全文获取类型
收费全文 | 279020篇 |
免费 | 19070篇 |
国内免费 | 10986篇 |
专业分类
电工技术 | 15159篇 |
技术理论 | 14篇 |
综合类 | 14720篇 |
化学工业 | 43008篇 |
金属工艺 | 15488篇 |
机械仪表 | 15538篇 |
建筑科学 | 17135篇 |
矿业工程 | 6652篇 |
能源动力 | 7686篇 |
轻工业 | 20669篇 |
水利工程 | 5098篇 |
石油天然气 | 13157篇 |
武器工业 | 2085篇 |
无线电 | 31438篇 |
一般工业技术 | 39652篇 |
冶金工业 | 22545篇 |
原子能技术 | 4949篇 |
自动化技术 | 34083篇 |
出版年
2024年 | 920篇 |
2023年 | 3178篇 |
2022年 | 6283篇 |
2021年 | 8941篇 |
2020年 | 6842篇 |
2019年 | 5794篇 |
2018年 | 7171篇 |
2017年 | 7885篇 |
2016年 | 7777篇 |
2015年 | 8987篇 |
2014年 | 11668篇 |
2013年 | 15495篇 |
2012年 | 16290篇 |
2011年 | 17799篇 |
2010年 | 15551篇 |
2009年 | 15239篇 |
2008年 | 14960篇 |
2007年 | 14272篇 |
2006年 | 13686篇 |
2005年 | 11578篇 |
2004年 | 9040篇 |
2003年 | 8168篇 |
2002年 | 7850篇 |
2001年 | 7171篇 |
2000年 | 6433篇 |
1999年 | 6347篇 |
1998年 | 7540篇 |
1997年 | 5836篇 |
1996年 | 4917篇 |
1995年 | 3972篇 |
1994年 | 3435篇 |
1993年 | 2806篇 |
1992年 | 2095篇 |
1991年 | 1923篇 |
1990年 | 1765篇 |
1989年 | 1656篇 |
1988年 | 1395篇 |
1987年 | 1196篇 |
1986年 | 1121篇 |
1985年 | 1091篇 |
1984年 | 895篇 |
1983年 | 856篇 |
1982年 | 779篇 |
1981年 | 755篇 |
1980年 | 743篇 |
1979年 | 682篇 |
1978年 | 642篇 |
1977年 | 796篇 |
1976年 | 974篇 |
1975年 | 598篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
Jun-Guo Lu Hill D.J. 《Circuits and Systems II: Express Briefs, IEEE Transactions on》2008,55(6):586-590
Sampled-data feedback control for master-slave synchronization schemes that consist of identical chaotic Lur'e systems is studied. Sufficient conditions for global asymptotic synchronization of such chaotic Lur'e systems are obtained using the free-weighting matrix approach and expressed in terms of linear matrix inequalities (LMIs). With the help of the LMI solvers, the sampled-data feedback control law can easily be obtained to globally asymptotically synchronize Lur'e chaotic systems. The effectiveness of the proposed method is finally illustrated via numerical simulations of chaotic Chua's circuits. 相似文献
62.
Xin Sun Qiang Lu Moroz V. Takeuchi H. Gebara G. Wetzel J. Shuji Ikeda Changhwan Shin Tsu-Jae King Liu 《Electron Device Letters, IEEE》2008,29(5):491-493
A tri-gate bulk MOSFET design utilizing a low-aspect-ratio channel is proposed to provide an evolutionary pathway for CMOS scaling to the end of the roadmap. 3-D device simulations indicate that this design offers the advantages of a multi-gate FET (reduced variability in performance and improved scalability) together with the advantages of a conventional planar MOSFET (low substrate cost and capability for dynamic threshold-voltage control). 相似文献
63.
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
64.
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
65.
Many approaches have been proposed to enhance software productivity and reliability. These approaches typically fall into three categories: the engineering approach, the formal approach and the knowledge-based approach. But the optimal gain in software productivity cannot be obtained if one relies on only one of these approaches. This paper describes the work in knowledge-based software engineering conducted by the authors for the past 10 years. The final goal of the research is to develop a paradigm for software engineering which integrates the three approaches mentioned above. A knowledge-based tool which can support the whole process of software development is provided in this paper. 相似文献
66.
67.
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
68.
LaNiO3 was synthesized by sol-gel method in which lanthanum nitrate and nickel nitrate were used as start materials and citric acid was used as complex for gel formation.The precursor was dried and subsequently heated at elevated temperature to form the desired product.XRD analysis shows that pure LaNiO3 was synthesized.Electrical conductivity and electrochemical performance of the material were tested.The electrical conductivity decreases from 34.5that there are current peaks in the curve, which is the evidence of the electrochemical activity of LaNiO3. 相似文献
69.
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
70.