全文获取类型
收费全文 | 613篇 |
免费 | 28篇 |
国内免费 | 7篇 |
专业分类
电工技术 | 10篇 |
综合类 | 4篇 |
化学工业 | 113篇 |
金属工艺 | 25篇 |
机械仪表 | 29篇 |
建筑科学 | 11篇 |
能源动力 | 42篇 |
轻工业 | 50篇 |
水利工程 | 5篇 |
石油天然气 | 2篇 |
无线电 | 50篇 |
一般工业技术 | 153篇 |
冶金工业 | 48篇 |
原子能技术 | 6篇 |
自动化技术 | 100篇 |
出版年
2024年 | 1篇 |
2023年 | 9篇 |
2022年 | 15篇 |
2021年 | 11篇 |
2020年 | 8篇 |
2019年 | 16篇 |
2018年 | 26篇 |
2017年 | 13篇 |
2016年 | 28篇 |
2015年 | 18篇 |
2014年 | 22篇 |
2013年 | 47篇 |
2012年 | 41篇 |
2011年 | 58篇 |
2010年 | 40篇 |
2009年 | 39篇 |
2008年 | 42篇 |
2007年 | 32篇 |
2006年 | 23篇 |
2005年 | 8篇 |
2004年 | 12篇 |
2003年 | 15篇 |
2002年 | 15篇 |
2001年 | 3篇 |
2000年 | 12篇 |
1999年 | 8篇 |
1998年 | 13篇 |
1997年 | 7篇 |
1996年 | 7篇 |
1995年 | 6篇 |
1994年 | 5篇 |
1993年 | 2篇 |
1992年 | 7篇 |
1991年 | 5篇 |
1990年 | 4篇 |
1989年 | 2篇 |
1988年 | 3篇 |
1987年 | 3篇 |
1986年 | 1篇 |
1985年 | 6篇 |
1984年 | 2篇 |
1983年 | 1篇 |
1980年 | 1篇 |
1979年 | 2篇 |
1978年 | 2篇 |
1977年 | 4篇 |
1976年 | 1篇 |
1973年 | 1篇 |
1971年 | 1篇 |
排序方式: 共有648条查询结果,搜索用时 0 毫秒
11.
Increasing the Efficiency of Organic Dye‐Sensitized Solar Cells over 10.3% Using Locally Ordered Inverse Opal Nanostructures in the Photoelectrode 下载免费PDF全文
Lin Xu Cyril Aumaitre Yann Kervella Gérard Lapertot Cristina Rodríguez‐Seco Emilio Palomares Renaud Demadrille Peter Reiss 《Advanced functional materials》2018,28(15)
3D inverse opal (3D‐IO) oxides are very appealing nanostructures to be integrated into the photoelectrodes of dye‐sensitized solar cells (DSSCs). Due to their periodic interconnected pore network with a high pore volume fraction, they facilitate electrolyte infiltration and enhance light scattering. Nonetheless, preparing 3D‐IO structures directly on nonflat DSSC electrodes is challenging. Herein, 3D‐IO TiO2 structures are prepared by templating with self‐assembled polymethyl methacrylate spheres on glass substrates, impregnation with a mixed TiO2:SiO2 precursor and calcination. The specific surface increases from 20.9 to 30.7 m2 g?1 after SiO2 removal via etching, which leads to the formation of mesopores. The obtained nanostructures are scraped from the substrate, processed as a paste, and deposited on photoelectrodes containing a mesoporous TiO2 layer. This procedure maintains locally the 3D‐IO order. When sensitized with the novel benzothiadiazole dye YKP‐88, DSSCs containing the modified photoelectrodes exhibit an efficiency of 10.35% versus 9.26% for the same devices with conventional photoelectrodes. Similarly, using the ruthenium dye N719 as sensitizer an efficiency increase from 5.31% to 6.23% is obtained. These improvements originate mainly from an increase in the photocurrent density, which is attributed to an enhanced dye loading obtained with the mesoporous 3D‐IO structures due to SiO2 removal. 相似文献
12.
