全文获取类型
收费全文 | 1065篇 |
免费 | 59篇 |
国内免费 | 1篇 |
学科分类
工业技术 | 1125篇 |
出版年
2023年 | 8篇 |
2022年 | 13篇 |
2021年 | 34篇 |
2020年 | 20篇 |
2019年 | 30篇 |
2018年 | 31篇 |
2017年 | 22篇 |
2016年 | 34篇 |
2015年 | 33篇 |
2014年 | 57篇 |
2013年 | 81篇 |
2012年 | 67篇 |
2011年 | 68篇 |
2010年 | 47篇 |
2009年 | 63篇 |
2008年 | 53篇 |
2007年 | 55篇 |
2006年 | 22篇 |
2005年 | 30篇 |
2004年 | 29篇 |
2003年 | 28篇 |
2002年 | 28篇 |
2001年 | 15篇 |
2000年 | 18篇 |
1999年 | 13篇 |
1998年 | 45篇 |
1997年 | 34篇 |
1996年 | 31篇 |
1995年 | 15篇 |
1994年 | 16篇 |
1993年 | 10篇 |
1992年 | 6篇 |
1991年 | 4篇 |
1989年 | 4篇 |
1987年 | 4篇 |
1986年 | 6篇 |
1985年 | 4篇 |
1984年 | 6篇 |
1983年 | 2篇 |
1982年 | 5篇 |
1981年 | 7篇 |
1980年 | 3篇 |
1977年 | 6篇 |
1976年 | 6篇 |
1975年 | 2篇 |
1974年 | 1篇 |
1973年 | 2篇 |
1972年 | 1篇 |
1970年 | 1篇 |
1968年 | 2篇 |
排序方式: 共有1125条查询结果,搜索用时 140 毫秒
21.
22.
Matteo Rubagotti Marco Carminati Giampiero Clemente Riccardo Grassetti Antonella Ferrara 《Asian journal of control》2012,14(5):1159-1170
In this paper, an accurate model of an airbrake electro‐hydraulic smart actuator is obtained by physical considerations, and then different control strategies (variable‐gain proportional control, PT1 control with switching integrator, and second order sub‐optimal sliding mode control) are proposed and analyzed. This application is innovative in the avionic field, and is one of the first attempts to realize a fly‐by‐wire system for airbrakes, oriented to its immediate employment and installation on current aircraft. The project was carried on with the participation of the Italian Ministry of Defense, and was commissioned to MAG, a leading provider of integrated systems and aviation services for aerospace. Copyright © 2011 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society 相似文献
23.
Jesús Prado-GonjalRainer Schmidt David ÁvilaUlises Amador Emilio Morán 《Journal of the European Ceramic Society》2012,32(3):611-618
Rare-earth chromite ErCrO3 powder was synthesized from metal nitrate precursors using microwave synthesis. (Micro-) structural characterizations were performed using X-ray diffraction, Rietveld refinement, High Resolution Transmission Electron Microscopy and Electron Micro-Diffraction. Magnetization vs. temperature measurements revealed anti-ferromagnetism with TNeel ≈ 135 K. An anti-ferrimagnetic moment of ≈0.4 μB was determined from magnetization vs. applied field measurements. Temperature dependent impedance spectroscopy (IS) indicated 3 dielectric relaxation processes: electrode interface, grain boundary and bulk. The intrinsic bulk activation energy was found to be 0.27 eV and the dielectric permittivity ?r was ≈23 in excellent agreement with Clausius-Mossotti predictions and showed no perceptible temperature dependence. This and the low ?r value suggested that ErCrO3 is a dielectric rather than ferroelectric compound. IS measurements with applied dc bias revealed the signs of an unconventional type of Schottky barrier at the metallic Au electrode/ceramic ErCrO3 interface. 相似文献
24.
Matteo Diez Daniele Peri Giovanni Fasano Emilio F. Campana 《Structural and Multidisciplinary Optimization》2012,46(4):613-625
The paper presents a formulation for multidisciplinary design optimization of vessels, subject to uncertain operating conditions. The formulation couples the multidisciplinary design analysis with the Bayesian approach to decision problems affected by uncertainty. In the present context, the design specifications are no longer given in terms of a single operating design point, but in terms of probability density function of the operating scenario. The optimal configuration is that which maximizes the performance expectation over the uncertain parameters variation. In this sense, the optimal solution is “robust” within the stochastic scenario assumed. Theoretical and numerical issues are addressed and numerical results in the hydroelastic optimization of a keel fin of a sailing yacht are presented. 相似文献
25.
Alberto Jimnez‐Solano Jos‐Maria Delgado‐Snchez Mauricio E. Calvo Jos M. Miranda‐Muoz Gabriel Lozano Diego Sancho Emilio Snchez‐Cortezn Hernn Míguez 《Progress in Photovoltaics: Research and Applications》2015,23(12):1785-1792
Herein, we present a prototype of a photovoltaic module that combines a luminescent solar concentrator integrating one‐dimensional photonic crystals and in‐plane CuInGaSe2 (CIGS) solar cells. Highly uniform and wide‐area nanostructured multilayers with photonic crystal properties were deposited by a cost‐efficient and scalable liquid processing amenable to large‐scale fabrication. Their role is to both maximize light absorption in the targeted spectral range, determined by the fluorophore employed, and minimize losses caused by emission at angles within the escape cone of the planar concentrator. From a structural perspective, the porous nature of the layers facilitates the integration with the thermoplastic polymers typically used to encapsulate and seal these modules. Judicious design of the module geometry, as well as of the optical properties of the dielectric mirrors employed, allows optimizing light guiding and hence photovoltaic performance while preserving a great deal of transparency. Optimized in‐plane designs like the one herein proposed are of relevance for building integrated photovoltaics, as ease of fabrication, long‐term stability and improved performance are simultaneously achieved. © 2015 The Authors. Progress in Photovoltaics: Research and Applications published by John Wiley & Sons Ltd. 相似文献
26.
