) rats divided in: 18-month-old (AL-18), 28-month-old (AL-28), and 32-month-old (AL-32) groups, and from CR-treated (CR) 28-month-old (CR-28) and 32-month-old (CR-32) counterparts to assay the effect of CR on several mitochondrial markers. The age-related decreases in citrate synthase activity, in TFAM, MFN2, and DRP1 protein amounts and in the mtDNA content in the AL-28 group were prevented in CR-28 counterparts. Accordingly, CR reduced oxidative mtDNA damage assessed through the incidence of oxidized purines at specific mtDNA regions in CR-28 animals. These findings support the anti-aging effect of CR up to 28 months. Conversely, the protein amounts of LonP1, Cyt c, OGG1, and APE1 and the 4.8 Kb mtDNA deletion content were not affected in CR-28 rats. The absence of significant differences between the AL-32 values and the CR-32 counterparts suggests an age-related boundary of CR efficacy at this age. However, this only partially curtails the CR benefits in counteracting the generalized aging decline and the related mitochondrial involvement. 相似文献
2.
Nitsa Buaron Antonella Mangraviti Francesco Volpin Ann Liu Mariangela Pedone Eric Sankey Dina Aranovich Itay Adar Fausto J. Rodriguez Abraham Nyska Riki Goldbart Tamar Traitel Henry Brem Betty Tyler Joseph Kost 《Advanced functional materials》2021,31(44):2100643
Treating neuroinflammation-related injuries and disorders through manipulation of neuroinflammation functions is being heralded as a new therapeutic strategy. In this study, a novel pectic galactan (PG) polysaccharide based gene therapy approach is developed for targeting reactive gliosis in neuroinflammation. Galectin-3 (Gal-3) is a cell protein with a high affinity to β-galactoside sugars and is highly expressed in reactive gliosis. Since PG carries galactans, it can target reactive gliosis via specific carbohydrate interaction between galactan and Gal-3 on the cell membrane, and therefore can be utilized as a carrier for delivering genes to these cells. The carrier is synthesized by modifying quaternary ammonium groups on the PG. The resulting quaternized PG (QPG) is found to form complexes with plasmid DNA with a mean diameter of 100 nm and have the characteristics required for targeted gene therapy. The complexes efficiently condense large amounts of plasmid per particle and successfully bind to Gal-3. The in vivo study shows that the complexes are biocompatible and safe for administration and can selectively transfect reactive glial cells of an induced cortical lesion. The results confirm that this PG-based delivery system is a promising platform for targeting Gal-3 overexpressing neuroinflammation cells for treating neuroinflammation-related injuries and neurodegenerative diseases. 相似文献
3.
Journal of Computer Virology and Hacking Techniques - 相似文献
4.
Andrea Bedon Jean Paul Viricelle Mathilde Rieu Simone Mascotto Antonella Glisenti 《International Journal of Hydrogen Energy》2021,46(27):14735-14747
In this contribution brownmillerite-based nanocomposite cathode for Single-Chamber Solid Oxide Fuel Cells is developed. These cells can be very attractive especially for small and cheap devices because of the absence of seals. The efficiency of SC-SOFCs is strictly connected to the selectivity of anode and cathode, the bottleneck for this technology. The development of a cathode inert in fuel oxidation is particularly challenging. Our strategy is to start from a catalytically un-active support (CFA = Ca2FeAl0.95Mg0.05O5) and induce the formation of iron oxide based nanoparticles, expected to activate oxygen. Symmetric (CFA + FeOx/CGO/CFA + FeOx) and complete cells (CFA + FeOx/CGO/Ni-CGO) are studied in air and methane/oxygen 2:1 mixture. The Area Specific Resistance of CFA + FeOx is less than 1/3 that of CFA. The high selectivity allows to reach an efficiency of 25%; power still needs to be increased but we demonstrated the possibility to develop selective low cost electrodes. The effect of air, methane/oxygen exposure and the heat treatments were carefully investigated. 相似文献
5.
M Soncini F Casazza R Mattioli C Bonfardeci A Motta C Cimminiello 《Canadian Metallurgical Quarterly》1997,88(12):501-505
BACKGROUND: We have studied 64 patients with congestive heart failure, half of them also with chronic nonvalvular atrial fibrillation (AF). Patients were also stratified according to a history of prior stroke. METHODS: The generation of thrombin was investigated by means of the molecular markers prothrombin fragment 1 + 2 (F1 + 2) and thrombin-antithrombin III complex (TAT), because AF patients may have a hypercoagulable state. There was only a trend toward higher values of TAT and F1 + 2 for AF patients, while subjects with previous stroke (irrespective of AF) had increased levels of the markers of thrombin generation (TAT stroke+ 18.95 +/- 5.15 vs TAT stroke- 8.34 +/- 2.41; F1 + 2 stroke+ 2.22 +/- 0.29 vs F1 + 2 stroke- 1.32 +/- 0.12). The presence of spontaneous echo contrast (SEC) within left atrium was also investigated in 32 AF patients by transesophageal echocardiography. RESULTS: TAT were significantly higher in subjects (n = 11) with SEC (TAT sec+ 37.5 +/- 13.41 vs TAT sec- 8.7 +/- 2.51, p = 0.008). CONCLUSIONS: Finally, when we grouped into 1) those with both AF and stroke, 2) AF alone, 3) stroke alone and 4) sinus rhythm without stroke, levels of F1 + 2 were higher (and marginally higher TAT) in patients with AF and stroke than in those without stroke, revealing that there is a true clotting activation state in these subjects. 相似文献
6.
7.
Damiana Chinese Antonella Meneghetti Gioacchino Nardin Patrizia Simeoni 《国际能源研究杂志》2007,31(9):829-848
A mixed integer linear programming model combined with a more traditional design by scenarios is proposed to optimize facilities size and operation mode of a municipal energy system involving significant civil centres and a hospital. Moving from the need of a new heat and power station for the local hospital due to the construction of new pavilions, the opportunity of involving other centres in the neighbourhood in a distributed cogeneration system is analysed, increasing system complexity step by step. Smaller cogeneration units tailored to hospital needs are rewarding ventures with relatively low risks but, in a country whose traditional power generation systems heavily rely on fossil fuels and where energy policy and market conditions can make it profitable to sell surplus power, district heating systems foster the installation of larger cogenerators and lead thereby to higher profits and to better performance as for primary energy savings and greenhouse gases emission reduction. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
8.
9.
An experimental analysis is developed for the corner-fed printed square patch antenna, taking into account the width of the feeding junction and the proximity of the microstrip feedline. New accurate design relations for resonance frequency and input impedance are deduced, directly usable for the computer aided design of printed antenna arrays.<> 相似文献
10.
Waste-to-energy based greenhouse heating: exploring viability conditions through optimisation models
An optimisation approach is proposed in order to assess the technical and economic feasibility of a renewable-energy-based greenhouse in North-Eastern Italy. A floor heating system that can exploit a low-temperature heat flow coming from the condenser of a waste-to-energy plant is chosen for the greenhouse and designed developing a non-linear optimisation model, solved by a genetic algorithm. In order to determine under what conditions the combination of a floor-heating-based greenhouse with a waste-to-energy plant can be profitable, a mixed integer optimisation model is introduced to allow selection of the minimum cost fuel solution as a function of different design variables of the greenhouse, such as indoor temperature settings and floor area. The ranges within which the renewable energy solution can lead to significant savings in comparison to traditional fossil fuel are identified both from the point of view of costs and of environmental impact. Furthermore, the sales prices for waste heat that would make investment in the renewable energy solution attractive for potential entrepreneurs are given. 相似文献