全文获取类型
收费全文 | 412789篇 |
免费 | 4564篇 |
国内免费 | 1735篇 |
专业分类
电工技术 | 6898篇 |
综合类 | 2855篇 |
化学工业 | 57844篇 |
金属工艺 | 20591篇 |
机械仪表 | 16168篇 |
建筑科学 | 9464篇 |
矿业工程 | 2707篇 |
能源动力 | 8998篇 |
轻工业 | 26693篇 |
水利工程 | 4892篇 |
石油天然气 | 7424篇 |
武器工业 | 45篇 |
无线电 | 47337篇 |
一般工业技术 | 86031篇 |
冶金工业 | 58278篇 |
原子能技术 | 8628篇 |
自动化技术 | 54235篇 |
出版年
2021年 | 2477篇 |
2020年 | 1893篇 |
2019年 | 2304篇 |
2018年 | 22804篇 |
2017年 | 22350篇 |
2016年 | 16177篇 |
2015年 | 3579篇 |
2014年 | 4865篇 |
2013年 | 12678篇 |
2012年 | 11909篇 |
2011年 | 24500篇 |
2010年 | 21009篇 |
2009年 | 19151篇 |
2008年 | 20110篇 |
2007年 | 22495篇 |
2006年 | 8132篇 |
2005年 | 11408篇 |
2004年 | 9773篇 |
2003年 | 9336篇 |
2002年 | 7764篇 |
2001年 | 7039篇 |
2000年 | 6815篇 |
1999年 | 6910篇 |
1998年 | 16554篇 |
1997年 | 11763篇 |
1996年 | 9096篇 |
1995年 | 6971篇 |
1994年 | 6137篇 |
1993年 | 6175篇 |
1992年 | 4488篇 |
1991年 | 4295篇 |
1990年 | 4125篇 |
1989年 | 4119篇 |
1988年 | 3814篇 |
1987年 | 3436篇 |
1986年 | 3440篇 |
1985年 | 3793篇 |
1984年 | 3514篇 |
1983年 | 3276篇 |
1982年 | 3087篇 |
1981年 | 3096篇 |
1980年 | 3083篇 |
1979年 | 2870篇 |
1978年 | 2893篇 |
1977年 | 3177篇 |
1976年 | 4155篇 |
1975年 | 2429篇 |
1974年 | 2408篇 |
1973年 | 2419篇 |
1972年 | 2022篇 |
排序方式: 共有10000条查询结果,搜索用时 10 毫秒
111.
112.
This paper presents an integrated passive damping approach in hybrid metal-CFRP parts for structural applications. In this concept a viscoelastic material is embedded in the joint zone of the hybrid component. To examine the connection strength single-lap-joint specimens were produced and tested and the influence of the used material combinations, different surface structures, and different process parameters i.e. the moment of cross-linking were evaluated. Afterwards, the metal-CFRP hybrids were tested in quasi-static tests to assess their connection strength and failure behaviour. Dynamic cyclic tensile tests with step-wise increased loading conditions were performed to determine the specimens damping behaviour and to estimate their fatigue performance. Finally, these results are compared to a state of the art metal-CFRP hybrid with rivets connecting both materials. 相似文献
113.
114.
Lecture capture with real‐time rearrangement of visual elements: impact on student performance
下载免费PDF全文
![点击此处可从《Journal of Computer Assisted Learning》网站下载免费的PDF全文](/ch/ext_images/free.gif)
The primary goal of this study is to create and test a lecture‐capture system that can rearrange visual elements while recording is still taking place, in such a way that student performance can be positively influenced. The system we have devised is capable of integrating and rearranging multimedia sources, including learning content, the instructor and students' images, into lecture videos that are embedded in a website for students to review after school. The present study employed a two‐group experimental design, with 153 participants (145 females and 8 males) making up an experimental group in which lecture courses were recorded using the new lecture‐capture system, and 149 participants (140 females and 9 males) forming a control group whose lectures were recorded by traditional means. All participants were in the freshman college and studying Introduction to Computer and Information Science in one of six classes, and were randomly assigned to one of the two groups. The participants' midterm examination and final examination scores were collected as indicators of their academic performance, with their mathematics entrance scores used as a pre‐test. The findings obtained from analysis of covariance (ANCOVA) suggest that appropriate rearrangement of visual elements in lecture videos can significantly impact students' learning performance. 相似文献
115.
A. M. Mirzabaev V. P. Kanonerov T. A. Makhkamov O. R. Sytdykov Sh. M. Mirzabekov 《Applied Solar Energy》2018,54(3):224-226
The data on the use of solar photovoltaic plants (PVPs) for providing a reliable and guaranteed power supply to telecommunication systems and cellular communication systems in the conditions prevalent in Uzbekistan are given. The research-based structures developed by OOO MIR SOLAR and the selection of PVP elements ensuring their reliable operation are described. The main influencing factors are discussed, and the use of effective combinations of different types of panels (from monocrystalline and polycrystalline silicon) and a specially developed controller are considered. 相似文献
116.
C. G. Prosgolitis S. G. Lambrakos A. D. Zervaki 《Journal of Materials Engineering and Performance》2018,27(10):5102-5113
This work presents simulation of microstructure evolution in the nugget zone (NZ) of a AZ31-Mg-alloy friction stir weld. The process parameters (tool geometrical characteristics, rotational speed, travel speed, applied load) have been correlated with the resulting microstructural features in the NZ of the weld (grain size and population) with the aid of the MICRESS software, which provides the ability to simulate both nucleation and grain growth during dynamic recrystallization phenomena evolving in the NZ during the weld thermal cycle. The input parameters of the developed model include the tool geometry, the welding conditions as well as the recrystallization energy, the grain boundary mobility and specific material properties. NZ microstructure obtained by simulation shows good agreement with experimental measurements for both grain population and size. 相似文献
117.
118.
119.
In this paper, we consider the classical finite mixture model, which is an effective tool for modeling lifetime distributions for random samples from heterogeneous populations. We discuss new results on stochastic comparison for two finite mixtures when each of them is drawn from one of the following semiparametric families, i.e., proportional hazards, accelerated lifetime and proportional reversed hazards. 相似文献
120.
Sukharev S. V. Zabolotskii A. V. Kotrovskii P. V. Turchin M. Yu. 《Refractories and Industrial Ceramics》2020,60(6):539-542
Refractories and Industrial Ceramics - We study the problem of evaluation of the influence of design of the metal receiver of a large-capacity tundish of slab continuous-casting machine on the... 相似文献