全文获取类型
收费全文 | 6994篇 |
免费 | 871篇 |
国内免费 | 576篇 |
专业分类
电工技术 | 237篇 |
综合类 | 756篇 |
化学工业 | 768篇 |
金属工艺 | 261篇 |
机械仪表 | 875篇 |
建筑科学 | 591篇 |
矿业工程 | 184篇 |
能源动力 | 125篇 |
轻工业 | 113篇 |
水利工程 | 92篇 |
石油天然气 | 173篇 |
武器工业 | 75篇 |
无线电 | 887篇 |
一般工业技术 | 1138篇 |
冶金工业 | 72篇 |
原子能技术 | 30篇 |
自动化技术 | 2064篇 |
出版年
2024年 | 16篇 |
2023年 | 101篇 |
2022年 | 154篇 |
2021年 | 170篇 |
2020年 | 185篇 |
2019年 | 172篇 |
2018年 | 192篇 |
2017年 | 229篇 |
2016年 | 248篇 |
2015年 | 284篇 |
2014年 | 558篇 |
2013年 | 481篇 |
2012年 | 645篇 |
2011年 | 637篇 |
2010年 | 498篇 |
2009年 | 478篇 |
2008年 | 499篇 |
2007年 | 563篇 |
2006年 | 445篇 |
2005年 | 413篇 |
2004年 | 249篇 |
2003年 | 259篇 |
2002年 | 206篇 |
2001年 | 153篇 |
2000年 | 146篇 |
1999年 | 98篇 |
1998年 | 70篇 |
1997年 | 68篇 |
1996年 | 50篇 |
1995年 | 32篇 |
1994年 | 30篇 |
1993年 | 25篇 |
1992年 | 24篇 |
1991年 | 10篇 |
1990年 | 10篇 |
1989年 | 6篇 |
1988年 | 7篇 |
1987年 | 4篇 |
1986年 | 5篇 |
1985年 | 4篇 |
1984年 | 1篇 |
1983年 | 6篇 |
1982年 | 2篇 |
1979年 | 1篇 |
1972年 | 1篇 |
1961年 | 2篇 |
1960年 | 1篇 |
1959年 | 1篇 |
1955年 | 1篇 |
1951年 | 1篇 |
排序方式: 共有8441条查询结果,搜索用时 187 毫秒
31.
Measurement selection for parametric IC fault diagnosis 总被引:1,自引:0,他引:1
This article presents experimental results which show feedforward neural networks are well-suited for analog IC fault diagnosis. Boundary band data (BBD) measurement selection is used to reduce the computational overhead of the FFN training phase. We compare the diagnostic accuracy between traditional statistical classifiers and feedforward neural networks trained with various measurement selection criteria. The feedforward networks consistently perform as well as or better than the other classifiers in term of accuracy. Training using BBD consistently reduces the FFN training efforts without degrading the performance. Experimental results suggest that feedforward networks provide a cost efficient method for IC fault diagnosis in a large scale production testing environment.This work is supported by NSF-IUC CDADIC, Project 90-1. 相似文献
32.
Human can handle a deformable object and damp its vibration with recognized skill. However, for an industrial robot, handling a deformable object with acute vibration is often a difficult task. This paper addresses the problem of active damping skill for handling deformable linear objects (DLOs) by using a strategy inspired from human manipulation skills. The strategy is illustrated by several rules, which are explained by a fuzzy and a P controller. A proportional-integral-derivative (PID) controller is also employed to explain the rules as a comparison. The interpretations from controllers are translated into high level commands in a robotic language V+. A standard industrial robot with a force/torque sensor mounted on the wrist was employed to demonstrate the skill. Experimental results showed the fuzzy based damping skill is quite effective and stable even without any previous acknowledge of the deformable linear objects.Category (5) 相似文献
33.
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
34.
35.
36.
助模板剂对MCM—41分子筛孔结构和性能的影响 总被引:2,自引:0,他引:2
在硅酸钠-硫酸铝-十六烷基三甲基氯化铵-水体系中,加入不同类型,如正庚烷、三甲基苯和十二胺的有机助模板剂(简称助剂)进行MCM-41分子筛的合成试验,并用XRD、IR及N2吸附等方法考察了助剂对MCM-41分子筛孔径、热稳定性及酸性的影响。结果表明,十二胺助剂对MCM-41分子筛的孔径影响最大,但热稳定性较差,相比之下,三甲基苯助剂合成的MCM-41分子筛具有孔径大、热稳定性好和酸性特征较好的特点。 相似文献
37.
以镍离子为模板剂,合成了乙醇双环氧丙基醚交联的壳聚糖树脂,研究了其对Cu(Ⅱ)、Ni(Ⅱ)、Co(Ⅱ)离子的吸附性能。结果表明,该法合成的树脂对Ni(Ⅱ)离子具有较强的“记忆”和“识别”能力,其对Cu(Ⅱ)、Ni(Ⅱ)、Co(Ⅱ)的吸附量分别达2.21、2.13、1.40mmol/g树脂。 相似文献
38.
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
39.
本文提出了一种基于色度滤波的唇动特征提取与识别方法 ,它通过唇的色度滤波 ,得到增强的唇动图像 ,再利用可变模板 ,描述口型轮廓并提取特征参数 ,并用HMM模型进行唇运动序列图像识别 .该方法鲁棒性强 ,对光照没有苛刻的要求 ,且针对非特定人 ,适用于自然条件下的实用环境 ,解决了可变模板对目标边缘有较高分辨率的要求 ,使方法更实用化 .本文的实验是基于单纯的视觉信息 (没有声音信道的信息 )的唇动识别 ,不加语音信息 ,实验集合只限于单韵母 ,识别率可达 95 8% . 相似文献
40.
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