全文获取类型
收费全文 | 2772篇 |
免费 | 154篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 28篇 |
综合类 | 1篇 |
化学工业 | 695篇 |
金属工艺 | 49篇 |
机械仪表 | 58篇 |
建筑科学 | 83篇 |
矿业工程 | 4篇 |
能源动力 | 109篇 |
轻工业 | 209篇 |
水利工程 | 8篇 |
石油天然气 | 4篇 |
无线电 | 313篇 |
一般工业技术 | 529篇 |
冶金工业 | 214篇 |
原子能技术 | 14篇 |
自动化技术 | 610篇 |
出版年
2023年 | 30篇 |
2022年 | 47篇 |
2021年 | 68篇 |
2020年 | 67篇 |
2019年 | 58篇 |
2018年 | 75篇 |
2017年 | 68篇 |
2016年 | 93篇 |
2015年 | 71篇 |
2014年 | 112篇 |
2013年 | 186篇 |
2012年 | 192篇 |
2011年 | 244篇 |
2010年 | 190篇 |
2009年 | 165篇 |
2008年 | 157篇 |
2007年 | 158篇 |
2006年 | 115篇 |
2005年 | 96篇 |
2004年 | 73篇 |
2003年 | 54篇 |
2002年 | 58篇 |
2001年 | 57篇 |
2000年 | 35篇 |
1999年 | 45篇 |
1998年 | 85篇 |
1997年 | 60篇 |
1996年 | 26篇 |
1995年 | 27篇 |
1994年 | 19篇 |
1993年 | 26篇 |
1992年 | 27篇 |
1991年 | 12篇 |
1990年 | 17篇 |
1989年 | 9篇 |
1988年 | 6篇 |
1987年 | 10篇 |
1986年 | 8篇 |
1985年 | 6篇 |
1984年 | 6篇 |
1983年 | 7篇 |
1982年 | 7篇 |
1981年 | 4篇 |
1980年 | 4篇 |
1979年 | 8篇 |
1978年 | 5篇 |
1977年 | 6篇 |
1976年 | 9篇 |
1975年 | 4篇 |
1970年 | 3篇 |
排序方式: 共有2928条查询结果,搜索用时 15 毫秒
51.
Unraveling Unprecedented Charge Carrier Mobility through Structure Property Relationship of Four Isomers of Didodecyl[1]benzothieno[3,2‐b][1]benzothiophene
下载免费PDF全文
![点击此处可从《Advanced materials (Deerfield Beach, Fla.)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Yusuke Tsutsui Guillaume Schweicher Basab Chattopadhyay Tsuneaki Sakurai Jean‐Baptiste Arlin Christian Ruzié Almaz Aliev Artur Ciesielski Alan R. Kennedy Vincent Lemaur Yoann Olivier Rachid Hadji Lionel Sanguinet Frédéric Castet Silvio Osella Dmytro Dudenko David Beljonne Jérôme Cornil Paolo Samorì Shu Seki Yves H. Geerts 《Advanced materials (Deerfield Beach, Fla.)》2016,28(33):7106-7114
52.
Sabeha Yala Mahfoud Boustta Olivier Gallet Mathilde Hindié Franck Carreiras Hamanou Benachour Djahida Sidane Hafit Khireddine 《Journal of materials science. Materials in medicine》2016,27(9):140
A novel synthetic method to synthesize hydroxyapatite/poly (D,L) lactic acid biocomposite is presented in this study by mixing only the precursors hydroxyapatite and (D,L) LA monomer without adding neither solvent nor catalyst. Three compositions were successfully synthesized with the weight ratios of 1/1, 1/3, and 3/5 (hydroxyapatite/(D,L) lactic acid), and the grafting efficiency of poly (D,L) lactic acid on hydroxyapatite surface reaches up to 84?%. Scanning electron microscopy and Fourier transform infrared spectroscopy showed that the hydroxyapatite particles were successfully incorporated into the poly (D,L) lactic acid polymer and X ray diffraction analysis showed that hydroxyapatite preserved its crystallinity after poly (D,L) lactic acid grafting. Differential scanning calorimetry shows that Tg of hydroxyapatite/poly (D,L) lactic acid composite is less than Tg of pure poly (D,L) lactic acid, which facilitates the shaping of the composite obtained. The addition of poly (D,L) lactic acid improves the adsorption properties of hydroxyapatite for fibronectin extracellular matrix protein. Furthermore, the presence of poly (D,L) lactic acid on hydroxyapatite surface coated with fibronectin enhanced pre-osteoblast STRO-1 adhesion and cell spreading. These results show the promising potential of hydroxyapatite/poly (D,L) lactic acid composite as a bone substitute material for orthopedic applications and bone tissue engineering. 相似文献
53.