Taris Thierry Begueret Jean-Baptiste Lapuyade Hervé Deval Yann 《Microelectronics Journal》2006,37(11):1251-1260
After a theoretical and analytical study of the body effect in MOS transistors, this paper offers two useful models of this parasitic phenomenon. Thanks to these models, a design methodology, which takes advantage of the bulk terminal, allows to turn this well-known body-effect drawback into an analog advantage, giving thus an efficient alternative to overcome the design constraints of the CMOS VLSI wireless mass market. To illustrate the approach, four RF building blocks are presented. First, a 0.9 V 10 dB gain LNA, covering a frequency range 1.8-2.4 GHz, thanks to a body-effect common mode feedback, is detailed. Secondly, a body-effect linearity controlled pre-power amplifier is presented exhibiting a 5 dB m input compression point (ICP1) variation under 1.8 V power supply for half the current consumption. Lastly, two mixers based on body-effect mixing are presented, which achieve a 10 dB conversion gain under 1.4 V for a −52 dB LO-to-RF isolation. Well suited for low-power/low-voltage applications, these circuits implemented in a 0.18 μm CMOS VLSI technology are dedicated to multi-standard architectures and system-on-chip implementations. 相似文献
13.
Feng Ning Damien Delhomme Yann LeCun Fabio Piano Léon Bottou Paolo Emilio Barbano 《IEEE transactions on image processing》2005,14(9):1360-1371
We describe a trainable system for analyzing videos of developing C. elegans embryos. The system automatically detects, segments, and locates cells and nuclei in microscopic images. The system was designed as the central component of a fully automated phenotyping system. The system contains three modules 1) a convolutional network trained to classify each pixel into five categories: cell wall, cytoplasm, nucleus membrane, nucleus, outside medium; 2) an energy-based model, which cleans up the output of the convolutional network by learning local consistency constraints that must be satisfied by label images; 3) a set of elastic models of the embryo at various stages of development that are matched to the label images. 相似文献
14.
Photoluminescence: Design and Integration in Electro‐Optic Devices of Highly Efficient and Robust Red‐NIR Phosphorescent Nematic Hybrid Liquid Crystals Containing [Mo6I8(OCOCnF2n+1)6]2− (n = 1, 2, 3) Nanoclusters (Adv. Funct. Mater. 31/2015) 下载免费PDF全文
15.
Assembly and Characterizations of Bifunctional Fluorescent and Magnetic Microneedles With One Decade Length Tunability 下载免费PDF全文
Jean‐Baptiste Lugagne Gwennhaël Brackx Emek Seyrek Sophie Nowak Yann Sivry Leticia Vitorazi Jean‐François Berret Pascal Hersen Gaëlle Charron 《Advanced functional materials》2017,27(31)
This report presents the fabrication of bifunctional magnetic and fluorescent microneedles (µNDs) made of a ternary mixture of magnetic nanoparticles (NPs), quantum dots (QDs), and polyelectrolyte. The assembly relies on the electrostatic complexation of negatively charged NPs with positively charged polymer strands and is controlled by the charge ratio between the nanoparticle building blocks and the polymer mortar. The resulting 1D objects can be actuated using an external magnetic field and can be imaged using fluorescence microscopy, thanks to the fluorescent and superparamagnetic properties inherited from their NP constituents. Using a combination of core and surface characterizations and a state‐of‐the‐art image analysis algorithm, the dependence of the brightness and length on the ternary composition is thoroughly investigated. In particular, statistics on hundreds of µNDs with a range of compositions show that the µNDs have a log‐lormal length distribution and that their mean length can be robustly tuned in the 5–50 µm range to match the relevant length scales of various applications in micromixing, bioassays or biomechanics. 相似文献
16.
