全文获取类型
收费全文 | 36010篇 |
免费 | 3374篇 |
国内免费 | 1778篇 |
专业分类
电工技术 | 2705篇 |
综合类 | 2468篇 |
化学工业 | 8389篇 |
金属工艺 | 6555篇 |
机械仪表 | 1502篇 |
建筑科学 | 3701篇 |
矿业工程 | 1052篇 |
能源动力 | 1220篇 |
轻工业 | 2350篇 |
水利工程 | 798篇 |
石油天然气 | 1202篇 |
武器工业 | 267篇 |
无线电 | 2170篇 |
一般工业技术 | 4158篇 |
冶金工业 | 1648篇 |
原子能技术 | 246篇 |
自动化技术 | 731篇 |
出版年
2024年 | 113篇 |
2023年 | 714篇 |
2022年 | 1128篇 |
2021年 | 1622篇 |
2020年 | 1364篇 |
2019年 | 1100篇 |
2018年 | 1043篇 |
2017年 | 1463篇 |
2016年 | 1363篇 |
2015年 | 1385篇 |
2014年 | 1937篇 |
2013年 | 2004篇 |
2012年 | 2447篇 |
2011年 | 2740篇 |
2010年 | 1890篇 |
2009年 | 2179篇 |
2008年 | 1759篇 |
2007年 | 2105篇 |
2006年 | 2106篇 |
2005年 | 1749篇 |
2004年 | 1445篇 |
2003年 | 1249篇 |
2002年 | 1040篇 |
2001年 | 900篇 |
2000年 | 753篇 |
1999年 | 692篇 |
1998年 | 548篇 |
1997年 | 466篇 |
1996年 | 334篇 |
1995年 | 355篇 |
1994年 | 287篇 |
1993年 | 200篇 |
1992年 | 162篇 |
1991年 | 129篇 |
1990年 | 89篇 |
1989年 | 78篇 |
1988年 | 51篇 |
1987年 | 41篇 |
1986年 | 22篇 |
1985年 | 12篇 |
1984年 | 15篇 |
1983年 | 11篇 |
1982年 | 16篇 |
1981年 | 6篇 |
1980年 | 12篇 |
1979年 | 5篇 |
1961年 | 2篇 |
1960年 | 3篇 |
1959年 | 6篇 |
1951年 | 4篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
151.
152.
153.
Yaping KeLU 《材料科学技术学报》2002,18(6):492-496
In this paper,glass transition and thermal stability of the Zr-Al-Cu-Ni metallic glasses were investigated by using electrical resistance measurement(ERM),DSC and X-ray diffraction techniques.The experimental results show that the ERM is capable of detecting the glass transition of the amorphous alloys and can help to distinguish the crystallization products of the Zr-Al-Cu-Ni metallic glasses owing to the difference of the electrical resistivity between the precipitation phases. 相似文献
154.
The objective of the present study is to develop multi-functioned coating to the components, which are made of copper with electroplated Ni and are widely used for steel making industry. In this paper, we report the mechanical and thermal properties of Ni based superalloys with carbide sprayed by high velocity oxygen fuel (HVOF), and the detailed effects of sprayed material, spraying conditions, and initial powder structure on these properties. It was found that, among commercial Ni self-fluxing alloys (without fusing treatment), coating with a carbon content of 0.58 mass% had the most preferable properties, with a good balance of the hardness, strength, and thermal shock resistance. The thermal shock resistance depended not only on the strength of the coating but also on the volume contraction when tested at high temperatures. For the several developed Ni based superalloys with carbide, Ni20Cr8Mo5Fe–WC and Ni16Cr15Mo3–WC demonstrated the prominent adhesion strength and thermal shock resistance with high Galvanic corrosion resistance through optimized spraying condition. Also, 20 mass% NiCr–Cr3C2 coating sprayed by using employed relatively small primary particle succeeded in achieving the multi-superior properties; high adhesion strength, high corrosion resistance and thermal shock resistance. 相似文献
155.
156.