Olivier Guillon Christian Elsässer Oliver Gutfleisch Jürgen Janek Sandra Korte-Kerzel Dierk Raabe Cynthia A. Volkert 《Materials Today》2018,21(5):527-536
The use of external electric and magnetic fields for the synthesis and processing of inorganic materials such as metals and ceramics has seen renewed interest in recent years. Electromagnetic energy can be utilized in different ways to improve or accelerate phase formation and stabilization, chemical ordering, densification and coarsening of particle-based materials (pore elimination and grain growth), and mechanical deformation (plasticity and creep). In these new synthesis and processing routes, the resulting microstructures and macroscopic material behavior are determined by the interaction of the applied fields with defects such as single or clustered point defects, dislocation networks, and interfaces. Multiscale experimental investigations and modeling are necessary to unveil the mechanisms underlying this field-assisted manipulation of matter. 相似文献
54.
Sinan Boztepe Rémi Gilblas Olivier de Almeida Christian Gerlach Yannick Le Maoult Fabrice Schmidt 《International Journal of Material Forming》2018,11(5):717-727
Infrared (IR) heating is widely used for thermoforming of thermoplastic polymers. The key benefit of radiation heating is that a significant amount of the radiative energy penetrates into the polymers thanks to their semi-transparency. For the case of heating unfilled semi-crystalline polymers, the relation between their microcrystalline structure and optical properties is the key to develop a predictive IR-heating model as microcrystalline structure introduces an optically heterogeneous medium. In this study, a relation between the microcrystalline structure of a polyethylene (PE) and its effect on the thermo-optical properties was experimentally analyzed considering a two-step analysis. At very first step, the relation was analyzed considering samples with identical thicknesses and different morphologies, characterized here in terms of degree of crystallinity (Xc (%)). Using Fourier Transform Infrared (FT-IR) spectroscopy and integrating sphere, optical characteristics of the PE samples were analyzed in near-infrared (NIR) and middle-infrared (MIR) spectral ranges. The analyses showed that a slight variation in Xc (%) has a great effect on the optical characteristics of PE, particularly the transmission characteristics in NIR range. The wavelength-dependent effect of Xc (%) on the transmission behaviors opened a discussion about the fact that the microcrystalline structures -in particular spherulites or their substructures such as lamellae- are responsible for optical scattering. Using the optical properties obtained from the two-step experimental analyses, two different thermo-optical properties were calculated, namely extinction and absorption coefficients, and used as a numerical input for the parametric numerical studies. The numerical studies were performed using an in-house developed radiation heat transfer algorithm -RAYHEAT-. Both the experimental and numerical analyses demonstrated the importance of the optical scattering regarding the identification of thermo-optical properties, used as a numerical input for radiation heat transfer models. 相似文献
55.
Fernando Maccari Tarini Prasad Mishra Monica Keszler Tobias Braun Esmaeil Adabifiroozjaei Iliya Radulov Tianshu Jiang Enrico Bruder Olivier Guillon Leopoldo Molina-Luna Martin Bram Oliver Gutfleisch 《Advanced Engineering Materials》2023,25(18):2300252
Flash spark plasma sintering (flash SPS) is an attractive method to obtain Nd–Fe–B magnets with anisotropic magnetic properties when starting from melt-spun powders. Compared to the benchmark processing route via hot pressing with subsequent die upsetting, flash SPS promises electroplasticity as an additional deformation mechanism and reduced tool wear, while maximizing magnetic properties by tailoring the microstructure—fully dense and high texture. A detailed parameter study is conducted to understand the influence of Flash SPS parameters on the densification and magnetic properties of commercial MQU-F powder. It is revealed that the presintering conditions and preheating temperature before applying the power pulse play a major role for tailoring grain size and texture in the case of hot deformation via Flash SPS. Detailed microstructure and magnetic domain evaluation disclose the texture enhancement with increasing flash SPS temperature at the expense of coercivity. The best compromise between remanence and coercivity (1.37 T and 1195 kA m−1, respectively) is achieved through a combination of presintering at 500 °C for 120 s and preheating temperature of 600 °C, resulting in a magnet with energy product (BH)max of 350 kJm−3. These findings show the potential of flash SPS to obtain fully dense anisotropic nanocrystalline magnets with high magnetic performance. 相似文献
56.
Olivier Guillon Wolfgang Rheinheimer Martin Bram 《Advanced Engineering Materials》2023,25(18):2201870
Novel sintering methods have emerged in the recent past years, which have raised great interest in the scientific community. Relying on electric field effects, high heating rates, the use of mechanical pressure, or hydrothermal conditions, they offer fundamental advantages compared to conventional sintering routes like minimizing the energy consumption and enhancing the process efficiency. This perspective aims at explaining these effects in a general way and presenting the status quo of using them for the processing of high-performing ceramic materials. In detail, this work focuses on flash sintering, ultrafast high-temperature sintering, spark plasma sintering, cold sintering, and photonic sintering methods based on different light sources. The specificities, potentials, and limitations of each method are compared, especially in the light of a possible industrialization. 相似文献
57.
