全文获取类型
收费全文 | 256篇 |
免费 | 23篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 5篇 |
化学工业 | 98篇 |
金属工艺 | 3篇 |
机械仪表 | 3篇 |
建筑科学 | 4篇 |
能源动力 | 7篇 |
轻工业 | 23篇 |
水利工程 | 1篇 |
石油天然气 | 1篇 |
无线电 | 35篇 |
一般工业技术 | 36篇 |
冶金工业 | 22篇 |
自动化技术 | 42篇 |
出版年
2023年 | 8篇 |
2022年 | 18篇 |
2021年 | 39篇 |
2020年 | 10篇 |
2019年 | 12篇 |
2018年 | 15篇 |
2017年 | 17篇 |
2016年 | 15篇 |
2015年 | 5篇 |
2014年 | 14篇 |
2013年 | 18篇 |
2012年 | 10篇 |
2011年 | 15篇 |
2010年 | 5篇 |
2009年 | 9篇 |
2008年 | 12篇 |
2007年 | 5篇 |
2006年 | 7篇 |
2005年 | 5篇 |
2004年 | 2篇 |
2003年 | 3篇 |
2002年 | 4篇 |
2001年 | 3篇 |
2000年 | 4篇 |
1999年 | 2篇 |
1998年 | 8篇 |
1997年 | 6篇 |
1996年 | 2篇 |
1995年 | 1篇 |
1994年 | 2篇 |
1993年 | 1篇 |
1990年 | 2篇 |
1988年 | 1篇 |
排序方式: 共有280条查询结果,搜索用时 656 毫秒
91.
92.
Enrico Della Gaspera Mattia PujattiMassimo Guglielmi Michael L. PostAlessandro Martucci 《Materials Science and Engineering: B》2011,176(9):716-722
Thin films composed of a matrix of titanium and nickel oxides, doped with gold nanoparticles have been prepared with the sol-gel method and annealed at different time/temperature combinations. Structural characterizations demonstrate the crystallization of nickel titanate and of TiO2-rutile due to nickel capability to promote rutile crystallization over anatase. Optical characterizations show a tunable refractive index of the samples according to the Ti/Ni ratio, and a high amount of residual porosity even after high temperature annealing. Sensor functionality measurements were performed with H2, CO and H2S: high sensitivity for hydrogen sulfide detection has been proved, and the cross sensitivity to the other two gases can be tuned by controlling the nickel amount. For high Ni concentrations, the matrix is composed of NiTiO3 and TiO2-rutile, and no cross sensitivity is experienced. For lower Ni amounts, TiO2-anatase starts to crystallize and the films become sensitive to H2 and CO. 相似文献
93.
Righi M Klinger C Eyring V Hendricks J Lauer A Petzold A 《Environmental science & technology》2011,45(8):3519-3525
Aerosol emissions from international shipping are recognized to have a large impact on the Earth's radiation budget, directly by scattering and absorbing solar radiation and indirectly by altering cloud properties. New regulations have recently been approved by the International Maritime Organization (IMO) aiming at progressive reductions of the maximum sulfur content allowed in marine fuels from current 4.5% by mass down to 0.5% in 2020, with more restrictive limits already applied in some coastal regions. In this context, we use a global bottom-up algorithm to calculate geographically resolved emission inventories of gaseous (NO(x), CO, SO(2)) and aerosol (black carbon, organic matter, sulfate) species for different kinds of low-sulfur fuels in shipping. We apply these inventories to study the resulting changes in radiative forcing, attributed to particles from shipping, with the global aerosol-climate model EMAC-MADE. The emission factors for the different fuels are based on measurements at a test bed of a large diesel engine. We consider both fossil fuel (marine gas oil) and biofuels (palm and soy bean oil) as a substitute for heavy fuel oil in the current (2006) fleet and compare their climate impact to that resulting from heavy fuel oil use. Our simulations suggest that ship-induced surface level concentrations of sulfate aerosol are strongly reduced, up to about 40-60% in the high-traffic regions. This clearly has positive consequences for pollution reduction in the vicinity of major harbors. Additionally, such reductions in the aerosol loading lead to a decrease of a factor of 3-4 in the indirect global aerosol effect induced by emissions from international shipping. 相似文献
94.
