全文获取类型
收费全文 | 21210篇 |
免费 | 1177篇 |
国内免费 | 949篇 |
专业分类
电工技术 | 2870篇 |
综合类 | 1019篇 |
化学工业 | 1443篇 |
金属工艺 | 1132篇 |
机械仪表 | 2430篇 |
建筑科学 | 965篇 |
矿业工程 | 575篇 |
能源动力 | 745篇 |
轻工业 | 320篇 |
水利工程 | 126篇 |
石油天然气 | 286篇 |
武器工业 | 195篇 |
无线电 | 2966篇 |
一般工业技术 | 1720篇 |
冶金工业 | 582篇 |
原子能技术 | 211篇 |
自动化技术 | 5751篇 |
出版年
2024年 | 35篇 |
2023年 | 185篇 |
2022年 | 321篇 |
2021年 | 443篇 |
2020年 | 420篇 |
2019年 | 350篇 |
2018年 | 364篇 |
2017年 | 495篇 |
2016年 | 581篇 |
2015年 | 718篇 |
2014年 | 1187篇 |
2013年 | 1149篇 |
2012年 | 1279篇 |
2011年 | 1682篇 |
2010年 | 1137篇 |
2009年 | 1326篇 |
2008年 | 1382篇 |
2007年 | 1516篇 |
2006年 | 1361篇 |
2005年 | 1318篇 |
2004年 | 1041篇 |
2003年 | 924篇 |
2002年 | 781篇 |
2001年 | 568篇 |
2000年 | 516篇 |
1999年 | 416篇 |
1998年 | 369篇 |
1997年 | 292篇 |
1996年 | 249篇 |
1995年 | 177篇 |
1994年 | 165篇 |
1993年 | 147篇 |
1992年 | 108篇 |
1991年 | 71篇 |
1990年 | 55篇 |
1989年 | 50篇 |
1988年 | 47篇 |
1987年 | 20篇 |
1986年 | 20篇 |
1985年 | 11篇 |
1984年 | 17篇 |
1983年 | 16篇 |
1982年 | 8篇 |
1981年 | 5篇 |
1979年 | 3篇 |
1977年 | 3篇 |
1966年 | 1篇 |
1962年 | 1篇 |
1959年 | 1篇 |
1955年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
随着设备高速化的日益发展,传统的螺杆设计方法及相应的供送特性评价体系已显落后。参照蜗型凸轮动力学性能的评价方法,建立了高速供送螺杆的动态性能评价体系,为高速化供送螺杆的设计提供了性能参照指标。 相似文献
72.
The correlation between the crack resistance measured from dynamic and quasi-static J-R tests has been investigated based on test data from instrumented Charpy impact tests and quasi-static single edge notched bend (SENB) J-R tests.The method originally proposed by Aurich et al. [Analyse und Weiterentwicklung Bruchmechanischer versagenskonzepte--Lokales Risswachstum, Ermittlung des Risswiderstandsverhaltens aus der Kerbslagarbeit. BAM Forschungsbericht 192, Berlin 1993, ISBN 3-89429-329-2], to develop a correlation coefficient between the net fracture resistance of Charpy V-notch (ISO) and quasi-static compact tension tests, was extended to establish correlations between so-called ductile-brittle transition fracture resistance curves obtained from instrumented Charpy V-notched (ISO) and fatigue precracked impact tests and quasi-static SENB J-R fracture resistance tests.The correlation between the dynamic and quasi-static crack resistance with regard to practical application to fracture assessments appears to be reasonably consistent, bearing in mind the inherent scatter in crack resistance data in general. The findings of the present research project from testing of ship grade NVE 36 and pressure vessel steel to ASTM A516 Gr. 70 as well as two weldments in the NVE 36 steel, are in excellent agreement with the results of the research conducted by Aurich et al. [Analyse und Weiterentwicklung Bruchmechanischer versagenskonzepte--Lokales Risswachstum, Ermittlung des Risswiderstandsverhaltens aus der Kerbslagarbeit. BAM Forschungsbericht 192, Berlin 1993, ISBN 3-89429-329-2] for structural and pressure vessel steels to the German DIN standard steels including St 52-3, StE 355 and StE 460. 相似文献
73.
