全文获取类型
收费全文 | 3025篇 |
免费 | 31篇 |
国内免费 | 35篇 |
专业分类
电工技术 | 42篇 |
综合类 | 74篇 |
化学工业 | 449篇 |
金属工艺 | 227篇 |
机械仪表 | 827篇 |
建筑科学 | 86篇 |
矿业工程 | 42篇 |
能源动力 | 184篇 |
轻工业 | 316篇 |
水利工程 | 12篇 |
石油天然气 | 26篇 |
武器工业 | 5篇 |
无线电 | 177篇 |
一般工业技术 | 385篇 |
冶金工业 | 62篇 |
原子能技术 | 24篇 |
自动化技术 | 153篇 |
出版年
2024年 | 1篇 |
2023年 | 32篇 |
2022年 | 68篇 |
2021年 | 93篇 |
2020年 | 66篇 |
2019年 | 78篇 |
2018年 | 63篇 |
2017年 | 78篇 |
2016年 | 57篇 |
2015年 | 58篇 |
2014年 | 109篇 |
2013年 | 301篇 |
2012年 | 129篇 |
2011年 | 220篇 |
2010年 | 140篇 |
2009年 | 183篇 |
2008年 | 176篇 |
2007年 | 160篇 |
2006年 | 134篇 |
2005年 | 120篇 |
2004年 | 131篇 |
2003年 | 125篇 |
2002年 | 89篇 |
2001年 | 78篇 |
2000年 | 68篇 |
1999年 | 55篇 |
1998年 | 53篇 |
1997年 | 39篇 |
1996年 | 42篇 |
1995年 | 27篇 |
1994年 | 27篇 |
1993年 | 21篇 |
1992年 | 12篇 |
1991年 | 11篇 |
1990年 | 13篇 |
1989年 | 7篇 |
1988年 | 8篇 |
1987年 | 7篇 |
1986年 | 2篇 |
1985年 | 6篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1977年 | 1篇 |
排序方式: 共有3091条查询结果,搜索用时 15 毫秒
41.
本文使用有限元法研究滤波减速器轮齿上开槽对滤波减速器轮齿的动力学性能和传动性能的影响。通过对滤波减速器齿上不同开槽形状进行有限元对比分析,结果显示直槽对轮齿力学性能有很好的改善作用。在此基础上分析了直槽的槽深、槽宽、应力释放孔大小和应力释放孔与直槽的倒角大小对轮齿力学性能的影响以及不同载荷下轮齿应力分布情况。研究结果表明在滤波减速器齿上开直槽,当槽深大于轮齿模数的三倍,应力释放孔和倒角的半径大于槽宽的十倍,槽缝宽度不超过轮齿模数的十分之一时,其接触应力、弯曲应力和冲击振动较小。 相似文献
42.
XU Xiang-yang HAN Jian-min XU Bin-shi LIU Shi-can ZHOU Zhong-rong . Institute of Materials Science Engineering Beijing Jiaotong University Beijing China . Institute of Surface Engineering Chinese Society of Mechanical Engineering Beijing China . Institute ofTribology Southwest Jiaotong University Chengdu China 《材料热处理学报》2004,25(5)
FRETTING is referring to a reciprocating motion withthe small displacement between two components incontact[1].Fretting wear is superficial materialremoval during the fretting.It severely reduces theperformance,efficiency and service lifetime of thecomponents[2],Thermal spraying has been employedto enhance the fretting wear resistance of components,and the fretting wear behavior of the coatings has beenalso explored.However,the experimental results wereoften contradictive and confusing.On … 相似文献
43.
