全文获取类型
收费全文 | 579532篇 |
免费 | 7130篇 |
国内免费 | 1870篇 |
专业分类
电工技术 | 11343篇 |
综合类 | 559篇 |
化学工业 | 86238篇 |
金属工艺 | 25884篇 |
机械仪表 | 21276篇 |
建筑科学 | 13141篇 |
矿业工程 | 3063篇 |
能源动力 | 14969篇 |
轻工业 | 43611篇 |
水利工程 | 5934篇 |
石油天然气 | 9332篇 |
武器工业 | 22篇 |
无线电 | 69508篇 |
一般工业技术 | 119155篇 |
冶金工业 | 99397篇 |
原子能技术 | 11650篇 |
自动化技术 | 53450篇 |
出版年
2021年 | 4491篇 |
2020年 | 3359篇 |
2019年 | 4437篇 |
2018年 | 13463篇 |
2017年 | 13853篇 |
2016年 | 11471篇 |
2015年 | 5547篇 |
2014年 | 8588篇 |
2013年 | 25303篇 |
2012年 | 15751篇 |
2011年 | 24970篇 |
2010年 | 20898篇 |
2009年 | 21896篇 |
2008年 | 22461篇 |
2007年 | 23953篇 |
2006年 | 15707篇 |
2005年 | 16871篇 |
2004年 | 14948篇 |
2003年 | 14524篇 |
2002年 | 13291篇 |
2001年 | 12716篇 |
2000年 | 12076篇 |
1999年 | 12372篇 |
1998年 | 29624篇 |
1997年 | 20857篇 |
1996年 | 16414篇 |
1995年 | 12485篇 |
1994年 | 11067篇 |
1993年 | 10974篇 |
1992年 | 8298篇 |
1991年 | 7866篇 |
1990年 | 7804篇 |
1989年 | 7495篇 |
1988年 | 7065篇 |
1987年 | 6272篇 |
1986年 | 6129篇 |
1985年 | 6982篇 |
1984年 | 6460篇 |
1983年 | 5939篇 |
1982年 | 5467篇 |
1981年 | 5466篇 |
1980年 | 5063篇 |
1979年 | 4974篇 |
1978年 | 4882篇 |
1977年 | 5610篇 |
1976年 | 7199篇 |
1975年 | 4261篇 |
1974年 | 3938篇 |
1973年 | 4055篇 |
1972年 | 3373篇 |
排序方式: 共有10000条查询结果,搜索用时 140 毫秒
991.
Nichols M.A. Siegel H.J. Dietz H.G. Quong R.W. Nation W.G. 《Parallel and Distributed Systems, IEEE Transactions on》1991,2(3):290-303
Efficient data layout is an important aspect of the compilation process. A model for the creation of perfect memory maps for large-scale parallel machines capable of user-controlled partitionable single-instruction-multiple data/single-program-multiple data (SIMD/SPMD) operation is developed. The term perfect implies that no memory fragmentation occurs and ensures that the memory map size is kept to a minimum. A major constraint on solving this problem is based on the single program nature of both the SIMD and SPMD modes of parallelism. It is assumed that all processors within the same submachine used identical addresses to access corresponding data items in each of their local memories. Necessary and sufficient conditions are derived for being able to create perfect memory maps, and results are applied to several partitionable interconnection networks 相似文献
992.
993.
A criterion for the local taper angle of a low-loss single-mode fibre coupler is established by considering the dominant mode coupling in the coupler taper. Effects due to structure parameters, such as cladding/core thickness ratio, corecladding index difference and core separation, are investigated. It is found that the criterion for the coupler taper can be well approximated by that for the single-mode fibre taper with the same structure parameters. 相似文献
994.
995.
996.
The evolution of RFID security 总被引:11,自引:0,他引:11
As RFID technology progresses, security and privacy threats also evolve. By examining RFID's history, we can learn from past mistakes, rediscover successful solutions, and inspire future research. 相似文献
997.
Imre T.G. Cronje W.A. van Wyk J.D. Ferreira J.A. 《Industry Applications, IEEE Transactions on》2002,38(6):1613-1621
This paper covers the experimental investigation and theoretical calculation of losses in a planar inductor under load. Finite-element software is used to perform the loss calculations. Thermally controlled experiments are performed for a range of frequencies to validate the corresponding finite-element method loss calculations. The thermal dependence of the loss mechanisms is also considered. 相似文献
998.
描述了在俄罗斯Dubna应用研究中心合成全硅欧泊的开发研究以及基本步骤. 阐述了这种漂亮的、相对无孔隙的合成欧泊的结构和基本特征以及这种合成欧泊切磨和抛磨的例子. 相似文献
999.
Electrochemical investigations on low-Si alloyed steels with Si content ranging from 0.25 to 3.2 wt.% were carried out in a 0.1 M NaCl borate-buffered solution (pH 8.4) in reducing conditions at 90 °C. Silicon as an alloying element was proved to degrade at first the steel ability to passivate. For longer immersion times, protective effects developed more efficiently on the steel containing 3.2 wt.% silicon. Passive layers electrochemically formed in the transpassive domain on the steel containing 3.2% Si were shown to be significantly different from those grown at rest potential. 相似文献
1000.
S. ReppA. Sadiki C. SchneiderA. Hinz T. LandenfeldJ. Janicka 《International Journal of Heat and Mass Transfer》2002,45(6):1271-1285
This work aims to compare numerical results obtained by using the Monte Carlo composition-PDF method and a presumed-β-PDF in order to reveal their effects on the prediction of flow and scalar fields in swirling confined methane diffusion flame. Using the intrinsic low dimensional manifolds method for modelling the chemistry and a second moment closure for the turbulence, it is shown that both PDF-methods provide a similar accuracy level of the prediction of mean quantities. While the presumed-β-PDF performs using reasonable computational efforts, the Monte Carlo-PDF allows to capture well the turbulence-chemistry interaction and strong finite-chemistry effects such as local extinction. 相似文献