74.
在道岔缺口超标报警系统中的软件设计 总被引:1,自引:0,他引:1
介绍了SED1335的性能及特点,重点阐述了它在道岔缺口超标报警系统中显示字符、汉字、构建友好界面的软件设计方法,提出了编写液晶显示程序的一些优良算法。 相似文献
75.
76.
Yuji Oie Tatsuya Suda Masayuki Murata Hideo Miyahara 《International Journal of Satellite Communications and Networking》1991,9(5):285-303
One of the most promising approaches for high speed networks for integrated service applications is fast packet switching, or ATM (asynchronous transfer mode). ATM can be characterized by very high speed transmission links and simple, hard-wired protocols within a network. To match the transmission speed of the network links, and to minimize the overhead due to the processing of network protocols, the switching of cells is done in hardware switching fabrics in ATM networks. A number of designs have been proposed for implementing ATM switches. Although many differences exist among the proposals, the vast majority of them are based on self-routeing multistage interconnection networks. This is because of the desirable features of multi-stage interconnection networks such as self-routeing capability and suitability for VLSI implementation. Existing ATM switch architectures can be classified into two major classes: blocking switches, where blockings of cells may occur within a switch when more than one cell contends for the same internal link, and non-blocking switches, where no internal blocking occurs. A large number of techniques have also been proposed to improve the performance of blocking and non-blocking switches. In this paper, we present an extensive survey of the existing proposals for ATM switch architectures, focusing on their performance issues. 相似文献
77.
Broadband packet networks based on asynchronous transfer mode (ATM) are expected to provide a wide range of services, including motion video, voice, data and image. When these networks become prevalent, some applications such as motion video and high-speed LAN interconnections will place a very large bit rate requirement on the channels. Currently, the physical layer supported by the synchronous optical network (SONET) allows the transmission of up to 2.4 Gbit/s with the OC-48 optical interface. However, it is not feasible for the electronic packet switch to route packets at this rate on a single link. In this paper we present a design of a broadband packet switch that uses multiple links in parallel to realize a high-speed channel. This implementation permits the switch to operate at the lower link rate, which can be at 150 Mbit/s, while having the ability to support a virtual circuit at a higher rate (up to 2.4 Gbit/s). The main contribution of the design is that packet sequence on a channel is still maintained even though packets are allowed to use any of the links belonging to the same channel. Besides allowing the switch to function at a slower rate than the transmission channel rate, the implementation of the multilinks benefits from statistical multiplexing gain. Analytical results show the performance advantages of multilink design with respect to delay, throughput and packet loss probability. 相似文献
78.
光电摆角动态测量原理及其测量系统 总被引:4,自引:1,他引:3
本文阐述了用于测量物体摆角及摆心浮动量的光电动态实时测量原理,以及根据此原理研制的光电导弹喷管摆角动态测量系统。 相似文献
79.
本文推导了计及惯性的Navier-Stokes方程的简化形式,分析了考虑开槽区流体周向惯性的上瓦开周向槽椭圆轴承的动态特性。 相似文献
80.
It is shown that steady-state kinetic data do not allow the discrimination between the redox and associated mechanisms of the partial oxidation reactions. A discrimination between these mechanisms was performed using transient experiments. The obtained rate expressions are in agreement with experimental kinetic data for catalytic partial oxidation of o-xylene.
An influence of the conjugate oxidation of a catalyst surface on dynamics and kinetics of the heterogeneous catalytic oxidative reactions is considered. Computing simulation of methane oxidative coupling of methane reaction at lowered temperature and elevated pressure has been performed. It showed that the reaction order with respect to oxygen exceeding unity is consistent with the chain branching mechanism of the reaction in the presence of TiSi2 and TiB2 and showed the important role of the branching chain cycles in the low-temperature OCM reaction at elevated pressure. 相似文献