全文获取类型
收费全文 | 10298篇 |
免费 | 854篇 |
国内免费 | 10篇 |
专业分类
电工技术 | 63篇 |
综合类 | 2篇 |
化学工业 | 3519篇 |
金属工艺 | 246篇 |
机械仪表 | 236篇 |
建筑科学 | 318篇 |
矿业工程 | 28篇 |
能源动力 | 286篇 |
轻工业 | 2461篇 |
水利工程 | 68篇 |
石油天然气 | 58篇 |
无线电 | 412篇 |
一般工业技术 | 1767篇 |
冶金工业 | 282篇 |
原子能技术 | 78篇 |
自动化技术 | 1338篇 |
出版年
2023年 | 146篇 |
2022年 | 438篇 |
2021年 | 586篇 |
2020年 | 348篇 |
2019年 | 383篇 |
2018年 | 448篇 |
2017年 | 451篇 |
2016年 | 526篇 |
2015年 | 377篇 |
2014年 | 527篇 |
2013年 | 927篇 |
2012年 | 682篇 |
2011年 | 739篇 |
2010年 | 591篇 |
2009年 | 563篇 |
2008年 | 428篇 |
2007年 | 357篇 |
2006年 | 264篇 |
2005年 | 199篇 |
2004年 | 166篇 |
2003年 | 151篇 |
2002年 | 132篇 |
2001年 | 95篇 |
2000年 | 89篇 |
1999年 | 89篇 |
1998年 | 73篇 |
1997年 | 72篇 |
1996年 | 76篇 |
1995年 | 56篇 |
1994年 | 62篇 |
1993年 | 59篇 |
1992年 | 43篇 |
1991年 | 33篇 |
1989年 | 39篇 |
1988年 | 32篇 |
1987年 | 43篇 |
1986年 | 32篇 |
1985年 | 52篇 |
1984年 | 52篇 |
1983年 | 47篇 |
1982年 | 58篇 |
1981年 | 43篇 |
1980年 | 49篇 |
1979年 | 44篇 |
1978年 | 48篇 |
1977年 | 46篇 |
1976年 | 49篇 |
1975年 | 41篇 |
1974年 | 42篇 |
1973年 | 47篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
Mariana Ušáková Jozef Lukáč Rastislav Dosoudil Vladimír Jančárik Anna Grusková Elemír Ušák Jozef Sláma Jan Šubrt 《Journal of Materials Science: Materials in Electronics》2007,18(12):1183-1189
The paper is devoted to the preparation of NiZn ferrite with small substitutions of copper by means of ceramic technology.
The influence of small Cu substitution on the microstructural and magnetic properties of NiZn ferrites have been analysed
by means of various experimental methods and interpreted from the point of view of preparation technology optimisation and
possible applications of such materials. A strong correlation between the substituent content and resulting properties has
been observed, thus allowing preparation of material with the properties tailored for any particular application. 相似文献
42.
Ana Cuesta Amelia Martí nez-Alonso Juan M. D. Tasc n 《Fullerenes, Nanotubes and Carbon Nanostructures》1997,5(5):1075-1081
Fullerene reactivity in an oxygen plasma was measured and compared with those determined under the same conditions for a comprehensive set of 50 carbon materials. The possible reasons for the high plasma reactivity of the fullerene sample in an oxygen plasma are discussed. 相似文献
43.
It was found, that To?pa Peat Preparation (TPP) administered to healthy volunteers in doses of 100-300 mg/day during 14 days evoked the stimulation of the phagocytic and bactericidal activity of the granulocytes. The dose of 600 mg/day causes only a transient and insignificant increase of phagocytic and bactericidal properties of the granulocytes. 相似文献
44.
45.
46.
V. Ocelík V. Z. Bengus E. B. Korolkova K. Csach J. Miškuf P. Duhaj 《Journal of Materials Science》1991,26(24):6699-6705
The fracture stress and the critical stress intensity factor of the Fe40Ni40B20 amorphous metallic ribbons 20 μm thick were measured in the temperature range 4.2–300 K and at deformation rates from 3.3×10−6 to 1.25×10−3 m−1 with the aim to obtain more information on the condition for the onset and development of the inhomogeneous plastic deformation
and fracture. 相似文献
47.
X-ray photoelectron spectroscopy (XPS) applied to the study of fluorinated polymer surfaces presents several problems related both to peak assignment and to degradation. In this work, we analyse extensively the question of XPS peak assignments in this kind of surfaces. We conclude that in this kind of surfaces using binding energy differences between fluorine and carbon is better than using absolute binding energies. Also a useful relation between fluorine photoelectron energy vs. polymer composition expressed through the atomic ratio fluorine/carbon (F/C) was found. A protocol for data treatment is proposed and applied to a XPS study of the degradation induced by X-ray on high-density polyethylene surfaces modified by direct fluorination. Results obtained for the degradation, namely the atomic ratio F/C obtained by two different methods, combined with angle resolved X-ray photoelectron spectroscopy (ARXPS) were used to study the fluorine concentration profile in depth, producing self-consistent results. 相似文献
48.
Victor Chabanenko Roman Puźniak Adam Nabiałek Sergei Vasiliev Vladimir Rusakov Loh Huanqian Ritta Szymczak Henryk Szymczak Jan Jun Janusz Karpiński Vitaly Finkel 《Journal of Low Temperature Physics》2003,130(3-4):175-191
We present a study of magneto-thermal instabilities in polycrystalline MgB2 superconductor, by magnetic hysteresis loop measurements and by investigations of magnetic flux dynamics with a miniature Hall probe. Temperature and magnetic field ranges where the flux jumps may be observed have been determined. On the basis of measurements of the magnetic flux dynamics, an average magnetic diffusivity describing the process of the flux jump is estimated. This parameter is compared with the thermal and magnetic diffusivities calculated on the basis of available data for thermal conductivity, heat capacity and resistivity. It is shown that the estimated value of the field of the first flux jump is influenced significantly by the field dependence of specific heat. In order to explain the observed phenomenon, the temperature reached by the sample during the flux jump at different magnetic fields is calculated. 相似文献
49.
Venezuela's vast natural resource base has largely shaped the nation's economic and energy-use patterns. Major opportunities exist for improving the efficiency of energy use in Venezuela and, consequently, restraining the growth of energy-related carbon emissions. This paper presents a detailed report of one potential development path for Venezuela and estimates the ensuing levels of energy demand and CO2 emissions associated with pursuing this path through the year 2025. The results indicate that by adopting a development strategy that incorporates structural changes in the economy, fuel-switching measures and improved end-use efficiencies, Venezuela can introduce energy efficiency and carbon restraints as part of its economic development process. 相似文献
50.