全文获取类型
收费全文 | 1859篇 |
免费 | 98篇 |
国内免费 | 7篇 |
专业分类
电工技术 | 25篇 |
综合类 | 2篇 |
化学工业 | 405篇 |
金属工艺 | 68篇 |
机械仪表 | 132篇 |
建筑科学 | 31篇 |
矿业工程 | 4篇 |
能源动力 | 83篇 |
轻工业 | 131篇 |
水利工程 | 12篇 |
石油天然气 | 4篇 |
武器工业 | 1篇 |
无线电 | 290篇 |
一般工业技术 | 386篇 |
冶金工业 | 113篇 |
原子能技术 | 21篇 |
自动化技术 | 256篇 |
出版年
2024年 | 1篇 |
2023年 | 39篇 |
2022年 | 39篇 |
2021年 | 76篇 |
2020年 | 54篇 |
2019年 | 71篇 |
2018年 | 58篇 |
2017年 | 57篇 |
2016年 | 78篇 |
2015年 | 51篇 |
2014年 | 111篇 |
2013年 | 141篇 |
2012年 | 131篇 |
2011年 | 145篇 |
2010年 | 93篇 |
2009年 | 98篇 |
2008年 | 94篇 |
2007年 | 98篇 |
2006年 | 78篇 |
2005年 | 50篇 |
2004年 | 50篇 |
2003年 | 46篇 |
2002年 | 22篇 |
2001年 | 41篇 |
2000年 | 24篇 |
1999年 | 25篇 |
1998年 | 43篇 |
1997年 | 24篇 |
1996年 | 19篇 |
1995年 | 12篇 |
1994年 | 9篇 |
1993年 | 16篇 |
1992年 | 12篇 |
1991年 | 3篇 |
1990年 | 5篇 |
1989年 | 9篇 |
1988年 | 4篇 |
1987年 | 6篇 |
1986年 | 3篇 |
1985年 | 4篇 |
1983年 | 3篇 |
1982年 | 1篇 |
1981年 | 2篇 |
1977年 | 7篇 |
1976年 | 2篇 |
1975年 | 2篇 |
1974年 | 2篇 |
1973年 | 3篇 |
1964年 | 1篇 |
1941年 | 1篇 |
排序方式: 共有1964条查询结果,搜索用时 0 毫秒
1.
A new excimer laser annealing (ELA) process that uses a floating amorphous-Silicon (a-Si) thin film with a multichannel structure is proposed for high-performance poly-Si thin-film transistors (TFTs). The proposed ELA method produces two-dimensional (2-D) grain growth, which can result in a high-quality grain structure. The dual-gate structure was employed to eliminate the grain boundaries perpendicular to the current flow in the channel. A multichannel structure was adapted in order to arrange the grain boundary to be parallel to the current flow. The proposed poly-Si TFT exhibits high-performance electrical characteristics, which are a high mobility of 504 cm/sup 2//Vsec and a low subthreshold slope of 0.337 V/dec. 相似文献
2.
During the 1997 winter season, shipborne polarimetric backscatter measurements of Great Lakes (freshwater) ice types using the Jet Propulsion Laboratory C-band scatterometer, together with surface-based ice physical characterization measurements and environmental parameters, were acquired concurrently with Earth Resource Satellite 2 (ERS-2) and RADARSAT Synthetic Aperture Radar (SAR) data. This polarimetric data set, composed of over 20 variations of different ice types measured at incident angles from 0° to 60° for all polarizations, was processed to radar cross-section to establish a library of signatures (look-up table) for different ice types. The library is used in the computer classification of calibrated satellite SAR data. Computer analysis of ERS-2 and RADARSAT ScanSAR images of Great Lakes ice cover using a supervised classification technique indicates that different ice types in the ice cover can be identified and mapped, and that wind speed and direction can have an influence on the classification of water as ice based on single frequency, single polarization data. Once satellite SAR data are classified into ice types, the ice map provides important and necessary input for environmental protection and management, ice control and ice breaking operations, and ice forecasting and modeling efforts. 相似文献
3.
Hyukmin Son Sanghoon Lee 《Communications Letters, IEEE》2006,10(5):360-362
A cell planning technique termed BRD (bandwidth and region division) is presented for overcoming interference, maintaining QoS (quality of service) and improving channel capacity over OFDM (orthogonal frequency division multiplexing)-based broadband cellular networks. Through an optimal combination of sectorization and zero padding, bandwidth and region division is achieved that minimizes the outage probability for forward-link cell planning. In order to verify the effectiveness of the proposed algorithm, a Monte Carlo simulation is performed over multi-cell environments. 相似文献
4.