27.
Dynamic modeling of a dual active bridge DC to DC converter with average current control and load‐current feed‐forward 下载免费PDF全文
Javier Guacaneme Gabriel Garcerá Emilio Figueres Iván Patrao Raúl González‐Medina 《International Journal of Circuit Theory and Applications》2015,43(10):1311-1332
Bidirectional power flow is needed in many power conversion systems like energy storage systems, regeneration systems, power converters for improvement of the power quality and some DC‐DC applications where bidirectional high power conversion and galvanic isolation are required. The dual active bridge (DAB) is an isolated, high voltage ratio DC‐DC converter suitable for high power density and high power applications, being a key interface between renewable energy sources and energy storage devices. This paper is focused on the modeling and control design of a DC‐DC system with battery storage based on a DAB converter with average current mode control of the output current and output voltage control. The dynamic response of the output voltage to load steps is improved by means of an additional load‐current feed‐forward control loop. An analytical study of the load‐current feed‐forward is presented and validated by means of both simulations and experimental results. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
28.
Unai Iriarte‐Velasco Irene Sierra Emilio Atilano Cepeda Raquel Bravo Jose Luis Ayastuy 《Coloration Technology》2015,131(4):322-332
Bone is an inorganic template containing organic material inside which can be converted into hydroxyapatite‐rich material by pyrolysis. Nowadays, there is a growing research interest in the use of hydroxyapatite, the chemical formula of which is Ca10(PO4)6(OH)2. In the present work, pork bone, an abundant biomass source and food waste, has been converted into structured porous hydroxyapatite by a three‐step process including precharring under mild conditions, chemical activation, and thermal activation. The investigated activating agents were NaOH, KOH, K2CO3, H2SO4, and H3PO4. A thorough investigation of the influence of different activating protocols on the chemical and textural properties of the produced material was carried out by nitrogen adsorption–desorption at 77 K, potentiometric titrations, Fourier transform infrared, and X‐ray diffraction techniques. Chemical activation with NaOH, K2CO3, and H2SO4 increased the specific surface area up to 53%. H3PO4 reduced both surface area and pore volume, and KOH showed little influence on the pore structure. The produced materials were evaluated by methylene blue adsorption tests and showed significant improvement as a result of chemical activation. As a main effect, acid treatment increased methylene blue adsorption kinetics, probably owing to an increase in micropororosity, whereas alkali activation enhanced the adsorption capacity of the resultant biochar. 相似文献
29.
Antonio Sánchez‐Díaz Marta Izquierdo Salvatore Filippone Nazario Martin Emilio Palomares 《Advanced functional materials》2010,20(16):2695-2700
Organic solar cells made using a blend of DPM12 and P3HT are studied. The results show that higher Voc can be obtained when using DPM12 in comparison to the usual mono‐substituted PCBM electron acceptor. Moreover, better device performances are also registered when the cells are irradiated with sun‐simulated light of 10–50 mW cm?2 intensity. Electrochemical and time‐resolved spectroscopic measurements are compared for both devices and a 100‐mV shift in the density of states (DOS) is observed for DPM12/P3HT devices with respect to PCBM/P3HT solar cells and slow polaron‐recombination dynamics are found for the DPM12/P3HT devices. These observations can be directly correlated with the observed increase in Voc, which is in contrast with previous results that correlated the higher Voc with different ideality factors obtained using dark‐diode measurements. The origin for the shift in the DOS can be correlated to the crystallinity of the blend that is influenced by the properties of the included fullerene. 相似文献
30.
Graziamaria Corbi Andrea Bianco Viviana Turchiarelli Michele Cellurale Federica Fatica Aurora Daniele Gennaro Mazzarella Nicola Ferrara 《International journal of molecular sciences》2013,14(6):12696-12713
The development of atherosclerosis is a multi-step process, at least in part controlled by the vascular endothelium function. Observations in humans and experimental models of atherosclerosis have identified monocyte recruitment as an early event in atherogenesis. Chronic inflammation is associated with ageing and its related diseases (e.g., atherosclerosis and chronic obstructive pulmonary disease). Recently it has been discovered that Sirtuins (NAD+-dependent deacetylases) represent a pivotal regulator of longevity and health. They appear to have a prominent role in vascular biology and regulate aspects of age-dependent atherosclerosis. Many studies demonstrate that SIRT1 exhibits anti-inflammatory properties in vitro (e.g., fatty acid-induced inflammation), in vivo (e.g., atherosclerosis, sustainment of normal immune function in knock-out mice) and in clinical studies (e.g., patients with chronic obstructive pulmonary disease). Because of a significant reduction of SIRT1 in rodent lungs exposed to cigarette smoke and in lungs of patients with chronic obstructive pulmonary disease (COPD), activation of SIRT1 may be a potential target for chronic obstructive pulmonary disease therapy. We review the inflammatory mechanisms involved in COPD-CVD coexistence and the potential role of SIRT1 in the regulation of these systems. 相似文献