全文获取类型
收费全文 | 909篇 |
免费 | 17篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 41篇 |
化学工业 | 127篇 |
金属工艺 | 43篇 |
机械仪表 | 3篇 |
建筑科学 | 10篇 |
能源动力 | 26篇 |
轻工业 | 13篇 |
水利工程 | 3篇 |
石油天然气 | 2篇 |
无线电 | 232篇 |
一般工业技术 | 211篇 |
冶金工业 | 102篇 |
原子能技术 | 3篇 |
自动化技术 | 112篇 |
出版年
2022年 | 8篇 |
2021年 | 11篇 |
2020年 | 15篇 |
2019年 | 16篇 |
2018年 | 19篇 |
2017年 | 15篇 |
2016年 | 16篇 |
2015年 | 11篇 |
2014年 | 13篇 |
2013年 | 39篇 |
2012年 | 18篇 |
2011年 | 39篇 |
2010年 | 23篇 |
2009年 | 43篇 |
2008年 | 29篇 |
2007年 | 33篇 |
2006年 | 36篇 |
2005年 | 27篇 |
2004年 | 21篇 |
2003年 | 30篇 |
2002年 | 26篇 |
2001年 | 26篇 |
2000年 | 17篇 |
1999年 | 16篇 |
1998年 | 30篇 |
1997年 | 28篇 |
1996年 | 26篇 |
1995年 | 36篇 |
1994年 | 25篇 |
1993年 | 17篇 |
1992年 | 20篇 |
1991年 | 23篇 |
1990年 | 19篇 |
1989年 | 10篇 |
1988年 | 22篇 |
1987年 | 7篇 |
1986年 | 7篇 |
1985年 | 14篇 |
1984年 | 5篇 |
1983年 | 13篇 |
1982年 | 9篇 |
1981年 | 6篇 |
1980年 | 5篇 |
1979年 | 6篇 |
1978年 | 7篇 |
1977年 | 8篇 |
1976年 | 7篇 |
1974年 | 6篇 |
1971年 | 4篇 |
1970年 | 4篇 |
排序方式: 共有928条查询结果,搜索用时 15 毫秒
101.
S. Chattopadhyay L. K. Bera C. K. Maiti S. K. Ray P. K. Bose D. Dentel L. Kubler J. L. Bischoff 《Journal of Materials Science: Materials in Electronics》1998,9(6):403-407
PtSi/p-strained-Si1-xGex (x=0.19 and x=0.29) Schottky barrier diodes have been fabricated and characterized for the determination of barrier height, ideality factor and the interface state density distribution with energy. Diodes having an epitaxial layer thickness of 20 and 52 nm were modeled with emphasis on comparison with experiment. To achieve better agreement with experimental data, an interfacial layer and associated series resistance were included in the model. The capacitance–voltage (C–V) technique has been used for the determination of the energy distribution of interface state density. The interface state density distribution for the Si0.81Ge0.19 and Si0.71Ge0.29 diodes is found to decrease with increasing energy from the valence band edge. 相似文献
102.
The idea of observability with delay for discrete-event dynamic systems in a finite state machine framework has been proposed (Ozveren and Wilsky 1990). This note points out some shortcomings in the existing definitions and proposes an alternative one. It also derives necessary and sufficient conditions for the above property that can be tested for easily 相似文献
103.
Multidimensional Systems and Signal Processing - 相似文献
104.
Energy efficiency has been a key design constraint for microprocessor development teams since the late 1990s. The fundamental technological issues that have led to this point are quite well understood at this time by industry and academia. Although active (or dynamic) and passive (or standby) components of the net power equation are of concern, in recent years the latter (leakage) aspect of chip power has been escalating at a much faster rate than active power. IEEE Micro, in putting together a special issue on this important theme, decided to focus on two recently held (and relatively new) conferences: Cool Chips VIII, held April 2005 in Yokohama, Japan, and the fourth Annual Austin Conference on Energy Efficient Design (ACEED), held in March 2005 in Austin, Texas. The papers in the issue, from those conferences, focus on energy efficient design, and the Cell processor. 相似文献
105.
Species richness, structural diversity and species composition in meadows created by visitors of a botanical garden in Switzerland 总被引:3,自引:0,他引:3
Biodiversity is an increasingly important criterion in designing ecological compensation areas and urban green areas. However, little is known about how important biodiversity is to the general public. This paper presents the results of two complementary studies investigating the meadow preferences of visitors to a botanical garden in Switzerland. In the first study, 152 people were asked to create their own favourite meadow patch by selecting 25 out of 779 local wild plants (54 species) that were displayed in flowerpots. In the second study, 143 people were asked with the help of a written questionnaire to imagine a bare piece of land the size of 100 m × 100 m close to their place of living and mentally create the meadow of their dreams. In both cases, study participants assembled meadows that were species-rich and rich in structural diversity (expressed by plant height and leaf forms). Moreover, they explicitly stated diversity as their main assemblage criterion. Although study participants favoured plants with large or colourful flowers, only a third of all plants in the meadows created with real plants were flowering and in people's imagined meadows grasses were frequently included, indicating that people like diverse meadows consisting of a green matrix with some colourful flowers. 相似文献
106.
Osteoid osteoma is an uncommon tumour in the very young. We present a case of osteoid osteoma in a three-year-old boy, who was treated as a case of sclerosing osteomyelitis of the femur. Because of persistent pain and lack of response to treatment, further radiological investigation confirmed the diagnosis to be that of an osteoid osteoma. 相似文献
107.
Design of some new efficient balanced codes 总被引:1,自引:0,他引:1
Tallini L.G. Capocelli R.M. Bose B. 《IEEE transactions on information theory / Professional Technical Group on Information Theory》1996,42(3):790-802
A balanced code with r check bits and k information bits is a binary code of length k+r and cardinality 2k such that each codeword is balanced; that is, it has [(k+r)/2] 1's and [(k+r)/2] 0's. This paper contains new methods to construct efficient balanced codes. To design a balanced code, an information word with a low number of 1's or 0's is compressed and then balanced using the saved space. On the other hand, an information word having almost the same number of 1's and 0's is encoded using the single maps defined by Knuth's (1986) complementation method. Three different constructions are presented. Balanced codes with r check bits and k information bits with k⩽2r+1-2, k⩽3×2r-8, and k⩽5×2r-10r+c(r), c(r)∈{-15, -10, -5, 0, +5}, are given, improving the constructions found in the literature. In some cases, the first two constructions have a parallel coding scheme 相似文献
108.
The relationship between the elements in the vector of any limit cycle due to rounding in ann-order direct-form digital filter is established. Some bounds on the elements in such vectors are also determined. Sufficient conditions for the accessibility of period-r limit cycles due to rounding inn-order digital filters are presented. 相似文献
109.
110.