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11.
12.
Tiziana Armaroli Maria Bevilacqua Marcella Trombetta Aìda Gutirrez Alejandre Jorge Ramirez Guido Busca 《Applied Catalysis A: General》2001,220(1-2):181-190
The interaction of aromatic hydrocarbons benzene, toluene, o-, m- and p-xylene and of methyl pyridines (in particular 2,6-lutidine) with H-ZSM-5 and H-FER zeolites has been studied. Two different H-ZSM-5 samples with strongly different intensity ratios between the two main OH stretching bands have been used. Benzene, toluene and p-xylene enter easily the cavities and give rise to three different H-bonded complexes. Two of them are strongly bonded while the third is likely a very hindered and distorted one. o-Xylene enters slowly the cavities and m-xylene even more slowly. Faster diffusion occurs at higher temperatures. On the contrary, xylenes do not enter the FER cavities. In spite of its steric hindrance, supposed to be the same of m-xylene, 2,6-lutidine enters fast the ZSM channels and is protonated by the internal sites. On the contrary, it does not enter the FER cavities, but it is protonated too on the external silanols sites. Evidence is provided for some kind of heterogeneity of the internal sites of ZSM-5 zeolite. Additionally, it is concluded that other effects besides the molecular sieving effect may play a role in the access and diffusion of molecules into the zeolite channels. 相似文献
13.
Marcella Mastromatteo Alessandra Danza Mariangela Guida Matteo Alessandro Del Nobile 《International Journal of Food Science & Technology》2012,47(10):2109-2116
In this work, the hydration process of durum wheat–based functional bread loaded with yellow pepper flour was optimised. In particular, the investigated vegetable flour and durum wheat semolina were mixed after they were separately hydrated. Three different amounts of water added to the yellow pepper flour were studied for assessing the effect of vegetable flour hydration level on the dough development and overall quality of bread. The bread formulation investigated in a previous work, based on 25% of yellow pepper and 2% of guar seed as structuring agent where the vegetable flour was directly added to the hydrated durum wheat semolina dough, was chosen as control sample. Results highlighted that dough samples with yellow pepper flour hydrated at highest water content showed a rheological behaviour similar to the durum wheat dough. Moreover, creep analysis showed that the sample added with no‐hydrated yellow pepper flour recorded the greatest resistance to deformation. Same results were obtained for the dough tensile and bread compression tests. The use of the hydrated yellow pepper flour also improved all sensorial attributes. 相似文献
14.
Marcella Trombetta Tiziana Armaroli Aìda Gutirrez Alejandre Horacio Gonzalez Jorge Ramirez Solis Guido Busca 《Catalysis Today》2001,65(2-4):285-292
The interaction of HZSM5 and Mo-ZSM5 with benzene, naphthalene, toluene, ortho-xylene, para-xylene, n-butane, isobutane, n-heptane, and methylcyclohexane, in the range 100–773 K has been investigated using FT-IR spectroscopy. Hydrogen bonded species with the internal bridging and the external terminal OHs has been detected. The reactivity at high temperature has also been studied. The access to the internal cavities and to the strongly acidic OHs is at least partly hindered in the case of Mo-ZSM5. The catalytic activity of ZSM5 was moderated by the addition of molybdenum, with lower cracking and higher liquid yields. 相似文献
15.
16.
Proteins from extremophiles as stable tools for advanced biotechnological applications of high social interest 下载免费PDF全文
Marcella de Champdor Maria Staiano Mos Rossi Sabato D'Auria 《Journal of the Royal Society Interface》2007,4(13):183-191
Extremophiles are micro-organisms adapted to survive in ecological niches defined as 'extreme' for humans and characterized by the presence of adverse environmental conditions, such as high or low temperatures, extreme values of pH, high salt concentrations or high pressure. Biomolecules isolated from extremophiles possess extraordinary properties and, in particular, proteins isolated from extremophiles represent unique biomolecules that function under severe conditions, comparable to those prevailing in various industrial processes. In this article, we will review some examples of recent applications of thermophilic proteins for the development of a new class of fluorescence non-consuming substrate biosensors for monitoring the levels of two analytes of high social interest, such as glucose and sodium. 相似文献
17.
