全文获取类型
收费全文 | 11859篇 |
免费 | 1094篇 |
国内免费 | 416篇 |
专业分类
电工技术 | 232篇 |
综合类 | 683篇 |
化学工业 | 2665篇 |
金属工艺 | 1332篇 |
机械仪表 | 293篇 |
建筑科学 | 1080篇 |
矿业工程 | 798篇 |
能源动力 | 439篇 |
轻工业 | 148篇 |
水利工程 | 133篇 |
石油天然气 | 136篇 |
武器工业 | 9篇 |
无线电 | 194篇 |
一般工业技术 | 929篇 |
冶金工业 | 4043篇 |
原子能技术 | 73篇 |
自动化技术 | 182篇 |
出版年
2024年 | 47篇 |
2023年 | 173篇 |
2022年 | 381篇 |
2021年 | 370篇 |
2020年 | 383篇 |
2019年 | 269篇 |
2018年 | 307篇 |
2017年 | 451篇 |
2016年 | 467篇 |
2015年 | 467篇 |
2014年 | 804篇 |
2013年 | 719篇 |
2012年 | 811篇 |
2011年 | 899篇 |
2010年 | 625篇 |
2009年 | 648篇 |
2008年 | 529篇 |
2007年 | 709篇 |
2006年 | 674篇 |
2005年 | 544篇 |
2004年 | 468篇 |
2003年 | 410篇 |
2002年 | 355篇 |
2001年 | 334篇 |
2000年 | 287篇 |
1999年 | 256篇 |
1998年 | 203篇 |
1997年 | 170篇 |
1996年 | 136篇 |
1995年 | 127篇 |
1994年 | 102篇 |
1993年 | 61篇 |
1992年 | 46篇 |
1991年 | 28篇 |
1990年 | 29篇 |
1989年 | 36篇 |
1988年 | 11篇 |
1987年 | 11篇 |
1986年 | 4篇 |
1985年 | 6篇 |
1984年 | 4篇 |
1982年 | 3篇 |
1981年 | 4篇 |
1977年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 968 毫秒
11.
Qianglong He Aiyang Wang Chun Liu Weimin Wang Hao Wang Zhengyi Fu 《Journal of the European Ceramic Society》2018,38(7):2832-2840
B4C-TiB2-SiC composites were fabricated via hot pressing using ball milled B4C, TiB2, and SiC powder mixtures as the starting materials. The impact of ball milling on the densification behaviors, mechanical properties, and microstructures of the ceramic composites were investigated. The results showed that the refinement of the powder mixtures and the removal of the oxide impurities played an important role in the improvement of densification and properties. Moreover, the formation of the liquid phases during the sintering was deemed beneficial for densification. The typical values of relative density, hardness, bending strength, and fracture toughness of the composites reached 99.20%, 32.84?GPa, 858?MPa and 8.21?MPa?m1/2, respectively. Crack deflection, crack bridging, crack branching, and microcracking were considered to be the potential toughening mechanisms in the composites. Furthermore, numerous nano-sized intergranular/intragranular phases and twin structures were observed in the B4C-TiB2-SiC composite. 相似文献
12.
Xianghui Wang Pengda Zhao Jianwei Chen Huizhong Zhao Kai He 《Ceramics International》2018,44(11):12162-12168
Al–Cr slag is the solid waste generated by the smelting of Cr metal. It presents a range of environmental hazards. This study addressed the corrosion resistance of Al–Cr slag containing chromium–corundum refractories to slags with different basicity. Herein, we provide suggestions for the use of Cr–corundum of different basicity in kilns. Al–Cr slag, brown fused Al2O3, and chrome green were used as the raw materials, with pure calcium aluminate cement being used as a binder. The brick samples, prepared using different blends of chrome green and corundum, were fired at 1600?°C, and subsequently subjected to a slag corrosion test. After corrosion by slag of different basicity, the phase composition and microstructure of the sample were analyzed by X-ray diffraction, energy dispersive spectrometer and scanning electron microscopy. There were two major findings. First, Cr–corundum brick made from Al–Cr slag has a better slag corrosion resistance than that made from Cr2O3 and brown fused Al2O3. Second, Cr–corundum brick made from Al–Cr slag has superior corrosion resistance to slag with a CaO:SiO2 ratio of 2:1. 相似文献
13.
The aim of this work was to establish the important parameters that control the hot compaction behaviour of woven oriented polypropylene. Five commercial woven cloths, based on four different polypropylene polymers, were selected so that the perceived important variables could be studied. These include the mechanical properties of the original oriented tapes or fibres, the geometry of the oriented reinforcement (fibres or tapes), the mechanical properties of the base polymer (which are crucially dependant on the molecular weight and morphology), and the weave style. The five cloths were chosen so as to explore the boundaries of these various parameters, i.e. low and high molecular weight: circular or rectangular reinforcement (fibres or tapes): low or high tape initial orientation: coarse or fine weave.A vital aspect of this study was the realisation that hot compacted polypropylene could be envisaged as a composite, comprising an oriented ‘reinforcement’ bound together by a matrix phase, formed by melting and recrystallisation of the original oriented material. We have established the crucial importance of the properties of the melted and recrystallised matrix phase, especially the level of ductility, in controlling the properties of the hot compacted composite. 相似文献
14.
15.
深亚微米MOSFET衬底电流的模拟与分析 总被引:1,自引:0,他引:1
利用器件模拟手段对深亚微米MOSFET的衬底电流进行了研究和分析,给出了有效的道长度,栅氧厚度,源漏结深,衬底掺杂浓度以及电源电压对深亚微米MOSFET衬底电流的影响,发现电源电压对深亚微米MOSFET的衬底电流有着强烈的影响,热载流子效应随电源电压的降低而迅速减小,当电源电压降低到一定程度时,热载流子效应不再成为影响深亚微米MOS电路可靠性的主要问题。 相似文献
16.
孙维銮 《自动化与仪器仪表》1994,(3):31-34,38
从理论上和实践上对武钢1700、鞍钢1700改造前后、本钢1700改造前后和攀钢1450精轧机组的电动压下机构在带钢压下时的动特性进行计算和探讨,得出有说服力的结论。主题词: 相似文献
17.
介绍侯马冶炼厂奥斯麦特熔炼炉3次炉渣恶化的原因,采取的措施和结果。粉煤灰积存,生料堆积和风料比失当造成炉渣SiO2含量升高,Fe含量降低是炉渣恶化的主要原因,添加高铁造渣成分调整渣组成或不加料浸沿喷枪正常熔炼状态操作,将生料中的铁氧化造渣,提高炉温,改善炉渣性质,使炉况恢复正常。 相似文献
18.
19.
研究结果表明 :水胶比、胶凝材料用量、钢纤维掺量、矿渣代水泥量对钢纤维砼强度影响显著。当矿渣取代水泥 10 %时 ,钢纤维砼强度最高。经试验选择出一个具有良好和易性和较高强度 (118MPa)的钢纤维砼配合比 ,为掺磨细矿渣的中含量超短异形钢纤维砼的设计和施工提供了试验依据 相似文献
20.
QifengShu JiayunZhang 《北京科技大学学报(英文版)》2005,12(3):221-224
Based on recently published experimental data, the Riboud model was modified for viscosity estimation of the slags containing calcium fluoride. The estimated values were in good agreement with measured data. Reasonable estimation can be achieved using the modified Riboud model for mould fluxes and ESR (eletro slag remelting) slags. Especially for ESR slags, the modified Riboud model can provide much more precise values than the original Riboud model. 相似文献