全文获取类型
收费全文 | 597篇 |
免费 | 38篇 |
专业分类
电工技术 | 3篇 |
化学工业 | 316篇 |
金属工艺 | 3篇 |
机械仪表 | 11篇 |
建筑科学 | 22篇 |
矿业工程 | 1篇 |
能源动力 | 14篇 |
轻工业 | 86篇 |
水利工程 | 6篇 |
无线电 | 18篇 |
一般工业技术 | 91篇 |
冶金工业 | 15篇 |
原子能技术 | 2篇 |
自动化技术 | 47篇 |
出版年
2024年 | 1篇 |
2023年 | 25篇 |
2022年 | 118篇 |
2021年 | 108篇 |
2020年 | 32篇 |
2019年 | 25篇 |
2018年 | 32篇 |
2017年 | 22篇 |
2016年 | 24篇 |
2015年 | 21篇 |
2014年 | 23篇 |
2013年 | 33篇 |
2012年 | 21篇 |
2011年 | 32篇 |
2010年 | 20篇 |
2009年 | 20篇 |
2008年 | 16篇 |
2007年 | 11篇 |
2006年 | 11篇 |
2005年 | 6篇 |
2004年 | 5篇 |
2003年 | 5篇 |
2002年 | 2篇 |
2001年 | 1篇 |
2000年 | 1篇 |
1999年 | 2篇 |
1998年 | 1篇 |
1997年 | 3篇 |
1996年 | 5篇 |
1995年 | 1篇 |
1993年 | 1篇 |
1992年 | 1篇 |
1990年 | 1篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1976年 | 1篇 |
排序方式: 共有635条查询结果,搜索用时 15 毫秒
1.
Nora Bloise Erik I. Waldorff Giulia Montagna Giovanna Bruni Lorenzo Fassina Samuel Fang Nianli Zhang Jiechao Jiang James T. Ryaby Livia Visai 《International journal of molecular sciences》2022,23(13)
Polyetheretherketone (PEEK) titanium composite (PTC) is a novel interbody fusion device that combines a PEEK core with titanium alloy (Ti6Al4V) endplates. The present study aimed to investigate the in vitro biological reactivity of human bone-marrow-derived mesenchymal stem cells (hBM-MSCs) to micro- and nanotopographies produced by an acid-etching process on the surface of 3D-printed PTC endplates. Optical profilometer and scanning electron microscopy were used to assess the surface roughness and identify the nano-features of etched or unetched PTC endplates, respectively. The viability, morphology and the expression of specific osteogenic markers were examined after 7 days of culture in the seeded cells. Haralick texture analysis was carried out on the unseeded endplates to correlate surface texture features to the biological data. The acid-etching process modified the surface roughness of the 3D-printed PTC endplates, creating micro- and nano-scale structures that significantly contributed to sustaining the viability of hBM-MSCs and triggering the expression of early osteogenic markers, such as alkaline phosphatase activity and bone-ECM protein production. Finally, the topography of 3D-printed PTC endplates influenced Haralick’s features, which in turn correlated with the expression of two osteogenic markers, osteopontin and osteocalcin. Overall, these data demonstrate that the acid-etching process of PTC endplates created a favourable environment for osteogenic differentiation of hBM-MSCs and may potentially have clinical benefit. 相似文献
2.
Giulia Gizzi Samuela Cataldi Claudia Mazzeschi Elisa Delvecchio Maria Rachele Ceccarini Michela Codini Elisabetta Albi 《International journal of molecular sciences》2022,23(13)
The relationship between cholesterol and cancer has been widely demonstrated. Clinical studies have shown changes in blood cholesterol levels in cancer patients. In parallel, basic research studies have shown that cholesterol is involved in the mechanisms of onset and progression of the disease. On the other hand, anorexic patients have high cholesterol levels and a high susceptibility to cancer. In this review, we first present a brief background on the relations among nutrition, eating disorders and cancer. Using several notable examples, we then illustrate the changes in cholesterol in cancer and in anorexia nervosa, providing evidence for their important relationship. Finally, we show a new possible link between cholesterol disorder in cancer and in anorexia nervosa. 相似文献
3.
4.
