全文获取类型
收费全文 | 110347篇 |
免费 | 10457篇 |
国内免费 | 6384篇 |
专业分类
电工技术 | 7915篇 |
技术理论 | 2篇 |
综合类 | 8307篇 |
化学工业 | 17098篇 |
金属工艺 | 6365篇 |
机械仪表 | 7389篇 |
建筑科学 | 8460篇 |
矿业工程 | 3490篇 |
能源动力 | 3186篇 |
轻工业 | 7115篇 |
水利工程 | 2154篇 |
石油天然气 | 5875篇 |
武器工业 | 1289篇 |
无线电 | 13563篇 |
一般工业技术 | 12514篇 |
冶金工业 | 4698篇 |
原子能技术 | 1317篇 |
自动化技术 | 16451篇 |
出版年
2024年 | 564篇 |
2023年 | 1744篇 |
2022年 | 3044篇 |
2021年 | 4447篇 |
2020年 | 3392篇 |
2019年 | 2899篇 |
2018年 | 3154篇 |
2017年 | 3558篇 |
2016年 | 3230篇 |
2015年 | 4536篇 |
2014年 | 5517篇 |
2013年 | 6683篇 |
2012年 | 7430篇 |
2011年 | 8059篇 |
2010年 | 7200篇 |
2009年 | 6960篇 |
2008年 | 6733篇 |
2007年 | 6467篇 |
2006年 | 6613篇 |
2005年 | 5440篇 |
2004年 | 3995篇 |
2003年 | 3485篇 |
2002年 | 3350篇 |
2001年 | 3012篇 |
2000年 | 2674篇 |
1999年 | 2452篇 |
1998年 | 1955篇 |
1997年 | 1625篇 |
1996年 | 1477篇 |
1995年 | 1216篇 |
1994年 | 1035篇 |
1993年 | 753篇 |
1992年 | 579篇 |
1991年 | 454篇 |
1990年 | 346篇 |
1989年 | 270篇 |
1988年 | 232篇 |
1987年 | 145篇 |
1986年 | 127篇 |
1985年 | 80篇 |
1984年 | 36篇 |
1983年 | 29篇 |
1982年 | 43篇 |
1981年 | 26篇 |
1980年 | 27篇 |
1979年 | 14篇 |
1978年 | 9篇 |
1976年 | 17篇 |
1975年 | 9篇 |
1973年 | 8篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
钢管内径光电检测装置 总被引:3,自引:0,他引:3
介绍了一种检测细长钢管内径的光电检测装置。该装置利用线阵CCD作传感器,采用8031单片机作为主控制。 相似文献
52.
Sha Lu Yong Hu O'Hara M. Bogy D.B. Singh Bhatia C. Yiao-Tee Hsia 《IEEE transactions on magnetics》1996,32(1):103-109
Three sub-25 nm fly height sliders are presented for near contact recording. The designs are geared towards the goal of achieving 10 Gb/in 2 areal density. The optimization procedure presented shows promise for facilitating achievement of this goal. The dynamic simulations show the stability of these designs when disturbed from their steady state conditions 相似文献
53.
针对“资产中心”模式对设备管理系统以及设备编码的要求,设计出松耦合的编码体系,并根据炼油化工企业的特点给出了主要的编码结构。解决了编码层次的固化与设备实际层次结构的多样化之间的矛盾,支持“资产中心”模式下设备管理对信息系统功能的需求。 相似文献
54.
Huiping Hu Qiyuan Chen Zhoulan Yin Pingmin Zhang Lusheng Ye 《Metallurgical and Materials Transactions A》2003,34(13):793-797
The thermal decompositions of mechanically activated and nonactivated galenas were studied by thermogravimetry analysis (TGA)
at the heating rate of 10 K min−1 in argon. Results indicate that the initial temperature of thermal decomposition (abbreviated as T
di) in the TGA curves for different galenas decreases gradually with increased grinding time. The specific granulometric surface
area (S
G), the structural disorder, and the content of elemental sulfur of mechanically activated galenas were analyzed by an X-ray
diffraction (XRD) laser particle-size analyzer, XRD analysis, and the gravimetric method, respectively, which shows that the
specific granulometric surface area of mechanically activated galenas remains almost constant after a certain grinding time,
but the lattice distortions (ε) rise, the crystallite sizes (D) decrease, and the elemental sulfur contents of mechanically activated galenas increase with increased grinding time. The
results imply that the decrease of the initial temperature of thermal decomposition in the TGA curves for mechanically activated
galenas is mainly caused by the increase of lattice distortions, and the formation of new dangling bonds resulted from the
production of elemental sulfur of mechanically activated galenas with increased grinding time. Finally, the differences in
the thermal-decomposition reactivity between nonactivated and mechanically activated galenas were also discussed. 相似文献
55.
56.
Study on Adsorption Behavior of Rare Earth Complexes on Nanometer-Size Titanium Dioxide with ICP-AES
Inrecentyears ,rareearthelements (REEs)havebeenwidelyusedinfunctionalmaterials ,cata lystsandotherproductsinindustry ,diagnosisreagentsofmagneticresonanceimaging (MRI)inmedicineandsomefertilizersinagricultureespeciallyinChina .However,asaresultoftheirusage ,moreandmoreREEsaregettingintotheenvironment,andalsointohumanbodyviafoodchain[1,2 ] .Itisnotclearwhetherrareearthelementsareessentialforman ,soitisveryurgenttostudythebiologicaleffectofrareearthelementsinhumanhealthandenvironment .Inthes… 相似文献
57.
本文论述了无线公话技术的实现原理,详细介绍了利用MCS8051系列单片机控制手机模块实现无线公话的方法,并给出了该类设备硬件各模块的功能描述以及关键部分软件的实现方法。 相似文献
58.
Preparation of Compound Ultrafine CeO2 by Wet-Solid-Phase Mechanochemical Modification 总被引:1,自引:0,他引:1
To satisfy practical requirements from industrial applications, an alternate route for synthesis compound ultrafine CeO2 powders by wet-solid-phase mechanochemical modification using industrial grade hydrated cerium carbonate as raw material was proposed.The effect of modifier reaction percentage, reaction time, calcining temperature and modifier amount on particle size, density, suspensibility, and hardness of compound CeO2 powder was investigated.The phase evolutions of preparation process were characterized by XRD.SEM micrograph of the final product shows that compound CeO2 powders obtained are well-dispersed, spherically-shaped, uniformly-sized and submicron-sized particles.The method is readily available in raw material, low in cost, simple in process, and has great potential for industrialization.The compound CeO2 powders of different physical properties can be synthesized by controlling the above-mentioned influence factors in preparation process. 相似文献
59.
60.