Yann Civale Guglielmo Vastola Lis K. Nanver Rani Mary-Joy Jae-Ryoung Kim 《Journal of Electronic Materials》2009,38(10):2052-2062
Mechanisms governing the aluminum-mediated solid-phase epitaxy of Si on patterned crystalline Si substrates have been identified
by studying the deposited material as a function of growth conditions when varying parameters such as temperature, growth
time, and layer-stack properties. Early growth stages can be discerned as first formation of “free” Si at the Al/α-Si interface,
then diffusion of Si along the Al grain boundaries, nucleation at the Si substrate surface, nuclei rearrangement, and finally
crystal growth. The acquired understanding is applied to control the selectivity and completeness of single-crystal growth
in various sizes of contact windows to the Si substrate. 相似文献
17.
Proton Transport in Electrospun Hybrid Organic–Inorganic Membranes: An Illuminating Paradox 下载免费PDF全文
Leslie Dos Santos Manuel Maréchal Armel Guillermo Sandrine Lyonnard Simona Moldovan Ovidiu Ersen Ozlem Sel Hubert Perrot Christel Laberty‐Robert 《Advanced functional materials》2016,26(4):594-604
Chemistry and processing have to be judiciously combined to structure the membranes at various length scales to achieve efficient properties for polymer electrolyte membrane fuel cell to make it competitive for transport. Characterizing the proton transport at various length and space scales and understanding the interplays between the nanostructuration, the confinement effect, the interactions, and connectivity are consequently needed. The goal here is to study the proton transport in multiscale, electrospun hybrid membranes (EHMs) at length scales ranging from molecular to macroscopic by using complementary techniques, i.e., electrochemical impedance spectroscopy, pulsed field gradient‐NMR spectroscopy, and quasielastic neutron scattering. Highly conductive hybrid membranes (EHMs) are produced and their performances are rationalized taken into account the balances existing between local interaction driven mobility and large‐scale connectivity effects. It is found that the water diffusion coefficient can be locally decreased (2 × 10?6 cm2 s?1) due to weak interactions with the silica network, but the macroscopic diffusion coefficient is still high (9.6 × 10?6 cm2 s?1). These results highlight that EHMs have slow dynamics at the local scale without being detrimental for long‐range proton transport. This is possible through the nanostructuration of the membranes, controlled via processing and chemistry. 相似文献
18.
Alexandre Joushomme Andr Garenne Mlody Dufosse Rmy Renom Hermanus Johannes Ruigrok Yann Loick Chappe Anne Canovi Lorenza Patrignoni Annabelle Hurtier Florence Poulletier de Gannes Isabelle Lagroye Philippe Lvêque Noëlle Lewis Muriel Priault Delia Arnaud-Cormos Yann Percherancier 《International journal of molecular sciences》2022,23(2)
It remains controversial whether exposure to environmental radiofrequency signals (RF) impacts cell status or response to cellular stress such as apoptosis or autophagy. We used two label-free techniques, cellular impedancemetry and Digital Holographic Microscopy (DHM), to assess the overall cellular response during RF exposure alone, or during co-exposure to RF and chemical treatments known to induce either apoptosis or autophagy. Two human cell lines (SH-SY5Y and HCT116) and two cultures of primary rat cortex cells (astrocytes and co-culture of neurons and glial cells) were exposed to RF using an 1800 MHz carrier wave modulated with various environmental signals (GSM: Global System for Mobile Communications, 2G signal), UMTS (Universal Mobile Telecommunications System, 3G signal), LTE (Long-Term Evolution, 4G signal, and Wi-Fi) or unmodulated RF (continuous wave, CW). The specific absorption rates (S.A.R.) used were 1.5 and 6 W/kg during DHM experiments and ranged from 5 to 24 W/kg during the recording of cellular impedance. Cells were continuously exposed for three to five consecutive days while the temporal phenotypic signature of cells behavior was recorded at constant temperature. Statistical analysis of the results does not indicate that RF-EMF exposure impacted the global behavior of healthy, apoptotic, or autophagic cells, even at S.A.R. levels higher than the guidelines, provided that the temperature was kept constant. 相似文献
19.