Marina Paiva Abuafy Regina Celia Galvao Frem Giulia Polinario Fernando Rogerio Pavan Heng Zhao Angelika Mielcarek Cedric Boissiere Christian Serre Leila Aparecida Chiavacci 《International journal of molecular sciences》2022,23(14)
Nanoparticles of metal–organic frameworks (MOF NPs) are crystalline hybrid micro- or mesoporous nanomaterials that show great promise in biomedicine due to their significant drug loading ability and controlled release. Herein, we develop porous capsules from aggregate of nanoparticles of the iron carboxylate MIL-100(Fe) through a low-temperature spray-drying route. This enables the concomitant one-pot encapsulation of high loading of an antitumor drug, methotrexate, within the pores of the MOF NPs, and the collagenase enzyme (COL), inside the inter-particular mesoporous cavities, upon the formation of the capsule, enhancing tumor treatment. This association provides better control of the release of the active moieties, MTX and collagenase, in simulated body fluid conditions in comparison with the bare MOF NPs. In addition, the loaded MIL-100 capsules present, against the A-375 cancer cell line, selective toxicity nine times higher than for the normal HaCaT cells, suggesting that MTX@COL@MIL-100 capsules may have potential application in the selective treatment of cancer cells. We highlight that an appropriate level of collagenase activity remained after encapsulation using the spray dryer equipment. Therefore, this work describes a novel application of MOF-based capsules as a dual drug delivery system for cancer treatment. 相似文献
5.
Giulia Poli Consuelo Fabi Chiara Sugoni Marina Maria Bellet Claudio Costantini Giovanni Luca Stefano Brancorsini 《International journal of molecular sciences》2022,23(9)
Varicocele (VC) is the most common abnormality identified in men evaluated for hypofertility. Increased levels of reactive oxygen species (ROS) and reduced antioxidants concentrations are key contributors in varicocele-mediated hypofertility. Moreover, inflammation and alterations in testicular immunity negatively impact male fertility. In particular, NLRP3 inflammasome activation was hypothesized to lead to seminal inflammation, in which the levels of specific cytokines, such as IL-1β and IL-18, are overexpressed. In this review, we described the role played by oxidative stress (OS), inflammation, and NLRP3 inflammasome activation in VC disease. The consequences of ROS overproduction in testis, including inflammation, lipid peroxidation, mitochondrial dysfunction, chromatin damage, and sperm DNA fragmentation, leading to abnormal testicular function and failed spermatogenesis, were highlighted. Finally, we described some therapeutic antioxidant strategies, with recognized beneficial effects in counteracting OS and inflammation in testes, as possible therapeutic drugs against varicocele-mediated hypofertility. 相似文献
6.
G.Trevisi R Frigeri M. Minelli P. Allegri V. Avanzini S. Franchi 《光电子快报》2007,3(3):161-164
This work deals with the study of optical and morphological properties of InGaAs/AlGaAs quantum dot (QD) structures grown by molecular beam epitaxy (MBE). Photoluminescence (PL) emission energies, activation energies of PL quenching and QD sizes are studied as functions of the Al content in the AlyGal-yAs confining layers (CL). We show that the PL emission energy of In(Ga)As/AlyGal-yAs QD structures increases with increasing y and that the sizes of InAs/AlyGal-yAs QDs decrease with increasing y. By the comparison of the experimental results with those of an effective-mass model developed to calculate the QD fundamental transition energies, we show that the blueshift of emission energy has to be ascribed not only to the increase in barrier discontinuities that confine the carriers into QDs but even to effects related to changes of the QD morphology dependent on CL composition. Moreover, we show that the Al content in the barriers determines also the activation energy of thermal quenching of PL, which depends on the thermal escape of carriers from QD levels. These studies resulted in the preparation of structures with efficient light-emission in the 980 nm spectral window of interest for lightwave communications. 相似文献
7.
Di Tomaso G Díaz-Zuccarini V Pichardo-Almarza C 《IEEE transactions on bio-medical engineering》2011,58(12):3460-3463
A multiscale model of atherosclerotic plaque formation at its early stage has been developed in order to integrate the various phenomena leading to fatty streak formation. The different scales considered in this model are in both the spatial domain (from cellular to organism level) and the time domain (from seconds to months). The cellular level was considered by modeling the transport and chemical interactions of low-density lipoproteins (LDL) and other agents in a stenosed artery. This was linked to arterial thickening (organ level). Mean blood LDL level (organism level) was selected as one of the critical factors for atherosclerotic formation along with wall shear stress (WSS) exerted on the endothelium (the inner portion of the artery). It was observed that plaque location was dependent on WSS and that plaque size, number, and growth was dependent on mean blood LDL levels as well. 相似文献
8.
