全文获取类型
收费全文 | 14626篇 |
免费 | 1024篇 |
国内免费 | 451篇 |
专业分类
电工技术 | 188篇 |
综合类 | 1089篇 |
化学工业 | 1270篇 |
金属工艺 | 4176篇 |
机械仪表 | 4156篇 |
建筑科学 | 471篇 |
矿业工程 | 534篇 |
能源动力 | 180篇 |
轻工业 | 286篇 |
水利工程 | 83篇 |
石油天然气 | 490篇 |
武器工业 | 174篇 |
无线电 | 208篇 |
一般工业技术 | 1792篇 |
冶金工业 | 806篇 |
原子能技术 | 28篇 |
自动化技术 | 170篇 |
出版年
2024年 | 108篇 |
2023年 | 319篇 |
2022年 | 413篇 |
2021年 | 495篇 |
2020年 | 487篇 |
2019年 | 433篇 |
2018年 | 474篇 |
2017年 | 627篇 |
2016年 | 580篇 |
2015年 | 530篇 |
2014年 | 621篇 |
2013年 | 626篇 |
2012年 | 776篇 |
2011年 | 835篇 |
2010年 | 658篇 |
2009年 | 735篇 |
2008年 | 617篇 |
2007年 | 926篇 |
2006年 | 967篇 |
2005年 | 692篇 |
2004年 | 673篇 |
2003年 | 533篇 |
2002年 | 471篇 |
2001年 | 419篇 |
2000年 | 337篇 |
1999年 | 273篇 |
1998年 | 249篇 |
1997年 | 261篇 |
1996年 | 212篇 |
1995年 | 188篇 |
1994年 | 118篇 |
1993年 | 80篇 |
1992年 | 85篇 |
1991年 | 58篇 |
1990年 | 48篇 |
1989年 | 51篇 |
1988年 | 44篇 |
1987年 | 25篇 |
1986年 | 6篇 |
1985年 | 13篇 |
1984年 | 13篇 |
1983年 | 8篇 |
1982年 | 13篇 |
1981年 | 1篇 |
1980年 | 3篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
41.
阐述了石灰竖窑的预热带、煅烧带和冷却带工作衬砖蚀损机理,并讨论了如何根据耐火砖性能和石灰竖窑不同区域的蚀损机理,选择耐火材料。 相似文献
42.
We analyze the wear resistance of plasma coatings for a constant work of friction. The dependences of the wear resistance
of the coatings are obtained for a broad range of loading conditions. It is shown that the minimum sensitivity to loading
conditions is exhibited by the molybdenum coatings. It is also established that the wear resistance of the coatings decreases
as the amplitude of displacements increases and the cyclic frequency of the tests decreases due to the intensification of
fatigue processes on the surfaces. The comparative characteristics of coatings are presented.
__________
Translated from Problemy Prochnosti, No. 5, pp. 94–100, September–October, 2007. 相似文献
43.
A. Rac 《Tribology International》1985,18(1):29-33
The wear of grey cast iron in dry sliding conditions has been studied with the aims of (1) finding the influence of working conditions on the wear rate, and (2) determining the region of speed and load where low wear is accomplished. Grey cast iron with flake and nodular graphite was submitted to investigation using a pin-on-disc machine. The results indicate that the flake graphite cast iron is more suitable for applications at speeds greater than 4 m s−1 and lower loads, while nodular cast iron has greater wear resistance at lower speeds in the range of loads investigated - from 50 N cm−2 to 200 N cm−2 相似文献
44.
球磨机衬板材料及热处理工艺 总被引:1,自引:0,他引:1
对传统的中碳低合金耐磨铸钢的化学成分和热处理工艺进行了优化设计 ,使新材料具有较高的强度、硬度和韧性 ,因而抗冲击、抗疲劳、抗磨损性能良好。实际应用表明 ,用此种材料代替油淬和风冷中碳低合金耐磨铸钢 ,不仅生产成本低 ,而且在矿山、电力球磨机制粉等工矿条件下 ,其使用寿命长 相似文献
45.
Witold Brostow Bernard Bujard Patrick E. Cassidy Haley E. Hagg Pablo E. Montemartini 《Materials Research Innovations》2002,6(1):7-12
Samples were prepared by addition of a fluorinated poly(aryl ether ketone) (12F-PEK) to a commercial epoxy resin and curing
at either 24 °C or 70 °C. The concentrations of fluoropolymer in the samples were 0, 5, 10, 20, 30, 40, and 50%. Phase inversion
facilitates the formation of more and more smooth surfaces for scratch testing with increasing fluoropolymer concentration.
