全文获取类型
收费全文 | 3444篇 |
免费 | 244篇 |
国内免费 | 247篇 |
专业分类
电工技术 | 47篇 |
综合类 | 221篇 |
化学工业 | 1100篇 |
金属工艺 | 509篇 |
机械仪表 | 68篇 |
建筑科学 | 60篇 |
矿业工程 | 147篇 |
能源动力 | 32篇 |
轻工业 | 233篇 |
水利工程 | 4篇 |
石油天然气 | 48篇 |
武器工业 | 48篇 |
无线电 | 114篇 |
一般工业技术 | 858篇 |
冶金工业 | 422篇 |
原子能技术 | 14篇 |
自动化技术 | 10篇 |
出版年
2024年 | 9篇 |
2023年 | 47篇 |
2022年 | 53篇 |
2021年 | 93篇 |
2020年 | 102篇 |
2019年 | 98篇 |
2018年 | 92篇 |
2017年 | 127篇 |
2016年 | 87篇 |
2015年 | 75篇 |
2014年 | 102篇 |
2013年 | 149篇 |
2012年 | 150篇 |
2011年 | 210篇 |
2010年 | 146篇 |
2009年 | 155篇 |
2008年 | 119篇 |
2007年 | 237篇 |
2006年 | 216篇 |
2005年 | 179篇 |
2004年 | 191篇 |
2003年 | 185篇 |
2002年 | 144篇 |
2001年 | 150篇 |
2000年 | 154篇 |
1999年 | 98篇 |
1998年 | 76篇 |
1997年 | 86篇 |
1996年 | 73篇 |
1995年 | 56篇 |
1994年 | 59篇 |
1993年 | 50篇 |
1992年 | 49篇 |
1991年 | 34篇 |
1990年 | 35篇 |
1989年 | 37篇 |
1988年 | 5篇 |
1987年 | 3篇 |
1983年 | 1篇 |
1980年 | 2篇 |
1951年 | 1篇 |
排序方式: 共有3935条查询结果,搜索用时 15 毫秒
1.
2.
用化学还原法合成了FeBP非晶态合金超细微粒,用电感耦合等离子体光谱(ICP)、X射线粉末衍射(XRD)、透射电子显微镜(TEM)和差热分析(DSC)等手段对其进行了物性表征,并用微型催化反应装置考察了其对PH3分解的催化作用,结果表明,非晶态合金FeBP对PH3的分解具有良好的催化作用,能使PH3的分解温度从800℃以上降到500℃左右。490℃时分解率超过90%,540℃时达100%。 相似文献
3.
4.
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
5.
This paper is a summary of an extensive research program carried out by the authors on the structure of rapidly solidified aluminum alloys; and a comparison with the work of others also involved in this field. The paper discusses the changes in the dendritic and non-dendritic structure of the matrix at cooling rates from 10–3 to 1010 K/s and discusses the hetergeneity of the structure caused by interdendritic-segretion during solidification. 相似文献
6.
用50W连续波CO_2激光器为热源,诱发SiH_4和C_2H_4反应,合成SiC超细粉末。实验确定了反应腔体内压力p、气源中的C/Si原子比、喷嘴内径2r以及激光功率密度与粉末特性之间的关系,并对合成的产物进行物理、化学表征。 相似文献
7.
8.
Humin Cheng Jiming Ma Zhenguo Zhao Di Qiang Yongxiang Li Xi Yao 《Journal of the American Ceramic Society》1992,75(5):1123-1128
A pure, acicular lead titanate (PbTiO3 ) fine powder with a white color has been prepared by hydrothermal synthesis. It is a new phase of PbTiO3 with I 4 symmetry, cell parameters of a = 12.358 Å and b = 14.541 Å, and a density of 6.80 g.cm−3 . The influences of pH (12.5 to 14.4), Pb/Ti ratio (1.0 to 1.6) in the feedstock, reaction temperature (130° to 230°C), time (0.25 to 4 h), starting materials, and additives on the formation of acicular PbTiO3 under hydrothermal conditions have been investigated. The acicular PbTiO3 with I 4 symmetry, referred to as the PX phase, can be converted to the perovskite-type (PE phase) of PbTiO3 at about 605°C while its acicular morphology is essentially unchanged. The preferable conditions for preparing pure acicular PX-phase PbTiO3 are that the pH is 13.0 to 14.0, Pb/Ti ratio is >1.3, reaction temperature is 170° to 200°C, time is 0.5 to 1.0 h, titanium butoxide (Ti[O(CH2 )3 CH3 ]4 ) is the starting material, and poly(vinyl alcohol) is an additive. The acicular grain of the PX phase is usually less than 100 nm in diameter and more than 1000 nm in length. 相似文献
9.
《Drying Technology》2007,25(6):959-969
Three major aspects of food powder are described and discussed. Stickiness is one issue that can cause production and product handling difficulties. Stickiness has been interpreted in a number of ways and thus measured differently. Functionality of the primary (single) particles or agglomerated powders is of practical interest to the consumers. The desired quality will have to be matched or exceeded by the powder manufacturers. Finally, microstructure provides a key linkage between the production and the functionality. Its formation has impacts on both the stickiness and functionality. 相似文献
10.
用保护共沉淀法制备纳米ZrO2(Y2O3)粉体 总被引:3,自引:0,他引:3
用Tween-80保护共沉淀法制备了ZrO2(Y2O3)纳米粉体,用差热分析,热重分析,X射线衍射及透射电子显微镜等技术研究所了粉体的特征,结果表明:在700℃燃烧0.5h后ZrO2(Y2O3)粉体的平均粒径为3-9nm,比表面为128.5-134.5m^3g^-1,在1250℃煅烧8h后ZrO2(Y2O3)粉体已完全形成了立方相的ZrO2L大溶体,并且有非常好的烧结性能。 相似文献