全文获取类型
收费全文 | 5815篇 |
免费 | 607篇 |
国内免费 | 372篇 |
专业分类
电工技术 | 596篇 |
综合类 | 600篇 |
化学工业 | 163篇 |
金属工艺 | 148篇 |
机械仪表 | 725篇 |
建筑科学 | 305篇 |
矿业工程 | 138篇 |
能源动力 | 88篇 |
轻工业 | 67篇 |
水利工程 | 61篇 |
石油天然气 | 43篇 |
武器工业 | 44篇 |
无线电 | 1859篇 |
一般工业技术 | 722篇 |
冶金工业 | 51篇 |
原子能技术 | 27篇 |
自动化技术 | 1157篇 |
出版年
2024年 | 15篇 |
2023年 | 77篇 |
2022年 | 73篇 |
2021年 | 106篇 |
2020年 | 138篇 |
2019年 | 129篇 |
2018年 | 133篇 |
2017年 | 193篇 |
2016年 | 184篇 |
2015年 | 194篇 |
2014年 | 334篇 |
2013年 | 428篇 |
2012年 | 407篇 |
2011年 | 443篇 |
2010年 | 335篇 |
2009年 | 288篇 |
2008年 | 344篇 |
2007年 | 357篇 |
2006年 | 353篇 |
2005年 | 298篇 |
2004年 | 249篇 |
2003年 | 272篇 |
2002年 | 208篇 |
2001年 | 189篇 |
2000年 | 163篇 |
1999年 | 140篇 |
1998年 | 117篇 |
1997年 | 97篇 |
1996年 | 97篇 |
1995年 | 89篇 |
1994年 | 68篇 |
1993年 | 73篇 |
1992年 | 46篇 |
1991年 | 31篇 |
1990年 | 31篇 |
1989年 | 20篇 |
1988年 | 19篇 |
1987年 | 8篇 |
1986年 | 6篇 |
1985年 | 9篇 |
1984年 | 4篇 |
1983年 | 11篇 |
1982年 | 6篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1977年 | 4篇 |
1972年 | 1篇 |
1961年 | 2篇 |
1960年 | 1篇 |
1955年 | 1篇 |
排序方式: 共有6794条查询结果,搜索用时 156 毫秒
41.
128×128红外焦平面阵列时序分析与温控电路设计 总被引:8,自引:0,他引:8
介绍了微测辐射热计的 12 8× 12 8凝视型非致冷红外热像仪的系统框图 ,论述了一种新型的红外焦平面阵列温控电路设计方案以及读出电路时序的FPGA实现方法 .该方案具有高集成度、高精度、低成本、布线简单等优点 ,为热像仪系统的研制开发提供了设计思想 . 相似文献
42.
参数强迫激励下非线性振子尖点型奇点的分叉 总被引:2,自引:0,他引:2
本文首先研究了不具有Z_2—对称性时的规范形理论和退化向量场的普适开折理论。然后利用这些理论研究了参数激励与强迫激励联合作用下非线性振动系统的尖点型奇点的余维2退化分叉。 相似文献
43.
44.
A technique for designing efficient checkers for conventional Berger code is proposed in this paper. The check bits are derived by partitioning the information bits into two blocks, and then using an addition array to sum the number of 1's in each block. The check bit generator circuit uses a specially designed 4-input 1's counter. Two other types of 1's counters having 2 and 3 inputs are also used to realize checkers for variable length information bits. Several variations of 2-bit adder circuits are used to add the number of 1's. The check bit generator circuit uses gates with fan-in of less than or equal to 4 to simplify implementation in CMOS. The technique achieves significant improvement in gate count as well as speed over existing approaches. 相似文献
45.
46.
V. Székely M. Rencz J.M. Karam M. Lubaszewski B. Courtois 《Journal of Electronic Testing》1998,12(1-2):81-92
With the increasing power density in integrated systems resulting from scaling down, the occurrence of field failures due to overheating has considerably increased. Faulty operation can be prevented by on-line temperature monitoring. This paper deals with questions of on-line temperature monitoring in safety-critical systems. First the possible temperature sensors are reviewed and basic principles of self-checking systems including such sensors are detailed, then a new temperature sensor cell with extremely good parameters designed especially for DfTT applications is presented. The basic questions of integrating thermal sensors into self-checking systems are also discussed. 相似文献
47.
M. Nicolaidis 《Journal of Electronic Testing》1991,1(4):257-273
It has been noted by several authors that the classical stuck-at logical fault model might not be an appropriate representation of certain real failures occurring in integrated circuits. Shorts are an important class of such faults. This article gives a detailed analysis of the effects of shorts in self-checking circuits and proposes techniques for dealing with them. More precisely, we show that, unlike other faults such as stuck-at, stuck-on, and stuck-open—which produce only single errors in the place they occur—shorts can produce double errors on the two shorted lines. In particular, feedback shorts can produce double errors on the two shorted lines. The double error is unidirectional for some feedback shorts and non-unidirectional for some others. Furthermore, in some technologies (e.g., CMOS), non-feedback shorts can also produce double non-unidirectional errors. We also show that unlike stuck-at, stuck-on, and stuck-open faults, redundant shorts can destroy the SFS property. Then we propose several techniques for coping with these problems and we illustrate the results by circuit implementation examples.The present study is given for NMOS and CMOS circuits but we show that it is valid for any other technology. 相似文献
48.
The importance of studies of alternative (as compared to traditional) methods of nonlinear stochastic parametric identification is demonstrated. Synthesis of a procedure of identification of the parameter, “discrete observer,” with the use of the criterion, “minimum probability of estimation error,” is proposed for the first time. A model example that demonstrates the efficiency of the proposed approach is considered. 相似文献
49.
Eugene Fiume† 《Computer Graphics Forum》1995,14(1):47-58
The main preoccupations of research in computer-aided geometric design have been on shape-specification techniques for polynomial curves and surfaces, and on the continuity between segments or patches. When modelling with such techniques, curves and surfaces can be compressed or expanded arbitrarily. There has been relatively little work on interacting with direct spatial properties of curves and surfaces, such as their arc length or surface area. As a first step, we derive families of parametric piecewise polynomial curves that satisfy various positional and tangential constraints together with arc-length constraints. We call these curves isometric curves. A space curve is defined as a sequence of polynomial curve segments, each of which is defined by the familiar Hermite or Bézier constraints for cubic polynomials; as well, each segment is constrained to have a specified arc length. We demonstrate that this class of curves is attractive and stable. We also describe the numerical techniques used that are sufficient for achieving real time interaction with these curves on low-end workstations. 相似文献
50.
针对传统分步式结构优化设计的不足,提出一种同时进行结构拓扑、形状和尺寸统一优化的设计方法.首先采用水平集函数描述统一的结构优化模型和几何尺寸边界,通过引入紧支径向插值基函数将结构拓扑优化变量、形状优化变量和尺寸优化变量变换为基函数的扩展系数;然后取该扩展系数为设计变量,借助一种参数的变化表达3种优化要素对结构性能的影响,将复杂的多变量优化问题变换为相对简单的参数优化问题,有利于与相对成熟的优化算法相结合提高求解效率;进一步用R函数将其融合为一个整体,构造出统一优化模型,并用最优化准则法进行求解.最后通过数值案例证明了该方法的有效性和精确性. 相似文献