全文获取类型
收费全文 | 658650篇 |
免费 | 8523篇 |
国内免费 | 1955篇 |
专业分类
电工技术 | 12238篇 |
综合类 | 621篇 |
化学工业 | 97443篇 |
金属工艺 | 25039篇 |
机械仪表 | 18896篇 |
建筑科学 | 15593篇 |
矿业工程 | 2836篇 |
能源动力 | 17823篇 |
轻工业 | 55857篇 |
水利工程 | 6356篇 |
石油天然气 | 11160篇 |
武器工业 | 44篇 |
无线电 | 77858篇 |
一般工业技术 | 126792篇 |
冶金工业 | 133432篇 |
原子能技术 | 12815篇 |
自动化技术 | 54325篇 |
出版年
2021年 | 5708篇 |
2020年 | 4139篇 |
2019年 | 5415篇 |
2018年 | 9144篇 |
2017年 | 8916篇 |
2016年 | 9314篇 |
2015年 | 6527篇 |
2014年 | 10941篇 |
2013年 | 29764篇 |
2012年 | 17420篇 |
2011年 | 24069篇 |
2010年 | 19077篇 |
2009年 | 21469篇 |
2008年 | 22075篇 |
2007年 | 21777篇 |
2006年 | 19148篇 |
2005年 | 17668篇 |
2004年 | 17085篇 |
2003年 | 16752篇 |
2002年 | 15930篇 |
2001年 | 16172篇 |
2000年 | 15109篇 |
1999年 | 16203篇 |
1998年 | 42385篇 |
1997年 | 29418篇 |
1996年 | 22655篇 |
1995年 | 16910篇 |
1994年 | 14686篇 |
1993年 | 14414篇 |
1992年 | 10234篇 |
1991年 | 9725篇 |
1990年 | 9507篇 |
1989年 | 9164篇 |
1988年 | 8475篇 |
1987年 | 7375篇 |
1986年 | 7282篇 |
1985年 | 8217篇 |
1984年 | 7581篇 |
1983年 | 6710篇 |
1982年 | 6276篇 |
1981年 | 6479篇 |
1980年 | 6049篇 |
1979年 | 5857篇 |
1978年 | 5631篇 |
1977年 | 6838篇 |
1976年 | 9015篇 |
1975年 | 4884篇 |
1974年 | 4603篇 |
1973年 | 4655篇 |
1972年 | 3843篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
102.
M. Ronen 《Journal of Computer Assisted Learning》1995,11(3):141-156
Abstract This article presents a study of a large scale incorporation of one data acquisitionsystem into physics teaching in Israel. By 1994 about 30% of the schools throughout the country used the V-scope, a 3-D multibody motion tracing system, in their lab programme. The views and reactions of post-training teachers, experienced teachers and students on various aspects of using the system are described, analysed and compared. 相似文献
103.
N. M. Sanghavi Hema Venkatesh Varsha Tandel 《Drug development and industrial pharmacy》1994,20(7):1275-1283
Gilbenclamide, a widely used potent hypoglycaemic agent was solubllized using β -Cyclodextrin and β -Cyclodextrin derivatives. Complexes were prepared by kneading method in a molar ratio of 1:1 of the drug and the cyclodextrlns respectively. The Glibenclamide β -Cyelocextrin complex was characterized and evaluated by I.R. studies, Differential Scanning Calorimotry 6 X-ray diffractometry. The in-vitro dissolution rates of drug from inclusion complexes of β Cyclodextrins and its derivatives were compared. A significant Improvement In dissolution lor, rates of Gllbenclamide was observed with Inclusion complexes of all the Cyclodextrins. However, the solubilizing effect was more in case of β-Cyclodextrin derivatives. 相似文献
104.
105.
106.
M. D. Korostash 《Drying Technology》1985,3(4):603-611
The paper presents the results of research in the convection drying of unidirectional glass fibre bobbins on the basis of which the relations are suggested required to calculate the process of drying in the design of drying equipment. 相似文献
107.
A. A. Konstantinov N. V. Kurenkov A. B. Malinin T. E. Sazonova S. V. Sepman 《Atomic Energy》1989,67(3):696-698
Translated from Atomnaya Énergiya, Vol. 67, No. 3, pp. 215–216, September, 1989. 相似文献
108.
109.
Nagpal R. Zambonelli F. Sirer E.G. Chaouchi H. Smirnov M. 《Intelligent Systems, IEEE》2006,21(2):50-58
No generally accepted principles and guidelines currently exist to help engineers design local interaction mechanisms that result in a desired global behavior. However, several communities have developed ways of approaching this problem in the context of niched application areas. Because the ideas underlying these approaches are often obscured or underemphasized in technical papers, the authors review the role of self-organization in their work. They provide a better picture of the status of the emerging field of self-organizing systems or autonomic computing. 相似文献
110.
Hayashi M. Tanaka H. Ohara K. Otani T. Suzuki M. 《Lightwave Technology, Journal of》2002,20(2):236-242
An all-optical multiplexing technique using wavelength division multiplexing (WDM)-time division multiplexing (TDM) conversion with an electroabsorption wavelength converter has been proposed and demonstrated. The effectiveness of this WDM-TDM conversion technique for various pulsewidth settings was experimentally investigated. The fluctuation of the signal performance, which was inevitably caused by the coherent crosstalk between adjacent pulses in the conventional optical time division multiplexing (OTDM) technique, were successfully suppressed, even in the case of wide pulse duration. High Q-factor performance has been maintained for a wide range of duty ration from 36% to 74%. By introducing this technique to the optical time division multiplexer, a highly stable and high-quality 40-Gb/s optical signal can be effectively produced without generating the short pulse or setting two tributaries at orthogonal polarization states, and without introducing high-speed electronics for signal multiplexing. The WDM-TDM conversion with an electroabsorption wavelength converter was extended to 60-Gb/s operation by using three 20-Gb/s tributaries. A clear eye opening was confirmed for a waveform after the WDM-TDM conversion of the 60-Gb/s signal 相似文献