全文获取类型
收费全文 | 436篇 |
免费 | 10篇 |
专业分类
电工技术 | 3篇 |
综合类 | 1篇 |
化学工业 | 146篇 |
金属工艺 | 2篇 |
机械仪表 | 9篇 |
建筑科学 | 8篇 |
能源动力 | 15篇 |
轻工业 | 17篇 |
水利工程 | 2篇 |
无线电 | 70篇 |
一般工业技术 | 94篇 |
冶金工业 | 14篇 |
原子能技术 | 6篇 |
自动化技术 | 59篇 |
出版年
2023年 | 6篇 |
2022年 | 21篇 |
2021年 | 15篇 |
2020年 | 5篇 |
2019年 | 10篇 |
2018年 | 10篇 |
2017年 | 9篇 |
2016年 | 13篇 |
2015年 | 8篇 |
2014年 | 11篇 |
2013年 | 19篇 |
2012年 | 28篇 |
2011年 | 25篇 |
2010年 | 33篇 |
2009年 | 25篇 |
2008年 | 23篇 |
2007年 | 19篇 |
2006年 | 20篇 |
2005年 | 14篇 |
2004年 | 9篇 |
2003年 | 10篇 |
2002年 | 8篇 |
2001年 | 7篇 |
2000年 | 9篇 |
1999年 | 7篇 |
1998年 | 7篇 |
1997年 | 7篇 |
1996年 | 6篇 |
1995年 | 5篇 |
1994年 | 4篇 |
1993年 | 4篇 |
1992年 | 6篇 |
1991年 | 2篇 |
1990年 | 3篇 |
1989年 | 4篇 |
1988年 | 2篇 |
1987年 | 2篇 |
1985年 | 6篇 |
1984年 | 3篇 |
1982年 | 3篇 |
1981年 | 3篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1978年 | 2篇 |
1977年 | 2篇 |
1976年 | 3篇 |
1975年 | 1篇 |
1973年 | 1篇 |
1972年 | 1篇 |
1957年 | 1篇 |
排序方式: 共有446条查询结果,搜索用时 0 毫秒
1.
Piero Barone 《时间序列分析杂志》1987,8(2):125-130
Abstract. A method for generating finite independent realizations of a normal multivariate stationary ARMA( p, q ) process is proposed. It is based on an AR (1) representation of an ARMA( p, q ) process allowing for an exact generation of the initial values of the simulation algorithm. Input facilities are supplied in order to assure stationarity and invertibility of the considered process. 相似文献
2.
Piero A. Bonatti 《Artificial Intelligence》2004,156(1):75-111
This paper illustrates extensively the theoretical properties, the implementation issues, and the programming style underlying finitary programs. They are a class of normal logic programs whose consequences under the stable model semantics can be effectively computed, despite the fact that finitary programs admit function symbols (hence infinite domains) and recursion. From a theoretical point of view, finitary programs are interesting because they enjoy properties that are extremely unusual for a nonmonotonic formalism, such as compactness. From the application point of view, the theory of finitary programs shows how the existing technology for answer set programming can be extended from problem solving below the second level of the polynomial hierarchy to all semidecidable problems. Moreover, finitary programs allow a more natural encoding of recursive data structures and may increase the performance of credulous reasoners. 相似文献
3.
Sergio Brovelli Francesco Meinardi Gustaf Winroth Oliver Fenwick Giuseppe Sforazzini Michael J. Frampton Leszek Zalewski James A. Levitt Francesco Marinello Piero Schiavuta Klaus Suhling Harry L. Anderson Franco Cacialli 《Advanced functional materials》2010,20(2):272-280
Here, it is demonstrated that energy transfer in a blend of semiconducting polymers can be strongly reduced by non‐covalent encapsulation of one constituent, ensured by threading of the conjugated strands into functionalized cyclodextrins. Such macrocycles control the minimum intermolecular distance of chromophores with similar alignment, at the nanoscale, and therefore the relevant energy transfer rates, thus enabling fabrication of white‐light‐emitting diodes (CIE coordinates: x = 0.282, y = 0.336). In particular, white electroluminescence in a binary blend of a blue‐emitting, organic‐soluble rotaxane based on a polyfluorene derivative and the green‐emitting poly(9,9‐dioctylfluorene‐alt‐benzothiadiazole ( F8BT ) is achieved. Morphological and structural analyses by atomic force microscopy, fluorescence mapping, µ‐Raman, and fluorescence lifetime microscopy are used to complement optical and electroluminescence characterization, and to enable a deeper insight into the properties of the novel blend. 相似文献
4.
