全文获取类型
收费全文 | 975篇 |
免费 | 46篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 12篇 |
化学工业 | 191篇 |
金属工艺 | 19篇 |
机械仪表 | 18篇 |
建筑科学 | 29篇 |
矿业工程 | 4篇 |
能源动力 | 44篇 |
轻工业 | 94篇 |
水利工程 | 10篇 |
石油天然气 | 8篇 |
无线电 | 107篇 |
一般工业技术 | 181篇 |
冶金工业 | 141篇 |
原子能技术 | 19篇 |
自动化技术 | 145篇 |
出版年
2023年 | 7篇 |
2022年 | 30篇 |
2021年 | 46篇 |
2020年 | 7篇 |
2019年 | 32篇 |
2018年 | 31篇 |
2017年 | 35篇 |
2016年 | 33篇 |
2015年 | 19篇 |
2014年 | 42篇 |
2013年 | 72篇 |
2012年 | 44篇 |
2011年 | 66篇 |
2010年 | 44篇 |
2009年 | 48篇 |
2008年 | 44篇 |
2007年 | 35篇 |
2006年 | 27篇 |
2005年 | 12篇 |
2004年 | 21篇 |
2003年 | 18篇 |
2002年 | 15篇 |
2001年 | 18篇 |
2000年 | 8篇 |
1999年 | 15篇 |
1998年 | 34篇 |
1997年 | 25篇 |
1996年 | 16篇 |
1995年 | 15篇 |
1994年 | 22篇 |
1993年 | 14篇 |
1992年 | 6篇 |
1991年 | 5篇 |
1990年 | 5篇 |
1989年 | 6篇 |
1988年 | 4篇 |
1987年 | 6篇 |
1986年 | 5篇 |
1985年 | 11篇 |
1982年 | 8篇 |
1981年 | 9篇 |
1980年 | 7篇 |
1979年 | 7篇 |
1978年 | 3篇 |
1977年 | 10篇 |
1976年 | 7篇 |
1974年 | 3篇 |
1973年 | 4篇 |
1972年 | 7篇 |
1971年 | 3篇 |
排序方式: 共有1022条查询结果,搜索用时 15 毫秒
141.
AJ Ferreira WP Elias JS Pelayo R Giraldi MZ Pedroso IC Scaletsky 《Canadian Metallurgical Quarterly》1997,19(4):285-288
In the present study, in order to get a better insight into the mechanism of action of cyclophosphamide (CY) in rheumatoid arthritis (RA), we monitored the changes in lymphocytes' expression of leukocyte function associated antigen 1 (LFA-1). A group of 28 patients with refractory severe RA were treated with CY and methylprednisolone (MO) intravenously. Using flow cytometry we evaluated the changes in LFA-1 molecule expression on peripheral lymphocytes. In the analyzed group of patients the proportion of LFA-1 "dim" cells was reduced. After the treatment the ratio was partly normalized. Twelve months after cessation of the therapy high proportion of LFA-1 "dim" was observed only among CY/MP treated patients. The changes were related to clinical improvement. Based on the obtained data, it seems, that the treatment affecting the expression of LFA-1 may slow down lymphocyte migration and by that limit chronic inflammation within the synovium. 相似文献
142.
Tiago de Araújo Elias Paulo Renato Costa Mendes Júlio Elias Normey‐Rico 《Asian journal of control》2019,21(4):1881-1891
This paper presents a control algorithm for reducing heat losses caused by clouds in large solar fields. The formulation is based on a Mixed Logical Dynamical (MLD) representation of the solar field plus the application of a Practical Nonlinear Model Predictive Controller (PNMPC) for calculating the optimal control action. The main purpose of the controller is to deactivate fields with inlet temperature greater than outlet temperature and to manipulate the oil flow rate of the activated fields for tracking the reference of the outlet temperature. A simplified lumped parameters model is used for prediction and simulation of the solar fields. 相似文献
143.
Hussain Ali Badran Ahmed Al-Maliki R. K. Fakher Alfahed Bahjat Ali Saeed A. Y. Al-Ahmad F. A. Al-Saymari Rita S. Elias 《Journal of Materials Science: Materials in Electronics》2018,29(13):10890-10903
Curcumin and other three curcuminoids (bisdemethoxycurcumin, α-chlorocurcumin and α-methylcurcumin) were synthesized. Fourier transform infrared spectroscopy, Fluorescence quantum yields, AFM analysis and image surface profiles were characterized. All compounds possessed electron donor moieties at both ends of the conjugated π-system and an electron acceptor moiety in the middle of the molecules (D-A-D system) and should exhibit different optical properties depending on substituents on the benzene rings. The third order nonlinear optical properties of the curcuminoids have been investigated by z-scan technique. The optical response was characterized by measuring the refractive index (n2) of the derivatives of curcumin using the Z-scan technique. The compounds showed negative and large nonlinear refractive index values of the order of 10?7 cm2/W and reverse saturable absorption with high values of the nonlinear absorption coefficient of the order of 10?4 cm/W. The nonlinear refractive index was found to vary with the different compound. The optical constants of the different compound films were studied and the dispersion of the refractive index was discussed in terms of the Wemple-DiDomenico single oscillator model. The photo-physical properties of these compounds are compared to those of native curcumin, in order to provide a rationale to the design of samples with molecular structures optimized for a photosensitizer. These types of materials may be considering new photonic applications. 相似文献
144.
145.
Multimedia Tools and Applications - Motion capture data describe human movements in the form of spatio-temporal trajectories of skeleton joints. Intelligent management of such complex data is a... 相似文献
146.
