全文获取类型
收费全文 | 3987篇 |
免费 | 224篇 |
国内免费 | 71篇 |
专业分类
电工技术 | 170篇 |
综合类 | 54篇 |
化学工业 | 833篇 |
金属工艺 | 110篇 |
机械仪表 | 152篇 |
建筑科学 | 94篇 |
矿业工程 | 19篇 |
能源动力 | 143篇 |
轻工业 | 204篇 |
水利工程 | 31篇 |
石油天然气 | 31篇 |
武器工业 | 8篇 |
无线电 | 814篇 |
一般工业技术 | 674篇 |
冶金工业 | 374篇 |
原子能技术 | 29篇 |
自动化技术 | 542篇 |
出版年
2024年 | 11篇 |
2023年 | 36篇 |
2022年 | 104篇 |
2021年 | 129篇 |
2020年 | 78篇 |
2019年 | 66篇 |
2018年 | 87篇 |
2017年 | 92篇 |
2016年 | 95篇 |
2015年 | 114篇 |
2014年 | 177篇 |
2013年 | 323篇 |
2012年 | 262篇 |
2011年 | 265篇 |
2010年 | 214篇 |
2009年 | 203篇 |
2008年 | 204篇 |
2007年 | 196篇 |
2006年 | 186篇 |
2005年 | 108篇 |
2004年 | 106篇 |
2003年 | 105篇 |
2002年 | 81篇 |
2001年 | 62篇 |
2000年 | 65篇 |
1999年 | 68篇 |
1998年 | 152篇 |
1997年 | 108篇 |
1996年 | 83篇 |
1995年 | 53篇 |
1994年 | 68篇 |
1993年 | 55篇 |
1992年 | 49篇 |
1991年 | 32篇 |
1990年 | 36篇 |
1989年 | 35篇 |
1988年 | 21篇 |
1987年 | 19篇 |
1986年 | 13篇 |
1985年 | 18篇 |
1984年 | 17篇 |
1983年 | 7篇 |
1982年 | 8篇 |
1981年 | 9篇 |
1980年 | 6篇 |
1978年 | 8篇 |
1977年 | 7篇 |
1976年 | 9篇 |
1975年 | 7篇 |
1973年 | 5篇 |
排序方式: 共有4282条查询结果,搜索用时 20 毫秒
121.
122.
Time-based coordinated checkpointing protocols are well suited for mobile computing systems because no explicit coordination message is needed while the advantages of coordinated checkpointing are kept. However, without coordination, every process has to take a checkpoint during a checkpointing process. In this paper, an efficient time-based coordinated checkpointing protocol for mobile computing systems over Mobile IP is proposed. The protocol reduces the number of checkpoints per checkpointing process to nearly minimum, so that fewer checkpoints need to be transmitted through the costly wireless link. Our protocol also performs very well in the aspects of minimizing the number and size of messages transmitted in the wireless network. In addition, the protocol is nonblocking because inconsistencies can be avoided by the piggybacked information in every message. Therefore, the protocol brings very little overhead to a mobile host with limited resource. Additionally, by taking advantage of reliable timers in mobile support stations, the time-based checkpointing protocol can adapt to wide area networks. 相似文献
123.
Dynamic RSVP protocol 总被引:5,自引:0,他引:5
Geng-Sheng Kuo Po-Chang Ko 《Communications Magazine, IEEE》2003,41(5):130-135
RSVP is a resource reservation setup protocol that can be used by a host to request specific QoS for multicast multimedia flows on the Internet. Multiprotocol label switching (MPLS) architecture also needs RSVP. The fact that the resolutions of the display system used in different receiver nodes might have different, multi-resolution characteristics is supported in the MPEG-4 standard, and the EZW compression algorithm can cease decoding at any point in the bitstream. However, RSVP does not provide a more flexible mechanism. In this article we propose an extension of RSVP to provide the needed mechanism, coined dynamic RSVP (DRSVP), to dynamically adjust reserved resources on nodes without much effort. It provides different video resolutions to different receiver nodes with different needed reserved resources. Therefore, it does not waste precious Internet resources to transmit unnecessary multimedia packets. 相似文献
124.
125.
Szu-Wei Lee C.-C. Jay Kuo 《Journal of Visual Communication and Image Representation》2011,22(6):557-562
In this work, we propose a novel entropy coding mode decision algorithm to balance the tradeoff between the rate-distortion (R-D) performance and the entropy decoding complexity for the H.264/AVC video coding standard. Context-based adaptive binary arithmetic coding (CABAC), context-based adaptive variable length coding (CAVLC), and universal variable length coding (UVLC) are three entropy coding tools adopted by H.264/AVC. CABAC can be used to encode the texture and the header data while CAVLC and UVLC are employed to encode the texture and the header data, respectively. Although CABAC can provide better R-D performance than CAVLC/UVLC, its decoding complexity is higher. Thus, by taking the entropy decoding complexity into account, CABAC may not be the best tool, which motivates us to examine the entropy coding mode decision problem in depth. It will be shown experimentally that the proposed mode decision algorithm can help the encoder generate the bit streams that can be decoded at much lower complexity with little R-D performance loss. 相似文献
126.
