全文获取类型
收费全文 | 74300篇 |
免费 | 8378篇 |
国内免费 | 5466篇 |
专业分类
电工技术 | 9564篇 |
技术理论 | 1篇 |
综合类 | 7138篇 |
化学工业 | 4806篇 |
金属工艺 | 4238篇 |
机械仪表 | 8195篇 |
建筑科学 | 4672篇 |
矿业工程 | 2706篇 |
能源动力 | 2597篇 |
轻工业 | 2053篇 |
水利工程 | 1973篇 |
石油天然气 | 6023篇 |
武器工业 | 1210篇 |
无线电 | 10616篇 |
一般工业技术 | 8944篇 |
冶金工业 | 2756篇 |
原子能技术 | 1517篇 |
自动化技术 | 9135篇 |
出版年
2024年 | 331篇 |
2023年 | 1020篇 |
2022年 | 1796篇 |
2021年 | 2107篇 |
2020年 | 2262篇 |
2019年 | 1854篇 |
2018年 | 1747篇 |
2017年 | 2608篇 |
2016年 | 2831篇 |
2015年 | 3085篇 |
2014年 | 4417篇 |
2013年 | 4147篇 |
2012年 | 5434篇 |
2011年 | 5754篇 |
2010年 | 4260篇 |
2009年 | 4285篇 |
2008年 | 4201篇 |
2007年 | 5182篇 |
2006年 | 4771篇 |
2005年 | 3951篇 |
2004年 | 3470篇 |
2003年 | 3064篇 |
2002年 | 2463篇 |
2001年 | 2084篇 |
2000年 | 1928篇 |
1999年 | 1625篇 |
1998年 | 1262篇 |
1997年 | 1272篇 |
1996年 | 991篇 |
1995年 | 777篇 |
1994年 | 724篇 |
1993年 | 509篇 |
1992年 | 385篇 |
1991年 | 301篇 |
1990年 | 282篇 |
1989年 | 241篇 |
1988年 | 166篇 |
1987年 | 101篇 |
1986年 | 64篇 |
1985年 | 52篇 |
1984年 | 70篇 |
1983年 | 34篇 |
1982年 | 41篇 |
1981年 | 23篇 |
1980年 | 18篇 |
1979年 | 12篇 |
1977年 | 9篇 |
1959年 | 18篇 |
1955年 | 10篇 |
1951年 | 8篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
51.
在印刷品质量控制中为了得到更多的可靠数值,越来越多地选择用仪器测量法来代替主观评价法.这就是密度测量法和色度测量法. 相似文献
52.
This paper describes the elastic response of a block sample of compressible Chicago glacial clay under a variety of stresses and its relationship with the deformation characteristics at relatively large strains. The elastic shear stiffness was obtained from bender element tests during consolidation and shearing in drained triaxial stress probe tests. An empirical correlation was established based on the elastic shear stiffness in a preyield condition. By comparing the empirical correlation with the measured elastic shear stiffness in the stress region during probing, the changes of elastic shear stiffness were investigated. The departure of elastic shear stiffness from values computed by the empirical relation based on K0 loading directly relates to the yielding characteristics of the clay. The large-scale change of soil structure at yielding alters the well-established relationship between the elastic shear stiffness and stresses in the preyield condition. The mechanical yielding response of clays can be detected based on the systematic analysis of the elastic shear wave velocities. 相似文献
53.
This paper describes an effective analysis of magnetic shielding based on homogenization. The analyses become time‐consuming if the problems include the magnetic substances having fine structure. The homogenization of the structure makes it possible to analyze effectively the magnetic fields. The authors introduce a method to estimate the effective permeability of the homogenized substance. This method can be applied to any periodic structure made of magnetic substance. The magnetic shielding effects by the structures against direct‐current (DC) fields generated by electric railways are analyzed by using the present method. As a result, it is found that the overhead way and the protective fence near the railway work as a magnetic shield, whose effects can be improved by appropriate arrangement of those constructions. © 2007 Wiley Periodicals, Inc. Electr Eng Jpn, 160(4): 7–15, 2007; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20310 相似文献
54.
Scale selection using three different representations for images 总被引:1,自引:0,他引:1
J. Martinez-Baena J. A. García J. Fdez-Valdivia Rosa Rodriguez-Sanchez 《Pattern recognition letters》1997,18(14):1453-1467
55.
56.
This paper reviews the current state of industry with regard to the introduction of software metrics. It discusses the benefits that organizations have derived from metrication, it looks at why organizations have sought to introduce metrics programmes, how they have gone about introducing those programmes and the problems that they have encountered during implementation. The review found that, on the whole, only the sanitized aspects of metrics experiences have actually been published. This seems to be especially the case with respect to practitioner resistance. Very few organizations admit to having encountered resistance during the introduction of a metrics programme. The paper also includes the results of a pilot study, conducted by the first author, which examines the attitudes that developers hold towards the introduction of software metrics. The key findings of this pilot study are that positive attitudes to metrics correlate highly with levels of education and to job satisfaction. 相似文献
57.
正交双频光栅CCD系统剪切干涉测量二维温度场 总被引:1,自引:1,他引:0
以半导体激光器为光源,利用正交双频光栅(ODFG)CCD系统剪切干涉对带平板边界的半圆柱体热源的二维温度场进行实时诊断,分析剪切干涉图时,用柱函数系作为拟合基底,给出二维自然对流温度场的定量分布。 相似文献
58.
Recently, a demand for small-capacity generators has been increasing as electric sources in small ships and automobiles or as portable electric sources driven by engines. It is desired that the structure of small-capacity generators be simple and robust, and that the generators be highly reliable, easily maintained and controlled. This paper describes an analysis of the original brushless synchronous generator without exciter. The output voltage can be adjusted in the wide range by controlling the stator dc current. To analyze the characteristics of this generator, the finite element method is applied. It is found that the results of theoretical analysis agree well with the experimental results. 相似文献
59.
给出了滑移线场近似作图法的原理、证明以及近似滑移线场的特点,为进一步利用计算机求解应力分布和变形规律,尤其是为近似滑移线的计算机绘制奠定了基础. 相似文献
60.
NUMERICALSIMULATIONSOFWHOLEFIELDBEHAVIORFORROUNDBUOYANTJETLiWei,HuaiWen-xin(WuhanUniversityofHydraulicandElectricEngineering,... 相似文献