全文获取类型
收费全文 | 1068篇 |
免费 | 62篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 25篇 |
化学工业 | 311篇 |
金属工艺 | 10篇 |
机械仪表 | 32篇 |
建筑科学 | 20篇 |
能源动力 | 30篇 |
轻工业 | 89篇 |
水利工程 | 10篇 |
石油天然气 | 3篇 |
无线电 | 130篇 |
一般工业技术 | 146篇 |
冶金工业 | 128篇 |
原子能技术 | 4篇 |
自动化技术 | 194篇 |
出版年
2024年 | 2篇 |
2023年 | 15篇 |
2022年 | 73篇 |
2021年 | 69篇 |
2020年 | 32篇 |
2019年 | 17篇 |
2018年 | 42篇 |
2017年 | 31篇 |
2016年 | 28篇 |
2015年 | 28篇 |
2014年 | 44篇 |
2013年 | 68篇 |
2012年 | 70篇 |
2011年 | 65篇 |
2010年 | 38篇 |
2009年 | 36篇 |
2008年 | 49篇 |
2007年 | 46篇 |
2006年 | 41篇 |
2005年 | 24篇 |
2004年 | 23篇 |
2003年 | 17篇 |
2002年 | 19篇 |
2001年 | 16篇 |
2000年 | 10篇 |
1999年 | 26篇 |
1998年 | 41篇 |
1997年 | 23篇 |
1996年 | 27篇 |
1995年 | 8篇 |
1994年 | 9篇 |
1993年 | 15篇 |
1992年 | 6篇 |
1991年 | 6篇 |
1990年 | 3篇 |
1989年 | 6篇 |
1988年 | 2篇 |
1987年 | 5篇 |
1986年 | 3篇 |
1985年 | 5篇 |
1984年 | 4篇 |
1983年 | 5篇 |
1982年 | 2篇 |
1981年 | 5篇 |
1977年 | 9篇 |
1976年 | 3篇 |
1975年 | 3篇 |
1974年 | 2篇 |
1966年 | 2篇 |
1957年 | 1篇 |
排序方式: 共有1132条查询结果,搜索用时 15 毫秒
81.
Conjugated copolymers are important materials for organic light-emitting diodes. Here, an investigation of the photophysical and charge-transporting properties of the prototypical poly(p-phenylene vinylene) based copolymer SuperYellow (SY) is reported. The study also investigated the effect of processing conditions by comparing the properties of spin-coated and solution-cast films. For both types of films, the results of time-resolved fluorescence and photoluminescence quantum yield measurements are similar. The high photoluminescence quantum yield of 60% and its independence of processing conditions shows the effectiveness of the bulky side groups in preventing concentration quenching of fluorescence. Time of flight measurements of charge mobility in both spin-coated and solution-cast films also showed similar results, with mobilities in the range 10?6–10?7 cm2/V s for both films. These results provide important information about a widely used copolymer and show that a good polymer light-emitting diode material can have low mobility. 相似文献
82.
Sabine Barrat Salvatore Tabbone 《Journal of Visual Communication and Image Representation》2010,21(4):355-363
In this paper, we propose a probabilistic graphical model to represent weakly annotated images. We consider an image as weakly annotated if the number of keywords defined for it is less than the maximum number defined in the ground truth. This model is used to classify images and automatically extend existing annotations to new images by taking into account semantic relations between keywords. The proposed method has been evaluated in visual-textual classification and automatic annotation of images. The visual-textual classification is performed by using both visual and textual information. The experimental results, obtained from a database of more than 30,000 images, show an improvement by 50.5% in terms of recognition rate against only visual information classification. Taking into account semantic relations between keywords improves the recognition rate by 10.5%. Moreover, the proposed model can be used to extend existing annotations to weakly annotated images, by computing distributions of missing keywords. Semantic relations improve the mean rate of good annotations by 6.9%. Finally, the proposed method is competitive with a state-of-art model. 相似文献
83.
84.
Paolo Ghetti Ubaldo De Robertis Salvatore DAntone Marco Villani Emo Chiellini 《Fuel》1985,64(7):950-955
A series of coals of different rank has been characterized by surface area measurements performed by sorption of both nitrogen and carbon dioxide. While the data obtained with nitrogen do not discriminate among the different coal samples, those based on carbon dioxide sorption do give a significant distinction between the samples. This technique has also been applied to the determination of the surface area of coal samples quenched after stepwise combustion in air atmosphere. It has been possible to establish a useful correlation between the latter data and the burning profile measured by derivative thermogravimetry. The aim of the present study was to gain a better understanding of the coal combustion process on a laboratory scale which could reasonably be extended to combustion plants. The results presented are relevant to some of the multivalent aspects inherent in the coal combustion process and some valuable information has been gained in respect of characterization of solid fuels. 相似文献
85.