A progressively increasing load from 0.03 N to 12 N was administered with a diamond tip to the surfaces of the samples; depths
were determined within ±7.5 nm. The original scratch depth is a function of the fluoropolymer concentration. Scratch recovery
(healing) reaches values up to 95%. Plots of the residual depth versus concentration of the fluoropolymer at 4, 6, 8, and
10 N reveal minima for all forces and both temperatures. Addition of only 5% or 10% 12F-PEK improves the scratch recovery
significantly. The results are explained by changes of material morphology with the fluoropolymer concentration.
Electronic Publication 相似文献
46.
高硬度耐磨电弧喷涂管状丝材的研究 总被引:2,自引:0,他引:2
利用自熔性合金与非晶态材料的特点,研制了Fe—B系管状丝材作为电弧喷涂材料,其形成的涂层具有良好的结合强度、低的孔隙率、高的硬度和耐磨损性能。 相似文献
47.
本文提出基于切削振动相关性识别刀具磨损状态的研究思想,建立了车削中刀杆双向横振动系统及其单输入双输出系统的数学模型。理论和实验均表明,刀杆双向横振动之加速度响应在固有基频处的相干函数与刀具磨损状态之间有很好的规律性,它反映了两者之间的本质机理,并提供了识别刀具磨损状态的新途径。 相似文献
48.
H. -C. Chiao H. -L. Lin X. -T. Li C. -X. Ding 《Journal of Thermal Spray Technology》1992,1(2):111-115
Diamond growth with rates up to 100 to 140 μm/hr was achieved using an oxygen-acetylene combustion spraying technique in an
atmospheric environment. Investigations on the processing indicated that the gas flow ratio, substrate position, substrate
temperature, temperature distribution, and substrate pretreatment were the most important factors affecting the growth of
diamond crystals. Evaluation by means of X-ray diffraction, Raman spectroscopy, scanning electron microscopy, and electron
probe microanalysis showed that the synthesized diamond was nearly perfect in morphology, structure, and purity. 相似文献
49.
In order to investigate the effect of partitioning procedures on microstructure and properties of a medium carbon Ti Mo bearing steel, the salt bath experiment, field emission SEM, TEM and tensile tests as well as wear tests were utilized to clarify the microstructural evolution and property changes treated by different partitioning parameters. The results show that the microstructures consist of tempered lath martensite, cementite and (Ti, Mo)C particles. With prolonging partitioning time or increasing partitioning temperature, the amount of laths martensite decreases and thicker martensite plates with blunt boundaries appear. In addition, with increasing partitioning temperature from 310℃ to 400℃, the tensile strength, hardness and low temperature toughness are simultaneously decreased, and the reduction reaches up to about 300MPa, 100HV and 20J, respectively. Finally, the wear performance of the samples partitioned below Ms is obviously better than that of samples partitioned above Ms. The morphology of worn surface of samples partitioned below Ms is characterized by plastic fatigue morphology, while the worn surfaces of samples partitioned above Ms are mainly dominated by grooves. 相似文献
50.
Scott C. Thompson Anjali Pandit Nitin P. Padture Subra Suresh 《Journal of the American Ceramic Society》2002,85(8):2059-2064
The processing of stepwise graded Si3 N4 /SiC ceramics by pressureless co-sintering is described. Here, SiC (high elastic modulus, high thermal expansion coefficient) forms the substrate and Si3 N4 (low elastic modulus, low thermal expansion coefficient) forms the top contact surface, with a stepwise gradient in composition existing between the two over a depth of ∼1.7 mm. The resulting Si3 N4 contact surface is fine-grained and dense, and it contains only 2 vol% yttrium aluminum garnet (YAG) additive. This graded ceramic shows resistance to cone-crack formation under Hertzian indentation, which is attributed to a combined effect of the elastic-modulus gradient and the compressive thermal-expansion-mismatch residual stress present at the contact surface. The presence of the residual stress is corroborated and quantified using Vickers indentation tests. The graded ceramic also possesses wear properties that are significantly improved compared with dense, monolithic Si3 N4 containing 2 vol% YAG additive. The improved wear resistance is attributed solely to the large compressive stress present at the contact surface. A modification of the simple wear model by Lawn and co-workers is used to rationalize the wear results. Results from this work clearly show that the introduction of surface compressive residual stresses can significantly improve the wear resistance of polycrystalline ceramics, which may have important implications for the design of contact-damage-resistant ceramics. 相似文献