全文获取类型
收费全文 | 43668篇 |
免费 | 6759篇 |
国内免费 | 3117篇 |
专业分类
电工技术 | 11644篇 |
技术理论 | 2篇 |
综合类 | 4330篇 |
化学工业 | 1471篇 |
金属工艺 | 1321篇 |
机械仪表 | 4340篇 |
建筑科学 | 3603篇 |
矿业工程 | 2807篇 |
能源动力 | 1240篇 |
轻工业 | 501篇 |
水利工程 | 1377篇 |
石油天然气 | 3114篇 |
武器工业 | 682篇 |
无线电 | 3977篇 |
一般工业技术 | 2306篇 |
冶金工业 | 1176篇 |
原子能技术 | 523篇 |
自动化技术 | 9130篇 |
出版年
2024年 | 330篇 |
2023年 | 701篇 |
2022年 | 1327篇 |
2021年 | 1580篇 |
2020年 | 1824篇 |
2019年 | 1325篇 |
2018年 | 1204篇 |
2017年 | 1546篇 |
2016年 | 1738篇 |
2015年 | 2046篇 |
2014年 | 3126篇 |
2013年 | 2651篇 |
2012年 | 3686篇 |
2011年 | 3627篇 |
2010年 | 2747篇 |
2009年 | 2824篇 |
2008年 | 2749篇 |
2007年 | 3203篇 |
2006年 | 2700篇 |
2005年 | 2223篇 |
2004年 | 1933篇 |
2003年 | 1657篇 |
2002年 | 1312篇 |
2001年 | 1173篇 |
2000年 | 965篇 |
1999年 | 800篇 |
1998年 | 504篇 |
1997年 | 423篇 |
1996年 | 337篇 |
1995年 | 340篇 |
1994年 | 217篇 |
1993年 | 144篇 |
1992年 | 154篇 |
1991年 | 111篇 |
1990年 | 83篇 |
1989年 | 66篇 |
1988年 | 44篇 |
1987年 | 22篇 |
1986年 | 11篇 |
1985年 | 12篇 |
1984年 | 11篇 |
1983年 | 9篇 |
1982年 | 7篇 |
1981年 | 7篇 |
1980年 | 11篇 |
1979年 | 7篇 |
1976年 | 4篇 |
1975年 | 5篇 |
1959年 | 5篇 |
1951年 | 4篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
11.
Iwao Shimizu Yuji Naito Iwao Yamaguchi Katsuyuki Kaiho Hitoshi Mizoguchi Satoru Yanabu 《Electrical Engineering in Japan》2008,164(1):52-61
Using conventional high‐temperature superconducting wire, a model superconducting fault current limiter (SFCL) is made and tested. Solenoid coil using Bi2223 silver sheath wire is so made that inductance is as small as possible and a vacuum interrupter is connected in series to it. A conventional reactor coil is connected in parallel. When the fault current flows in this equipment, superconducting wire is quenched and current is transferred into the parallel coil because of voltage drop of superconducting wire. This large current in parallel coil actuates magnetic repulsion mechanism of vacuum interrupter. Due to opening of vacuum interrupter, the current in superconducting wire is broken. By using this equipment, current flow time in superconducting wire can be easily minimized. On the other hand, the fault current is also easily limited by large reactance of parallel coil. © 2008 Wiley Periodicals, Inc. Electr Eng Jpn, 164(1): 52–61, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20315 相似文献
12.
Bingyong Yan Zuohua Tian Songjiao Shi 《International Journal of Electrical Power & Energy Systems》2008,30(5):343-360
In this paper, we propose a novel distributed robust fault detection and identification (RFDI) scheme for a class of nonlinear systems. Firstly, a detection and identification estimator—robust fault tracking approximator (RFTA) is designed for online health monitoring. A novel feature of the RFTA is that it can simultaneously detect and accurately identify the shape and magnitude of the fault and disturbance. Moreover, it takes less online training time compared with the traditional neural network based fault diagnosis schemes. For some distributed systems, a network of distributed estimators is constructed where the RFTA is embedded into each estimator. Then we use consensus filter to filter the outputs of each estimator. One of the most important merits of the consensus filter is that its outputs can dramatically improve the accuracy of fault detection and identification. Next, the stability of the distributed RFDI scheme is rigorously investigated. Finally, two numerical examples are given to illustrate the feasibility and effectiveness of the proposed approach. 相似文献
13.