Andrea Zambotti Emanuel Ionescu Nicola Gargiulo Domenico Caputo Cekdar Vakifahmetoglu Balanand Santhosh Mattia Biesuz Gian Domenico Sorarù 《Journal of the American Ceramic Society》2023,106(8):4891-4901
Porous polymer-derived ceramics (PDCs) are outperforming materials when low-density and thermal inertia are required. In this frame, thermal insulating foams such as silicon carbide (SiC) ones possess intriguing requisites for aerospace applications, but their thermal conductivity is affected by gas phase heat transfer and, in the high temperature region, by radiative mechanisms. Owing to the versatility of the PDC route, we present a synthesis pathway to embed PDC SiC aerogels within the open cells of a SiC foam, thus sensibly decreasing the thermal conductivity at 1000°C from 0.371 W·m−1K−1 to 0.243 W·m−1K−1. In this way, it was possible to couple the mechanical properties of the foam with the insulating ability of the aerogels. The presented synthesis was optimized by selecting, among acetone, n-hexane, and cyclohexane, the proper solvent for the gelation step of the aerogel formation to obtain a proper mesoporous colloidal structure that, after ceramization at 1000°C, presents a specific surface area of 193 m2·g−1. The so-obtained ceramic composites present a lowest density of 0.18 g·cm−3, a porosity of 90% and a compressive strength of 0.76 MPa. 相似文献
95.
Satalino G. Mattia F. Davidson M.W.J. Thuy Le Toan Pasquariello G. Borgeaud M. 《Geoscience and Remote Sensing, IEEE Transactions on》2002,40(11):2438-2447
Assesses the feasibility of retrieving soil moisture content over smooth bare-soil fields using European Remote Sensing synthetic aperture radar (ERS-SAR) data. The roughness conditions considered in this study correspond to those observed in agricultural fields at the time of sowing. Within this context, the retrieval possibilities of a single-parameter ERS-SAR configuration is assessed using appropriately trained neural networks. Three sources of error affecting soil moisture retrieval (inversion, measurement, and model errors) are identified, and their relative influence on retrieval performance is assessed using synthetic datasets as well as a large pan-European database of ground and ERS-1 and ERS-2 measurements. The results from this study indicate that no more than two soil moisture classes can reliably be distinguished using the ERS configuration, even for the restricted roughness range considered. 相似文献
96.
PtSi Schottky-barrier detectors, which are conventionally used in the back-illumination mode for thermal imaging in the 3-5-μm infrared (IR) spectral band, are shown to exhibit excellent photoresponse in the near-ultraviolet and visible regions when operated in the front-illumination mode. For devices without antireflection coatings, external quantum efficiency in excess of 60% has been obtained for wavelengths between 400 and 800 nm. The efficiency decreases below 400 nm but is still about 35% at 290 nm. High-quality imaging has been demonstrated in both the visible and 3-5-μm spectral bands for front-illuminated 160×244-element PtSi focal plane arrays integrated with monolithic CCD readout circuitry 相似文献
97.
G De Mattia MC Bravi O Laurenti M Cassone-Faldetta A Armiento C Ferri F Balsano 《Canadian Metallurgical Quarterly》1998,47(8):993-997
To evaluate the relationship between oxidative stress and glucose metabolism, insulin sensitivity and intraerythrocytic reduced glutathione (GSH)/oxidized glutathione (GSSG) ratio were measured in 10 non-insulin-dependent diabetes mellitus (NIDDM) patients and 10 healthy subjects before and after the intravenous administration of GSH. In particular, after baseline insulin sensitivity was assessed by a 2-hour euglycemic hyperinsulinemic clamp, either glutathione (1.35 g x m2 x min(-1)) or placebo (saline) were infused over a period of 1 hour. The same protocol was repeated at a 1-week interval, in cross-over, according to a randomized, single-blind design. In healthy subjects, baseline intraerythrocytic GSH/GSSG ratio (P < .0005) and total glucose uptake (P < .005) were significantly higher than in NIDDM patients. In the same subjects, GSH infusion significantly increased total glucose uptake (from 37.1 +/- 6.7 micromol kg(-1) x min(-1) to 39.5 +/- 7.7 micromol x kg(-1) x min(-1), P < .05), whereas saline infusion was completely ineffective. In addition, the mean intraerythrocytic GSH/GSSG ratio significantly increased after GSH infusion (from 21.0 +/- 0.9 to 24.7 +/- 1.3, P < .05). Similar findings were found in diabetic patients, in whom GSH infusion significantly increased both total glucose uptake (from 25.3 +/- 9.0 micromol x kg(-1) x min(-1) to 31.4 +/- 10.0 micromol x kg(-1) x min(-1), P < .001) and intraerythrocytic GSH/GSSG ratio (from 14.8 +/- 4.1 to 21.7 +/- 6.7, P < .01). Pooling diabetic patients and controls, significant correlations were found between intraerythrocytic GSH/GSSG ratio and total glucose uptake (r = .425, P < .05), as well as between increments of the same variables after GSH infusion (r = .518, P < .05). In conclusion, our data support the hypothesis that abnormal intracellular GSH redox status plays an important role in reducing insulin sensitivity in NIDDM patients. Accordingly, intravenous GSH infusion significantly increased both intraerythrocytic GSH/GSSG ratio and total glucose uptake in the same patients. 相似文献
98.