钢铁表面黑色转化膜处理技术 总被引:1,自引:1,他引:0
黑色转化膜技术是目前较为先进的钢铁表面处理技术 ,本文试验研究了一种新工艺 ,提出了TB值的概念 ,通过控制TB值即可控制处理液的质量 ,获得性能优良的转化膜。此工艺性能可靠 ,可操作性强 ,并可应用于激光热处理前的预处理。 相似文献
157.
本文描述用离子束透过钽金属膜进行混合和快速热处理方法来形成钽的硅化物.用溅射方法在P型硅衬底上淀积一层金属钽,然后用砷离子束透过钽金属模进行混合,采用快速热处理后形成了平整的硅化钽薄层.使用厚度为500埃的钽金属膜,得到钽的硅化物薄层电阻为5.5Ω/□.研究了砷离子能量、剂量及钽膜厚度对钽的硅化物薄层电阻的影响.用透射电镜和台阶仪对所形成的硅化钽进行了分析和厚度测量. 相似文献
158.
C R Chakravorty 《Bulletin of Materials Science》1994,17(6):733-745
Magnesium-lithium alloys are among the lowest density metallic materials. Addition of lithium, with a relative density of
0·53, in magnesium reduces the density of the alloy significantly. Furthermore, addition of nearly 11 wt.% lithium converts
hexagonal close packed structure of pure magnesium to a body centered cubic lattice, markedly improving formability of the
alloy. The development of these alloys, however, had been hampered due to the high reactivity of lithium and magnesium in
the molten state and also, due to poor creep resistance and instability of mechanical properties at room temperature. In an
attempt to indigenize these ultra light alloys for possible applications in Indian satellite programme, detailed research
work was initiated in DMRL. The difficulties associated with producing sound cast ingots have been overcome by controlling
melting and casting parameters of these alloys. Extensive work has been done on structure-property correlation of alloys with
varying lithium content and minor alloying additions. Based on these work, advanced magnesium-lithium alloys have been developed
with improved tensile properties, room temperature stability and creep resistance. Wrought products (plates/sheets) of magnesium-lithium
alloy have been supplied to ISAC, Bangalore and are being used in their INSAT-2 programme. This paper describes the systematic
studies carried out in the laboratory to indigenize these ultra light alloys. 相似文献
159.
A protein which masks galactose receptor mediated phage susceptibility in Lactococcus lactis subsp. lactis MPL56 总被引:1,自引:0,他引:1
Yasin Tuncer & Mustafa Akçelik 《International Journal of Food Science & Technology》2002,37(2):139-144
A 28.5-kb plasmid, isolated from Lactococcus lactis subsp. lactis MPL56, causes complete inhibition of four lactococcal phages. Cell wall characteristics of wild-type strain MPL56 were compared with its 28.5 kb plasmid-cured, phage-sensitive derivative MPL56-22. After proteolytic enzyme treatments, adsorption of phages occurred at high levels, an example is 94.6–98.5% in MPL56 cells. Analysis of cell wall extracts of MPL56-22 by sodium dodecyl sulphate–polyacrylamide gel electrophoresis (SDS–PAGE) indicated that the only difference between strains was the 55.4 kDa band in protein patterns of MPL56. Adsorption of the four phages was completely inhibited when MPL56-22 cells were subjected to SDS, Triton-X-100, HCl and NaOH treatments. Lectins that were specific for glucose/mannose and N-acetylglucosamine did not prevent adsorption of phages in cell wall extracts of MPL 56-22. However a lectin specific for galactose (MCA; Momordica charantia ) completely inhibited adsorption of these phages in cell wall extracts of MPL56-22. HPLC patterns of cell wall carbohydrates of MPL56-22 and its HCl treated preparations showed that the most prevalent difference was the galactose on untreated MPL56-22 cell wall chromatograms. 相似文献
160.
从分析某高架桥中异形板板底裂缝的特点及成因着手 ,对设计与施工工艺诸方面提出防止裂缝的对策和对裂缝进行加固的全过程。 相似文献