全文获取类型
收费全文 | 467372篇 |
免费 | 6319篇 |
国内免费 | 2060篇 |
专业分类
电工技术 | 8847篇 |
技术理论 | 5篇 |
综合类 | 1242篇 |
化学工业 | 74786篇 |
金属工艺 | 23473篇 |
机械仪表 | 16340篇 |
建筑科学 | 10170篇 |
矿业工程 | 4898篇 |
能源动力 | 9031篇 |
轻工业 | 33444篇 |
水利工程 | 6348篇 |
石油天然气 | 16177篇 |
武器工业 | 269篇 |
无线电 | 44793篇 |
一般工业技术 | 102017篇 |
冶金工业 | 73646篇 |
原子能技术 | 14619篇 |
自动化技术 | 35646篇 |
出版年
2021年 | 4834篇 |
2019年 | 4436篇 |
2018年 | 7955篇 |
2017年 | 8211篇 |
2016年 | 8722篇 |
2015年 | 5434篇 |
2014年 | 9032篇 |
2013年 | 20009篇 |
2012年 | 13836篇 |
2011年 | 17675篇 |
2010年 | 14236篇 |
2009年 | 15495篇 |
2008年 | 16357篇 |
2007年 | 16140篇 |
2006年 | 13733篇 |
2005年 | 12028篇 |
2004年 | 11236篇 |
2003年 | 10646篇 |
2002年 | 10605篇 |
2001年 | 10454篇 |
2000年 | 10008篇 |
1999年 | 9450篇 |
1998年 | 18969篇 |
1997年 | 14435篇 |
1996年 | 11000篇 |
1995年 | 8592篇 |
1994年 | 7992篇 |
1993年 | 8020篇 |
1992年 | 6585篇 |
1991年 | 6451篇 |
1990年 | 6586篇 |
1989年 | 6464篇 |
1988年 | 6140篇 |
1987年 | 5651篇 |
1986年 | 5560篇 |
1985年 | 6092篇 |
1984年 | 5933篇 |
1983年 | 5622篇 |
1982年 | 5143篇 |
1981年 | 5318篇 |
1980年 | 5109篇 |
1979年 | 5436篇 |
1978年 | 5552篇 |
1977年 | 5674篇 |
1976年 | 6883篇 |
1975年 | 5056篇 |
1974年 | 4972篇 |
1973年 | 5001篇 |
1972年 | 4400篇 |
1971年 | 4023篇 |
排序方式: 共有10000条查询结果,搜索用时 10 毫秒
991.
Biodiesel has become an attractive diesel fuel substitute due to its environmental benefits since it can be made from renewable resource. However, the high costs surrounding biodiesel production remains the main problem in making it competitive in the fuel market either as a blend or as a neat fuel. More than 80% of the production cost is associated with the feedstock itself and consequently, efforts are focused on developing technologies capable of using lower-cost feedstocks, such as recycled cooking oils and wastes from animal or vegetable oil processing operations. 相似文献
992.
A. V. Popov 《Glass and Ceramics》2008,65(3-4):77-78
It was shown that use of AS32–AS50 diamond powders (instead of AS6–AS15 powders) combined with a new metal bond with hardness of HB 75–85 (in comparison to M2-01 binder) allows prolonging the lifetime of wheels by 1.5–2 times in grinding articles made of commercial and art glass, reducing the specific diamond consumption, and increasing the cutability of the instrument. 相似文献
993.
P. S. Gordienko V. A. Kolzunov L. G. Zorina T. A. Kaidalova S. B. Yarusova 《Theoretical Foundations of Chemical Engineering》2008,42(5):680-683
The possibility of processing fluorine-containing wastes of fluorite ore, which include fluorite, calcite, quartz, and anorthite, has been investigated. A manufacturing flow chart of the complex processing of the ore waste materials with the production of sodium fluoride, alumina, soda ash, and raw materials suitable for the production of Portland cement and wollastonite is suggested. 相似文献
994.
V. N. Babak T. B. Babak L. P. Kholpanov 《Theoretical Foundations of Chemical Engineering》2008,42(6):852-867
Mass transfer with solvent evaporation in the vapor-liquid two-phase film evaporators used for the removal of undesirable
impurities from liquid solutions at low pressure is studied. The average concentrations of solution components in the falling
liquid film are determined. The most efficient operating conditions for impurity removal, in which the resistance to mass
transfer is concentrated in the liquid phase, are found.
Original Russian Text ? V.N. Babak, T.B. Babak, L.P. Kholpanov, 2008, published in Teoreticheskie Osnovy Khimicheskoi Tekhnologii,
2008, Vol. 42, No. 6, pp. 654–670. 相似文献
995.
V. M. Vorotyntsev G. M. Mochalov M. A. Kolotilova S. S. Suvorov A. V. Koroleva A. Yu. Sharov 《Theoretical Foundations of Chemical Engineering》2008,42(2):197-202
The results of theoretical and experimental studies for the kinetics of separating dichlorosilane from a mixture of volatile chlorosilanes and ultrapurifying the dichlorosilane concentrate by batch distillation are reported. A mathematical model of the process is proposed. It is shown that the model and computational algorithm adequately describe both processes. The obtained experimental and theoretical data made it possible to design a concentration and ultrapurification process with a maximal productivity at a specified product purity. 相似文献
996.
The kinetics of the reaction of olefin synthesis from dimethyl ether and methanol is studied. A kinetic model of the nine-route reaction under study is constructed. The constants of the model are estimated using experimental data. The adequacy of the model to the results of experiments is shown 相似文献
997.
Y.M. Wong W.P. Kang J.L. Davidson J.H. Huang D.V. Kerns 《Diamond and Related Materials》2008,17(4-5):552-555
A novel integrated vacuum field emission (VFE) differential amplifier (diff-amp) utilizing carbon nanotube (CNT) emitters has been developed. A dual-mask microfabrication process was employed to achieve a VFE diff-amp by integrating identical CNT VFE transistors with built-in split gates and integrated anodes. The identical pair of triode amplifiers was well-matched in their device characteristics. The measured ac small-signal characteristics of the diff-amp showed a common-mode-rejection ratio (CMRR) of ~ 320 (~ 50 dB). The proposed analytical model of the CMRR was verified to be in good agreement with the experimental data. The successful implementation of the CNT diff-amp demonstrates a new way to achieve temperature and radiation tolerant VFE integrated microelectronics. 相似文献
998.
M. L. Malinkovich 《Glass and Ceramics》2008,65(3-4):136-138
The capabilities of x-ray spectral instruments for fast analysis of raw materials and glass and ceramics were demonstrated. The range of the content of determinable elements in a sample ranges from 1 ppm to 100%. The measurement time is 10–15 sec. 相似文献
999.
The results of the oxidation of carbon nanofibers and materials obtained on their basis are presented; these results demonstrate that the nanofibers were formed by carbon with different degrees of crystal structure ordering. The experimental data supported previous hypotheses that amorphous carbon results from the decomposition of metal carbides. The subsequent formation of spatial structures and the appearance of crystalline carbon species resulted from catalytic graphitization. It was demonstrated that sorbents can be prepared based on carbon nanofibers after pyrolytic consolidation followed by activation, and these sorbents are more effective than well-known sorbents. 相似文献
1000.
Yu. V. Pokonova 《Solid Fuel Chemistry》2008,42(6):369-372
Impregnants prepared from shale phenols for cellular materials had a cohesive strength of 2.4–18.5 J/m2 and a specific elongation of 160–170%. The adhesive strength toward a metal was 3.5–6.0 J/m2; in the case of concrete, it was greater than the concrete strength. 相似文献