Formation of a Quasi‐Free‐Standing Single Layer of Graphene and Hexagonal Boron Nitride on Pt(111) by a Single Molecular Precursor
下载免费PDF全文
![点击此处可从《Advanced functional materials》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Silvia Nappini Igor Píš Tevfik Onur Menteş Alessandro Sala Mattia Cattelan Stefano Agnoli Federica Bondino Elena Magnano 《Advanced functional materials》2016,26(7):1120-1126
It is shown that on Pt(111) it is possible to prepare hexagonal boron nitride (h‐BN) and graphene (G) in‐plane heterojunctions from a single molecular precursor, by thermal decomposition of dimethylamine borane (DMAB). Photoemission, near‐edge X‐ray absorption spectroscopy, low energy electron microscopy, and temperature programmed desorption measurements indicate that the layer fully covers the Pt(111) surface. Evidence of in‐plane layer continuity and weak interaction with Pt substrate has been established. The findings demonstrate that dehydrogenation and pyrolitic decomposition of DMAB is an efficient and easy method for obtaining a continuous almost freestanding layer mostly made of G, h‐BN with only a low percentage (<3%) of impurities (B and N‐doped G domains or C‐doped h‐BN or boron carbonitride, BCN at the boundaries) in the same 2D sheet on a metal substrate, such as Pt(111), paving the way for the advancement of next‐generation G‐like‐based electronics and novel spintronic devices. 相似文献
99.
Renzo Campostrini Andrea Zambotti Mattia Biesuz Gian Domenico Sorarù 《Journal of the American Ceramic Society》2022,105(4):2465-2473
Polymer-derived SiOC-C composites are typically obtained through pyrolysis of a polysiloxane precursor in inert atmosphere. Recent studies have shown that novel SiOC microstructures and compositions can be obtained when the pyrolysis is carried out in a reactive environment, as CO2, which leads to a selective oxidation of the Si─C bonds leaving a microstructure constituted by a nano-dispersed sp2 carbon phase within an SiO2 matrix. However, little is known about the reaction mechanisms between CO2 and the preceramic polymer to date. In this work, we investigated the pyrolysis of a methyl-silsesquioxane in reactive (CO2) and inert (Ar or He) atmosphere by combining TG/MS and FT-IR analysis. The results showed that CO2 starts to react with the preceramic polymer from ≈750°C when the Si─CH3 groups start to form Si─CHx-Si units. The reaction breaks the Si─C bond increasing the amount of the free carbon phase and releasing water vapor, detected by MS, even at temperatures exceeding 900°C. At higher temperatures (≈950°C), CO2 reacts with the free carbon phase leading to a weight loss and the formation of CO. 相似文献
100.
Fabio Chiesi Mattia Borgarino Andrea Mazzanti Enrico Sacchi Guido Albasini Walter Audoglio 《International Journal of Electronics》2013,100(4):305-312
The present work addresses the design of a 65 nm CMOS wide-band single-sideband mixer for UWB synthesiser. The circuit has been designed inductorless and with few capacitors, in order to save silicon area and, at the same time, to get a mixer independent of the adopted frequency plan and synthesiser architecture. Particular attention has been paid to reducing the spurs as much as possible. In order to address a realistic investigation, the design has accounted also for the corner cases and the possible impairments in the input signals. A comparison with the state-of-the-art of the SSB mixers shows the low power consumption of the present work. 相似文献