Problems related to unpopular housing are not new in Britain's social rented sector. In the past, however, these have generally been associated with housing provided directly by the state through local authorities. For many, the term 'difficult to let' has become synonymous with large, ageing, poor quality estates managed under a centralised framework and subject to a long period of low investment and indifferent management. There has also been a long-standing assumption that social housing allocations systems tend to channel the most vulnerable tenants into the least desirable housing. In fact, the problem of difficult to let property is now as pervasive in the not-for-profit sector managed by housing associations as it is within council housing. In many cases the developments affected are small in scale and, in a significant proportion of cases, recently constructed. In explaining why property becomes difficult to let, the local and regional context is clearly important. The balance between social, economic and housing demand circumstances and property and estate characteristics varies between regions. There is relatively little evidence that difficult to let housing association properties are occupied by disproportionate numbers of the most severely disadvantaged tenants and this suggests that something has happened to modify the segregating effects of allocations systems observed in earlier studies. Nevertheless, this apparent change must be seen within the context of the general trend towards a residual role for social housing in its entirety. The social class and income range of new social sector tenants now is much diminished by comparison with earlier decades with few distinctions between the occupiers of difficult to let and other housing. 相似文献
5.
A chimeric dopamine transporter (DAT) cDNA encoding mutant human DAT (hDAT) protein in which the intracellular carboxyl-terminal tail is replaced by that of the bovine dopamine transporter (bDAT) was constructed. The chimeric hDAT cDNA was expressed in COS-7 cells, and [3H]dopamine and [3H]MPP+ uptake and [3H]CFT binding capacities were assessed. Substrate transport and ligand binding of bDAT were reduced by 32-43% as a result of substitution of the carboxyl tail in hDAT, suggesting that the functional characteristics of bDAT arise from differences in the carboxyl tail between human and bovine DAT. Thus, it appears that the sequences encoded within the carboxyl terminal of DAT would be one of the important determinants for its functions. 相似文献
6.
Yurak Son Takuya Kamano Takashi Yasuno Takayuki Suzuki Hironobu Harada 《Electrical Engineering in Japan》2006,155(1):35-43
This paper describes the generation of adaptive gait patterns using new Central Pattern Generators (CPGs) including motor dynamic models for a quadruped robot under various environments. The CPGs act as the flexible oscillators of the joints and adjust joint angles to required values. The CPGs are interconnected with each other and sets of their coupling parameters are adjusted by a genetic algorithm so that the quadruped robot can realize stable and adequate gait patterns. Generation of gait patterns results in the formation of the CPG networks suitable for the formation of not only a straight walking pattern but also of rotating gait patterns. Experimental results demonstrate that the proposed CPG networks are effective for the automatic adjustment of the adaptive gait patterns for the tested quadruped robot under various environments. Furthermore, the target tracking control based on image processing is achieved by combining the general gait patterns. © 2006 Wiley Periodicals, Inc. Electr Eng Jpn, 155(1): 35–43, 2006; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20225 相似文献
7.
A new high-slew-rate CMOS buffer amplifier consuming a very small quiescent current is proposed. This buffer amplifier recursively copies the output driving current and increases the tail current of the input differential pair during slewing. Since the proposed buffer has a possible slew rate higher than 10 V//spl mu/s for a load capacitance of 1 nF almost independently of static currents as low as 1 /spl mu/A, this buffer amplifier is promising for column driver ICs of flat panel displays that require low static power consumption, high current driving capabilities, and small silicon areas. 相似文献
8.
Vinit D. Makwana L. Javier Garces Jia Liu Jun Cai Young-Chan Son Steven L. Suib 《Catalysis Today》2003,85(2-4):225-233
Manganese oxides having a tunnel structure (OMS-2) have been utilized as selective catalysts for alcohol oxidation. In this study manganese oxide catalysts were synthesized in different media and modified by exchanging the tunnel cation by H+, using acid treatment or exchanging with NH4+ followed by thermolysis. Various alcohol oxidations were performed using these catalysts to ascertain the influence of synthesis method on their activity. A correlation is made between lattice oxygen instability and activity of the catalysts, which indicates involvement of the lattice oxygen in the mechanism. The exchange of the tunnel cation with the smaller H+ ions leads to weakening of the Mn–O bond, as verified by temperature programmed desorption (TPD) results. Only the chemisorbed oxygen on the surface (O−) and the lattice oxygen in the layers close to the surface is involved in the oxygen transfer during the reaction. 相似文献
9.
10.