全文获取类型
收费全文 | 541篇 |
免费 | 32篇 |
专业分类
电工技术 | 29篇 |
化学工业 | 172篇 |
金属工艺 | 4篇 |
机械仪表 | 21篇 |
建筑科学 | 27篇 |
能源动力 | 29篇 |
轻工业 | 27篇 |
水利工程 | 3篇 |
无线电 | 31篇 |
一般工业技术 | 100篇 |
冶金工业 | 42篇 |
原子能技术 | 2篇 |
自动化技术 | 86篇 |
出版年
2024年 | 1篇 |
2023年 | 11篇 |
2022年 | 31篇 |
2021年 | 31篇 |
2020年 | 11篇 |
2019年 | 12篇 |
2018年 | 11篇 |
2017年 | 16篇 |
2016年 | 21篇 |
2015年 | 23篇 |
2014年 | 28篇 |
2013年 | 56篇 |
2012年 | 39篇 |
2011年 | 33篇 |
2010年 | 19篇 |
2009年 | 36篇 |
2008年 | 21篇 |
2007年 | 22篇 |
2006年 | 20篇 |
2005年 | 9篇 |
2004年 | 10篇 |
2003年 | 10篇 |
2002年 | 8篇 |
2001年 | 10篇 |
2000年 | 7篇 |
1999年 | 4篇 |
1998年 | 12篇 |
1997年 | 16篇 |
1996年 | 10篇 |
1995年 | 4篇 |
1994年 | 2篇 |
1993年 | 2篇 |
1990年 | 2篇 |
1989年 | 3篇 |
1988年 | 3篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1984年 | 4篇 |
1983年 | 1篇 |
1981年 | 2篇 |
1980年 | 2篇 |
1979年 | 3篇 |
1977年 | 1篇 |
1976年 | 1篇 |
1974年 | 1篇 |
1972年 | 2篇 |
排序方式: 共有573条查询结果,搜索用时 15 毫秒
41.
Oxidation reactivity studies are imperative for improving carbon re-burn technologies and valuing the heat content of unburned carbon within coal combustion ashes. Non-isothermal, thermal gravimetric analysis (TGA) was used to examine the oxidation kinetics of unburned carbon in coal combustion fly ashes having different particle size distributions; TGA results were related to combustion efficiencies as measured in a bench-scale rotary kiln. The activation energy and pre-exponential factor were determined for the chemically-controlled reaction regime; the transition temperatures between chemically-controlled and partially diffusion-controlled combustion regimes were obtained for unburned carbon particles of different sizes. After the oxidation reaction rates were evaluated, the residence time distribution (RTD) of fly ashes in the rotary kiln were experimentally measured and the mean residence times related to process parameters, including the rotating velocity and kiln inclination. By comparing these results with an advective-dispersive model, the axial dispersion coefficient of fly ashes was determined. The reaction rates obtained by thermal analyses and the RTDs were used to predict combustion efficiencies within the kiln and oxidation conditions of unburned carbon using various processing options. 相似文献
42.
Dr. Maria L. Di Paolo Dr. Michael S. Christodoulou Dr. Alessandra M. Calogero Dr. Luca Pinzi Prof. Giulio Rastelli Prof. Daniele Passarella Prof. Graziella Cappelletti Prof. Lisa Dalla Via 《ChemMedChem》2019,14(18):1641-1652
A series of 2-phenyloxazoles bearing an amide group at position 4 were designed and synthesized for evaluation as potential inhibitors of human recombinant monoamine oxidases (hrMAOs). Results of kinetics experiments demonstrated that all compounds behave as competitive MAO inhibitors, with good selectivity toward the MAO-B isoform. The most potent and selective derivatives are characterized by inhibition constant (Ki) values in the sub-micromolar range and a good selectivity index (Ki MAO-A/Ki MAO-B>50). Some derivatives were also found to be able to inhibit MAO activity in nerve growth factor (NGF)-differentiated PC12 cells, taken as a model of neuronal cells. In particular, 2-(2-hydroxyphenyl)-N-phenyloxazole-4-carboxamide (compound 4 a ) may be a promising new scaffold, exerting the highest selectivity and inhibitory effect toward MAOs in NGF-differentiated PC12 cell lysates, without compromising cell viability. Molecular docking analysis allowed a rationalization of the experimentally observed binding affinity and selectivity. 相似文献
43.
Matteo Ageno Gabriella Bolzon Giulio Maier 《Structural and Multidisciplinary Optimization》2009,38(3):229-243
A model calibration technique is considered for the estimation of material parameters in free-standing thin foils. The experimental
apparatus is inspired by bursting strength testers for paper, textile fabrics and polymer coatings such as geo-membranes.
The procedure referred to herein consists of the following phases. A controlled fluid pressure is applied to the foil specimen
placed on an horizontal plane with a suitably shaped hole. The induced out-of-plane displacements are measured by a laser
profilometer. The material parameters are then inferred from these measurements through inverse analysis, by simulation of
the test and minimisation of a suitable norm which defines the discrepancy between measured and computed displacements. Potentialities
and limitations of the proposed method are assessed on the basis of computer-generated “pseudo-experimental” data, where modelling
errors are ruled out. The identifiability of some industrially meaningful material parameters is established. 相似文献
44.
We introduce a model of fluid which has four main features: it readily emerges by a general continuum mechanical framework; it is a generalization maintaining most of the physical features of incompressible Newtonian fluids; it can model adherence interactions with one-dimensional structures surrounded by the fluid; the associated initial boundary-value problem is well-posed on three-dimensional domains. 相似文献
45.
