全文获取类型
收费全文 | 25414篇 |
免费 | 1976篇 |
国内免费 | 1255篇 |
专业分类
电工技术 | 810篇 |
综合类 | 2296篇 |
化学工业 | 1945篇 |
金属工艺 | 4462篇 |
机械仪表 | 3541篇 |
建筑科学 | 2910篇 |
矿业工程 | 940篇 |
能源动力 | 1144篇 |
轻工业 | 719篇 |
水利工程 | 324篇 |
石油天然气 | 662篇 |
武器工业 | 270篇 |
无线电 | 880篇 |
一般工业技术 | 3364篇 |
冶金工业 | 2909篇 |
原子能技术 | 176篇 |
自动化技术 | 1293篇 |
出版年
2024年 | 109篇 |
2023年 | 288篇 |
2022年 | 610篇 |
2021年 | 731篇 |
2020年 | 703篇 |
2019年 | 574篇 |
2018年 | 525篇 |
2017年 | 704篇 |
2016年 | 741篇 |
2015年 | 877篇 |
2014年 | 1621篇 |
2013年 | 1360篇 |
2012年 | 1897篇 |
2011年 | 2042篇 |
2010年 | 1564篇 |
2009年 | 1551篇 |
2008年 | 1250篇 |
2007年 | 1651篇 |
2006年 | 1494篇 |
2005年 | 1258篇 |
2004年 | 1056篇 |
2003年 | 994篇 |
2002年 | 854篇 |
2001年 | 770篇 |
2000年 | 671篇 |
1999年 | 547篇 |
1998年 | 444篇 |
1997年 | 346篇 |
1996年 | 284篇 |
1995年 | 267篇 |
1994年 | 201篇 |
1993年 | 165篇 |
1992年 | 120篇 |
1991年 | 89篇 |
1990年 | 80篇 |
1989年 | 79篇 |
1988年 | 42篇 |
1987年 | 25篇 |
1986年 | 16篇 |
1985年 | 4篇 |
1984年 | 11篇 |
1983年 | 13篇 |
1982年 | 3篇 |
1981年 | 6篇 |
1980年 | 5篇 |
1979年 | 3篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
通过对3100m^3/h斗轮挖掘机斗齿的材料、铸造工艺、热处理工艺及焊接工艺的试验研究,研制出了满足矿山使用要求的新型斗齿,使用性能达到国外同类产品先进水平,完全可以替代进口斗齿。 相似文献
92.
D. Chang R. Schafrik 《金属学报(英文版)》2005,18(5):561-574
1. Introduction Freedom to travel anywhere in the world, both quickly and inexpensively, defines our modern era. Despite year-to-year variation, the long term demand for travel by airplane continues to grow. Three ma- jor systems comprise the modern airplane: the aircraft structure that encompasses the fuselage, wings, and landing gear; the avionics that enable flight through crowded skies in nearly all weather conditions; and the propulsion system that powers the aircraft. Improvements in mat… 相似文献
93.
浅析影响汽车轮毂跳动的几个因素 总被引:1,自引:0,他引:1
李忠国 《组合机床与自动化加工技术》2007,(5):35-36,39
汽车轮毂的跳动是一个非常重要的性能尺寸,它影响着汽车运行的平稳性及安全性。论文从理论上简单地分析影响轮毂跳动的五个环节,同时对影响轮毂跳动较大的环节进行试验分析,并运用统计过程控制的方法进行了验证。 相似文献
94.
气动逻辑元件在多气缸顺序动作气压控制回路中的应用 总被引:1,自引:0,他引:1
朱光力 《组合机床与自动化加工技术》2003,(8):60-61
以三坐标气动机械手为例子来说明气动逻辑元件在多气缸顺序动作的气压控制回路中的应用,从而使得气动控制回路的设计变得简单明了。 相似文献
95.
