全文获取类型
收费全文 | 60076篇 |
免费 | 7711篇 |
国内免费 | 4652篇 |
专业分类
电工技术 | 5578篇 |
技术理论 | 4篇 |
综合类 | 5766篇 |
化学工业 | 9369篇 |
金属工艺 | 2343篇 |
机械仪表 | 5222篇 |
建筑科学 | 4169篇 |
矿业工程 | 1819篇 |
能源动力 | 5245篇 |
轻工业 | 1214篇 |
水利工程 | 5377篇 |
石油天然气 | 4196篇 |
武器工业 | 665篇 |
无线电 | 3143篇 |
一般工业技术 | 4992篇 |
冶金工业 | 3237篇 |
原子能技术 | 1532篇 |
自动化技术 | 8568篇 |
出版年
2024年 | 324篇 |
2023年 | 976篇 |
2022年 | 1749篇 |
2021年 | 2100篇 |
2020年 | 2193篇 |
2019年 | 1828篇 |
2018年 | 1723篇 |
2017年 | 2185篇 |
2016年 | 2436篇 |
2015年 | 2542篇 |
2014年 | 3554篇 |
2013年 | 4029篇 |
2012年 | 4136篇 |
2011年 | 4764篇 |
2010年 | 3400篇 |
2009年 | 3660篇 |
2008年 | 3352篇 |
2007年 | 3930篇 |
2006年 | 3666篇 |
2005年 | 3265篇 |
2004年 | 2658篇 |
2003年 | 2386篇 |
2002年 | 1951篇 |
2001年 | 1587篇 |
2000年 | 1359篇 |
1999年 | 1141篇 |
1998年 | 945篇 |
1997年 | 773篇 |
1996年 | 720篇 |
1995年 | 638篇 |
1994年 | 542篇 |
1993年 | 433篇 |
1992年 | 347篇 |
1991年 | 229篇 |
1990年 | 228篇 |
1989年 | 175篇 |
1988年 | 125篇 |
1987年 | 90篇 |
1986年 | 67篇 |
1985年 | 33篇 |
1984年 | 46篇 |
1983年 | 36篇 |
1982年 | 18篇 |
1981年 | 12篇 |
1980年 | 7篇 |
1979年 | 16篇 |
1978年 | 5篇 |
1975年 | 4篇 |
1959年 | 23篇 |
1951年 | 24篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
Giulio Croce Paola Dagaro Carlo Nonino 《International Journal of Heat and Mass Transfer》2007,50(25-26):5249-5259
102.
Arash Sarhangi Fard Navid M. Famili Patrick D. Anderson 《Computers & Chemical Engineering》2008,32(7):1471-1481
The main objective of the present work is to modify the traditional mapping method for the simulation of distributive mixing of multiphase flows in geometries involving moving parts such as, internal mixers or twin-screw extruders without a limitation on their geometrical periodicity. The periodicity condition, limits the results of traditional mapping method to tracking mapping mesh between specific discrete time intervals or distances for that geometry is repeated, hence, result is only for fixed orientation of rotors. Imaginary domain method is introduced to track mapping mesh from one state to the next free of geometrical periodicity limitations. In this work the method is introduced and its applicability and accuracy is discussed in details. A two-dimensional (2D) simulation of mixing of two Newtonian fluids with different viscosities in an intermeshing internal mixer is used as a test case study. In this example the key issues of ability to predict mixing state in details for all orientations of rotors is presented. To reduce diffusion errors of mapping method in the boundaries of the rotors, mapping mesh refinement technique that relies upon one single reference mesh is also presented. 相似文献
103.
Jaber Almedeij 《Powder Technology》2008,186(3):218-223
An empirical relationship of drag coefficient of flow around a sphere is developed for the entire range of Particle Reynolds numbers reported in the literature from Stokes regime to the condition when turbulent boundary layer prevails. The relationship is obtained using an approach to match asymptotically the wide trend of drag coefficient. The matching approach, which relies on dividing the wide trend into smaller segments that can be combined into an overall relationship, employs regression techniques and thus warrants the best-fit accuracy results. The relationship is calibrated with experimental data available in the literature covering the entire range for Reynolds numbers up to ~ 106. For Reynolds values greater than 106, the relationship renders a drag coefficient of 0.2. The performance of the relationship is tested and compared with other suitable models found in the literature. This relationship is also transformed into an explicit expression for settling velocity calculations. 相似文献
104.
J. L. Barron R. E. Mercer X. Chen P. Joe 《International journal of imaging systems and technology》2005,15(3):189-198
We present local least squares and regularization frameworks for computing 3D velocity (3D optical flow) from 3D radial velocity measured by a Doppler radar. We demonstrate the performance of our algorithms quantitatively on synthetic radial velocity data and qualitatively on real radial velocity data, obtained from the Doppler radar at Kurnell Radar station, Botany Bay, New South Wales, Australia. Radial velocity can be used to predict the future positions of storms in sequences of Doppler radar datasets.© 2005 Wiley Periodicals, Inc. Int J Imaging Syst Technol, 15, 189–198, 2005 相似文献
105.
106.
建立了水驱强度影响下的水驱油渗流数学模型,在获得数学模型解的基础上,计算了考虑井筒储存、表皮效应以及水驱强度影响下油井的压力及压力导数典型曲线,分析了压力动态特征,通过这些研究为水驱油藏的试井分析提供了理论基础,为水驱油藏的识别提供了一种新的手段。 相似文献
107.
108.
109.
In the present study a continuum model for one-dimensional plane Couette-Poiseuille flow is implemented to turbomolecular pumps in different flow regimes. Pumping performance of various turbomolecular pumps including 6 single rotors, a rotor-stator row, a rotor-stator-rotor row, and a multi-row with 13 alternative rotor-stator rows is considered here. The obtained results show that the model provides good quantitative values for pumping performance of turbomolecular pumps over the whole regimes ranging from molecular flow to transition to slip flow. 相似文献
110.