全文获取类型
收费全文 | 230065篇 |
免费 | 17560篇 |
国内免费 | 9205篇 |
专业分类
电工技术 | 12625篇 |
技术理论 | 24篇 |
综合类 | 14232篇 |
化学工业 | 38923篇 |
金属工艺 | 13201篇 |
机械仪表 | 14591篇 |
建筑科学 | 17654篇 |
矿业工程 | 7536篇 |
能源动力 | 6504篇 |
轻工业 | 13498篇 |
水利工程 | 3618篇 |
石油天然气 | 16726篇 |
武器工业 | 1675篇 |
无线电 | 25220篇 |
一般工业技术 | 27425篇 |
冶金工业 | 12865篇 |
原子能技术 | 2283篇 |
自动化技术 | 28230篇 |
出版年
2024年 | 1008篇 |
2023年 | 3828篇 |
2022年 | 6556篇 |
2021年 | 9199篇 |
2020年 | 7147篇 |
2019年 | 6050篇 |
2018年 | 6765篇 |
2017年 | 7586篇 |
2016年 | 6784篇 |
2015年 | 8936篇 |
2014年 | 11316篇 |
2013年 | 13340篇 |
2012年 | 14275篇 |
2011年 | 15527篇 |
2010年 | 13504篇 |
2009年 | 12742篇 |
2008年 | 12407篇 |
2007年 | 11908篇 |
2006年 | 12394篇 |
2005年 | 10790篇 |
2004年 | 7274篇 |
2003年 | 6246篇 |
2002年 | 5484篇 |
2001年 | 4900篇 |
2000年 | 5454篇 |
1999年 | 6454篇 |
1998年 | 5447篇 |
1997年 | 4459篇 |
1996年 | 4203篇 |
1995年 | 3511篇 |
1994年 | 2819篇 |
1993年 | 1975篇 |
1992年 | 1546篇 |
1991年 | 1229篇 |
1990年 | 936篇 |
1989年 | 744篇 |
1988年 | 537篇 |
1987年 | 339篇 |
1986年 | 278篇 |
1985年 | 198篇 |
1984年 | 139篇 |
1983年 | 114篇 |
1982年 | 124篇 |
1981年 | 98篇 |
1980年 | 70篇 |
1979年 | 37篇 |
1978年 | 26篇 |
1977年 | 20篇 |
1976年 | 35篇 |
1973年 | 13篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
A novel soft decision-based median subtraction filter is presented for clutter suppression and infrared (IR) point targets enhancement. The decision is made based on a jump Markov model and its state and parameter estimation using a particle filter. The scheme is compared with other conventional clutter background removal techniques and good results are obtained. 相似文献
62.
63.
锆(Ⅳ)-3,5-diBr-PADAP-安替比林三元配合物的分光光度研究与应用 总被引:1,自引:0,他引:1
本文提出在安替比林存在下,以3,5-diBr-PADAP为显色剂,分光光度测定微量锆的新方法。在pH1~2的HCl介质中,锆(W)与试剂和安替比林形成配合比为1:1:1的红色三元配合物,最大吸收值在615nm波长处,摩尔吸光系数ε=1.35×10~5。锆(Ⅳ)量在0~25μg/25ml范围内,遵守比尔定律。方法简单、快速、准确。若采用钽试剂—苯萃取法分离共存离子,可适用于钽铌矿和合金中痕量锆的测定。 相似文献
64.
本文阐述对贵冶动力车间二期反渗透进行改造的成功实践 ,主要从反渗透系统设计、反渗透系统中容易出现的问题及解决方法等进行介绍。 相似文献
66.
A two‐phase flow CFD model using the volume of fluid (VOF) method is presented for predicting the hydrodynamics of falling film flow on inclined plates, corresponding to the surface texture of structured packing. Using the proposed CFD model the influence of the solid surface microstructure, liquid properties and gas flow rate on the flow behavior was investigated. From the simulated results it was shown that under the condition of no gas flow the liquid flow patterns are dependent on the microstructure of the plates, and proper microstructuring of the solid surface will improve the formation of a continuous liquid film. It was also found that liquid properties, especially surface tension, play an important role in determining the thin‐film pattern. However, there are very different liquid film patterns under the action of gas flow. Thinner liquid films break easily, but thicker liquid films can remain continuous even at higher gas flow rates, which demonstrates that all factors affecting the liquid film thickness will affect the liquid film patterns under conditions of counter‐current two‐phase flow. 相似文献
67.
Sutomo W. Xuefeng Wang Bullen D. Braden S.K. Chang Liu 《Journal of microelectromechanical systems》2003,12(1):64-69
Parylene is an emerging material for MEMS. It is an organic material that is grown by using the chemical vapor deposition method at room temperature. The deposition thickness is commonly controlled by the amount of solid-phase dimer loaded in a sublimation chamber. In a conventional deposition machine, the end point of the process is designated by the moment the dimer is exhausted. However, this end-of-process criterion does not offer precise, repeatable control of film thickness. We present the results of the development of an in situ end-point detector for a Parylene chemical vapor deposition process. The detector is based on the thermal transfer principle and can be implemented on commercial parylene deposition systems with minimal system modification. Such a sensor enables a user to stop the deposition when a targeted thickness is reached. The end point detector is very simple to implement on existing parylene deposition systems. A series of such sensors with different target deposition thickness would allow extraction of the actual deposition rate within a deposition run. 相似文献
68.
69.
Hydrothermal Synthesis of Magnesium Aluminate Platelets 总被引:1,自引:0,他引:1
Zhi-Zhan Chen Er-Wei Shi Hua-Wei Zhang Yong Zhang Xiang-Biao Li Xue-Chao Liu Bing Xiao 《Journal of the American Ceramic Society》2006,89(12):3635-3637
Magnesium aluminate (MgAl2 O4 ) platelets were first synthesized by hydrothermal treatment of γ-AlO(OH) in a magnesium nitrate aqueous solution at 400°C. The platelets are 100–200 nm in width and 25 nm in thickness. The influence of temperature, the anions of the magnesium salt, the amount of magnesium salt, and precursor pH on the formation of such structure was investigated. The experimental results indicated that the anions of the magnesium salt and precursor pH could have a significant influence on the growth of MgAl2 O4 . MgAl2 O4 formation followed the in situ transformation mechanism, which was the reason why the MgAl2 O4 crystallites had a platelet morphology. 相似文献
70.