全文获取类型
收费全文 | 144552篇 |
免费 | 1051篇 |
国内免费 | 430篇 |
专业分类
电工技术 | 2375篇 |
综合类 | 2334篇 |
化学工业 | 18391篇 |
金属工艺 | 10400篇 |
机械仪表 | 8728篇 |
建筑科学 | 3130篇 |
矿业工程 | 1288篇 |
能源动力 | 1696篇 |
轻工业 | 4008篇 |
水利工程 | 2008篇 |
石油天然气 | 1840篇 |
无线电 | 14805篇 |
一般工业技术 | 32909篇 |
冶金工业 | 8314篇 |
原子能技术 | 1315篇 |
自动化技术 | 32492篇 |
出版年
2023年 | 30篇 |
2022年 | 30篇 |
2021年 | 55篇 |
2020年 | 50篇 |
2019年 | 62篇 |
2018年 | 20680篇 |
2017年 | 20372篇 |
2016年 | 13071篇 |
2015年 | 1130篇 |
2014年 | 372篇 |
2013年 | 369篇 |
2012年 | 5207篇 |
2011年 | 16101篇 |
2010年 | 14764篇 |
2009年 | 11561篇 |
2008年 | 12069篇 |
2007年 | 14853篇 |
2006年 | 234篇 |
2005年 | 4814篇 |
2004年 | 2956篇 |
2003年 | 2652篇 |
2002年 | 1135篇 |
2001年 | 178篇 |
2000年 | 306篇 |
1999年 | 101篇 |
1998年 | 188篇 |
1997年 | 120篇 |
1996年 | 124篇 |
1995年 | 56篇 |
1994年 | 67篇 |
1993年 | 62篇 |
1992年 | 37篇 |
1991年 | 58篇 |
1976年 | 31篇 |
1969年 | 65篇 |
1968年 | 143篇 |
1967年 | 127篇 |
1966年 | 164篇 |
1965年 | 139篇 |
1964年 | 88篇 |
1963年 | 74篇 |
1962年 | 72篇 |
1961年 | 78篇 |
1960年 | 97篇 |
1959年 | 72篇 |
1958年 | 88篇 |
1957年 | 145篇 |
1956年 | 126篇 |
1955年 | 153篇 |
1954年 | 165篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
91.
I. A. Zvereva O. I. Silyukov A. V. Markelov A. B. Missyul’ M. V. Chislov I. A. Rodionov D. -Sh. Li 《Glass Physics and Chemistry》2008,34(6):749-755
The processes of phase formation in the Na2CO3-TiO2 and Na2CO3-TiO2-Nd2O3 systems are investigated in the temperature range 600–900°C. The high-temperature solid-phase reactions underlying the process of formation of complex oxide NaNdTiO4 are studied. It is established that the synthesis of the NaNdTiO4 compound occurs through the reaction of the intermediate product Na8Ti5O14 with neodymium oxide in the temperature range 720–780°C. The optimum method is proposed for synthesizing NaNdTiO4, which makes it possible to reduce the temperature of the synthesis, to avoid the formation of impurities, and to obtain the product in a finely dispersed state. 相似文献
92.
N. A. Kochetov B. S. Seplyarskii S. G. Vadchenko 《International Journal of Self-Propagating High-Temperature Synthesis》2008,17(3):206-209
Combustion of bulk density Ti powder (containing 20 wt % TiN as a diluent) in a coflow of N2-Ar mixture was investigated upon variation in the nitrogen content of the gaseous mixture. The obtained data are believed
to open up new horizons for fabrication of layered and composite ceramics by infiltration-mediated combustion.
相似文献
93.
94.
95.
Yu. A. Zolotukhin 《Coke and Chemistry》2008,51(8):291-296
The codification of coal in State Standard 25543-88 is compared with the international codification of coal of medium and high rank. The ranking of coking coal on the basis of State Standard GOST 25543-88 is evaluated. 相似文献
96.
97.
98.
Various heat insulation materials produced at home and abroad are compared. The advantage of using natural nano-structured
materials is substantiated.
Translated from Novye Ogneupory, No. 7, pp. 41–44, July 2008. 相似文献
99.
100.
The X-ray scattering intensity curves for vitreous As2S3 are experimentally measured using soft (copper) and hard (molybdenum) X rays. The inclusion of all the specific features revealed in the experimental scattering intensity curves makes it possible to obtain the experimental atomic radial distribution function (ARDF) in the ordering range up to ~1 nm. The experimental ARDF is interpreted in the framework of the fragmentary model. A comparison of the experimental ARDF with the model ARDF calculated from the crystal structure data obtained for orpiment demonstrates that the corrugated layers inherent in crystalline As2S3 are retained in the glass structure but the characteristic interlayer interatomic distances are absent. The layers are joined together through the As4S5 molecular clusters. Microcrystals consisting of several unit cells are absent in the glass structure, which involves only the structural fragments of both crystalline analogs. One of the possible variants of their joining is proposed. 相似文献