Luca Picolli Marco Grassi Andrea Fornasari Piero Malcovati 《Analog Integrated Circuits and Signal Processing》2011,66(2):223-233
In this paper an integrated interface circuit for condenser MEMS microphones is presented. It consists of an input buffer
followed by a multi-bit (12-levels), analog, second-order ΣΔ modulator and a fully-digital, single-bit, fourth-order ΣΔ modulator,
thus providing a single-bit output signal with fourth order noise shaping, compatible with standard audio chipsets. The circuit,
supplied with 3.3 V, exhibits a current consumption of 215 μA for the analog part and 95 μA for the digital part. The measured
signal-to-noise and distortion ratio (SNDR) is 71 dB, with an input signal amplitude as large as −1.8 dB with respect to full-scale, obtained thanks to the use of a
feed-forward architecture in the analog ΣΔ modulator, which relaxes the voltage swing requirements of the operational amplifiers.
The test chip, fabricated in a 0.35-μm CMOS process, occupies an area of 3 mm2, including pads. 相似文献
5.
Arunachalam K Maccarini P De Luca V Tognolatti P Bardati F Snow B Stauffer P 《IEEE transactions on bio-medical engineering》2011,58(6):1629-1636
Microwave (MW) radiometry is proposed for passive monitoring of kidney temperature to detect vesicoureteral reflux (VUR) of urine that is externally heated by a MW hyperthermia device and thereafter reflows from the bladder to kidneys during reflux. Here, we characterize in tissue-mimicking phantoms the performance of a 1.375 GHz radiometry system connected to an electromagnetically (EM) shielded microstrip log spiral antenna optimized for VUR detection. Phantom EM properties are characterized using a coaxial dielectric probe and network analyzer (NA). Power reflection and receive patterns of the antenna are measured in layered tissue phantom. Receiver spectral measurements are used to assess EM shielding provided by a metal cup surrounding the antenna. Radiometer and fiberoptic temperature data are recorded for varying volumes (10-30 mL) and temperaturesg (40-46°C) of the urine phantom at 35 mm depth surrounded by 36.5°C muscle phantom. Directional receive pattern with about 5% power spectral density at 35 mm target depth and better than -10 dB return loss from tissue load are measured for the antenna. Antenna measurements demonstrate no deterioration in power reception and effective EM shielding in the presence of the metal cup. Radiometry power measurements are in excellent agreement with the temperature of the kidney phantom. Laboratory testing of the radiometry system in temperature-controlled phantoms supports the feasibility of passive kidney thermometry for VUR detection. 相似文献
6.
P. Migliorato C. Reita G. Tallarida M. Quinn G. Fortunato 《Solid-state electronics》1995,38(12):2075-2079
The anomalous off-current (Ioff) in polysilicon thin film transistors (polysilicon TFTs) is one of the major problems preventing a wide use of these devices in active matrix liquid crystal displays. While previous investigations have focused on the temperature range above 300 K, in this study we have investigated the behaviour of Ioff over a wide range of temperatures, namely 180–400 K. The data have been analysed by combining 2D simulations and existing analytic models. By this approach we have identified a pure trap-to-band tunnelling mechanism in polysilicon TFTs and deduced, by a simple procedure, the physical constants. The temperature and bias dependence of the off-current has been explained quantitatively in terms of phonon-assisted tunnelling. The number of generating centres, the dominant trap energy and the thermal capture cross section are deduced from this analysis. 相似文献
7.