Fractal fragmentation of rocks within sturzstroms: insight derived from physical experiments within the ETH geotechnical drum centrifuge 总被引:1,自引:0,他引:1
An investigation of the behaviour and energy budget of sturzstroms has been carried out using physical, analytical and numerical
modelling techniques. Sturzstroms are rock slides of very large volume and extreme run out, which display intensive fragmentation
of blocks of rock due to inter-particle collisions within a collisional flow. Results from centrifugal model experiments provide
strong arguments to allow the micro-mechanics and energy budget of sturzstroms to be described quantitatively by a fractal
comminution model. A numerical experiment using a distinct element method (DEM) indicates rock mass and boundary conditions,
which allow an alternating fragmenting and dilating dispersive regime to evolve and to sustain for long enough to replicate
the spreading and run out of sturzstroms without needing to resort to peculiar mechanism. The fragmenting spreading model
supported here is able to explain the run out of a fluid-absent granular flow beyond the travel distance predicted by a Coulomb
frictional sliding model. This, and its strong relation to internal fragmentation, suggests that a sturzstrom constitutes
a landslide category of its own. This study provides a novel framework for the understanding the physics of such sturzstroms. 相似文献
18.
Marcella Roba Christoph Bruhin Urs Ebneter Roman Ehrbar Rowena Crockett Nicholas D. Spencer 《Tribology Letters》2010,38(3):267-273
Latex versus glass has frequently been used as a model system for the investigation of natural lubrication mechanisms, despite
its significant differences from articular cartilage pairings. The differences in surface chemistry account for its different
behavior in terms of protein adsorption and lubrication. While cartilage is well known for its protein resistance, most proteins
present in synovial fluid can non-specifically adsorb onto latex or glass. We have investigated latex-versus-glass lubrication
by means of pin-on-disk tribometry in the presence of synovial-fluid proteins and glycoproteins, focusing on the influence
of the glass-cleaning procedure on friction. In order to simulate the effects of possible contamination of glass in previous
studies, both hydrophilic and hydrophobic glass substrates were tested. Albumin was shown to impair lubrication (in comparison
to PBS) when latex was slid against both types of glass surface, whereas bovine synovial fluid (BSF) and alpha-1-acid glycoprotein
(AGP) impaired the lubrication of latex versus hydrophilic glass and improved the lubrication of latex versus hydrophobic
glass. Protein adsorption on the surfaces was monitored by means of fluorescence imaging and optical waveguide lightmode spectroscopy
(OWLS), which revealed a faster and greater amount of adsorption of AGP on hydrophobic surfaces than on hydrophilic ones.
The influence of surface chemistry on the friction behavior of BSF and on the adsorption of AGP suggests that it plays a role
in determining the relative amounts of adsorbed synovial fluid proteins. When BSF is used as a lubricant in the latex-versus-hydrophobic-glass
system, more of the AGP, relative to albumin, appears to adsorb on both surfaces, counteracting the negative effect of albumin
on friction. It therefore seems that latex on glass, while displaying nominal similarities to cartilage on cartilage under
certain conditions, is not a useful model system. Moreover, surface contamination of the glass can play a major role in determining
the results. 相似文献
19.
Ronald D. Boyd Marcella Strahan Penrose Cofie Ali Ekhlassi Rashad Martin 《International Journal of Heat and Mass Transfer》2003,46(21):4105-4117
High heat flux removal from plasma-facing components and electronic heat sinks involves conjugate heat transfer analysis of the applicable substrate and flowing fluid. For the present case of subcooled flow boiling inside a single-side heated circular channel, the dimensional results show the significant radial, circumferential and axial variations in all thermal quantities for the present radial aspect ratio (Ro=outside radius to inside radius) of 3.0. A unified, dimensionless representation of the two-dimensional inside wall heat flux, and the dimensional inside wall heat flux (qi(φ,z)) and temperature (Ti(φ,z)) data was found and used to collapse the data for all circumferential locations. Finally, 2-D boiling curves are presented and are among the first full set of 2-D boiling data presented for a single-side heated circular configuration. 相似文献
20.
Francesco Salvo Maria Marcella Tripodo Giacomo Dugo 《Journal of the science of food and agriculture》1984,35(2):212-214
High performance liquid chromatography (h.p.l.c.) was used to characterise and quantify fructose and glucose in seven members of the Cucurbitaceae family. The h.p.l.c. system consisted of a μ-Bondapak/Carbohydrate packed column, a solvent system of acetonitrile-water (800 ml l?-1) with a flow rate of 2.5 ml min?-1, and a refractive index detector. The analysis, including sample preparation, was completed in less than 45 min. The quantities of fructose and glucose obtained were, except for one sample, <1% on a fresh weight basis, and the glucose: fructose ratios ranged from 0.41:1 to 0.93:1. 相似文献