全文获取类型
收费全文 | 135860篇 |
免费 | 2799篇 |
国内免费 | 844篇 |
专业分类
电工技术 | 2117篇 |
综合类 | 156篇 |
化学工业 | 23645篇 |
金属工艺 | 4678篇 |
机械仪表 | 3887篇 |
建筑科学 | 5372篇 |
矿业工程 | 783篇 |
能源动力 | 3611篇 |
轻工业 | 11515篇 |
水利工程 | 1456篇 |
石油天然气 | 2495篇 |
武器工业 | 48篇 |
无线电 | 11387篇 |
一般工业技术 | 26836篇 |
冶金工业 | 22660篇 |
原子能技术 | 3044篇 |
自动化技术 | 15813篇 |
出版年
2022年 | 1308篇 |
2021年 | 2114篇 |
2020年 | 1474篇 |
2019年 | 1728篇 |
2018年 | 2822篇 |
2017年 | 2675篇 |
2016年 | 3130篇 |
2015年 | 2174篇 |
2014年 | 3414篇 |
2013年 | 7554篇 |
2012年 | 5158篇 |
2011年 | 6447篇 |
2010年 | 5133篇 |
2009年 | 5243篇 |
2008年 | 5698篇 |
2007年 | 5441篇 |
2006年 | 4716篇 |
2005年 | 4221篇 |
2004年 | 3791篇 |
2003年 | 3598篇 |
2002年 | 3433篇 |
2001年 | 2824篇 |
2000年 | 2646篇 |
1999年 | 2600篇 |
1998年 | 4956篇 |
1997年 | 3723篇 |
1996年 | 2942篇 |
1995年 | 2446篇 |
1994年 | 2187篇 |
1993年 | 2223篇 |
1992年 | 1761篇 |
1991年 | 1575篇 |
1990年 | 1704篇 |
1989年 | 1692篇 |
1988年 | 1484篇 |
1987年 | 1427篇 |
1986年 | 1389篇 |
1985年 | 1617篇 |
1984年 | 1424篇 |
1983年 | 1276篇 |
1982年 | 1144篇 |
1981年 | 1207篇 |
1980年 | 1089篇 |
1979年 | 1087篇 |
1978年 | 1025篇 |
1977年 | 1170篇 |
1976年 | 1346篇 |
1975年 | 919篇 |
1974年 | 838篇 |
1973年 | 813篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
Rajoo R. Lim S.S. Wong E.H. Hnin W.Y. Seah S.K.W. Tay A.A.O. Iyer M. Tummala R.R. 《Advanced Packaging, IEEE Transactions on》2008,31(2):377-385
A wafer level packaging technique has been developed with an inherent advantage of good solder joint co-planarity suitable for wafer level testing. A suitable weak metallization scheme has also been established for the detachment process. During the fabrication process, the compliancy of the solder joint is enhanced through stretching to achieve a small shape factor. Thermal cycling reliability of these hourglass-shaped, stretch solder interconnections has been found to be considerably better than that of the conventional spherical-shaped solder bumps. 相似文献
52.
Porous carbon nanofibers are synthesized by CVD method from acetylene with use of iron-containing catalysts. Activation of the nanofibers in melted potassium hydroxide results in increasing surface area from initial 300–400 m2 g−1 to 1700 m2 g−1. As follows from XRD data, activated nanofibers do not contain regular packages of graphene layers, but retain high electric conductivity. Deposition of copper improves electrochemical hydrogen storing characteristics of carbon nanofibers. Carbon nanomaterials obtained can be used as hydrogen storing materials in batteries instead of hydride forming metals. 相似文献
53.
54.
S. M. Obraztsov G. A. Birzhevoi Yu. V. Konobeev V. A. Solov'ev O. S. Silkina 《Atomic Energy》2004,96(2):111-116
The results of a computational experiment with a neural-net model simulating the effect of the chemical composition on the plastic properties of ÉP-450 steel are presented. It is shown that computer-aided development of reactor steel with prescribed properties is, in principle, possible. 相似文献
55.
PeterTopping 《世界电子元器件》2004,(1):73-74
串行多路传输总线如CAN或LIN可以解决车内因导线过多所带来的许多问题。低成本的LIN总线很适合应用于车门等这些对传输速率要求不高的场合,最高速率为20kbit/s的LIN总线完全可以满足要求。车外温度显示就是这样一个应用实例,外部温度传感器通常布置在后视镜中,数据产生于车门。但是实际显示位置是距此一定距离的车内,LIN总线可使布线简单,因为LIN节点只有3根导线:LIN数据线、电源线和地线。 相似文献
56.
The dielectric and pyroelectric properties of Ge-doped (0.1 mol %) TlInS2 crystals are studied. The results demonstrate that TlInS2 is a ferroelectric relaxor. The experimental data are used to evaluate, using the Vogel–Fulcher relation, the activation energy (0.045 eV), preexponential factor (f
0 = 2 × 1013 Hz), and the dipole-freezing temperature (T
F = 142 K) and to determine the temperature range of the stable relaxor (nanodomain) state and the temperature of the transition to the ferroelectric (macrodomain) state, accompanied by an anomaly in the temperature-dependent pyroelectric coefficient. 相似文献
57.
58.
O. R. Dornyak 《Journal of Engineering Physics and Thermophysics》2003,76(3):648-654
A rheological equation of state for wood which allows for the running values of its porosity and humidity is considered. 相似文献
59.
In this paper we design an experiment which can be depicted as a simple scenario, a very limited 'world'. In this world, there are an actor that can pursue a project and an observer that is keeping its eyes on the actor. We try to show in the experiment that the observer can to some degree understand the actor based on its knowledge and some metaphors, i.e. understand what the actor is doing and why. As the conclusion of this experiment, we try to show some features of 'understanding'. These are (1) that 'understanding' has to be based on some preliminary knowledge; (2) that 'understanding' is a process of incremental learning; (3) that, as for symbolic systems, some metaphors are necessary for mapping real entities into concepts in mind. 相似文献
60.
Conclusions The chemical mutagenesis method is recommended for use in local purification installations for cleaning up of caprolactam-containing wastewater.Use of this method permits one to carry out a biochemical clean-up of wastewater having a caprolactam content up to 600 mg/liter while increasing the oxidative power of the aeration tank by a factor of two.Translated from Khimicheskie Volokna, No. 6, p. 46, November–December, 1985. 相似文献