Piero Malcovati Luca Picolli Lorenzo Crespi Faouzi Chaahoub Andrea Baschirotto 《Analog Integrated Circuits and Signal Processing》2010,64(2):159-172
In this paper a dual operating mode 8-bit, 1.1-V pipeline ADC for Gigabit Ethernet applications is presented. In the two operating
modes, the ADC features different sampling frequency (125 and 250 MHz) and power consumption (9.4 and 22.8 mW). Considering
a signal bandwidth of 60 MHz in both operating modes, as required by the Gigabit Ethernet standard, the ADC achieves a SNDR always larger than 39.4 dB at 125 MHz and 38.7 dB at 250 MHz (6.25-bit and 6.13-bit ENOB, respectively), with a FoM of 0.84 pJ/conv at 125 MHz and 2.2 pJ/conv at 250 MHz. The ENOB achieved is mainly limited by clock jitter. The ADC is fabricated with a 90-nm CMOS technology, with an active area of 1.25
× 0.65 mm2. 相似文献
8.
Davide Cartasegna Piero Malcovati Lorenzo Crespi Kyehyung Lee Andrea Baschirotto 《Analog Integrated Circuits and Signal Processing》2014,78(3):785-798
This paper presents a design methodology for high-order class-D amplifiers, based on their similarity with sigma–delta ( $\Upsigma\Updelta$ ) modulators, for which established theory and toolboxes are available. The proposed methodology, which covers the entire design flow, from specifications to component sizing, is validated with three design examples, namely a second-order, a third-order, and a fourth-order class-D amplifier. Moreover, the third-order class-D amplifier has been integrated on silicon and characterized, further confirming the validity of the whole design flow. The achieved results demonstrate that high-order class-D amplifiers can achieve total-harmonic-distortion (THD) performance compatible with the specifications of high-end audio applications (THD ≈ 90 dB), which would be unfeasible with conventional first-order class-D amplifiers. 相似文献
9.
Gian Piero Gallerano Andrea Doria Marzia Germini Emilio Giovenale Giovanni Messina Ivan P. Spassovsky 《Journal of Infrared, Millimeter and Terahertz Waves》2009,30(12):1351-1361
Two Free Electron Laser sources have been developed at ENEA-Frascati for a variety of applications: A Compact Free Electron
Laser (C-FEL) that provides coherent radiation in the frequency range between 90 and 150 GHz Gallerano et al. (Infrared Phys. and Techn. 40:161, 1999), and a second source, FEL-CATS, which utilizes a peculiar radio-frequency structure to generate coherent emission in the
range 0.4 to 0.7 THz Doria et al. (Phys. Rev. Lett 93:264801, 2004). The high peak power of several kW in 15 to 50 ps pulses, makes these sources particularly suitable for the assessment of
exposure limits in biological systems and for long range detection. In this paper we present a phase-sensitive reflective
imaging device in the mm-wave and THz regions, which has proven to be a valuable tool in the biological Ramundo-Orlando et al. (Bioelectromagnetics 28:587–598, 2007), environmental Doria et al. (2005) and art conservation fields Gallerano et al. (2008). Different setups have been tested at different levels of spatial resolution to image objects from a few centimeter square
to larger sizes. Images have been compared to identify and characterize the contrast mechanism. 相似文献
10.
In this paper the contrasting effects of transmission impairments and capture on both the network and single user performance of a slotted Aloha system are investigated in a mobile radio environment, accounting for frequency non-selective random propagation phenomena, and employing the packet error probability in order to define packet losses and capture. With this study we demonstrate that it is possible to generalize in a real propagation context a method previously proposed in literature for evaluating the network behavior in terms of steady-state throughput, backlog and stability in conventional transmission conditions, i.e., when all the transmission channels were error-free and the collisions caused the loss of all the packets involved. Moreover, we indicate under which specific constraints on the terminal mobility we can apply this method to analytically predict the single user performance, which we show being an important design parameter. Through the numerical results reported we quantitatively point out that in the absence of coding capture increases system stability and moderately improves the overall system throughput and backlog. We also outline the trade-off between an increased capture gain obtained by means of coding and the corresponding system cost in terms of complexity and bandwidth occupancy. Furthermore, we demonstrate the unfairness which affects the single user performance and the consequent need for countermeasures in order not to discriminate among users differently located within the network; yet, this last solution is detrimental as regards the positive capture effects.This work was supported by M.U.R.S.T. and C.N.R. (Italy). 相似文献