首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   5226篇
  免费   296篇
  国内免费   34篇
电工技术   51篇
综合类   19篇
化学工业   1197篇
金属工艺   89篇
机械仪表   86篇
建筑科学   334篇
矿业工程   9篇
能源动力   193篇
轻工业   905篇
水利工程   41篇
石油天然气   16篇
无线电   369篇
一般工业技术   972篇
冶金工业   228篇
原子能技术   28篇
自动化技术   1019篇
  2023年   54篇
  2022年   57篇
  2021年   112篇
  2020年   82篇
  2019年   84篇
  2018年   204篇
  2017年   204篇
  2016年   231篇
  2015年   191篇
  2014年   226篇
  2013年   373篇
  2012年   331篇
  2011年   338篇
  2010年   293篇
  2009年   245篇
  2008年   290篇
  2007年   280篇
  2006年   270篇
  2005年   188篇
  2004年   163篇
  2003年   173篇
  2002年   146篇
  2001年   100篇
  2000年   83篇
  1999年   84篇
  1998年   78篇
  1997年   72篇
  1996年   54篇
  1995年   48篇
  1994年   43篇
  1993年   32篇
  1992年   22篇
  1991年   21篇
  1990年   22篇
  1989年   16篇
  1987年   12篇
  1986年   21篇
  1985年   24篇
  1984年   37篇
  1983年   27篇
  1982年   19篇
  1981年   28篇
  1980年   32篇
  1979年   17篇
  1978年   13篇
  1977年   17篇
  1976年   17篇
  1975年   11篇
  1974年   14篇
  1973年   15篇
排序方式: 共有5556条查询结果,搜索用时 15 毫秒
51.
A comparative study is presented on the pore propagation directions of porous silicon layers (PSL) formed on p+-type substrates of different orientations. PSLs were formed on plain (0 0 1) and (1 1 1) silicon wafers as well as on structured (0 0 1) wafers containing facets of various orientations. During anodization, regular pores follow the 0 0 1 direction on the (0 0 1) planes. While on the (1 1 1) planes fewer regular pores develop and seemingly propagate closely to the 1 1 1 direction. These results indicate that the pores propagate perpendicular to the surface i.e. along the field lines when the surface orientation is either (0 0 1) or (1 1 1).When the silicon surface provided (1 1 0) orientation (Chuang, Collins, and Smith, 1989), or its position is in between the (0 0 1) and (1 1 1) planes then the pores do not propagate perpendicular to the surface but along the 0 0 1 direction.All the phenomena exhibited might be explained by presuming that during formation, the pores propagate along the 1 0 0 directions, and that those 1 0 0 directions are preferred which are closely to the field lines. In PSLs formed on (0 0 1) surfaces the field lines and the 0 0 1 crystallographic direction are coincident. However, in the (1 1 1) oriented wafer where three equally probable 1 0 0 directions exist around the field lines, more irregular structure of PSLs will develop.  相似文献   
52.
53.
54.
55.
56.
We provide a theoretical framework that fits realistic challenges related to spacecraft formation with disturbances. We show that the input‐to‐state stability of such systems guarantees some robustness with respect to a class of signals with bounded average‐energy, which encompasses the typical disturbances acting on spacecraft formations. Solutions are shown to converge to the desired formation, up to an offset, which is somewhat proportional to the considered moving average of disturbances. In the presence of fast peaking perturbations, the approach provides a tighter evaluation of the disturbances' influence, which allows for the use of more parsimonious control gains. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   
57.
This paper investigates whether employees’ assessment of their primary task quality has a significant impact on their well‐being and job satisfaction, respectively. Furthermore, the paper hypothesizes that professional values and norms affect employees’ quality expectations on their work tasks and thus their assessment of primary task quality. The paper proposes a measure for primary task quality and uses it in the analyses of responses from 1,247 preschool teachers and teaching assistants in 94 public daycare centers in Denmark. The results indicate that an important factor for employees is their experience of quality in the job they perform. Moreover, quality expectations can differ between employees performing the same task due to, for example, difference in professional training. This leads us to propose a new research direction for job design theory that addresses employees’ assessment of the quality of their primary task job performance.  相似文献   
58.
59.
We present a corpus-based prosodic analysis with the aim of uncovering the relationship between dialogue acts, personality and prosody in view to providing guidelines for the ECA Greta’s text-to-speech system. The corpus used is the SEMAINE corpus, featuring four different personalities, further annotated for dialogue acts and prosodic features. In order to show the importance of the choice of dialogue act taxonomy, two different taxonomies were used, the first corresponding to Searle’s taxonomy of speech acts and the second, inspired by Bunt’s DIT++, including a division of directive acts into finer categories. Our results show that finer-grained distinctions are important when choosing a taxonomy. We also show with some preliminary results that the prosodic correlates of dialogue acts are not always as cited in the literature and prove more complex and variable. By studying the realisation of different directive acts, we also observe differences in the communicative strategies of the ECA depending on personality, in view to providing input to a speech system.  相似文献   
60.
Technology is often seen as seamless, or making (life/work) boundaries go away. Ubicomp designs for that and for seamlessness in general. However, there may be better ways of understanding boundaries, as to design technologies in the space of changing work/life boundaries, which is the topic of this special issue. This paper makes a theoretical argument to insist that boundaries are not fixed, neither can or should they be made away with technologically, through seamless technologies. Based on this argument, it discusses various presumed technology-mediated boundaries of work and home, life, etc., as they can be found in the Ubicomp, CSCW and HCI literature: The ways in which work and work technologies are stereotypically connected to effectiveness and hard labor, and non-work technologies to fun and enjoyment; the ways in which technologies move back and forth between mediating work activity and non-work; the role of place and time boundaries in relation to the ability to work any time, anywhere and the metaphors used to address these boundaries; and the perceived boundaries of private versus public, and the new boundaries created by technologies in and across our lives and work. Using an empirical case, the paper offers an alternative use of boundaries as resources to be activated and used in design. It suggests that we need to more carefully design technologies that provide seamfulness on these specific and dynamic boundaries.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号