全文获取类型
收费全文 | 11602篇 |
免费 | 954篇 |
国内免费 | 648篇 |
专业分类
电工技术 | 977篇 |
综合类 | 927篇 |
化学工业 | 1610篇 |
金属工艺 | 981篇 |
机械仪表 | 2265篇 |
建筑科学 | 645篇 |
矿业工程 | 307篇 |
能源动力 | 457篇 |
轻工业 | 772篇 |
水利工程 | 209篇 |
石油天然气 | 324篇 |
武器工业 | 118篇 |
无线电 | 978篇 |
一般工业技术 | 1713篇 |
冶金工业 | 419篇 |
原子能技术 | 85篇 |
自动化技术 | 417篇 |
出版年
2024年 | 39篇 |
2023年 | 190篇 |
2022年 | 292篇 |
2021年 | 341篇 |
2020年 | 417篇 |
2019年 | 329篇 |
2018年 | 338篇 |
2017年 | 394篇 |
2016年 | 405篇 |
2015年 | 461篇 |
2014年 | 678篇 |
2013年 | 847篇 |
2012年 | 735篇 |
2011年 | 807篇 |
2010年 | 560篇 |
2009年 | 638篇 |
2008年 | 584篇 |
2007年 | 778篇 |
2006年 | 708篇 |
2005年 | 554篇 |
2004年 | 478篇 |
2003年 | 405篇 |
2002年 | 352篇 |
2001年 | 304篇 |
2000年 | 253篇 |
1999年 | 205篇 |
1998年 | 220篇 |
1997年 | 183篇 |
1996年 | 144篇 |
1995年 | 116篇 |
1994年 | 103篇 |
1993年 | 61篇 |
1992年 | 67篇 |
1991年 | 45篇 |
1990年 | 40篇 |
1989年 | 25篇 |
1988年 | 25篇 |
1987年 | 15篇 |
1986年 | 7篇 |
1985年 | 11篇 |
1984年 | 14篇 |
1983年 | 3篇 |
1982年 | 9篇 |
1980年 | 3篇 |
1979年 | 5篇 |
1977年 | 5篇 |
1966年 | 2篇 |
1965年 | 1篇 |
1959年 | 3篇 |
1951年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 313 毫秒
21.
22.
重载齿轮齿面疲劳损坏及预防 总被引:1,自引:0,他引:1
丁守祥 《兵器材料科学与工程》2002,25(1):49-52
点蚀和剥落是重载齿轮齿面疲劳损坏最普遍的形式.根据齿轮失效分析实例,对齿面初始点蚀、破坏性点蚀和齿面剥落等三种主要疲劳损坏的特征、发生部位及破损危害程度进行了分析研究,较系统地论述了齿轮接触疲劳破坏机理,影响因素及其产生原因,并对有关的齿面破坏提出了相应的预防措施. 相似文献
23.
24.
提出了一种具有特殊运转方式的新型RBC系统--回转升降生物接触工艺,对回转升降生物接触工艺的工作原理和工艺特征进行了论述。并通过动态实验,对回转升降生物接触工艺小型实验装置的性能和效果进行了初步考察。 相似文献
25.
26.
PENGLiming MAOXiemin XUKuangdi DINGWenjiang 《稀有金属(英文版)》2002,21(1):62-66
In order to develop a new type of contact cable with high strength and high electrical conductivity, Cu-Cr alloy series were selected as materials and Cu-Cr alloy castings were produced by means of directional solidification continuous casting (DSCC) process. The results show that the fibrillar strengthening phase, 13-Cr, orderly arranges among the copper matrix phase along the wire direction; and a microstructure of in-situ composite forms, which retains the basic property of good conductivity of the copper matrix and meanwhile obtains the strengthening effect of [3-Cr phase. The production technology as well as the mechanical property, electrical property, and synthetic property of the in-situ composite contact cables was discussed. 相似文献
27.
Behaviour of a series of lubricant oils and the effect of a non stoichiometric inorganic compound, as solid extreme pressure additive, on rolling fatigue life are studied using the rolling four-ball accelerated service simulation test proposed by Barwell and Scott. The results show, in all tested cases, the remarkable efficacy of this type of additive. The Total Acidity Number (tan) was found to increase with performance time for the case of the base lubricant, while for the oils with additives, it remained at its constant low value. This led to a proposal of a possible mechanism of the additive performance in the rolling process. 相似文献
28.
In the paper, a model typical for contact situations of automotive brakes is established based on the method of movable cellular automata. The processes taking place at local contacts in an automotive brake system are analysed. Based on microscopic and micro-analytical observations, the following contact situations were simulated: (i) a couple of ferritic steel against pearlitic steel, both covered by an oxide layer mixed with graphite nanoparticles and (ii) the same situation but without oxide layers. The results of calculated mean coefficients of friction of the oxide-on-oxide contact correspond well to expected values for a real braking system, whereas steel-on-steel contact are twice as high. This allows one to make some conclusions; for example, oxide formation will take place more quickly than friction layer elimination, and finally this is responsible for the stabilisation of the coefficient of friction. 相似文献
29.
The short contact time dissolution of vitrinite and inertinite concentrates of an Australian bituminous coal was studied under isothermal conditions with tetralin as solvent. The reactivity of the two maceral types and the yields and nature of the products were determined for a range of reaction temperatures (400, 420 and 440 °C) and reaction times (2–20 min). The dissolution of vitrinite proceeded at a significantly greater rate than for inertinite and was associated with greater selectivity to soluble non-gaseous products. At very short reaction times (2 min), the vitrinite underwent solubilizing reactions to yield products of higher molecular weight and greater oxygen functionality than was the case for inertinite, for which changes in the chemical nature of the products were negligible over the range of conditions studied. At longer reaction times (5 min), the composition of the vitrinite-derived products was similar to that of the inertinite-derived products. 相似文献
30.
Roberto Leoni Bruno Buonomo Gabriella Castellano Francesco Mattioli Guido Torrioli Luciana Di Gaspare Florestano Evangelisti 《Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment》2004,520(1-3):44-47
We discuss the performance, of a normal metal hot electron bolometer (NHEB) that we have measured at 0.3 K. We found that the noise equivalent power was limited by the amplifier noise. To improve the NHEB power response and to make it more robust and reliable we propose to substitute the normal metal with heavily doped silicon. The heavily doped silicon behaves like a metal with lower carrier concentration and has a smaller electron–phonon thermal coupling. We have fabricated superconductor-doped silicon-superconductor contacts (S-Sm-S) and we have used them as thermometers and coolers. 相似文献