胜利炼油厂重油加氢 (VRDS)装置的常压分馏塔为填料塔 ,2 0 0 1年检修开工后该系统出现异常 ,经过查找分析 ,确定轻烃 /产品减压渣油换热器和柴油汽提塔重沸器内漏是装置异常的主要原因 相似文献
15.
复杂目标近场电磁散射的可视化计算方法 总被引:9,自引:1,他引:8
首次介绍了复杂目标近场散射计算的可视化方法。采用非均匀有理B样条曲面(NURBS)精确构造任意形状散射体,结合几何体近场透视变换和Z-Buffer技术实现了基于Windows平台的近场散射计算。提出广义雷达散射截面的概念并给出的若干算例。该方法充分利用了计算机3D图形设备的几何运算能力,运算速度快,严谨高,可扩展性好。 相似文献
16.
Thomas L. Landers Melinda K. Beavers Malik Sadiq Don E. Stuart 《Computers & Industrial Engineering》1994,27(1-4):245-248
This paper describes an approach, conceptual framework, and software architecture for dynamic reconfiguration of the order picking system. The research and development project was sponsored by the Material Handling Research Center (MHRC), a National Science Foundation sponsored Cooperative Industry/University Research Center. The storage configuration is assumed to be an in-the-aisle order picking system in which stockkeeping units (SKUs) can occupy variable capacity storage locations and stock-splitting is allowed among zones (clusters). The product mix may include multiple product families with different life cycles, correlated demand within families and commonality of demand across families. 相似文献
17.
本文从梯形水力最优断面的基本思路出发,通过理论分析找到了梯形断面水力计算的一种新方法——即通过特征参数进行梯形断面的水力计算。 相似文献
18.
改进的第三代相干算法及应用 总被引:1,自引:0,他引:1
在讨论相干技术发展及三代相干算法优缺点的基础上,介绍了改进的第三代相干算法。应用自行开发的相干软件对多个油气勘探和开发区块的三维地震资料进行处理、分析,对相干时窗长度、相关道数等参数对算法效果的影响及相干体对断层、异常地质体的识别,以及解释方法进行了探讨。应用实例证明,改进的第三代相干算法抗干扰能力强,横向分辨率高,不仅适用于倾斜地层,而且对断层尤其对小断层、异常地质体具有较高的检测能力,是油气勘探和开发的一项有效和实用的技术。 相似文献
19.
大规格圆钢质量分析和控制 总被引:1,自引:0,他引:1
针对湘钢棒材厂生产大规格圆钢出现的表面质量问题,重点介绍了在成品轧机后采用U形辊道和立活套替换棍道;冷床输入辊道采用镶WT合金套;增设高压水除鳞装置;中间轧件尺寸精度控制等措施,成功的解决了大规格圆钢表面擦伤、“麻面”、尺寸超差等表面质量问题,产品质量显著提高。 相似文献
20.
Atilla Bilgin 《国际能源研究杂志》2002,26(11):987-1000
Flame front surface area and enflamed volume (the volume enclosed with flame front) is theoretically analysed for a spark‐ignition engine, having cylindrical disc‐shaped combustion chamber with two spark plugs located axisymmetrically on cylinder head, between cylinder axis and cylinder wall. Spherical flame front assumption is used. A computer code is developed based on purely geometric consideration of the flame development process in combustion chamber, and is used to investigate the effects of variations of spark plugs' locations on geometric features of the flame front. A comparison has also been made with a spark‐ignition engine having one spark plug at the same location. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献