全文获取类型
收费全文 | 264578篇 |
免费 | 2942篇 |
国内免费 | 1273篇 |
专业分类
电工技术 | 4744篇 |
综合类 | 196篇 |
化学工业 | 38821篇 |
金属工艺 | 11030篇 |
机械仪表 | 8305篇 |
建筑科学 | 6268篇 |
矿业工程 | 1717篇 |
能源动力 | 6755篇 |
轻工业 | 22610篇 |
水利工程 | 3022篇 |
石油天然气 | 6032篇 |
武器工业 | 48篇 |
无线电 | 29195篇 |
一般工业技术 | 54126篇 |
冶金工业 | 48094篇 |
原子能技术 | 7302篇 |
自动化技术 | 20528篇 |
出版年
2021年 | 2385篇 |
2020年 | 1777篇 |
2019年 | 2245篇 |
2018年 | 3929篇 |
2017年 | 4007篇 |
2016年 | 4300篇 |
2015年 | 2632篇 |
2014年 | 4423篇 |
2013年 | 12044篇 |
2012年 | 7052篇 |
2011年 | 9395篇 |
2010年 | 7617篇 |
2009年 | 8592篇 |
2008年 | 8704篇 |
2007年 | 8697篇 |
2006年 | 7465篇 |
2005年 | 6865篇 |
2004年 | 6592篇 |
2003年 | 6410篇 |
2002年 | 5999篇 |
2001年 | 6111篇 |
2000年 | 6020篇 |
1999年 | 6063篇 |
1998年 | 14570篇 |
1997年 | 10378篇 |
1996年 | 8114篇 |
1995年 | 6005篇 |
1994年 | 5409篇 |
1993年 | 5289篇 |
1992年 | 4085篇 |
1991年 | 3978篇 |
1990年 | 3802篇 |
1989年 | 3837篇 |
1988年 | 3657篇 |
1987年 | 3155篇 |
1986年 | 3080篇 |
1985年 | 3524篇 |
1984年 | 3190篇 |
1983年 | 3014篇 |
1982年 | 2688篇 |
1981年 | 2816篇 |
1980年 | 2609篇 |
1979年 | 2699篇 |
1978年 | 2667篇 |
1977年 | 3060篇 |
1976年 | 4026篇 |
1975年 | 2344篇 |
1974年 | 2252篇 |
1973年 | 2248篇 |
1972年 | 1871篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
102.
Y. Rey-Tauriac J. Badoc B. Reynard R.A. Bianchi D. Lachenal A. Bravaix 《Microelectronics Reliability》2005,45(9-11):1349
This paper presents results of reliability investigation of 20 V N-Drift MOS transistor in 0.13 μm CMOS technology. Due to high performances required for CMOS applications, adding high voltage devices becomes a big challenge to guarantee the reliability criteria. In this context, new reliability approaches are needed. Safe Operating Area are defined for switch, Vds limited and Vgs limited applications in order to improve circuit designs. For Vds limited applications, deep doping dose effects in drift area are investigated in correlation to lifetime evaluations based on device parameter shifts under hot carrier stressing. To further determine the amount and locations of hot carriers injections, accurate 2D technological and electrical simulations are performed and permit to select the best compromise between performance and reliability for N-Drift MOS transistor. 相似文献
103.
Ya. O. Shablovskii 《Inorganic Materials》2007,43(12):1345-1349
The pyroelectric properties of lithium sulfate have been studied theoretically on the hypothesis of a pseudosymmetry of the structure of its polar phase. Analytical expressions are proposed for the temperature dependences of its pyroelectric polarization and pyroelectric coefficient at low temperatures and near the polymorphic transformation. The pyroelectric and piezoelectric coefficients of a polar crystal are shown to be in direct proportion. 相似文献
104.
105.
This paper is devoted to presenting controllability and stabilizability issues associated to a class of nonsmooth dynamical systems, namely complementarity dynamical systems. The main existing results are summarized, and some possible research directions are provided. Convex analysis and complementarity problems are claimed to be the main analysis tools for control related studies. This paper mainly focuses on mechanical applications. 相似文献
106.
O. A. Dolgopolov 《Glass and Ceramics》2005,62(5-6):155-156
Magnetic roll separators on rare-earth magnets are suitable for removing iron impurities from various materials. The advantages
of these magnetic separators over traditional ones are demonstrated.
__________
Translated from Steklo i Keramika, No. 5, p. 33, May, 2005. 相似文献
107.
O Prez‐Camacho S Sepúlveda‐Guzmn M Prez‐lvarez M García‐Zamora G Cadenas‐Pliego 《Polymer International》2005,54(12):1626-1631
New functionalized styrene–maleimide copolymers were prepared by free radical copolymerization of styrene (St) and N‐4‐carboxybutylmaleimide (NBMI) in chloroform, using 2,2′‐azobisisobutyronitrile (AIBN) as initiator. Monomer and copolymer characterization was carried out by 1H‐ and 13C‐NMR. Copolymer composition was determined by elemental analysis and Fourier‐transform infrared (FTIR) spectroscopy. The glass transition temperature (from DSC) and the thermogravimetric analysis (TGA) of the copolymers were consistent with the thermal behavior and stability observed for alternating St–maleimide copolymers. St–NBMI copolymers crosslinked with divinylbenzene (DVB) were also synthesized and their cation exchange properties evaluated in order to assess the capacity of the new copolymers to bind metallic ions. Copyright © 2005 Society of Chemical Industry 相似文献
108.
The Metaflow architecture, a unified approach to maximizing the performance of superscalar microprocessors, is introduced. The Metaflow architecture exploits inherent instruction-level parallelism in conventional sequential programs by hardware means, without relying on optimizing compilers. It is based on a unified structure, the DRIS (deferred-scheduling, register-renaming instruction shelf), that manages out-of-order execution and most of the attendant problems. Coupling the DRIS with a speculative-execution mechanism that avoids conditional branch stalls results in performance limited only be inherent instruction-level parallelism and available execution resources. Although presented in the context of superscalar machines, the technique is equally applicable to a superpipelined implementation. Lightning, the first implementation of the Metaflow architecture, which executes the Sparc RISC instruction set is described 相似文献
109.
110.