An iron electrode was modified by electrolytic reduction in deaerated acetonitrile solution of p-toluenediazonium tetrafluoroborate CH3C6H4N2BF4 (TDFB) or p-hydroxymethylbenzenediazonium tetrafluoroborate HOCH2C6H4N2BF4 (HOTDFB) below 10 °C to form a self-assembled monolayer (SAM) of toluene CH3C6H4- or hydroxymethylbenzene HOCH2C6H4- (HOMB) moiety, probably adsorbed on the electrode by the formation of a covalent bond between carbon and iron atoms, as shown in references. The protective ability of the layer was examined by polarization measurement of the electrode in an aerated 0.5 M NaCl solution. The protective efficiencies of these two SAMs were not high, around 30%, a little higher than that of the toluenethiol CH3C6H4SH SAM which was anchored on iron via a coordinate bond between sulfur and iron atoms. The iron surfaces modified with TDFB and HOTDFB were characterized by contact angle measurement, FTIR reflection spectroscopy and X-ray photoelectron spectroscopy. The persistence in protection of iron against corrosion by coverage with the HOMB SAM was confirmed by polarization measurements after immersion in 0.5 M NaCl for a long period of the time. 相似文献
44.
溶剂萃取法从废电子元件中回收钯 总被引:4,自引:3,他引:4
用溶剂萃取法从硝酸浸取液中提取Pd~(2+)与Cu~(2+),Ni~(2+).N_(235)作Pd~(2+)的萃取剂,煤油作稀释剂,癸醇作调相剂,最佳工艺条件是萃取剂组成,25%N_(235)—10%癸醇—65%煤油;硝酸浓度,0.5~3mol/L;温度,室温;1.5mol/L HNO_2作负载有机相杂质离子Ni~(2+),Cu~(2+)的洗涤剂,其一次洗涤率近100%;6%硫脲,或5%氨水作负载有机相中Pd~(2+)的反萃剂,其一次反萃率分别为98.6%,68.5%. 相似文献
45.
46.
47.
48.
Nano-ZrO2/Ni composite coatings were prepared through co-depositing nano-ZrO2 particles and pure nickel by electro-brush plating (EBP). By analyzing the effects of microstructure, annealing and load on contact fatigue life, the contact fatigue behavior of the nano-ZrO2/Ni EBP coating was investigated. Furthermore, the contact fatigue behaviors of the nano-ZrO2/Ni EBP coating and the nickel EBP coating were compared. The results show that the nano-ZrO2 particles in the as-deposited nano-ZrO2/Ni EBP coating were partially conglomerated, and the microstructure of the annealed nano-ZrO2/Ni EBP coating was finer. Under the as-deposited condition, the contact fatigue life of the nano-ZrO2/Ni EBP coating was much lower than that of the nickel EBP coating. After the annealing process, the contact fatigue life of the nano-ZrO2/Ni EBP coating was greatly increased and much higher than that of the nickel EBP coating. The scanning electron microscope (SEM) images of the fatigue fracture zones and the transmission electron microscope (TEM) images of microstructure of the deformation layer show that the annealing could improve the ductility of the nano-ZrO2/Ni EBP coating, and the nano-ZrO2 particles could restrain the propagation of the fatigue cracks, which contributed to the enhancement of the contact fatigue properties of the nano-ZrO2/Ni EBP coating. 相似文献
49.
对新型蜗轮剐齿面啮合进行理论分析,指出它的一些特性:齿面容易获得较高精度;接触线走向容易形成油膜;齿面诱导曲率小,可承受较大载荷,使用寿命长。 相似文献
50.
在任何严峻条件下现代机械运行中综合性能的迫切需求促进了许多先进表面工程技术的迅速发展。因而,设计者在结构设计时将有许多表面工程技术可以选择。但是,怎样为一种特定的应用选择一种最优化的表面工程方法对设计者来说又是一种挑战。为了这个目标,在现代多层表面接触理论的基础上建立起一种接触力学模型,考虑到了多层结构、真实表面粗糙度和摩擦影响。这种力学模型可以成功地预测表面工程结构的性能。文中首先回顾了赫兹接触理论的发展过程,然后讨论了伯明翰多层真实粗糙表面接触力学模型,并用实例示范了一系列关于动载荷下表面工程结构设计的主要步骤。 相似文献