Mixed‐Conducting Perovskites as Cathode Materials for Protonic Ceramic Fuel Cells: Understanding the Trends in Proton Uptake 下载免费PDF全文
Reihaneh Zohourian Rotraut Merkle Giulia Raimondi Joachim Maier 《Advanced functional materials》2018,28(35)
The proton uptake of 18 compositions in the perovskite family (Ba,Sr,La)(Fe,Co,Zn,Y)O3‐δ, perovskites, which are potential cathode materials for protonic ceramic fuel cells (PCFCs), is investigated by thermogravimetry. Hydration enthalpies and entropies are derived, and the doping trends are explored. The uptake is found to be largely determined by the basicity of the oxide ions. Partial substitution of Zn on the B‐site strongly enhances proton uptake, while Co substitution has the opposite effect. The proton concentration in Ba0.95La0.05Fe0.8Zn0.2O3‐δ is found to be 10% per formula unit at 250 °C, 5.5% at 400 °C, and 2.3% at 500 °C, which are the highest values reported so far for a mixed‐conducting perovskite exhibiting hole, proton, and oxygen vacancy transport. A comprehensive set of thermodynamic data for proton uptake in (Ba,Sr,La)(Fe,Co,Zn,Y)O3‐δ is determined. Defect interactions between protons and holes partially delocalized from the B‐site transition metal to the adjacent oxide ions decrease the proton uptake. From these results, guidelines for the optimization of PCFC cathode materials are derived. 相似文献
9.
The Role of Higher Lying Electronic States in Charge Photogeneration in Organic Solar Cells 下载免费PDF全文
Giulia Grancini Maddalena Binda Stefanie Neutzner Luigino Criante Vittorio Sala Alberto Tagliaferri Guglielmo Lanzani 《Advanced functional materials》2015,25(44):6893-6899
The role of excess photon energy on charge generation efficiency in bulk heterojunction solar cells is still an open issue for the organic photovoltaic community. Here, the spectral dependence of the internal quantum efficiency (IQE) for a poly[2,6‐(4,4‐bis‐(2‐ethylhexyl)‐4H‐cyclopenta[2,1‐b;3,4‐b]dithiophene)‐alt‐4,7‐(2,1,3‐benzothiadiazole)]:6,6‐phenyl‐C61‐butyric acid methyl ester (PCPDTBT:PC60BM)‐based solar cell is derived combining accurate optoelectronic characterization and comprehensive optical modeling. This joint approach is shown to be essential to get reliable values of the IQE. Photons with energy higher than the bandgap of the donor material can effectively contribute to enhance the IQE of the solar cell. This holds true independently of the device architecture, reflecting an intrinsic property of the active material. Moreover, the nanomorphology of the bulk heterojunction plays a crucial role in determining the IQE spectral dependence: the coarser and more crystalline, the lesser the gain in IQE upon high energy excitation. 相似文献
10.
Giulia Grancini R. Sai Santosh Kumar Agnese Abrusci Hin‐Lap Yip Chang‐Zhi Li Alex‐K. Y. Jen Guglielmo Lanzani Henry J. Snaith 《Advanced functional materials》2012,22(10):2160-2166
Hybrid solar cells based on light absorbing semiconducting polymers infiltrated in nanocrystalline TiO2 electrodes, have emerged as an attractive concept, combining benefits of both low material and processing costs with well controlled nano‐scale morphology. However, after over ten years of research effort, power conversion efficiencies remain around 0.5%. Here, a spectroscopic and device based investigation is presented, which leads to a new optimization route where by functionalization of the TiO2 surface with a molecular electron acceptor promotes photoinduced electron transfer from a low‐band gap polymer(poly[2,6‐(4,4‐bis‐(2‐ethylhexyl)‐4H‐cyclopenta[2,1‐b;3,4‐b0]dithiophene)‐alt‐4,7‐(2,1,3‐benzothiadia‐zole)] (PCPDTBT) to the metal oxide. This boosts the infrared response and the power conversion efficiency to over 1%. As a further step, by “co‐functionalizing” the TiO2 surface with the electron acceptor and an organic dye‐sensitizer, panchromatic spectral photoresponse is achieved in the visible to near‐IR region. This novel architecture at the heterojunction opens new material design possibilities and represents an exciting route forward for hybrid photovoltaics. 相似文献