全文获取类型
收费全文 | 19436篇 |
免费 | 2402篇 |
国内免费 | 1762篇 |
专业分类
电工技术 | 2097篇 |
综合类 | 1722篇 |
化学工业 | 1506篇 |
金属工艺 | 1931篇 |
机械仪表 | 1477篇 |
建筑科学 | 2832篇 |
矿业工程 | 1238篇 |
能源动力 | 466篇 |
轻工业 | 447篇 |
水利工程 | 768篇 |
石油天然气 | 1263篇 |
武器工业 | 268篇 |
无线电 | 947篇 |
一般工业技术 | 2782篇 |
冶金工业 | 2144篇 |
原子能技术 | 219篇 |
自动化技术 | 1493篇 |
出版年
2024年 | 88篇 |
2023年 | 279篇 |
2022年 | 651篇 |
2021年 | 782篇 |
2020年 | 783篇 |
2019年 | 693篇 |
2018年 | 541篇 |
2017年 | 785篇 |
2016年 | 815篇 |
2015年 | 840篇 |
2014年 | 1297篇 |
2013年 | 1345篇 |
2012年 | 1475篇 |
2011年 | 1649篇 |
2010年 | 1218篇 |
2009年 | 1230篇 |
2008年 | 1010篇 |
2007年 | 1171篇 |
2006年 | 1186篇 |
2005年 | 927篇 |
2004年 | 787篇 |
2003年 | 702篇 |
2002年 | 620篇 |
2001年 | 480篇 |
2000年 | 380篇 |
1999年 | 324篇 |
1998年 | 250篇 |
1997年 | 233篇 |
1996年 | 190篇 |
1995年 | 159篇 |
1994年 | 126篇 |
1993年 | 101篇 |
1992年 | 94篇 |
1991年 | 66篇 |
1990年 | 60篇 |
1989年 | 44篇 |
1988年 | 44篇 |
1987年 | 21篇 |
1986年 | 15篇 |
1985年 | 21篇 |
1984年 | 14篇 |
1983年 | 17篇 |
1982年 | 6篇 |
1981年 | 5篇 |
1980年 | 10篇 |
1979年 | 14篇 |
1961年 | 5篇 |
1960年 | 6篇 |
1959年 | 7篇 |
1955年 | 7篇 |
排序方式: 共有10000条查询结果,搜索用时 8 毫秒
71.
用化学成分分析、金相组织检验、硬度测试以及对刹车鼓的宏观和微观分析等方法,对刹车鼓刹车失灵进行分析,并探讨了刹车鼓失效的原因、失效形式以及对刹车鼓铸件质量控制。 相似文献
72.
73.
综述合成氨二段转化废热锅炉失效历程分析,废热锅炉列管穿孔、管板泄漏及水压试验泄漏的原因,提出解决对策。 相似文献
74.
75.
In this paper we describe an apparatus for reproducibly measuring thermal shock resistance of thick polymer layers bonded to metals. The thermal shock behavior is discussed in terms of epoxy samples bonded to an aluminum substrate. It was found that both high resin toughness and low resin thermal expansion coefficient improved thermal shock resistance of thick coatings, but only a sample containing 60wt. % glass beads did not develop a failure crack. Effects of sample thickness, temperature gradient, and resin composition on thermal shock behavior are discussed. 相似文献
77.
The crystal structure of urea-polyethylene complex in the hexagonal form, obtained by one of our preparation methods, is analysed by X-ray power diffractometry. In this analysis, the fixed molecular parameters of urea are used, and three models with respect to rotational disorder of the guest polyethylene molecule are assumed. It is shown that the host lattice structure constructed by urea molecules is essentially the same as that of urea-n-paraffin complex. Effects of the disorder structure of the guest on X-ray scattering of the complex are presented. However, there is a difficulty in identifying the disorder structure by X-ray analysis. With the aid of a potential energy calculation between the hexagonal urea tunnel and the guest molecule, a rotational disorder model is preferred. 相似文献
78.
《Journal of Process Control》2014,24(5):613-620
This paper presents a state space model predictive fault-tolerant control scheme for batch processes with unknown disturbances and partial actuator faults. To develop the model predictive fault-tolerant control, the batch process is first treated into a non-minimal representation using state space transformation. The relevant concepts of the corresponding model predictive fault-tolerant control is thus introduced through state space formulation, where improved closed-loop control performance is achieved even with unknown disturbances and actuator faults, because, unlike traditional model predictive fault-tolerant control, the proposed control method can directly regulate the process output/input changes in the design. For performance comparison, a traditional model predictive fault-tolerant control is also designed. Application to injection velocity control shows that the proposed scheme achieve the design objective well with performance improvement. 相似文献
79.
The objective of this study was to determine how the fracture of adhesive joints depends on elastic beam parameters describing the adherends and the applied loads. The basic specimen geometry was the cracked lap shear joint constructed of aluminium alloy with various adherend and bondline thicknesses. Loads were applied in different combinations of bending, tension and shear to generate a failure envelope for each adhesive and specimen geometry. It was found that crack propagation for precracked specimens occured at a critical strain energy release rate but was also a function of the GI/GII ratio and the bondline thickness. The experiments also showed that the loads required to propagate a crack in a precracked specimen were always lower than the loads required to break the fillet. Hence, by treating uncracked joints as being cracked, where the fictitious crack tip is assumed to coincide with the location of the fillet, a conservative estimate of the failure load is obtained. 相似文献
80.
This paper reviews the brittle fracture behavior of dielectric ceramics such as barium titanate, and describes some of the relationships between defects such as cracks and electrical degradation and failure of multilayer capacitors. Stresses arising from the ferroelectric phase transformation in these dielectric materials are shown to play a part as a driving force for crack growth. In addition, possible contributions to failure from stresses arising from thermal excursions in the capacitor are discussed. Low-voltage failures arising from a short between the electrodes in multilayer capacitors are shown to be related to the growth of cracks in the dielectric. A technique for predicting the onset of these types of failures based upon fracture mechanics techniques is described. Possible effects of the electric field itself in promoting or retarding the growth of cracks are discussed. 相似文献