全文获取类型
收费全文 | 331559篇 |
免费 | 3441篇 |
国内免费 | 970篇 |
专业分类
电工技术 | 5389篇 |
综合类 | 2468篇 |
化学工业 | 47524篇 |
金属工艺 | 19368篇 |
机械仪表 | 14063篇 |
建筑科学 | 6809篇 |
矿业工程 | 3230篇 |
能源动力 | 6162篇 |
轻工业 | 16619篇 |
水利工程 | 4662篇 |
石油天然气 | 8960篇 |
武器工业 | 22篇 |
无线电 | 34440篇 |
一般工业技术 | 72967篇 |
冶金工业 | 40666篇 |
原子能技术 | 7601篇 |
自动化技术 | 45020篇 |
出版年
2021年 | 2078篇 |
2019年 | 2022篇 |
2018年 | 22194篇 |
2017年 | 21717篇 |
2016年 | 16041篇 |
2015年 | 3158篇 |
2014年 | 4092篇 |
2013年 | 8992篇 |
2012年 | 10157篇 |
2011年 | 21310篇 |
2010年 | 18748篇 |
2009年 | 16352篇 |
2008年 | 17235篇 |
2007年 | 19419篇 |
2006年 | 5749篇 |
2005年 | 8880篇 |
2004年 | 7085篇 |
2003年 | 6840篇 |
2002年 | 5352篇 |
2001年 | 4615篇 |
2000年 | 4447篇 |
1999年 | 4268篇 |
1998年 | 10238篇 |
1997年 | 7212篇 |
1996年 | 5544篇 |
1995年 | 4153篇 |
1994年 | 3635篇 |
1993年 | 3877篇 |
1992年 | 3008篇 |
1991年 | 3041篇 |
1990年 | 2892篇 |
1989年 | 2854篇 |
1988年 | 2875篇 |
1987年 | 2508篇 |
1986年 | 2568篇 |
1985年 | 2857篇 |
1984年 | 2689篇 |
1983年 | 2554篇 |
1982年 | 2302篇 |
1981年 | 2269篇 |
1980年 | 2346篇 |
1979年 | 2359篇 |
1978年 | 2383篇 |
1977年 | 2487篇 |
1976年 | 2876篇 |
1975年 | 2188篇 |
1974年 | 2068篇 |
1973年 | 2166篇 |
1972年 | 1940篇 |
1971年 | 1755篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
971.
O. E. Narivs’kyi 《Materials Science》2007,43(1):124-132
We have studied the micromechanism of corrosion fracture of heat-transfer plates of a heat exchanger. The operation of heat
exchangers under conditions of contamination of the plates with a sediment from water leads to their local corrosion under
the sediment. The conditions of operation of the heat exchangers being equal, heat-transfer plates made of AiSi316Ti steel
worked 2.36 times as long as those of AiSi304L steel. The corrosion fracture of plates under the sediment began from pitting
initiation near nonmetallic inclusions of a certain nature. Afterwards, these pittings built up into corrosion spots by the
mechanism of stress corrosion and hydrogen embrittlement.
__________
Translated from Fizyko-Khimichna Mekhanika Materialiv, Vol. 43, No. 1, pp. 110–116, January–February, 2007. 相似文献
972.
Published data on the preparation procedures, stability, and complexation of U(III) in aqueous solutions are summarized and correlated. Reactions with inorganic and organic free radicals studied by the flash radiolysis method, the spectroscopic properties, the extraction and ion-exchange behavior of U(III), and methods for isolation of solid U(III) compounds from aqueous solutions are discussed. 相似文献
973.
Boundary objects are a critical, but understudied, theoretical construct in CSCW. Through a field study of aircraft technical
support, we examined the role of boundary objects in the practical achievement of safety by service engineers. Their resolution
of repair requests was preserved in the organization’s memory via three compound boundary objects. These crystallizations
did not manifest a static interpretation, but instead were continually reinterpreted in light of meta-negotiations. This suggests
design implications for organizational memory systems which can more fluidly represent the meta-negotiations surrounding boundary
objects. 相似文献
974.
975.
[110]-surface strained-SOI CMOS devices 总被引:1,自引:0,他引:1
Mizuno T. Sugiyama N. Tezuka T. Moriyama Y. Nakaharai S. Takagi S. 《Electron Devices, IEEE Transactions on》2005,52(3):367-374
We have newly developed [110]-surface strained-silicon-on-insulator (SOI) n- and p-MOSFETs on [110]-surface relaxed-SiGe-on-insulator substrates with the Ge content of 25%, fabricated by applying the Ge condensation technique to SiGe layers grown on [110]-surface SOI wafers. We have demonstrated that the electron and the hole mobility enhancement of [110]-surface strained-SOI devices amounts to 23% and 50%, respectively, against the mobilities of [110]-surface unstrained MOSFETs. As a result, the electron and the hole mobility ratios of [110]-surface strained-SOI MOSFETs to the universal mobility of (100)-surface bulk-MOSFETs increase up to 81% and 203%, respectively. Therefore, the current drive imbalance between n- and p-MOS can be reduced. Moreover, both the electron and the hole mobilities of the [110]-surface strained-SOIs strongly depend on the drain current flow direction, which is qualitatively explained by the anisotropic effective mass characteristics of the carriers on a [110]-surface Si. As a result, the [110]-surface strained-SOI technology with optimization of the current flow directions of n- and p-MOS is promising for realizing higher speed scaled CMOS. 相似文献
976.
The results of studying the effect of nontraditional additives, namely, metallic aluminum and zinc powders on the process
of silicate and glass formation using polythermal and thermogravimetric analysis, are described. The specifics of the glass-melting
process for decorative glasses using the nontraditional additives are considered.
__________
Translated from Steklo i Keramika, No. 5, pp. 7 – 10, May, 2005. 相似文献
977.
E. N. Gnezdov 《Glass and Ceramics》2005,62(9-10):295-297
Two variants of thermostats for measuring instruments are developed and tested. The temperature from 5 to 50°C required for normal operation of the instrument is maintained during the entire time the thermostat stays inside the drier, i.e., 43 h. 相似文献
978.
IR spectroscopic and x-ray phase analysis established the structural specifics of glasses in the system Na2O-SiO2-TiO2-Na3AlF6, as well as the dependence on the type of crystallizing phases on the chemical composition of the glass matrix. The effect of the structure of titanium-bearing clusters on the leachability of glasses, the effect of the second coordination sphere on the coordination of the central cation (Ti4+), and the propensity of experimental glass coatings to opacification are registered. 相似文献
979.
A technology for producing ShA and ShB refractories uses high-melting clays from the Rostov Region and high-alumina technogenic waste. The effect of the chamotte-to-clay ratio, the granulometric composition, and the additive introduction method on the properties of products is investigated.__________Translated from Steklo i Keramika, No. 1, pp. 15 – 16, January, 2005. 相似文献
980.