Mariaelena Tagliabue Osvaldo Da PosAndrea Spoto Giulio Vidotto 《Accident; analysis and prevention》2013
Riding a moped, like many other everyday activities, is a complex behavior in which attention plays a crucial role. This study aims to investigate the role of attention in enhancing the skills required to ride a moped simulator. Two experiments were conducted with 207 and 60 students (14–15 years old), respectively, using a moped simulator to ride on 12 different tracks. The assignment was to ride safely and avoid hazards. In experiment 1, we divided the hazard scenes of the tracks on the basis of the fact that a shift in attention was required to escape the danger. We showed that during the riding training, when no attentional shift was required, the ability to avoid hazards was constantly higher. In experiment 2, participants were asked to cope with the same basic experimental setting but with an additional attentive task. The results showed that they performed in such a way that not only did the attentive task not impair their performance, but it also produced an improvement in the ability to shift attentional focus, preserving performance efficiency. On the basis of these data, it can be claimed that, primarily, attentional shift plays a prominent role in accounting for accident circumstances. Secondarily, it can be claimed that attentional training contributes to improved processing efficiency so as to prevent mishaps. 相似文献
46.
Giulio Giovannetti Francesca Frijia Simona Attanasio Luca Menichetti Valentina Hartwig Nicola Vanello Jan Henrik Ardenkjaer-Larsen Daniele De Marchi Vincenzo Positano Rolf Schulte Luigi Landini Massimo Lombardi Maria Filomena Santarelli 《Measurement》2013
Hyperpolarized 13C magnetic resonance spectroscopy in pig models enables cardiac metabolism assessment and provides a powerful tool for heart physiology studies, although the low molar concentration of derivate metabolites gives rise to technological limitations in terms of data quality. The design of dedicated coils capable of providing large field of view with high Signal-to-Noise Ratio (SNR) data is of fundamental importance. 相似文献
47.
In this article, using a large sample of Italian manufacturing firms, we estimate a structural model of research, innovation,
productivity and export performance augmented to take account for the role played by spatial agglomeration externalities.
This model, which is an ‘augmented’ version of Crépon et al. (Econ Innov New Technol 7(2):115–158, 1998) model, comprises
five main equations. The first two identify the factors underlying the decision and intensity of Research and Development
(R&D) investments; the third links R&D capital to innovation output; the fourth focuses on Total Factor Productivity (TFP)
as determined by innovation; the fifth relates TFP to export performance. Our estimates show the significant role played by
local externalities in these processes. In particular, related variety and urbanization positively affect the creation of
new ideas through R&D, while specialization impacts on TFP to complement innovation output. Finally, urbanization economies
support TFP in driving firms’ export performance. 相似文献
48.
Tetiana Borzda Christoph Gadermaier Natasa Vujicic Peter Topolovsek Milos Borovsak Tomaz Mertelj Daniele Viola Cristian Manzoni Eva A. A. Pogna Daniele Brida Maria Rosa Antognazza Francesco Scotognella Guglielmo Lanzani Giulio Cerullo Dragan Mihailovic 《Advanced functional materials》2015,25(22):3351-3358
The 2D semiconductor MoS2 in its mono‐ and few‐layer form is expected to have a significant exciton binding energy of several 100 meV, suggesting excitons as the primary photoexcited species. Nevertheless, even single layers show a strong photovoltaic effect and work as the active material in high sensitivity photodetectors, thus indicating efficient charge carrier photogeneration. Here, modulation spectroscopy in the sub‐ps and ms time scales is used to study the photoexcitation dynamics in few‐layer MoS2. The results suggest that the primary photoexcitations are excitons that efficiently dissociate into charges with a characteristic time of 700 fs. Based on these findings, simple suggestions for the design of efficient MoS2 photovoltaic and photodetector devices are made. 相似文献
49.
Michael Köhler Richard BatesCeleste Fleta Karl JakobsManuel Lozano Chris ParkesUlrich Parzefall Giulio PellegriniJens Preiss 《Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment》2011,659(1):272-281
Silicon detectors in 3D technology are a candidate for applications in environments requiring an extreme radiation hardness, as in the innermost layers of the detectors at the proposed High-Luminosity LHC. In 3D detectors, the electrodes are made of columns etched into the silicon perpendicular to the surface. This leads to higher electric fields, a smaller depletion voltage and a reduced trapping probability of the charge carriers compared to standard planar detectors. In this article, the signal and the noise of irradiated n-in-p and p-in-n 3D silicon strip detectors are compared. The devices under test have been irradiated up to a fluence of 2×1016 1 MeV neutron equivalent particles per square centimetre (neq/cm2), which corresponds to the fluence expected for the inner pixel detector layers at the High-Luminosity LHC. A relative charge collection efficiency of approximately 70% was obtained even after the highest irradiation fluence with both detector types. The influence of different temperatures on the signal and the noise is investigated and results of annealing measurements are reported. 相似文献
50.
A bench-scale sequencing batch reactor was used to study factors affecting the endogenous decay of the ammonium oxidizing biomass (AOB) in different operating conditions. AOB decay was very sensitive to oxygen concentration, and increased up to 0.4 d−1 for oxygen concentration of 7 mg O2 L−1. The decay in anaerobic conditions was shown to be very low (0.03 d−1) when compared to literature data.The effect of nitrite and nitrate on AOB decay was also studied. The correlation was quite weak suggesting that both nitrate and nitrite absence had little impact on decay which is contrary to what is typically assumed in some of the existing process models. A simple expression for the decay of AOB was proposed, calibrated and validated using the results of batch kinetic tests and of the continuous sequencing batch reactor monitoring. 相似文献