Julie Bonnemason Jean-Pierre Friconneau David Maisonnier Yann Perrot 《Fusion Engineering and Design》2009,84(2-6):480-484
The scope of this paper is a preliminary assessment of the maintenance scheme in support of the European study for the next generation of fusion reactor: DEMO. Despite other fusion machine requiring remote handling maintenance operations, DEMO is supposed to work under steady state operational conditions. Therefore, requirement on the maintenance scheme is stronger. To target a good availability of the machine along machine operation plan, it is necessary to draw an adequate maintenance scheme. Indeed, due to the high fluxes generated by the plasma in the vacuum vessel, the first wall lifetime is limited, so the frequent replacement is necessary. On current fusion experimental machine, as first wall load conditions are less severe, DEMO condition implies high level of requirement on maintenance time. During DEMO lifetime, several full first wall replacements are expected. To provide access to the vacuum vessel machine for first wall removal, preparatory work is required to set the machine to adequate maintenance conditions and to open the machine properly, the same situation at the end of the maintenance period. Shutdown duration for first wall replacement should be as short as possible to reach the availability target of the machine. From this statement, the maintenance duration should not exceed 20% of the total lifetime of the reactor operation. First wall segmentation (i.e. total number of component to replace) has a high impact onto the replacement time. Considering the number of feasible designs for the first wall segmentation, we concentrate remote handling concept assessments one type of segmentation, the one minimizing the numbers of modules to replace [4], [5], [6]. Assumption on Divertor segmentation for these DEMO studies have similarities with Divertor ITER design; therefore ITER design output is relevant [1], [2]. We assume divertor removal performed in shadow time, while removing the other first wall modules. 相似文献
20.
The Spheron 6 surface acidity has been investigated by adsorption of ammonia at 70°C and microcalorimetry. The carbon samples are degassed at temperatures up to 950°C. The effects of degassing temperature on the adsorption isotherms of ammonia are shown in Fig. 2. Up to 350°C, the isotherms are characterized by a very slight decrease in the total amount adsorbed. On the contrary, these amounts considerably decrease for higher degassing temperatures. The differential heats of adsorption (Fig. 3), which are initially close to 100 kJ/mole, are shown to decrease with the amount of adsorbed ammonia: the higher the degassing temperature, the greater the decrease. By desorption, the adsorption of ammonia is found partly irreversible. By readsorption it is possible to measure the differential heat of the reversible adsorption and to deduce from it the differential heat of the irreversible adsorption (Fig. 4) as well as the amount irreversibly adsorbed, i.e. chemisorbed.The amounts of chemisorbed ammonia are found to be respectively 0.36 ± 0.01 × 10?6 mole m2 at 150°C and 0.29 ± 0.01 × 10?6 mole m?2 at 350°C. With the surface covering the differential heat of chemisorption of ammonia slightly decreases from 105 to 88 kJ. mole?1.These values suggest that carboxyl groups are responsible for irreversible adsorption of ammonia. This assumption has been checked by various experiments: the irreversible uptake of ammonia lies in the same range as the number of carboxyl surface groups determined by chemical analysis of functional groups (Table 1); the evolving of H2O during the decomposition of the ammonium salt formed by reacting with ammonia has been observed and is probably correlated with the irreversible uptake of ammonia (Fig. 8); moreover it must be pointed out that irreversible adsorption of ammonia disappears after methylation of sample by diazomethane (Figs. 5 and 6). Then, the amounts of carboxyl groups can be determined by measuring the irreversibly adsorbed ammonia.This method has been applied to the study of the thermal stability of functional groups. Carboxyl groups are shown to be quickly decomposed by heat treatment above 500–600°C (Fig. 8).It appears from our experiments that the oxidation at constant temperature followed by a cooling under nitrogen is unable to regenerate functional groups on the surface of carbon after their removal at 950°C. On the contrary, by an oxidation at decreasing temperature it is possible to regenerate functional groups because they are stabilized by the oxidising atmosphere.The groups thus created behave like those initially present on Spheron 6: particularly the graph of the thermal elimination of carbon dioxide presents two peaks (Table 2, Fig. 12). The amount of regenerated carboxyl groups is found to be 0.25 × 10?6 instead of 0.36 × 10?6mole m?2 on untreated Spheron 6. 相似文献