全文获取类型
收费全文 | 248986篇 |
免费 | 1665篇 |
国内免费 | 265篇 |
专业分类
电工技术 | 4039篇 |
综合类 | 91篇 |
化学工业 | 40326篇 |
金属工艺 | 15143篇 |
机械仪表 | 10061篇 |
建筑科学 | 4175篇 |
矿业工程 | 3760篇 |
能源动力 | 3872篇 |
轻工业 | 9696篇 |
水利工程 | 4094篇 |
石油天然气 | 13006篇 |
武器工业 | 28篇 |
无线电 | 20188篇 |
一般工业技术 | 62748篇 |
冶金工业 | 32135篇 |
原子能技术 | 11134篇 |
自动化技术 | 16420篇 |
出版年
2021年 | 2756篇 |
2019年 | 2730篇 |
2018年 | 5428篇 |
2017年 | 5710篇 |
2016年 | 6045篇 |
2015年 | 3051篇 |
2014年 | 5322篇 |
2013年 | 10079篇 |
2012年 | 7304篇 |
2011年 | 8927篇 |
2010年 | 7295篇 |
2009年 | 8104篇 |
2008年 | 8172篇 |
2007年 | 7855篇 |
2006年 | 6357篇 |
2005年 | 5561篇 |
2004年 | 5479篇 |
2003年 | 5299篇 |
2002年 | 5132篇 |
2001年 | 4947篇 |
2000年 | 4937篇 |
1999年 | 4253篇 |
1998年 | 7174篇 |
1997年 | 5833篇 |
1996年 | 4421篇 |
1995年 | 3654篇 |
1994年 | 3422篇 |
1993年 | 3623篇 |
1992年 | 3214篇 |
1991年 | 3359篇 |
1990年 | 3481篇 |
1989年 | 3369篇 |
1988年 | 3267篇 |
1987年 | 3260篇 |
1986年 | 3156篇 |
1985年 | 3315篇 |
1984年 | 3252篇 |
1983年 | 3146篇 |
1982年 | 2993篇 |
1981年 | 3046篇 |
1980年 | 3071篇 |
1979年 | 3258篇 |
1978年 | 3490篇 |
1977年 | 3460篇 |
1976年 | 3911篇 |
1975年 | 3209篇 |
1974年 | 3293篇 |
1973年 | 3343篇 |
1972年 | 2989篇 |
1971年 | 2754篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
961.
É. I. Golovko G. N. Makarenko R. F. Voitovich V. B. Fedorus 《Powder Metallurgy and Metal Ceramics》1994,32(11-12):917-920
Boron silicide and compounds based on it containing titanium, chromium, nickel, and yttrium and scandium oxides are studied for their oxidation in air from room temperature to 1300°C. It is shown that chromium boride markedly improves the heat resistance of B4Si over a wide temperature range (700–1300°C) probably as a result chromium-oxide dissolution in borosilicate glass and alteration of its structure. A favorable effect of yttrium and scandium oxides as well of nickel silicide appears at above 100°C as a result of forming complex oxide compounds in the scale. 相似文献
962.
963.
964.
G Gaffney MV Squier A Johnson V Flavell S Sellers 《Canadian Metallurgical Quarterly》1994,70(2):F101-F106
Neuropathological examinations were carried out at necropsy on 274 cases of intrauterine death or neonatal death at or before three days after birth. Fifty six (20.4%) subjects had evidence of prenatal ischaemic brain damage. On review of the maternal case notes to ascertain antenatal clinical associations there was an increased incidence of intrauterine growth retardation, either based on birth weight for gestational age (odds ratio (OR) 2.0; 95% confidence interval (CI) 1.1 to 3.7) or diagnosed antenatally (OR 2.7; 95% CI 1.3 to 5.6). Oligohydramnios was also more common (OR 2.9; 95% CI 1.2 to 7.0). The association of intrauterine growth retardation and white matter damage remained after excluding fetuses with a major congenital anomaly (OR 2.4; 95% CI 1.1 to 5.1). The findings suggest that chronic intrauterine hypoxia may be associated with damage to cerebral white matter among fetuses and infants who die. The relation between ischaemic white matter damage and cerebral palsy among survivors remains speculative. 相似文献
965.
966.
967.
R. P. Voitovich Yu. V. Naidich G. A. Kolesnichenko 《Powder Metallurgy and Metal Ceramics》1992,31(6):494-497
Translated from Poroshkovaya Metallurgiya, No. 6(354), pp. 40–44, June, 1992. 相似文献
968.
E. A. Ivanova D. F. Kasatkin L. A. Akishina E. V. Nepomnyashchaya 《Chemistry and Technology of Fuels and Oils》1992,28(5):241-243
Translated from Khimiya i Tekhnologiya Topliv i Masel, No. 5, pp. 2–3, May, 1992. 相似文献
969.
The main principles of a measurement procedure are given and its implementation with the aid of an IR-imager AGA-780 is shown.State Institute of Applied Optics, Kazan. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 63, No. 1, pp. 109–113. July, 1992. 相似文献
970.
On the Theory of Electrical Phenomena in Combustion of Heterogeneous Systems with Condensed Products
V. K. Smolyakov A. I. Kirdyashkin Yu. M. Maksimov 《Combustion, Explosion, and Shock Waves》2002,38(6):675-680
The effect of the electromotive force arising in combustion of heterogeneous systems with condensed products is explained. A convective mechanism of arising regions with different charge densities due to charge transfer by the gas filtered in the pores is formulated on the basis of the developed physical concepts, estimates, and analysis of experimental data. Key words: combustion, electron emission, filtration, electromotive force. 相似文献