全文获取类型
收费全文 | 12909篇 |
免费 | 455篇 |
国内免费 | 55篇 |
专业分类
电工技术 | 263篇 |
综合类 | 16篇 |
化学工业 | 2292篇 |
金属工艺 | 369篇 |
机械仪表 | 363篇 |
建筑科学 | 222篇 |
矿业工程 | 73篇 |
能源动力 | 712篇 |
轻工业 | 1179篇 |
水利工程 | 191篇 |
石油天然气 | 85篇 |
无线电 | 1649篇 |
一般工业技术 | 2802篇 |
冶金工业 | 1553篇 |
原子能技术 | 216篇 |
自动化技术 | 1434篇 |
出版年
2024年 | 32篇 |
2023年 | 176篇 |
2022年 | 485篇 |
2021年 | 512篇 |
2020年 | 420篇 |
2019年 | 416篇 |
2018年 | 559篇 |
2017年 | 524篇 |
2016年 | 487篇 |
2015年 | 288篇 |
2014年 | 453篇 |
2013年 | 909篇 |
2012年 | 523篇 |
2011年 | 684篇 |
2010年 | 550篇 |
2009年 | 541篇 |
2008年 | 479篇 |
2007年 | 396篇 |
2006年 | 335篇 |
2005年 | 266篇 |
2004年 | 248篇 |
2003年 | 220篇 |
2002年 | 182篇 |
2001年 | 143篇 |
2000年 | 149篇 |
1999年 | 158篇 |
1998年 | 357篇 |
1997年 | 234篇 |
1996年 | 257篇 |
1995年 | 219篇 |
1994年 | 183篇 |
1993年 | 171篇 |
1992年 | 145篇 |
1991年 | 155篇 |
1990年 | 114篇 |
1989年 | 108篇 |
1988年 | 130篇 |
1987年 | 110篇 |
1986年 | 89篇 |
1985年 | 116篇 |
1984年 | 97篇 |
1983年 | 107篇 |
1982年 | 101篇 |
1981年 | 91篇 |
1980年 | 80篇 |
1979年 | 54篇 |
1978年 | 47篇 |
1977年 | 58篇 |
1976年 | 79篇 |
1975年 | 34篇 |
排序方式: 共有10000条查询结果,搜索用时 296 毫秒
61.
62.
63.
H.U. Khan K.M. Agrawal M. Anwar S.P. Nautiyal B.S. Rawat 《Petroleum Science and Technology》1998,16(1):145-166
Lubricating oil base stocks differ greatly in their chemical composition and consequently in their physical properties and applications. Influence of waxes and various hydrocarbon type constituents viz saturates and aromatic components on the viscosity and shear stress as a function of temperature in different lube oil base stocks has been studied in the present paper. 相似文献
64.
65.
Packaging engineers need to be able to accurately determine the forces present in the shipping environment in order to protect packaged goods. The purpose of this study was to determine the vertical vibration levels measured in three separate truck-trailer suspension systems; conventional leaf-spring, conventional air-ride and damaged air-ride. The main conclusion reached in this study is that the air-ride suspension when maintained gives lower power density (PD) levels on all road surfaces studied. A damaged air-ride suspension and leaf-spring suspension are very similar in response frequencies, although the damaged air-ride produces higher vibration levels at lower frequencies. 相似文献
66.
67.
Summary The thermal post buckling behavior of simply-supported, antisymmetric cross-ply plates with immovable edges is investigated in this paper. For this purpose, a one term approximation for the inplane and transverse displacements is assumed and Rayleigh-Ritz method is used to obtain the equations of equilibrium. The question, whether the true thermal buckling (bifurcation buckling under thermal loads) exists for such plates is also addressed to. The conditions under which the thermal buckling in the classical sense occurs are derived. It is shown that nonlinear bending stiffness for such plates is direction dependent, because of an extra quadratic nonlinear term in addition to the usual cubic nonlinear term in the governing equilibrium equation. Results are presented for various plate configurations. 相似文献
68.
In the conventional plane-frame model of framed-tube buildings, only the primary interaction between the web frame and the flange frame is considered, through vertical shear transfer at corner columns. In addition to this, a secondary interaction takes place due to horizontal shear transfer at each floor level, through the floor slab having high in-plane rigidity. This interaction causes a discrepancy in member forces of a few bottom and top storeys. A simple modification is suggested in the form of an additional cantilever column connected to the conventional plane-frame model by axial force transfer members at every floor level. The improved model yields member forces in all the storeys that are very close to those obtained using 3D analysis. 相似文献
69.
70.
Russell B. Pillers Banmali S. Rawat 《Journal of Infrared, Millimeter and Terahertz Waves》1996,17(11):1809-1820
The nonlinearity of a frequency-ramped single-mode laser source to be used in optical heterodyne interferometry has been investigated. The analysis is based on mode-hopping due to variation in injection current, temperature and mismatch reflections. 相似文献