全文获取类型
收费全文 | 51425篇 |
免费 | 5596篇 |
国内免费 | 3892篇 |
专业分类
电工技术 | 4812篇 |
综合类 | 4643篇 |
化学工业 | 7239篇 |
金属工艺 | 3003篇 |
机械仪表 | 3668篇 |
建筑科学 | 4131篇 |
矿业工程 | 1476篇 |
能源动力 | 1678篇 |
轻工业 | 3567篇 |
水利工程 | 1255篇 |
石油天然气 | 2081篇 |
武器工业 | 866篇 |
无线电 | 6403篇 |
一般工业技术 | 5279篇 |
冶金工业 | 1803篇 |
原子能技术 | 788篇 |
自动化技术 | 8221篇 |
出版年
2024年 | 218篇 |
2023年 | 665篇 |
2022年 | 1373篇 |
2021年 | 2063篇 |
2020年 | 1553篇 |
2019年 | 1255篇 |
2018年 | 1348篇 |
2017年 | 1519篇 |
2016年 | 1406篇 |
2015年 | 2246篇 |
2014年 | 2738篇 |
2013年 | 3396篇 |
2012年 | 3764篇 |
2011年 | 4025篇 |
2010年 | 3922篇 |
2009年 | 3844篇 |
2008年 | 3758篇 |
2007年 | 3565篇 |
2006年 | 3389篇 |
2005年 | 2746篇 |
2004年 | 2113篇 |
2003年 | 1881篇 |
2002年 | 1913篇 |
2001年 | 1704篇 |
2000年 | 1224篇 |
1999年 | 796篇 |
1998年 | 478篇 |
1997年 | 378篇 |
1996年 | 348篇 |
1995年 | 272篇 |
1994年 | 210篇 |
1993年 | 192篇 |
1992年 | 161篇 |
1991年 | 93篇 |
1990年 | 89篇 |
1989年 | 59篇 |
1988年 | 49篇 |
1987年 | 26篇 |
1986年 | 30篇 |
1985年 | 22篇 |
1984年 | 6篇 |
1983年 | 11篇 |
1982年 | 14篇 |
1981年 | 11篇 |
1980年 | 9篇 |
1979年 | 6篇 |
1976年 | 3篇 |
1973年 | 4篇 |
1959年 | 6篇 |
1951年 | 6篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
This paper focuses on H∞ filtering for linear time‐delay systems. A new Lyapunov–Krasovskii functional (LKF) is constructed by uniformly dividing the delay interval into two subintervals, and choosing different Lyapunov matrices on each subinterval. Based on this new LKF, a less conservative delay‐dependent bounded real lemma (BRL) is established to ensure that the resulting filtering error system is asymptotically stable with a prescribed H∞ performance. Then, this new BRL is equivalently converted into a set of linear matrix inequalities, which guarantee the existence of a suitable H∞ filter. Compared with some existing filtering results, some imposed constraints on the Lyapunov matrices are removed through derivation of the sufficient condition for the existence of the filter. Numerical examples show that the results obtained in this paper significantly improve the H∞ performance of the filtering error system over some existing results in the literature. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
992.
Tzu‐Ming Wang Yu‐Hsuan Li Ming‐Dou Ker 《Journal of the Society for Information Display》2009,17(10):785-794
Abstract— Low‐temperature polysilicon (LTPS) technology has a tendency towards integrating all circuits on glass substrate. However, the poly‐Si TFTs suffered poor uniformity with large variations in the device characteristics due to a narrow laser process window for producing large‐grained poly‐Si TFTs. The device variation is a serious problem for circuit realization on the LCD panel, so how to design reliable on‐panel circuits is a challenge for system‐on‐panel (SOP) applications. In this work, a 6‐bit R‐string digital‐to‐analog converter (DAC) with gamma correction on glass substrate for TFT‐panel applications is proposed. The proposed circuit, which is composed of a folded R‐string circuit, a segmented digital decoder, and reordering of the decoding circuit, has been designed and fabricated in a 3‐μm LTPS technology. The area of the new proposed DAC circuit is effectively reduced to about one‐sixth compared to that of the conventional circuit for the same LTPS process. 相似文献
993.
The present work is an archival paper for a series of contributions proposed in last few years on building a theory of roughness over pure mereological relations among information granules. There are five major efforts taken in the present paper: (1) emphasizing on the representational semantics of theory of roughness: to approximately represent a class of entities characterized by some aspects in terms of entity collections described at other aspects; (2) defining a representation model Granular Representation Calculus (GrRC) to synthesize complex information systems from information granules; (3) establishing notion of Granular Rough Theory (GrRT) over information granules operated in terms of GrRC; (4) extending GrRC/GrRT to various computational environments such as multi-agent systems and ontological computing environments; (5) exploring pragmatic aspects of GrRC/GrRT in implementing prototypes with data model and object programming orientations, and proposing an Ontology-Driven Web Information System as a granular-rough computational Web intelligence framework over GrRC/GrRT. 相似文献
994.
995.
基于模糊定性趋势分析的故障诊断方法研究 总被引:2,自引:0,他引:2
趋势能够反映过程重要参数的运行状态和发展趋向;利用定性趋势分析进行故障诊断时,趋势固有的定性特性使得趋势分类的界限变得模糊,带来诊断的模糊性和规则知识库的组合爆炸等一系列问题;将模糊理论与定性趋势分析相结合,给出了趋势提取及基于模糊逻辑的趋势匹配算法,研究了一种基于模糊定性趋势分析的故障诊断方法来有效地解决这些问题;实例分析表明,基于模糊定性趋势分析的故障诊断方法能大大缩小规则知识库的规模,提高定性趋势分析故障诊断的准确性和实时性,及时发现和预测控制过程的早期故障。 相似文献
996.
在Matlab环境下运用基于二维小波变换边缘检测方法提取车牌信息的边缘。实验证明这种方法对车牌边缘信息提取的效果比传统的边缘提取算子提取车牌信息边缘的效果要好,特别是对伪边缘和图片噪声的过滤作用比较明显。 相似文献
997.
一种基于ZigBee协议的矿井人员定位技术研究 总被引:1,自引:0,他引:1
针对目前矿井无线通信技术存在的不足,详细分析了IEEE802.15.4标准和ZigBee技术,讨论了二者的关系及技术特点,在此基础上,提出了一种基于ZigBee技术的无线传感器网络定位系统.网络采用基于到达时间(time of arrival,TOA)的定位机制,先根据信号的传播时间和传播速度计算出节点间的距离,然后由极大似然估计法(maximum likelihoodestimation,MLE)确定目标节点的位置.系统满足井下通信的要求,安装简单方便,精度高,稳定性好. 相似文献
998.
X-ray detectors based on straight-channel microchannel plates (MCPs) are a powerful diagnostic tool for two-dimensional, time-resolved imaging and time-resolved x-ray spectroscopy in the fields of laser-driven inertial confinement fusion and fast Z-pinch experiments. Understanding the behavior of microchannel plates as used in such detectors is critical to understanding the data obtained. The subject of this paper is a Monte Carlo computer code we have developed to simulate the electron cascade in a MCP under a static applied voltage. Also included in the simulation is elastic reflection of low-energy electrons from the channel wall, which is important at lower voltages. When model results were compared to measured MCP sensitivities, good agreement was found. Spatial resolution simulations of MCP-based detectors were also presented and found to agree with experimental measurements. 相似文献
999.
1000.