全文获取类型
收费全文 | 9673篇 |
免费 | 348篇 |
国内免费 | 39篇 |
专业分类
电工技术 | 129篇 |
综合类 | 22篇 |
化学工业 | 2166篇 |
金属工艺 | 185篇 |
机械仪表 | 243篇 |
建筑科学 | 625篇 |
矿业工程 | 31篇 |
能源动力 | 181篇 |
轻工业 | 808篇 |
水利工程 | 57篇 |
石油天然气 | 11篇 |
武器工业 | 1篇 |
无线电 | 630篇 |
一般工业技术 | 1567篇 |
冶金工业 | 1779篇 |
原子能技术 | 75篇 |
自动化技术 | 1550篇 |
出版年
2023年 | 60篇 |
2022年 | 121篇 |
2021年 | 149篇 |
2020年 | 109篇 |
2019年 | 122篇 |
2018年 | 174篇 |
2017年 | 117篇 |
2016年 | 202篇 |
2015年 | 198篇 |
2014年 | 260篇 |
2013年 | 593篇 |
2012年 | 412篇 |
2011年 | 561篇 |
2010年 | 422篇 |
2009年 | 406篇 |
2008年 | 458篇 |
2007年 | 442篇 |
2006年 | 387篇 |
2005年 | 327篇 |
2004年 | 323篇 |
2003年 | 240篇 |
2002年 | 241篇 |
2001年 | 188篇 |
2000年 | 184篇 |
1999年 | 185篇 |
1998年 | 340篇 |
1997年 | 242篇 |
1996年 | 192篇 |
1995年 | 158篇 |
1994年 | 138篇 |
1993年 | 152篇 |
1992年 | 135篇 |
1991年 | 84篇 |
1990年 | 103篇 |
1989年 | 83篇 |
1988年 | 107篇 |
1987年 | 72篇 |
1986年 | 58篇 |
1985年 | 84篇 |
1984年 | 96篇 |
1983年 | 62篇 |
1982年 | 72篇 |
1981年 | 84篇 |
1980年 | 74篇 |
1979年 | 94篇 |
1978年 | 72篇 |
1977年 | 74篇 |
1976年 | 67篇 |
1975年 | 63篇 |
1973年 | 53篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
目前,分布式电源架构被广泛用于通信和计算设备中,该电源架构经常采用板载电源(BMP)模块,在尽可能靠近负载点的地方进行电源变换. 相似文献
52.
Sherman Elisabeth M. S.; Strauss Esther; Spellacy Frank; Hunter Michael 《Canadian Metallurgical Quarterly》1995,7(4):440
A 3-factor solution of the Wechsler Adult Intelligence Scale—Revised (WAIS—R; Wechsler, 1981) in 260 adults with suspected head injury suggested relatively good construct validity for the factors, based on correlations with neuropsychological tests purported to measure similar abilities. The Verbal Comprehension factor was related to verbal ability, verbal memory, and executive functioning. The Perceptual Organization factor, although measuring primarily visual–spatial perception and visual constructional ability, was related to visual–spatial memory, visual attention, and executive functioning. The Freedom From Distractibility factor was correlated with two attention measures and was not associated with memory measures. Its association with executive functioning was inconsistent. The findings are discussed in terms of the multidimensional nature of neuropsychological tests and WAIS—R factors. (PsycINFO Database Record (c) 2011 APA, all rights reserved) 相似文献
53.
This article reviews the steps necessary to configure and implement a complex router internetwork. This article will specifically concentrate on Cisco routers, and since they support Transmission Control Protocol/Internet Protocol (TCP/IP) natively, it will concentrate on a backbone network employing that protocol. 相似文献
54.
Matthew John M. Krane Frank P. Incropera 《Metallurgical and Materials Transactions A》1995,26(9):2329-2339
Numerical calculations based on a continuum model are used to examine the effects of solidification shrinkage on the redistribution
of solute in a Pb-19.2 pct Sn mixture which is convectively cooled at a sidewall. For each of three different cooling rates,
separate calculations are performed for shrinkage and buoyancy-induced flows, as well as for the combined influence of shrinkage
and buoyancy effects. The calculations reveal that flow and macrosegregation patterns are more strongly influenced by buoyancy
effects over a wide range of solidification rates. Although extremely large solidification rates yield small regions near
the chilled wall in which shrinkage-induced flows control the redis-tribution of solute, the overall effect on macrosegregation
is small relative to that associated with buoyancy. Scaling analysis of the governing equations produces reference shrinkage
and buoyancy velocities which can be used to extend the current numerical results to other binary systems. 相似文献
55.
A. Lowe 《Journal of Materials Science》1996,31(4):1005-1011
The transverse compressive behaviour of a structurally complex carbon-epoxy unidirectional composite (T300/914) has been investigated over various temperatures and test rates. The mechanical behaviour was found to mirror the transverse tensile behaviour of the material, with the viscoelastic response being different between micro- and macroproperties. Composite macrofracture was found to occur at ±34 ° to the loading axis and was regular, whereas fracture of the bulk resin was irregular and occurred by Poisson forces, rather than compressive forces. The performance of the test fixture was assessed and found to be adequate for composites testing. An optimum specimen gauge length was determined as the ASTM recommendation was found to be unsatisfactory. 相似文献
56.
TheSpecial Issue on Applications of Temporal Models raises many issues of time: What are the important properties of time? How can time be best represented? How can one reason about time-dependent properties? What are the important directions of temporal research? This introductory piece very briefly surveys the current wide variety of temporal models, temporal reasoning methods, and applications to time-varying phenomena. Promising areas of investigation such as the verification of concurrent systems, knowledge-base representation methods, and dealing with theFrame Problem pass in fleeting review. Brief introductions to each of the works in the volume close the section. 相似文献
57.
Extending the Kernighan/Lin Heuristic for Hardware and Software Functional Partitioning 总被引:5,自引:0,他引:5
The Kernighan/Lin graph partitioning heuristic, also known as min-cut or group migration, has been extended over several decades very successfully for circuit partitioning. Those extensions customized the heuristic and its associated data structure to rapidly compute the minimum-cut metric central to circuit partitioning; as such, those extensions are not directly applicable to other problems. In this paper, we extend the heuristic for functional partitioning, which in turn can solve the much investigated codesign problem of partitioning a system's coarse-grained functions among hardware and software components. The key extension customizes the heuristic and data structure to rapidly compute execution-time and communication metrics, crucial to hardware and software partitioning, and leads to near-linear time-complexity and excellent resulting quality. Another extension uses a new criteria for terminating the heuristic, eliminating time-consuming and unnecessary fine-tuning of a partition. Our experiments demonstrate extremely fast execution times (just a few seconds) with results matched only by the slower simulated annealing heuristic, meaning that the extended Kernighan/Lin heuristic will likely prove hard to beat for hardware and software functional partitioning. 相似文献
58.
59.
Amitava Roy Harvill C. Eaton Frank K. Cartledge Marty E. Tittlebaum 《Journal of hazardous materials》1992,30(3):297-316
The effect of sodium sulfate on the solidification/stabilization of a large quantity of a synthetic electroplating sludge in cementitious binders was s 相似文献
60.