全文获取类型
收费全文 | 3342篇 |
免费 | 99篇 |
国内免费 | 6篇 |
专业分类
电工技术 | 26篇 |
化学工业 | 735篇 |
金属工艺 | 125篇 |
机械仪表 | 79篇 |
建筑科学 | 100篇 |
矿业工程 | 37篇 |
能源动力 | 67篇 |
轻工业 | 317篇 |
水利工程 | 101篇 |
石油天然气 | 230篇 |
无线电 | 205篇 |
一般工业技术 | 621篇 |
冶金工业 | 155篇 |
原子能技术 | 40篇 |
自动化技术 | 609篇 |
出版年
2022年 | 52篇 |
2021年 | 65篇 |
2020年 | 46篇 |
2019年 | 39篇 |
2018年 | 48篇 |
2017年 | 59篇 |
2016年 | 107篇 |
2015年 | 68篇 |
2014年 | 86篇 |
2013年 | 260篇 |
2012年 | 186篇 |
2011年 | 220篇 |
2010年 | 166篇 |
2009年 | 143篇 |
2008年 | 159篇 |
2007年 | 110篇 |
2006年 | 120篇 |
2005年 | 74篇 |
2004年 | 74篇 |
2003年 | 66篇 |
2002年 | 71篇 |
2001年 | 43篇 |
2000年 | 37篇 |
1999年 | 38篇 |
1998年 | 43篇 |
1997年 | 43篇 |
1994年 | 26篇 |
1993年 | 33篇 |
1992年 | 28篇 |
1991年 | 37篇 |
1990年 | 29篇 |
1989年 | 30篇 |
1988年 | 30篇 |
1987年 | 25篇 |
1985年 | 28篇 |
1984年 | 41篇 |
1981年 | 28篇 |
1980年 | 34篇 |
1979年 | 36篇 |
1978年 | 44篇 |
1977年 | 42篇 |
1976年 | 35篇 |
1975年 | 47篇 |
1974年 | 50篇 |
1973年 | 38篇 |
1972年 | 28篇 |
1971年 | 28篇 |
1970年 | 35篇 |
1969年 | 29篇 |
1968年 | 23篇 |
排序方式: 共有3447条查询结果,搜索用时 15 毫秒
1.
2.
3.
Frédéric Gaschet 《Papers in Regional Science》2002,81(1):63-81
This article examines the relationships between the employment suburbanisation from central cities towards their suburbs,
and the process of intra-urban specialisation that occurred simultaneously in the fifty largest French metropolitan areas.
A methodology is proposed to identify urban subcentres and to analyse the effects of the intra-urban specialisations on suburbanisation
patterns. We conclude that the specialisation of both subcentres and central cities has a significant effect on suburbanisation
rates. Lastly, an intra-metropolitan shift/share analysis provides additional insights into the employment dynamics of central
cities and suburbs during the last twenty years.
Received: 25 July 2000 / Accepted: 29 May 2001 相似文献
4.
The article established the regularities of change of the physicomechanical characteristics and strength of glass textolites in single and repeated thermal loading. It shows that under multiple loading the intense loss of strength of the investigated materials is due to increased porosity on account of the large number of microcracks appearing in the structure. A correlation is obtained between the elastic and strength characteristics and porosity in dependence on the temperature of multiple heating which in the first approximation is described by a polynomial of second degree with respect to temperature, multiplied by the reciprocal of porosity.Translated from Problemy Prochnosti, No. 6, pp. 53–58, June, 1991. 相似文献
5.
Ér. V. Kal’yanov 《Technical Physics Letters》2007,33(6):451-453
A new simple model of a system with chaotic dynamics, based on the equations of bistable systems, is considered. The possibility of converting harmonic signals into chaotic oscillations, which represent intermittent irregular and switching quasi-regular motions, is demonstrated by numerical methods. The mechanism of chaotization is analyzed using the results of numerical calculations. 相似文献
6.
7.
8.
Frédéric Soisson 《Journal of Nuclear Materials》2006,349(3):235-250
Kinetics of radiation induced segregation and precipitation in binary alloys are studied by Monte Carlo simulations. The simulations are based on a simple atomic model of diffusion under electron irradiation, which takes into account the creation of point defects, the recombination of close vacancy-interstitial pairs and the point defect annihilation at sinks. They can reproduce the coupling between point defect fluxes towards sinks and atomic fluxes, which controls the segregation tendency. In pure metals and ideal solid solutions, the Monte Carlo results are found to be in very good agreement with classical models based on rate equations. In alloys with an unmixing tendency, we show how the interaction between the point defect distribution, the solute segregation and the precipitation driving force can generate complex microstructural evolutions, which depend on the very details of atomic-scale diffusion properties. 相似文献
9.
Frdric Boschet Catherine Branger Andr Margaillan Thieo E Hogen‐Esch 《Polymer International》2005,54(1):90-95
The synthesis of 2,2,3,3‐tetrahydro‐perfluoroundecanoyl end‐functionalized polystyrene–poly(ethylene oxide) block (PS‐block‐PEO‐RF) copolymers and their matching PS‐block‐PEO diblock copolymers was carried out by sequential anionic polymerization. Viscometry and 19F NMR studies show that the PS‐block‐PEO copolymers, in contrast to their matching PS‐block‐PEO‐RF copolymers, exhibit a micellar rather than the associative behavior seen for the latter. However, the presence of an excess of fluorinated acid, used for end‐functionalization, produces a reduction of the associative behavior above the overlap concentration, with the fluorinated acid acting like a surfactant. A competition may also occur between PS—and RF—mediated micellization. Copyright © 2004 Society of Chemical Industry 相似文献
10.
The properties of glasses of the lithium-aluminoborosilicate system were investigated, namely, the density, spreadability, thermal expansion, and nature of crystallized phases at various temperatures. A crystal-optical analysis was conducted. The glasses were used to prepare abrasive compositions. Their strength properties were studied as a function of the composition of the glass binder and the regime of heat treatment.Translated from Steklo i Keramika, No. 3, pp. 27–30, March, 1996. 相似文献