The oxidation behavior of a single-crystal (SC) Ni-base superalloy was studied over the temperature range from 1000–1150°C and analysed by TGA, XRD, EDAX, and SEM. The results indicated that the SC Ni-base superalloy exhibited parabolic oxidation kinetics, which were controlled by the growth of the inner -Al2O3 layer. A mixed scale formed on the SC Ni-base superalloy after prolonged oxidation. The scale consisted of an outer layer of spinel, a sublayer of mainly -Al2O3 with small amount of spinel adjoined by a very thin and even discontinuous layer of CrTaO4-rich oxide, and an inner -Al2O3 layer. The inner -Al2O3 layer provided good protection. No internal oxides or nitrides were observed below the inner -Al2O3 layer after 1000 hr at 1000°C, and after 200 hr at 1100 and 1150°C. 相似文献
96.
管子-管板焊接是换热器生产的关键工序,通过对缩进式管子-管板焊接技术进行的试验和分析,确定了最佳的焊接参数,供换热器制造厂有关技术人员参考. 相似文献
97.
98.
The oxidation behavior in air at 1473 K, and sulfidation behavior in a H2S–H2 gas mixture with a sulfur partial pressure of 10–2 Pa at 973 K of Al–Re coated CMSX-4 were studied. Investigation on the sulfidation behavior of the Re-coated CMSX-4 was carried out in a H2S–H2 gas mixture with a sulfur partial pressure of 10–2 Pa at 973 K. The experimental results show that a Re-rich alloy layer was formed between an -Al2O3 layer and the inner concentration zone of Ta and Ti for the CMSX-4 single crystal alloy with an Al–Re coating after oxidation. The Re-rich alloy layer containing Cr, W, Ni, Co, and Mo effectively inhibited the outward diffusion of alloying elements and the inward diffusion of Al. The Al/Re-coated CMSX-4 single crystal alloy had excellent sulfidation resistance; the Re-rich alloy layer, containing W, Ti, Ta, and Mo, which formed during the sulfidation process and located between the alumina scale and the CMSX-4 base alloy, plays a role in inhibiting the outward diffusion of alloying elements. The sulfidation resistance of CMSX-4 single-crystal alloy is greatly improved by a Re coating on the CMSX-4 alloy surface; this is attributed to a Re–Cr–W alloy layer that retarded the outward diffusion of cations and the oxide layer containing Ta, Ti, and Al, which inhibited the inward penetration of sulfur. 相似文献
99.
H. Mughrabi H. Biermann T. Ungar 《Journal of Materials Engineering and Performance》1993,2(4):557-564
The γ-γ lattice mismatch of specimens of the monocrystalline nickel-base superalloy SRR 99 has been measured by a high-resolution
X-ray diffraction technique for the undeformed state and after high-tem-perature creep deformation. During creep deformation
beyond the minimum creep rate (total strain =0.5%), the lattice mismatches, measured in and perpendicular to the [001] stress
axis, respectively, un-dergo changes in opposite directions. This reflects the buildup of a complex deformation-induced triaxial
state of internal stress in the phases y and γ. The overall resolved shear stresses that act in γ and y due to the combined
action of the external and internal stresses are estimated, and the conditions under which cutting of the γ phase by dislocations
should occur are discussed. 相似文献
100.
Jung-Chel Chang Cheol Choi Jae-Chul Kim Young-Hoon Yun 《Journal of Materials Engineering and Performance》2003,12(4):420-425
Effects of the hot-isostatic pressing (HIP) process on microstructures and mechanical properties of Ni-base single crystal
superalloy CMSX-4 were investigated. In the overall heat treatment process, the HIP treatment remarkably induced the healing
behavior of micropores and decreased the pore size and porosity of superalloy CMSX-4 compared with normally treated specimens.
The microstructure of γ′ phase after the HIP process showed rather a coarsening tendency and could be developed by the partially solution and aging
treatment. Consequently, the elimination of cast micropores using the HIP step resulted in the inhibition of crack initiation
in microstructure and improved the stress-rupture lives of Ni-base single crystal superalloy by 185%. 相似文献