全文获取类型
收费全文 | 1874篇 |
免费 | 37篇 |
国内免费 | 3篇 |
专业分类
电工技术 | 4篇 |
化学工业 | 230篇 |
金属工艺 | 29篇 |
机械仪表 | 20篇 |
建筑科学 | 21篇 |
能源动力 | 11篇 |
轻工业 | 65篇 |
水利工程 | 4篇 |
石油天然气 | 12篇 |
无线电 | 90篇 |
一般工业技术 | 272篇 |
冶金工业 | 998篇 |
原子能技术 | 16篇 |
自动化技术 | 142篇 |
出版年
2022年 | 7篇 |
2021年 | 16篇 |
2020年 | 6篇 |
2019年 | 7篇 |
2018年 | 17篇 |
2017年 | 10篇 |
2016年 | 20篇 |
2015年 | 16篇 |
2014年 | 27篇 |
2013年 | 46篇 |
2012年 | 40篇 |
2011年 | 48篇 |
2010年 | 40篇 |
2009年 | 27篇 |
2008年 | 39篇 |
2007年 | 43篇 |
2006年 | 20篇 |
2005年 | 31篇 |
2004年 | 31篇 |
2003年 | 25篇 |
2002年 | 27篇 |
2001年 | 28篇 |
2000年 | 22篇 |
1999年 | 55篇 |
1998年 | 285篇 |
1997年 | 168篇 |
1996年 | 114篇 |
1995年 | 70篇 |
1994年 | 79篇 |
1993年 | 57篇 |
1992年 | 25篇 |
1991年 | 31篇 |
1990年 | 30篇 |
1989年 | 25篇 |
1988年 | 25篇 |
1987年 | 24篇 |
1986年 | 19篇 |
1985年 | 27篇 |
1984年 | 14篇 |
1983年 | 13篇 |
1982年 | 29篇 |
1981年 | 18篇 |
1980年 | 21篇 |
1979年 | 8篇 |
1978年 | 16篇 |
1977年 | 36篇 |
1976年 | 65篇 |
1975年 | 13篇 |
1972年 | 6篇 |
1970年 | 7篇 |
排序方式: 共有1914条查询结果,搜索用时 15 毫秒
71.
72.
Leonard J. Borucki Thomas Witelski Colin Please Peter R. Kramer Donald Schwendeman 《Journal of Engineering Mathematics》2004,50(1):1-24
Statistical models are presented to describe the evolution of the surface roughness of polishing pads during the pad-conditioning process in chemical-mechanical polishing. The models describe the evolution of the surface-height probability-density function of solid pads during fixed height or fixed cut-rate conditioning. An integral equation is derived for the effect of conditioning on a foamed pad in terms of a model for a solid pad. The models that combine wear and conditioning are then discussed for both solid and foamed pads. Models include the dependence of the surface roughness on the shape and density of the cutting tips used in the conditioner and on other operating parameters. Good agreement is found between the model, Monte Carlo simulations and with experimental data. 相似文献
73.
The road map of fusion power is compared to the development and deployment of other energy technologies. A generic deployment model is presented, which describes the fastest deployment (of any new technology) achievable with the constraint that the industrial capacity that needs to be built up must be continuous and should not overshoot the replacement market in the final, saturated state. It is shown that the development needs an ‘investment’ phase to build up industrial capacity which takes several decades, during which growth is typically exponential, but net energy production is negligible. During the exponential growth the cost is dominated by the capital investment, which allows for a simple comparison of different energy technologies. Fusion is at the start of the exponential growth phase, while still having significant uncertainties concerning its technical feasibility. In comparison to e.g. solar PV and wind, fusion is ‘late’, lagging by some 50 years. To follow the same rate of development that fission, wind and PV have shown, fusion will need to have 3 DEMO reactors operational in the early 2050s, followed by 10 generation one (GEN1) plants in the early 2060s and 100 GEN2 plants in the early 2070s. For the cost development to be comparable, an estimated allowable cost for one DEMO reactor is ~20 G$. While these indicative numbers for the pace and cost of development are very challenging but perhaps not unthinkable for fusion, this analysis does point towards an emphasis on ‘simpler and cheaper’ reactor designs. 相似文献
74.
75.
76.
P.R. Brito-Parada S.C. Kramer C.R. Wilson C.C. Pain S.J. Neethling J.J. Cilliers 《Chemical engineering science》2012,69(1):279-286
In this paper, a numerical model for the flow of foams in flotation cells in up to three dimensions is described. By using finite elements to solve Laplace's equation for a potential scalar, the flow pattern and velocity of the foam can be obtained. This has allowed, for the first time, the carrying out of numerical investigations of foam flow patterns regardless of the symmetry of the system. The numerical model has been implemented in Fluidity, a general purpose finite element method code that allows simulations to be carried out on anisotropic unstructured meshes. Such a model is of particular interest since other phenomena occurring in flotation depend on the foam velocity. Convergence tests that verify the numerical model are presented, and simulation results that showcase important features of the present implementation are discussed. 相似文献
77.
78.
79.
80.
Boars fed diets containing rapeseed oil for 8 weeks showed significantly higher levels of neutral lipids and similar levels
of phospholipids, compared to those fed corn oil. Erucic and eicosenoic acids were found to be high in ethanolamine phosphoglycerides,
and in particular alkenyl acyl-ethanolamine phosphoglyceride. Furthermore, both long chain monoenes were incorporated preferentially
in position 2 of the choline and ethanolamine phosphoglycerides. The alkenyl group composition of the cardiac lipids of pigs
was influenced by dietary fatty acids. When rapeseed oil was fed, small amounts of 20∶1 and 22∶1 alkenyl constituents were
detected.
Contribution No. 641 Animal Research Institute 相似文献