全文获取类型
收费全文 | 74764篇 |
免费 | 709篇 |
国内免费 | 689篇 |
专业分类
电工技术 | 1428篇 |
综合类 | 47篇 |
化学工业 | 11163篇 |
金属工艺 | 3444篇 |
机械仪表 | 2637篇 |
建筑科学 | 1639篇 |
矿业工程 | 503篇 |
能源动力 | 1851篇 |
轻工业 | 6378篇 |
水利工程 | 845篇 |
石油天然气 | 2303篇 |
武器工业 | 41篇 |
无线电 | 7195篇 |
一般工业技术 | 16443篇 |
冶金工业 | 12407篇 |
原子能技术 | 2627篇 |
自动化技术 | 5211篇 |
出版年
2022年 | 574篇 |
2021年 | 904篇 |
2020年 | 696篇 |
2019年 | 777篇 |
2018年 | 1549篇 |
2017年 | 1563篇 |
2016年 | 1760篇 |
2015年 | 945篇 |
2014年 | 1555篇 |
2013年 | 3563篇 |
2012年 | 2360篇 |
2011年 | 2819篇 |
2010年 | 2367篇 |
2009年 | 2638篇 |
2008年 | 2617篇 |
2007年 | 2551篇 |
2006年 | 2182篇 |
2005年 | 1912篇 |
2004年 | 1837篇 |
2003年 | 1786篇 |
2002年 | 1704篇 |
2001年 | 1676篇 |
2000年 | 1669篇 |
1999年 | 1562篇 |
1998年 | 3666篇 |
1997年 | 2597篇 |
1996年 | 1934篇 |
1995年 | 1522篇 |
1994年 | 1325篇 |
1993年 | 1348篇 |
1992年 | 994篇 |
1991年 | 1050篇 |
1990年 | 1071篇 |
1989年 | 1050篇 |
1988年 | 940篇 |
1987年 | 874篇 |
1986年 | 877篇 |
1985年 | 934篇 |
1984年 | 777篇 |
1983年 | 766篇 |
1982年 | 675篇 |
1981年 | 689篇 |
1980年 | 661篇 |
1979年 | 646篇 |
1978年 | 620篇 |
1977年 | 773篇 |
1976年 | 930篇 |
1975年 | 580篇 |
1974年 | 551篇 |
1973年 | 543篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
42.
M. Guerioune Y. Amiour W. Bounour O. Guellati A. Benaldjia A. Amara N. E. Chakri M. Ali-Rachedi D. Vrel 《International Journal of Self-Propagating High-Temperature Synthesis》2008,17(1):41-48
Aiming at preparation of shape memory alloys (SMAs), we explored the SHS of Cu1 − x
Zn1 − y
Al1 − z
alloys (0.29 < x < 0.30, 0.74 < y < 0.75, and 0.83 < z < 0.96). The most pronounced shape memory effect was exhibited by the alloys of the following compositions (wt %): (1) Cu(70.6)Zn(25.4)Al(4.0),
(2) Cu(70.1)Zn(25.9)Al(4.0), and (3) Cu(69.9)Zn(26.1)Al(4.0). The effect of process parameters on the synthesis of CuZnAl
alloys was studied by XRD, optical microscopy, and scanning electron microscopy (SEM). The grain size of CuZnAl was found
to depend on the relative amount of the primary CuZn and AlZn phases. Changes in the transformation temperature and heat of
transformation are discussed in terms of ignition intensity and compaction. Mechanism of the process depends on the level
of the temperature attained relative to the melting point of components. At the melting point of AlZn, the process is controlled
by the solid-state diffusion of AlZn into a product layer. The ignition temperature for this system depends on the temperature
of the austenite-martensite transformation in CuZnAl alloys. The composition and structure of the products was found to markedly
depend on process parameters. The SHS technique has been successfully used to prepare a variety of SMAs.
相似文献
43.
A. I. Nikolaev F. D. Larichkin O. A. Nikolaeva 《Theoretical Foundations of Chemical Engineering》2008,42(5):675-679
The main rules and principles which govern the choice of new variants for chemical technology of combined processing of titanium-rare-metal raw materials are considered. The existing variants of the technology are characterized from the viewpoint of their technological, economical, and ecological efficiency and social importance for a given region. A realistic choice of a technology from a large number of available variants should take into account the entire combination of their advantages and disadvantages The implementation of a rational technological scheme will result in the creation of economically profitable and efficient domestic production satisfying the demands of Russian industry in rare-metal and titanium materials. Directions are noted in which it is expedient to continue studies on designing a rational technology of loparite concentrate or some other concentrate. 相似文献
44.
Cross-linking additions of silicon carbide and waste material from ferroalloy production make it possible to increase the
heat-resistance index for mullite-containing refractories. For briquette specimens based on a charge containing aluminum powder
it reaches 45 thermal cycles (1300°C – water).
Translated from Novye Ogneupory, No. 11, pp. 44–46, November 2008. 相似文献
45.
E. P. Velikhov N. N. Ponomarev-Stepnoi V. G. Volkov G. G. Gorodetskii Yu. A. Zverkov O. P. Ivanov S. M. Koltyshev V. D. Muzrukova S. G. Semenov V. E. Stepanov A. V. Chesnokov A. D. Shisha 《Atomic Energy》2007,102(5):375-381
This article is devoted to work done in 2002–2006 as part of the unified project Reabilitatsiya to rehabilitate radiation
hazardous objects and sections of the radioactively contaminated territory of the Russian Science Center Kurchatov Institute.
The main objects of the rehabilitation work were old storage sites built for radioactive wastes on the territory of the Institute
when military and civilian nuclear technologies were under development. The structural features of the storage sites, including
the volumes and characteristics of the wastes stored, are presented. The salient aspects of the disposal sites, taken into
account during the rehabilitation work, are discussed. The organization of the rehabilitation operations and the sequence
in which they are performed, the special features of the technical design solutions used, the technological methods, and ways
for conducting the work are described.
__________
Translated from Atomnaya énergiya, Vol. 102, No. 5, pp. 300–306, May, 2007. 相似文献
46.
47.
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
48.
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
49.
O. E. Aleksandrov 《Atomic Energy》2004,96(3):196-201
The theory of separation, based on radial averaging, in a Zippe centrifuge is developed. Certain aspects of the theory of the rotational potential and the errors in understanding the essence of the Helmholtz decomposition as it applies to a gas centrifuge are elucidated. It is shown that the Helmholtz decomposition method does not have cetain drawbacks of the classical theory of the radial averaging method and makes it possible to take account of the rotational flows due to the feed, find expicitly the transit flow distribution, take account of the radial nonuniformity, and take account of the radial convective transport of an isotope by the circulation and transit flows, and the method is not limited by the assumption that the feed flow is small. 相似文献
50.
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