Robust ordinal regression in preference learning and ranking 总被引:1,自引:0,他引:1
Salvatore Corrente Salvatore Greco Miłosz Kadziński Roman Słowiński 《Machine Learning》2013,93(2-3):381-422
Multiple Criteria Decision Aiding (MCDA) offers a diversity of approaches designed for providing the decision maker (DM) with a recommendation concerning a set of alternatives (items, actions) evaluated from multiple points of view, called criteria. This paper aims at drawing attention of the Machine Learning (ML) community upon recent advances in a representative MCDA methodology, called Robust Ordinal Regression (ROR). ROR learns by examples in order to rank a set of alternatives, thus considering a similar problem as Preference Learning (ML-PL) does. However, ROR implements the interactive preference construction paradigm, which should be perceived as a mutual learning of the model and the DM. The paper clarifies the specific interpretation of the concept of preference learning adopted in ROR and MCDA, comparing it to the usual concept of preference learning considered within ML. This comparison concerns a structure of the considered problem, types of admitted preference information, a character of the employed preference models, ways of exploiting them, and techniques to arrive at a final ranking. 相似文献
86.
Davide Marano Gaetano Palumbo Salvatore Pennisi 《Analog Integrated Circuits and Signal Processing》2010,65(2):289-298
The present paper addresses a new compact low-power high-speed output buffer amplifier topology for large-size liquid crystal
display applications. The suggested buffer achieves fast driving performance, draws a low quiescent current during static
operation and offers a rail-to-rail common-mode input range. The circuit provides enhanced slewing capabilities with a limited
power consumption by simultaneously exploiting the push–pull output sections of two basic complementary-type input amplifiers
to realize a dual-path push–pull operation of the output stage. An auxiliary biasing network integrated in the input differential
stage allows the quiescent bias conditions of the class-AB output stage to be inherently controlled without additional current
dissipation. Post-layout simulation results confirm that the proposed amplifier can drive a 1-nF column line load within a
0.9-μs settling time under a 3-V full voltage swing, while drawing only 3.5-μA quiescent current. Monte Carlo simulations
are finally carried out, showing a good degree of robustness of the proposed output buffer against process and mismatch variations. 相似文献
87.
Giovanna Rassu Elisabetta Gavini Gianpiera Spada Salvatore Marceddu 《Drug development and industrial pharmacy》2013,39(11):1178-1187
The preparation of ketoprofen spray-dried microspheres can be affected by the long drug recrystallization time. Polymer type and drug–polymer ratio as well as manufacturing parameters affect the preparation. The purpose of this work was to evaluate the possibility to obtain ketoprofen spray-dried microspheres using the Eudragit® RS and RL; the influence of the spray-drying parameters on morphology, dimension, and physical stability of microspheres was studied. Ketoprofen microspheres based on Eudragit® blend can be prepared by spray-drying and the nebulization parameters do not influence significantly particle properties; nevertheless, they can be affected by drying and storage methods. No effect of the container material is found. 相似文献
88.
Monsurro P. Pennisi S. Scotti G. Trifiletti A. 《IEEE transactions on instrumentation and measurement》2008,57(7):1431-1437
This paper presents a unity-gain amplifier architecture, which, unlike already known solutions, provides a theoretically zero gain error without requiring an infinitely large loop gain. The architecture is based on two amplifiers nested in a feedback configuration, which allows a straightforward complementary metal-oxide-semiconductor (CMOS) implementation. Performances are analytically evaluated and compared to those of the traditional solution under similar design settings. Simulations using a 0.35-mum CMOS process are found to be in agreement with theory, and Monte Carlo simulations have also shown the robustness of the proposed approach against process tolerances. 相似文献
89.
A new method is proposed for the analysis of waveforms in a three-phase system when both distortion and unbalance are present. The method makes it possible to obtain the positive and negative-sequence components of each harmonic system present in the three phases. This method provides a way to get information both on the degree of unbalance and on the distortion factors of the waveforms generated by pulsewidth-modulated inverters supplying induction motors 相似文献
90.
Salvatore Federico Shoji Imatani Walter Herzog 《International Journal of Engineering Science》2008,46(2):164-181
We demonstrate that for the class of anisotropic hyperelastic materials with stiffening behaviour (i.e., the stiffness increases for increasing strain), it is possible to find an approximation by means of the linear superposition of an anisotropic quadratic potential, generated by the true linear elasticity tensor of the target material, and a suitable correction potential that is isotropic and hyperelastic. The proposed method can be implemented into commercially available Finite Element software by use of featured options only. This approach is intended to provide the solution to a stress-strain problem, based entirely on energetic considerations, which ensures the convexity of the potentials, and provides a simple material characterisation procedure. 相似文献