Olivier Llopis Jean-Marc Dienot Jacques Verdier Robert Plana Michel Gayral Jacques Graffeuil 《电信纪事》1996,51(3-4):121-129
The conversion of low frequency noise into phase noise in microwave oscillators is studied through an analytical calculation of the pushing factor. This calculation is based on a simplified equivalent circuit for two types of active devices : field effect transistors (Fet) and heterojunction bipolar transistors (hbt). The preeminence in the conversion process of the gate- source capacitance in theFet and the base- emitter junction in thehbt is pointed out. Practical methods are proposed to reduce the phase noise in these circuits. 相似文献
58.
Motion of points and lines in the uncalibrated case 总被引:4,自引:4,他引:0
Thierry Viéville Olivier Faugeras Quang-Tuan Luong 《International Journal of Computer Vision》1996,17(1):7-41
In the present paper we address the problem of computing structure and motion, given a set point and/or line correspondences, in a monocular image sequence, when the camera is not calibrated.Considering point correspondences first, we analyse how to parameterize the retinal correspondences, in function of the chosen geometry: Euclidean, affine or projective geometry. The simplest of these parameterizations is called the FQs-representation and is a composite projective representation. The main result is that considering N+1 views in such a monocular image sequence, the retinal correspondences are parameterized by 11 N–4 parameters in the general projective case. Moreover, 3 other parameters are required to work in the affine case and 5 additional parameters in the Euclidean case. These 8 parameters are calibration parameters and must be calculated considering at least 8 external informations or constraints. The method being constructive, all these representations are made explicit.Then, considering line correspondences, we show how the the same parameterizations can be used when we analyse the motion of lines, in the uncalibrated case. The case of three views is extensively studied and a geometrical interpretation is proposed, introducing the notion of trifocal geometry which generalizes the well known epipolar geometry. It is also discussed how to introduce line correspondences, in a framework based on point correspondences, using the same equations.Finally, considering the F Qs-representation, one implementation is proposed as a motion module, taking retinal correspondences as input, and providing and estimation of the 11 N–4 retinal motion parameters. As discussed in this paper, this module can also estimate the 3D depth of the points up to an affine and projective transformation, defined by the 8 parameters identified in the first section. Experimental results are provided. 相似文献
59.
An improved algorithm for disaggregating microwave-derived soil moisture based on red, near-infrared and thermal-infrared data 总被引:3,自引:0,他引:3
Accurate high-resolution soil moisture data are needed for a range of agricultural and hydrologic activities. To improve the spatial resolution of ∼ 40 km resolution passive microwave-derived soil moisture, a methodology based on 1 km resolution MODIS (MODerate resolution Imaging Spectroradiometer) red, near-infrared and thermal-infrared data has been implemented at 4 km resolution. The three components of that method are (i) fractional vegetation cover, (ii) soil evaporative efficiency (defined as the ratio of actual to potential evaporation) and (iii) a downscaling relationship. In this paper, 36 different disaggregation algorithms are built from 3 fractional vegetation cover formulations, 3 soil evaporative efficiency models, and 4 downscaling relationships. All algorithms differ with regard to the representation of the nonlinear relationship between microwave-derived soil moisture and optical-derived soil evaporative efficiency. Airborne L-band data collected over an Australian agricultural area are used to both generate ∼ 40 km resolution microwave pixels and verify disaggregation results at 4 km resolution. Among the 36 disaggregation algorithms, one is identified as being more robust (insensitive to soil, vegetation and atmospheric variables) than the others with a mean slope between MODIS-disaggregated and L-band derived soil moisture of 0.94. The robustness of that algorithm is notably assessed by comparing the disaggregation results obtained using composited (averaged) Terra and Aqua MODIS data, and using data from Terra and Aqua separately. The error on disaggregated soil moisture is systematically reduced by compositing daily Terra and Aqua data with an error of 0.012 vol./vol. 相似文献
60.
Yacine Rebahi Mohamed Nassar Thomas Magedanz Olivier FestorAuthor vitae 《Information Security Technical Report》2011,16(1):12-19
The migration from circuit-switched networks to packet-switched networks necessitates the investigation of related issues such as service delivery, QoS, security, and service fraud and misuse. The latter can be seen as a combination of accounting and security aspects. In traditional telecommunication networks, fraud accounts for annual losses at an average of 3%–5% of the operators’ revenue and still increasing at a rate of more than 10% yearly. It is also expected that in VoIP networks, the situation will be worse due to the lack of strong built-in security mechanisms, and the use of open standards. This paper discusses the fraud problem in VoIP networks and evaluates the related available solutions. 相似文献