全文获取类型
收费全文 | 1724篇 |
免费 | 66篇 |
专业分类
电工技术 | 16篇 |
综合类 | 3篇 |
化学工业 | 555篇 |
金属工艺 | 27篇 |
机械仪表 | 28篇 |
建筑科学 | 138篇 |
矿业工程 | 6篇 |
能源动力 | 41篇 |
轻工业 | 186篇 |
水利工程 | 5篇 |
石油天然气 | 1篇 |
无线电 | 100篇 |
一般工业技术 | 341篇 |
冶金工业 | 226篇 |
原子能技术 | 15篇 |
自动化技术 | 102篇 |
出版年
2021年 | 22篇 |
2019年 | 21篇 |
2018年 | 23篇 |
2017年 | 28篇 |
2016年 | 37篇 |
2015年 | 41篇 |
2014年 | 46篇 |
2013年 | 70篇 |
2012年 | 63篇 |
2011年 | 76篇 |
2010年 | 45篇 |
2009年 | 63篇 |
2008年 | 64篇 |
2007年 | 56篇 |
2006年 | 52篇 |
2005年 | 50篇 |
2004年 | 55篇 |
2003年 | 34篇 |
2002年 | 36篇 |
2001年 | 31篇 |
2000年 | 28篇 |
1999年 | 18篇 |
1998年 | 33篇 |
1997年 | 36篇 |
1996年 | 41篇 |
1995年 | 26篇 |
1994年 | 23篇 |
1993年 | 33篇 |
1992年 | 19篇 |
1991年 | 29篇 |
1990年 | 21篇 |
1989年 | 27篇 |
1988年 | 16篇 |
1986年 | 16篇 |
1985年 | 31篇 |
1984年 | 34篇 |
1983年 | 28篇 |
1982年 | 28篇 |
1981年 | 31篇 |
1980年 | 28篇 |
1979年 | 22篇 |
1978年 | 27篇 |
1976年 | 19篇 |
1975年 | 18篇 |
1974年 | 28篇 |
1973年 | 20篇 |
1972年 | 17篇 |
1971年 | 15篇 |
1970年 | 16篇 |
1969年 | 17篇 |
排序方式: 共有1790条查询结果,搜索用时 7 毫秒
1.
2.
3.
A novel soft-switching full-bridge DC/DC converter: analysis,design considerations, and experimental results at 1.5 kW, 100 kHz 总被引:1,自引:0,他引:1
The addition of an external commutating inductor and two clamp diodes to the phase-shifted PWM (pulsewidth modulated) full-bridge DC/DC converter substantially reduces the switching losses of the transistors and the rectifier diodes, under all loading conditions. The authors give analyses, practical design considerations, and experimental results for a 1.5 kW converter with 60 V, 25 A output, operating at 100 kHz clock frequency and 95% efficiency 相似文献
4.
Improving the vacuum would increase the insulation capacity of commercially available glass containers by a factor of about two. To do this, pressures of 10?4 mbar must be attained. Different approaches were taken to meet this objective. As an alternative to today's commonly practiced sealing method, three possibilities are introduced which eliminate the necessity of pump stub narrowing which causes reduced conductance. Furthermore, depending on the sealing process used, the gases occuring during sealing are either avoided completly or they can at least be reduced by having the chance of exact temperature control resp. by a lower separation temperature. A completly different approach was taken by using Getters, of which a metal hydride on a TiVMn base proved especially suitable. It is activated by heat and can be integrated into the normal production process without any problem. Aside from a shorter pump period, the added advantage here is the containment of the gasses occuring during sealing as well as that of the longterm gasses. 相似文献
5.
Karl Heinz Schwalbe 《Engineering Fracture Mechanics》1993,45(6):751-758
The Engineering Treatment Model (ETM) provides a means for estimating the load line displacement of a cracked body. Under contained yielding conditions the model uses available linear elastic solutions with an Irwin-type plasticity correction of the crack length. The magnification factor (F/Fy)1/n describing the material's strain hardening behaviour is applied for extrapolation into the regime of net section yielding. Comparison of ETM estimates with finite element and experimental results shows that the assumptions of the model are realistic. 相似文献
6.
P. B. Malafaya A. J. Pedro A. Peterbauer C. Gabriel H. Redl R. L. Reis 《Journal of materials science. Materials in medicine》2006,17(7):675-675
In the XML file of the original article, H. Redl’s affiliation is incorrect. It is listed correctly in both the paper and
PDF versions of the article, and can be found below:
The online version of the original article can be found at 相似文献
7.
8.
9.
10.
Dieter Braun Manfred Rtzsch Peter Fiedler Günter Weber Heinz Hofmann Bernd Gutschalk 《大分子材料与工程》1991,187(1):101-121
Based on the example of PE-LD grades and on model substances obtained by preparative fractionation (fractions in the molecular weight range M?w = 1.2 ? 390·104 g/mol), comprehensive investigations regarding the problems of structure/properties have been carried out. The correlations of M?w with 15 physical and application technological perameters have been investigated taking into account the reaction mechanism during the manufacturing of PE-LD in the tubular and agitated autoclave reactor, resulting in the formation of so-called primary structure perameters M?n, M?w, molar mass distribution, short chain branching and long chain branching. For the interpretation of the results, among other factors, also the morphological conditions have been taken into consideration, which in connection with the molecular parameters reveal — for specific M?w-ranges — strong changes and saturation ranges, resp., for the physical and application technological properties. 相似文献