全文获取类型
收费全文 | 108176篇 |
免费 | 1968篇 |
国内免费 | 1395篇 |
专业分类
电工技术 | 2144篇 |
技术理论 | 2篇 |
综合类 | 476篇 |
化学工业 | 11540篇 |
金属工艺 | 5749篇 |
机械仪表 | 3503篇 |
建筑科学 | 2543篇 |
矿业工程 | 359篇 |
能源动力 | 3086篇 |
轻工业 | 6354篇 |
水利工程 | 794篇 |
石油天然气 | 1071篇 |
武器工业 | 66篇 |
无线电 | 16567篇 |
一般工业技术 | 22377篇 |
冶金工业 | 25499篇 |
原子能技术 | 1415篇 |
自动化技术 | 7994篇 |
出版年
2023年 | 336篇 |
2022年 | 618篇 |
2021年 | 943篇 |
2020年 | 725篇 |
2019年 | 842篇 |
2018年 | 1307篇 |
2017年 | 1303篇 |
2016年 | 1351篇 |
2015年 | 1154篇 |
2014年 | 1762篇 |
2013年 | 5029篇 |
2012年 | 2938篇 |
2011年 | 4225篇 |
2010年 | 3424篇 |
2009年 | 3995篇 |
2008年 | 4177篇 |
2007年 | 4341篇 |
2006年 | 3985篇 |
2005年 | 3562篇 |
2004年 | 3345篇 |
2003年 | 3160篇 |
2002年 | 2795篇 |
2001年 | 3066篇 |
2000年 | 2809篇 |
1999年 | 3203篇 |
1998年 | 9555篇 |
1997年 | 6258篇 |
1996年 | 4837篇 |
1995年 | 3224篇 |
1994年 | 2835篇 |
1993年 | 2759篇 |
1992年 | 1656篇 |
1991年 | 1612篇 |
1990年 | 1532篇 |
1989年 | 1335篇 |
1988年 | 1177篇 |
1987年 | 868篇 |
1986年 | 891篇 |
1985年 | 918篇 |
1984年 | 808篇 |
1983年 | 700篇 |
1982年 | 702篇 |
1981年 | 682篇 |
1980年 | 570篇 |
1979年 | 477篇 |
1978年 | 414篇 |
1977年 | 535篇 |
1976年 | 959篇 |
1975年 | 299篇 |
1974年 | 276篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
992.
Y. W. Kim 《International Journal of Thermophysics》2007,28(2):732-741
Thermophysical properties are collective measures of a material to transport dynamical quantities of physical nature on its
surface or through the bulk. As such, the exact nature of couplings between particles in a many-body assembly of building
block atoms or molecules sensitively determines their values. The couplings between nearest neighbors are the product of the
local elemental composition and the material phase. In this study, thermal cycling of a four-element Wood’s alloy specimen
brings out cadmium-rich patches to the top surface of the specimen. An assembly of such patches leads to depth-dependent deviations
of elemental composition from that of the bulk. Surface-layer atoms are driven to form a high temperature laser-produced plasma
(LPP), and time-resolved spectroscopy of their emissions show the variability of elemental composition over surface positions
as well as over depth from the surface. These thermal history-driven composition anomalies contribute to significant variability
in the measured values of spectral emissivity and thermal diffusivity. 相似文献
993.
The thermal degradation of ITO Schottky contacts on GaAs has been studied. The rectifying contacts show rapid degradation with heating and could have serious implications for optoelectronic devices that operate at elevated temperatures.<> 相似文献
994.
Y. C. Wu Darning Feng W. F. Koch 《Journal of research of the National Institute of Standards and Technology》1991,96(6):757-762
Ionic interactions in the two systems NaCl-HEPES (N-2-hydroxyethylpiperazine-N′-2-ethanesulfonic acid) and NaCl-MOPSO (3-(N-Morpholino)-2-hydroxypropanesulfonic acid) have been studied in terms of their mutual influence on the respective activity coefficients of each component. Activity coefficients for each component of the two systems and for corresponding buffers are calculated from emf measurements of solutions containing NaCl, the aminosulfonic acid, and its conjugate base in a NalSE/solution/AgCl-Ag cell at 5, 15, 25, and 37 °C. 相似文献
995.
A compact lumped‐element equivalent circuit model of two‐layer integrated spiral inductors on silicon substrates is developed in this article. Based on this proposed model, excellent agreements are achieved between the measured and simulated S‐parameters for different inductors. Also, both self‐ and mutual inductances of two‐layer inductors are accurately extracted, and their overall performances are understood clearly. © 2003 Wiley Periodicals, Inc. Int J RF and Microwave CAE 13: 148–153, 2003. 相似文献
996.
Yamaguchi Y. Mitsumoto M. Sengoku M. Abe T. 《Geoscience and Remote Sensing, IEEE Transactions on》1992,30(1):186-189
An FM-CW radar system was applied to detect a human body buried in a very wet snowpack. This radar uses the L -band microwave frequency with a maximum output power of 100 mW, and utilizes digital signal processing techniques. Field experiments were carried out to detect and map a human body embedded at a depth of 125 cm in a natural snowpack. The radar is shown to have a potential ability to detect avalanche victims, indicating that it may become a tool for snow rescuer operations 相似文献
997.
998.
999.
A mode based on an additive mechanism of heat transfer is proposed for forced convection subcooled boiling of binary mixtures. The contributing modes of heat transfer are: (i) the heat transferred as latent heat by the rising bubbles, (ii) the heat transferred as the heat contained in the superheated thermal layer that is removed from the surface in the wake of the rising bubbles and (iii) the single phase forced convection heat transfer from the heating surface not influenced by the bubbles. Experimental data from the literature on binary systems show good agreement with the model, validating the postulated mechanism. 相似文献
1000.
Abstract: Non-classical fractals generated by many generators are of interest. Random fractals caused by the random action of given generators and by random generrrtors are discussed The generators may have different scales. The fractal spectral function, the generalized fractal dimensions and scaling index are derived explicitly. Examples include the cracking patterns of concrete mix. 相似文献