全文获取类型
收费全文 | 14082篇 |
免费 | 1785篇 |
国内免费 | 625篇 |
专业分类
电工技术 | 7326篇 |
综合类 | 838篇 |
化学工业 | 537篇 |
金属工艺 | 204篇 |
机械仪表 | 709篇 |
建筑科学 | 137篇 |
矿业工程 | 295篇 |
能源动力 | 542篇 |
轻工业 | 88篇 |
水利工程 | 64篇 |
石油天然气 | 91篇 |
武器工业 | 46篇 |
无线电 | 2437篇 |
一般工业技术 | 212篇 |
冶金工业 | 1904篇 |
原子能技术 | 82篇 |
自动化技术 | 980篇 |
出版年
2024年 | 48篇 |
2023年 | 199篇 |
2022年 | 340篇 |
2021年 | 426篇 |
2020年 | 476篇 |
2019年 | 358篇 |
2018年 | 313篇 |
2017年 | 536篇 |
2016年 | 612篇 |
2015年 | 650篇 |
2014年 | 941篇 |
2013年 | 739篇 |
2012年 | 1105篇 |
2011年 | 1231篇 |
2010年 | 920篇 |
2009年 | 824篇 |
2008年 | 898篇 |
2007年 | 1047篇 |
2006年 | 1012篇 |
2005年 | 769篇 |
2004年 | 591篇 |
2003年 | 502篇 |
2002年 | 392篇 |
2001年 | 342篇 |
2000年 | 321篇 |
1999年 | 227篇 |
1998年 | 170篇 |
1997年 | 124篇 |
1996年 | 95篇 |
1995年 | 71篇 |
1994年 | 65篇 |
1993年 | 43篇 |
1992年 | 37篇 |
1991年 | 19篇 |
1990年 | 13篇 |
1989年 | 7篇 |
1988年 | 11篇 |
1987年 | 9篇 |
1986年 | 2篇 |
1985年 | 3篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1978年 | 1篇 |
1959年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
941.
介绍了转炉溅渣护炉技术在临钢20t转炉上应用的基本情况,对应用中出现的主要技术问题提出了解决措施。 相似文献
942.
中央空调领域的节能技术 总被引:5,自引:4,他引:1
论述了我国空调耗能的现状和空调节能的意义,从中央空调系统的选择、设备选型及系统运行管理三方面分析了影响空调节能的主要因素,简述了实现节能的几个方面,并着重讨论了设计中最普遍实施的冷却水系统节能的原理和方法。 相似文献
943.
一种新型井间地震井下数据采集系统 总被引:1,自引:0,他引:1
介绍了一种用于井间地震的新型井下数据采集系统,它以数字信号处理单片机为核心,采用新型的高精度过采样∑-△A/D转换器作为采集部件,首次将数字信号处理单片机放于下,进行数据采集的控制与实时数据处理,大大生意 化了采集电路并提高了采集数据的质量。 相似文献
944.
PLC与变频器在自动给水系统中的应用 总被引:1,自引:0,他引:1
田芮 《山东轻工业学院学报》1998,12(2):23-25
本文介绍的是自动变频调整速恒压供水系统。着重介绍了单个变频器对多个马达对象实现自动变频的系统硬件构成、软件编制以及整个模拟调节系统的实现。 相似文献
945.
介绍了内冷-绝热氨合成塔内件和准等温型甲醇合成塔内件的技术特性、操作要点及应用情况,并对存在的问题进行了分析。 相似文献
946.
《IEEJ Transactions on Electrical and Electronic Engineering》2017,12(4):615-622
Series‐connected lithium batteries can be charged in the pack‐charging mode, which is most widely used in the lithium battery application field. But the pack‐charging mode will lead to cell imbalance because of the difference in the electrochemical characteristics of the cells of series‐connected batteries. On the other hand, the cell‐charging mode can avoid the imbalance problem by charging each cell independently, but it will reduce the charging efficiency and increase the cost. In this paper, a novel balancing strategy is proposed with a mixed pack‐charging and cell‐charging mode to implement the balancing algorithm. The proposed strategy aims to solve the problem of charge/discharge imbalance with the simplest balancing algorithm with high balancing performance. There is no complex balancing behaviors during the charging process – as is the case with many other existing schemes – so the control algorithm can be greatly simplified. Because each cell can be fully charged and discharged with the proposed algorithm, it helps to make full use of the energy and capacity of each cell. The system stability and reliability of the proposed system, as well as its good performance, are verified through experiments. © 2017 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. 相似文献
947.
《IEEJ Transactions on Electrical and Electronic Engineering》2017,12(6):925-935
In this paper, we report a novel single‐switch AC to DC step‐down converter suitable for light emitting diodes. The proposed topology has a buck and a buck–boost converter. The circuit is designed to operate in the discontinuous conduction mode in order to improve the power factor. In this topology, a part of the input power is connected to the load directly. This feature of the proposed topology increases the efficiency of power conversion, improves the input power factor, produces less voltage stress on intermediate stages, and reduces the output voltage in the absence of a step‐down transformer. The theoretical analysis, design procedure, and performance of the proposed converter are verified by simulation and experiment. A 36 V, 60 W prototype has been built to demonstrate the merits of this circuit. © 2017 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. 相似文献
948.
949.
C. Pliangos I.V. Yentekakis V.G. Papadakis C.G. Vayenas X.E. Verykios 《Applied catalysis. B, Environmental》1997,14(3-4):161-173
The kinetics of oxidation of a light hydrocarbon (C2H4) were studied on catalysts comprising of combinations of one of three metals, Pt, Pd or Rh supported on five different supports, that is, SiO2, γ-Al2O3, ZrO2 (8% Y2O3), TiO2 or TiO2 (W6+). Significant variation of turnover frequency with the carrier was observed, which cannot be explained by structure sensitivity considerations and is attributed to interactions between the metal crystallites and the carrier. The catalytic activity of these metal-support combinations was investigated over a wide range of partial pressures of ethylene and oxygen. In a separate set of experiments, the kinetics of C2H4 oxidation were also investigated on polycrystalline Rh films interfaced with ZrO2 (8 mol% Y2O3) solid electrolyte in a galvanic cell of the type: C2H4, O2, Rh/YSZ/Pt, air, during regular open-circuit conditions as well as under Non-Faradic Electrochemical Modification of Catalytic Activity (NEMCA), that is, closed-circuit conditions. Up to 100-fold increase in catalytic activity was observed by supplying O2− ions to the catalyst surface via positive potential application to the catalyst. The observed kinetic behavior upon increasing catalyst potential parallels qualitatively the observed alteration of turnover frequency with variation of the support of the Rh crystallites. 相似文献
950.
通过把互感滤波器应用到ZVS-PWM移相变换器的输出端,详细分析了互感滤波器对全桥移相ZVS-PWM变换器的影响,并利用PSPICE软件对全桥移相ZVS-PWM变换器及其改进电路进行了仿真,分析了互感滤波器应用在ZVS-PWM中的二阶滤波模式,比较了互感滤波与L、C滤波的效果,通过仿真验证了理论分析的结果。 相似文献