This paper reports a 1.5-V full-swing bootstrapped CMOS large capacitive-load driver circuit using two bootstrap capacitors to enhance the switching speed for low-voltage CMOS VLSI. For a supply voltage of 1.5 V, the full-swing bootstrapped CMOS driver circuit shows a 2.2 times improvement in switching speed in driving a capacitive load of 10 pF as compared to the conventional CMOS driver circuit. Even for a supply voltage of 1 V, this full-swing bootstrapped CMOS large capacitive-load driver circuit is still advantageous 相似文献
127.
Chin-Te Chen Wen-Li Lin Te-Son Kuo Cheng-Yi Wang 《IEEE transactions on bio-medical engineering》1997,44(7):601-609
The authors discuss a two-model multilayer neural network controller for adaptive control of mean arterial blood pressure (MABP) using sodium nitroprusside. A model with an autoregressive moving average (ARMA), representing the dynamics of the system, and a modified backpropagation training algorithm are used to design the control system to meet specified objectives of design (settling time and undershoot/overshoot) and clinical constraints. The controller is associated with a weighting-determinant unit (WDU) to determine and update the output weighting factor of the parallel two-model neural network for adequate control action and a control-signal modification unit (CMU) to comply with clinical constraints and to suppress the effect of adverse noise and to improve the WDU performance. Extensive computer simulations indicate satisfactory performance and robustness of the proposed controller in the presence of much noise, over the full range of plant parameters, uncertainties, and large variations of parameters 相似文献
128.
Quasi-saturation capacitance behavior of a DMOS device 总被引:1,自引:0,他引:1
This paper reports a simulation study on the capacitance characteristics of a double-diffused metal-oxide semiconductor (DMOS) device operating in the quasi-saturation region. From the analysis, the capacitance effect of the gate oxide upon the drift region cannot be modeled as an overlap capacitance, because the drain-gate/source-gate capacitances of the DMOS device may exceed the gate-oxide capacitance due to the larger voltage drop over the gate oxide than the change in the imposed gate bias when entering the quasi-saturation region. This effect can be the explanation for the plateau behavior in the gate charge plot during turn-on and turn-off of the DMOS device. Based on the small-signal equivalent capacitance model, the accumulated charge in the drift region below the gate oxide may thoroughly associate with the drain terminal in the prequasi-saturation region and with the source terminal in the quasi-saturation region 相似文献
129.
Chung S.S. Shui-Ming Cheng Lee R.G.-H. Song-Nian Kuo Mong-Song Liang 《Electron Devices, IEEE Transactions on》1997,44(12):2220-2226
This paper reports a simple I-V method for the first time to determine the lateral lightly-doped source/drain (S/D) profiles (n- region) of LDD n-MOSFETs. One interesting result is the direct observation of the reverse-short-channel effect (RSCE). It is observed that S/D n- doping profile is channel length dependent if reverse short-channel effect exists as a result of the interstitial imperfections caused by Oxide Enhanced Diffusion (OED) or S/D implant. Not only the lateral profiles for long-channel devices but also for short-channel devices can be determined. One other practical application of the present method for device drain engineering has been demonstrated with a LATID MOS device drain engineering work. It is convincible that the proposed method is well suited for the characterization and optimization of submicron and deep-submicron MOSFETs in the current ULSI technology 相似文献
130.
Chung‐Wei Kung Hsin‐Wei Chen Chia‐Yu Lin Yi‐Hsuan Lai R. Vittal Kuo‐Chuan Ho 《Progress in Photovoltaics: Research and Applications》2014,22(4):440-451
A double‐layer film, consisting of an upper layer of ZnO nanosheets and a lower layer of ZnO nanoparticles (designated as ZnONS/NP), was synthesized for the photoanode of a dye‐sensitized solar cell (DSSC) by a one‐step potentiostatic electrodeposition on a conducting fluorine‐doped tin oxide substrate at 70 °C in a solution containing zinc nitrate and sodium acetate, followed by the pyrolysis of the film at 300 °C. The growth mechanism of the double‐layer nanostructure was studied by monitoring the morphological changes at various periods of electrodeposition. The effects of the concentration of acetate anion on the morphology of the double‐layer structure were also studied. The double‐layer film of ZnONS/NP showed a better self‐established light scattering property, compared with that of a thin film of ZnO nanoparticles, prepared without acetate anion. The concentration of an acetate anion in the electrolyte for the electrodeposition of the double‐layer film, the electrodeposition period, and the period for dye adsorption were optimized for obtaining the best performance for a DSSC with a photoanode consisting of the double layer. A metal‐free dye, coded as D149, was used in this research. A conversion efficiency of 4.65% was achieved for a DSSC (0.2376 cm2) with the photoanode, consisting of the double‐layer film, under 100 mW/cm2 illumination in the wavelength range of 400–800 nm. X‐ray diffraction patterns, thermo gravimetric curves, elemental analysis, scanning electron microscopic images, transmission electron microscopic image, transmission spectra, and electrochemical impedance spectra were used to explain observations. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献