全文获取类型
收费全文 | 55995篇 |
免费 | 6099篇 |
国内免费 | 4304篇 |
专业分类
电工技术 | 4368篇 |
技术理论 | 1篇 |
综合类 | 5348篇 |
化学工业 | 7440篇 |
金属工艺 | 4400篇 |
机械仪表 | 3174篇 |
建筑科学 | 5611篇 |
矿业工程 | 3078篇 |
能源动力 | 2224篇 |
轻工业 | 3310篇 |
水利工程 | 1979篇 |
石油天然气 | 3461篇 |
武器工业 | 829篇 |
无线电 | 4921篇 |
一般工业技术 | 6514篇 |
冶金工业 | 3548篇 |
原子能技术 | 1214篇 |
自动化技术 | 4978篇 |
出版年
2024年 | 203篇 |
2023年 | 715篇 |
2022年 | 1539篇 |
2021年 | 1905篇 |
2020年 | 1998篇 |
2019年 | 1771篇 |
2018年 | 1604篇 |
2017年 | 2144篇 |
2016年 | 2317篇 |
2015年 | 2389篇 |
2014年 | 3633篇 |
2013年 | 3883篇 |
2012年 | 4382篇 |
2011年 | 4531篇 |
2010年 | 3365篇 |
2009年 | 3323篇 |
2008年 | 2979篇 |
2007年 | 3575篇 |
2006年 | 3138篇 |
2005年 | 2648篇 |
2004年 | 2272篇 |
2003年 | 2003篇 |
2002年 | 1705篇 |
2001年 | 1412篇 |
2000年 | 1187篇 |
1999年 | 990篇 |
1998年 | 833篇 |
1997年 | 724篇 |
1996年 | 639篇 |
1995年 | 528篇 |
1994年 | 409篇 |
1993年 | 315篇 |
1992年 | 287篇 |
1991年 | 214篇 |
1990年 | 180篇 |
1989年 | 138篇 |
1988年 | 102篇 |
1987年 | 58篇 |
1986年 | 53篇 |
1985年 | 58篇 |
1984年 | 42篇 |
1983年 | 32篇 |
1982年 | 21篇 |
1981年 | 15篇 |
1980年 | 25篇 |
1979年 | 17篇 |
1978年 | 9篇 |
1975年 | 10篇 |
1959年 | 15篇 |
1955年 | 8篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
氧化铝生产过程结疤溶解的研究 总被引:1,自引:0,他引:1
针对氧化铝生产过程结疤现象。研制出一种新型清洗溶剂,溶垢率可达95%,清洗效果达到《工业设备化学清洗质量标准》要求。 相似文献
92.
Flame structure and NO emission characteristics in counterflow diffusion flame of blended fuel of H2/CO2/Ar have been numerically simulated with detailed chemistry. The combination of H2, CO2 and Ar as fuel is selected to clearly display the contribution of hydrocarbon products to flame structure and NO emission characteristics due to the breakdown of CO2. A radiative heat loss term is involved to correctly describe the flame dynamics especially at low strain rates. The detailed chemistry adopts the reaction mechanism of GRI 2.11, which consists of 49 species and 279 elementary reactions. All mechanisms including thermal, NO2, N2O and Fenimore are taken into account to separately evaluate the effects of CO2 addition on NO emission characteristics. The increase of added CO2 quantity causes flame temperature to fall since at high strain rates a diluent effect is prevailing and at low strain rates the breakdown of CO2 produces relatively populous hydrocarbon products and thus the existence of hydrocarbon products inhibits chain branching. It is also found that the contribution of NO production by N2O and NO2 mechanisms are negligible and that thermal mechanism is concentrated on only the reaction zone. As strain rate and CO2 quantity increase, NO production is remarkably augmented. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献
93.
MA Gui-shengSenior Engineer Comprehensive Reconnaissance Bureau Changjiang Water Resources Commission Wuhan China 《人民长江》2002,(Z1)
1 IntroductionBecauseofthecomplicatedsubsoilprofile ,theleveealongmiddleandlowerreachesofYangtze ,about 36 0 0kmlong ,hasmanyhiddenperils .Amongthedangerouseventsduring 1998’sfloodseasoninthewholevalley ,12 .7%oc curredalongthetrunkstreamdykes,ofwhich 6 98werethemostd… 相似文献
94.
旋风分离器结构改进的研究 总被引:3,自引:0,他引:3
根据旋风分离器的工作原理及应用特点 ,分析了影响旋风分离器分离效率的因素及结构存在的问题 ,并提出了改进措施 ,即内管外壁增设螺旋翼片 ,扩散形锥体改为悬挂挡板。通过实验观察 ,改进结构的旋风分离器分离效率比常规旋风分离器高。实践证明 ,对于密度差异较小的非均相物系的分离 ,只要对旋风分离器作适当改进 ,仍能取得令人满意的效果 ,这大大拓宽了旋风分离器的应用领域 相似文献
95.
Sung D. Kwon Sung J. Song Dong H. Bae Young Z. Lee 《Journal of Mechanical Science and Technology》2002,16(9):1084-1092
The frequency dependency of Rayleigh surface wave is investigated indirectly by measuring the angular dependency of the backward
radiation of the incident ultrasonic wave in two kinds of degraded specimens by scuffing or corrosion. Then, the frequency
dependency is compared with the residual stress distribution or the corrosion-fatigue characteristics for the scuffed or corroded
specimens, respectively. The width of the backward radiation profile increases with the increase of the variation in residual
stress distribution for the scuffed specimens. In the corroded specimens, the profile width decreases with the increase of
the effective aging layer thickness and is inversely proportional to the exponent, m, in the Paris’ law that can predict the
crack size increase due to fatigue. The result observed in this study demonstrates high potential of backward radiated ultrasound
as a tool for nondestructive evaluation of subsurface gradient of material degradation generated by scuffing or corrosion. 相似文献
96.
97.
98.
99.
100.
Wang Hai-dou Xu Bin-shi Wei Shi-cheng Zhang Xian-cheng Jin Guo Jiang Yi 《中南工业大学学报(英文版)》2005,12(2):30-33
The guide-pieces, used in the process line of steel rolling, were the important components. The guidepieces, which were slide
contacting with the rolled-piece, had a high temperature and high speed. The wear was very serious. The results from failure
analysis showed that there were three failure forms in the guide-pieces: the first was the wear during heat friction, the
second was the heat fatigue under the cycle of deep heating and deep cooling, and the third was the impact rupture. Among
them, the wear was the main reason. To the wear of guidepieces, there were four mechanisms, namely abrasive wear, adhesive
wear, fatigue wear and corrosion wear. The failure analysis to the guide-piece laid the foundation for its remanufacturing.
Foundation item: Project(50235030) supported by the National Natural Science Foundation of China 相似文献