Henri Rebecq Guillermo Gallego Elias Mueggler Davide Scaramuzza 《International Journal of Computer Vision》2018,126(12):1394-1414
Event cameras are bio-inspired vision sensors that output pixel-level brightness changes instead of standard intensity frames. They offer significant advantages over standard cameras, namely a very high dynamic range, no motion blur, and a latency in the order of microseconds. However, because the output is composed of a sequence of asynchronous events rather than actual intensity images, traditional vision algorithms cannot be applied, so that a paradigm shift is needed. We introduce the problem of event-based multi-view stereo (EMVS) for event cameras and propose a solution to it. Unlike traditional MVS methods, which address the problem of estimating dense 3D structure from a set of known viewpoints, EMVS estimates semi-dense 3D structure from an event camera with known trajectory. Our EMVS solution elegantly exploits two inherent properties of an event camera: (1) its ability to respond to scene edges—which naturally provide semi-dense geometric information without any pre-processing operation—and (2) the fact that it provides continuous measurements as the sensor moves. Despite its simplicity (it can be implemented in a few lines of code), our algorithm is able to produce accurate, semi-dense depth maps, without requiring any explicit data association or intensity estimation. We successfully validate our method on both synthetic and real data. Our method is computationally very efficient and runs in real-time on a CPU. 相似文献
147.
Mirjana Dimitrievska Fredrik S. Hage Simon Escobar Steinvall Alexander P. Litvinchuk Elias Z. Stutz Quentin M. Ramasse Anna Fontcuberta i Morral 《Advanced functional materials》2021,31(41):2105426
Earth-abundant and environmentally friendly semiconductors offer a promising path toward low-cost mass production of solar cells. A critical aspect in exploring new semiconducting materials and demonstrating their enhanced functionality consists in disentangling them from the artifacts of defects. Nanowires are diameter-tailored filamentary structures that tend to be defect-free and thus ideal model systems for a given material. Here, an additional advantage is demostrated, which is the determination of the band structure, by performing high energy and spatial resolution electron energy-loss spectroscopy in aloof and inner beam geometry in a scanning transmission electron microscope. The experimental results are complemented by spectroscopic ellipsometry and are excellently correlated with first principles calculations. This study opens the path for characterizing the band structure of new compounds in a non-destructive and prompt manner, strengthening the route of new materials discovery. 相似文献
148.
The subunit structure of human macrophage migration inhibitory factor: evidence for a trimer 总被引:1,自引:0,他引:1
Sun Hong-Wei; Swope Melissa; Craig Cinquina; Bedarkar Sudhir; Bernhagen Jurgen; Bucala Richard; Lolis Elias 《Protein engineering, design & selection : PEDS》1996,9(8):631-635
The subunit structure of human macrophage migration inhibitoryfactor (MIF) has been studied by preliminary X-ray analysisof wild-type and selenomethionine-MIF and dynamic light scattering.Crystal form I of MIF belongs to space group P212121 and isgrown from 2 M ammonium sulfate at pH 8.5. A native data sethas been collected to 2.4 Å resolution. Self-rotationstudies and Vm values indicate that three molecules per asymmetricunit are present A data set to 2.8 Å resolution has beencollected for crystal form II, which belongs to space groupP3121 or P3221 and grows from 2 M ammonium sulfate, 2% polyethyleneglycol (average molecular mass 400), 0.1 M HEPES, pH 7.5. Three,four, five or six monomers in the asymmetric unit are consistentwith Vm values for this crystal form. Analysis of crystal formII containing selenomethionine-MIF indicates nine selenium sitesare present per asymmetric unit. Dynamic light scattering ofMIF suggests that the major form of the protein in solutionis a trimer. The results of these studies are in contrast toprevious reports indicating that MIF is a monomer or dimer.The subunit arrangement of MIF is similar to that of tumor necrosisfactor and suggests that signal transduction might require trimerizationof receptor subunits. 相似文献
149.
Elias Saab Samer Aouad Edmond Abi-Aad Elena Zhilinskaya Antoine Aboukaïs 《Catalysis Today》2007,119(1-4):286-290
Carbon black oxidation in the presence of CeO2, Al2O3 and manganese oxide catalysts has been studied in tight contact conditions. In the presence of manganese based catalysts, the temperature gain is about 275 °C compared to the non-catalysed carbon black oxidation. The contribution of the manganese species to enhance the reactivity of carbon black oxidation has been evaluated by EPR technique. For Mn/Ce + CB mixtures the Mn2+ content considerably increases consequently to tight milled treatment indicating the reduction of some manganese species with higher oxidation states into Mn2+ ions. This phenomenon can be considered as the first step in the carbon black oxidation mechanism in the presence of Mn/Ce catalysts. 相似文献
150.
Brock J. DeLong Sandhiya Reddy Govindarajulu Markus H. Novak Elias A. Alwan John L. Volakis 《Analog Integrated Circuits and Signal Processing》2018,97(3):557-563
We present a 60 GHz phased array system that combines several key technologies to realize 10 GHz bandwidth coverage. Particularly, a tightly coupled dipole array centered at 60 GHz is designed and tested for its wideband performance. The tightly coupled dipole elements offer excellent wideband behavior of 10 GHz with voltage standing wave ratio?<?3 with scanning to 45°, as well as low cost printed circuit board fabrication. Additionally, we demonstrate a measurement setup with de-embedding procedure to measure gain at the antenna feed point. A feeding structure was designed and fabricated for de-embedding gain pattern measurements. Recovered measurements are shown to be in agreement with simulation. 相似文献