全文获取类型
收费全文 | 21817篇 |
免费 | 4003篇 |
国内免费 | 2661篇 |
专业分类
电工技术 | 4702篇 |
综合类 | 2316篇 |
化学工业 | 421篇 |
金属工艺 | 172篇 |
机械仪表 | 1140篇 |
建筑科学 | 431篇 |
矿业工程 | 277篇 |
能源动力 | 550篇 |
轻工业 | 153篇 |
水利工程 | 383篇 |
石油天然气 | 442篇 |
武器工业 | 310篇 |
无线电 | 4331篇 |
一般工业技术 | 927篇 |
冶金工业 | 218篇 |
原子能技术 | 88篇 |
自动化技术 | 11620篇 |
出版年
2024年 | 63篇 |
2023年 | 388篇 |
2022年 | 674篇 |
2021年 | 850篇 |
2020年 | 965篇 |
2019年 | 808篇 |
2018年 | 746篇 |
2017年 | 986篇 |
2016年 | 1023篇 |
2015年 | 1221篇 |
2014年 | 1650篇 |
2013年 | 1490篇 |
2012年 | 1778篇 |
2011年 | 1718篇 |
2010年 | 1382篇 |
2009年 | 1408篇 |
2008年 | 1512篇 |
2007年 | 1686篇 |
2006年 | 1332篇 |
2005年 | 1215篇 |
2004年 | 1045篇 |
2003年 | 868篇 |
2002年 | 714篇 |
2001年 | 603篇 |
2000年 | 424篇 |
1999年 | 357篇 |
1998年 | 303篇 |
1997年 | 231篇 |
1996年 | 199篇 |
1995年 | 176篇 |
1994年 | 150篇 |
1993年 | 112篇 |
1992年 | 79篇 |
1991年 | 56篇 |
1990年 | 34篇 |
1989年 | 32篇 |
1988年 | 24篇 |
1987年 | 12篇 |
1986年 | 24篇 |
1985年 | 19篇 |
1984年 | 17篇 |
1983年 | 20篇 |
1982年 | 19篇 |
1981年 | 17篇 |
1980年 | 17篇 |
1979年 | 11篇 |
1978年 | 8篇 |
1977年 | 9篇 |
1973年 | 2篇 |
1959年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
The static behaviour of Bi-Steel beams was simulated using a finite element model. The model was compared to test results showing good agreement. It was then used in parametric studies of transverse shear capacity and uniformly distributed load cases of Bi-Steel beams. It was possible to isolate the transverse shear failure mode and prevent other failure modes from using the FE model. This enabled the comparison and verification of the proposed design equations for transverse shear. Based on parametric studies, modifications to the design method were also proposed to accommodate udl cases. 相似文献
992.
In this paper, the problem of exponential H∞ filter problem for a class of discrete‐time polytopic uncertain switched linear systems with average dwell time switching is investigated. The exponential stability result of the general discrete‐time switched systems using a discontinuous piecewise Lyapunov function approach is first explored. Then, a new µ‐dependent approach is proposed, which means the analysis or synthesis of the underlying systems is dependent on the increase degree µ of the piecewise Lyapunov function at the switching instants. A mode‐dependent full‐order filter is designed such that the developed filter error system is robustly exponentially stable and achieves an exponential H∞ performance. Sufficient existence conditions for the desired filter are derived and formulated in terms of a set of linear matrix inequalities, and consequently the minimal average dwell time and the corresponding filter are obtained from such conditions for a given system decay degree. A numerical example is presented to demonstrate the potential and effectiveness of the developed theoretical results. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
993.
Theoretical results are reviewed that are concerned with the construction of speed-optimal parallel-pipeline algorithms for
mass calculations in solving filtering problems. The optimality is proved in the corresponding classes of algorithms equivalent
in terms of information graphs. The effectiveness of using the developed algorithmic constructions for filtering problems
is investigated.
__________
Translated from Kibernetika i Sistemnyi Analiz, No. 4, pp. 3–14, July–August 2008. 相似文献
994.
The theoretical analysis of reconstruction problem of distributed physical fields in integrating measuring systems has been
carried out. The integrating measuring systems are compared with the systems of direct measuring in rare points of the field.
And the application prospects have been revealed.
The text was submitted by the authors in English. 相似文献
995.
本文叙述了铝电解槽智能控制系统的组成,介绍了分布式控制系统在铝电解生产控制中的应用,并对铝电解过程控制的基本思想及其主要控制方法进行了详细阐述。本系统在实际应用中取得了良好的控制效果,为企业实现节能增效奠定了坚实的基础。 相似文献
996.
Characteristics of internal-wave and internal-tide deposits and their hydrocarbon potential 总被引:1,自引:0,他引:1
The study of internal-wave and internal-tide deposits is a new research field on sedimentology during the last ten years. Deep-water traction currents induced by internal waves and internal tides are developed on the modern sea floor, which can form not only all kinds of small scale and dispersal deepwater traction currents deposits, but also large-scale sediment wave in km-size scale. In this paper, the concepts and features of internal waves and internal tides in oceanography are introduced, and the characteristics, sedimentary sequences, sedimentary microfacies and sedimentation models of internalwave and internal-tide deposits found and the origin of large scale sediment waves in deep sea bottom are summarized. The relationship between internal-wave and internal-tide deposits and petroleum is discussed, and finally internal-wave and internal-tide deposits are shown to be a new potential field for petroleum exploration. 相似文献
997.
在机械加工中,金属物体的表面粗糙程度往往会影响加工零件的许多性能,所以针对粗糙度的检测是非常重要的。粗糙度的测量方法很多,但许多是接触式测量,不够方便快捷,并有可能对工件表面造成一定的损伤。针对非接触式的粗糙度测量方法,利用激光干涉技术对金属表面进行粗糙度测量,搭建一整套检测系统,并利用改进的滤波技术提高粗糙度的检测精度。 相似文献
998.
介绍马钢一钢厂平炉改转炉项目中新建转炉、连铸以及轧制系统的循环水处理工艺,同时对水处理设施和主要构筑物的设计进行分析和探讨。 相似文献
999.
用解卷积同态滤波识别桩身单缺陷界面反射 总被引:6,自引:0,他引:6
利用解卷积同态滤波,从桩顶反射波曲线的功率谱中分解得到频响函数│H(f)│,在单缺陷界面反射条件下,根据│H(f)│函数的基本特性可以确定反射系数及反射波往返时,进而确定桩身缺陷位置及缺陷严重程度,以实现桩身质量定量诊断的目的。给出了两根桩的桩身缺陷识别实例。 相似文献
1000.
高效节能陶瓷真空过滤机的研制及其应用 总被引:3,自引:0,他引:3
介绍了陶瓷真空过滤机的设计、原理及组成及其在硫精矿脱水中的应用。 相似文献