全文获取类型
收费全文 | 438163篇 |
免费 | 6089篇 |
国内免费 | 1728篇 |
专业分类
电工技术 | 8020篇 |
综合类 | 394篇 |
化学工业 | 66179篇 |
金属工艺 | 20516篇 |
机械仪表 | 13669篇 |
建筑科学 | 10165篇 |
矿业工程 | 2632篇 |
能源动力 | 10794篇 |
轻工业 | 36853篇 |
水利工程 | 4669篇 |
石油天然气 | 8980篇 |
武器工业 | 25篇 |
无线电 | 50107篇 |
一般工业技术 | 87766篇 |
冶金工业 | 80852篇 |
原子能技术 | 10144篇 |
自动化技术 | 34215篇 |
出版年
2021年 | 3907篇 |
2019年 | 3628篇 |
2018年 | 6261篇 |
2017年 | 6166篇 |
2016年 | 6665篇 |
2015年 | 4278篇 |
2014年 | 7109篇 |
2013年 | 19460篇 |
2012年 | 11292篇 |
2011年 | 15143篇 |
2010年 | 12188篇 |
2009年 | 13427篇 |
2008年 | 14013篇 |
2007年 | 13944篇 |
2006年 | 12382篇 |
2005年 | 11341篇 |
2004年 | 10610篇 |
2003年 | 10560篇 |
2002年 | 10328篇 |
2001年 | 10469篇 |
2000年 | 9653篇 |
1999年 | 10152篇 |
1998年 | 25207篇 |
1997年 | 17775篇 |
1996年 | 13837篇 |
1995年 | 10355篇 |
1994年 | 9064篇 |
1993年 | 9168篇 |
1992年 | 6768篇 |
1991年 | 6728篇 |
1990年 | 6262篇 |
1989年 | 6123篇 |
1988年 | 6113篇 |
1987年 | 5258篇 |
1986年 | 5207篇 |
1985年 | 5994篇 |
1984年 | 5483篇 |
1983年 | 5067篇 |
1982年 | 4637篇 |
1981年 | 4636篇 |
1980年 | 4551篇 |
1979年 | 4426篇 |
1978年 | 4428篇 |
1977年 | 5110篇 |
1976年 | 6840篇 |
1975年 | 3939篇 |
1974年 | 3719篇 |
1973年 | 3817篇 |
1972年 | 3310篇 |
1971年 | 2969篇 |
排序方式: 共有10000条查询结果,搜索用时 72 毫秒
61.
Dorofeyev V. Yu. Sviridova A. N. Svistun L. I. 《Russian Journal of Non-Ferrous Metals》2020,61(3):354-361
Russian Journal of Non-Ferrous Metals - Rolling bearing rings comprise a large reserve for expanding powder metallurgy production. This reserve is being incompletely implemented. The hot forging of... 相似文献
62.
63.
64.
65.
66.
67.
C. Doga Demirhan William W. Tso Joseph B. Powell Efstratios N. Pistikopoulos 《American Institute of Chemical Engineers》2019,65(7):e16498
Current ammonia production technologies have a significant carbon footprint. In this study, we present a process synthesis and global optimization framework to discover the efficient utilization of renewable resources in ammonia production. Competing technologies are incorporated in a process superstructure where biomass, wind, and solar routes are compared with the natural gas-based reference case. A deterministic global optimization-based branch-and-bound algorithm is used to solve the resulting large-scale nonconvex mixed-integer nonlinear programming problem (MINLP). Case studies for Texas, California, and Iowa are conducted to examine the effects of different feedstock prices and availabilities. Results indicate that profitability of ammonia production is highly sensitive to feedstock and electricity prices, as well as greenhouse gas (GHG) restrictions. Under strict 75% GHG reductions, biomass to ammonia route is found to be competitive with natural gas route, whereas wind and solar to ammonia routes require further improvement to compete with those two routes. © 2018 American Institute of Chemical Engineers AIChE J, 65: e16498 2019 相似文献
68.
69.
In this paper, a new inverse identification method of constitutive parameters is developed from full kinematic and thermal field measurements. It consists in reconstructing the heat source field from two different approaches by using the heat diffusion equation. The first one requires the temperature field measurement and the value of the thermophysical parameters. The second one is based on the kinematic field measurement and the choice of a thermo-hyperelastic model that contains the parameters to be identified. The identification is carried out at the local scale, ie, at any point of the heat source field, without using the boundary conditions. In the present work, the method is applied to the challenging case of hyperelasticity from a heterogeneous test. Due to large deformations undergone by the rubber specimen tested, a motion compensation technique is developed to plot the kinematic and the thermal fields at the same points before reconstructing the heterogeneous heat source field. In the present case, the constitutive parameter of the Neo-Hookean model has been identified, and its distribution has been characterized with respect to the strain state at the surface of a cross-shaped specimen. 相似文献