全文获取类型
收费全文 | 18114篇 |
免费 | 1695篇 |
国内免费 | 1269篇 |
专业分类
电工技术 | 640篇 |
综合类 | 1927篇 |
化学工业 | 2479篇 |
金属工艺 | 1145篇 |
机械仪表 | 1458篇 |
建筑科学 | 1506篇 |
矿业工程 | 1060篇 |
能源动力 | 1347篇 |
轻工业 | 565篇 |
水利工程 | 1420篇 |
石油天然气 | 2081篇 |
武器工业 | 796篇 |
无线电 | 906篇 |
一般工业技术 | 1997篇 |
冶金工业 | 549篇 |
原子能技术 | 339篇 |
自动化技术 | 863篇 |
出版年
2024年 | 39篇 |
2023年 | 205篇 |
2022年 | 510篇 |
2021年 | 511篇 |
2020年 | 477篇 |
2019年 | 460篇 |
2018年 | 446篇 |
2017年 | 586篇 |
2016年 | 730篇 |
2015年 | 697篇 |
2014年 | 938篇 |
2013年 | 1127篇 |
2012年 | 1094篇 |
2011年 | 1277篇 |
2010年 | 938篇 |
2009年 | 1038篇 |
2008年 | 934篇 |
2007年 | 1236篇 |
2006年 | 1126篇 |
2005年 | 971篇 |
2004年 | 875篇 |
2003年 | 736篇 |
2002年 | 691篇 |
2001年 | 565篇 |
2000年 | 444篇 |
1999年 | 400篇 |
1998年 | 354篇 |
1997年 | 263篇 |
1996年 | 267篇 |
1995年 | 257篇 |
1994年 | 219篇 |
1993年 | 153篇 |
1992年 | 127篇 |
1991年 | 99篇 |
1990年 | 63篇 |
1989年 | 69篇 |
1988年 | 43篇 |
1987年 | 36篇 |
1986年 | 16篇 |
1985年 | 12篇 |
1984年 | 12篇 |
1983年 | 2篇 |
1982年 | 5篇 |
1981年 | 3篇 |
1980年 | 3篇 |
1979年 | 5篇 |
1975年 | 2篇 |
1959年 | 4篇 |
1956年 | 1篇 |
1951年 | 9篇 |
排序方式: 共有10000条查询结果,搜索用时 62 毫秒
41.
An experimental and numerical study have been carried out to investigate the distribution of radial local heat transfer coefficients of impinging submerged circular jets. Good agreement is achieved between the experimental results and the predicted value. Results show that the outer peak usually occurs at the radial location of r/d= 1.8~2.0, in which transition from laminar to turbulence happens resulting from disappeared pressure gradient abruptly, and that the inner peak appears rigidly at r/d=0.5, where the boundary layer has a minimum thickness because of elevating pressure gradient. 相似文献
42.
43.
44.
45.
天然河流的横断面多为由主槽和漫滩组成的复式断面,水流在这种断面中比在单一断面中受到更多因素影响,流态也更加复杂。通过将明渠横断面上微元体在水流方向的N-S控制方程沿水深积分,得出描述垂线平均流速和边界剪切应力横向分布的模型,并通过对实验数据的验证,确定了模型的实用性。 相似文献
46.
Bedich ika Helena Bendov Ivan Macha
《Chemical Engineering and Processing: Process Intensification》2005,44(12):1312-1319
A procedure has been proposed for the estimation of the terminal falling velocity of non-spherical particles moving in a Carreau model fluid in the transition flow region. The procedure is based on a modification of the relationship formerly developed for the fall of spherical particles including the particle dynamic shape factor. The suitability of the proposed procedure has been confirmed by good agreement between experimental and calculated terminal falling velocity data. In the experiments, the terminal falling velocity of short cylinders and rectangular prisms in polymer solutions of different measure of shear thinning and elasticity has been measured. 相似文献
47.
48.
This paper presents the mass transfer results from an impinging liquid jet to a rotating disk. The mass transfer coefficients were measured using the electrochemical limiting diffusion current technique (ELDCT). Rotational Reynolds number (Rer) in the range of 3.4 × 104–1.2 × 105, jet Reynolds number (Rej) 1.7 × 104–5.3 × 104 and non-dimensional jet-to-disk spacing (H/d) 2–8 were taken into consideration as parameters. It was found that the jet impingement resulted in a substantial enhancement in the mass transfer compared to the case of the rotating disk without jet. 相似文献
49.
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
50.
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