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   1349篇
  免费   91篇
  国内免费   1篇
电工技术   10篇
综合类   4篇
化学工业   469篇
金属工艺   25篇
机械仪表   26篇
建筑科学   54篇
能源动力   19篇
轻工业   162篇
水利工程   11篇
石油天然气   1篇
无线电   65篇
一般工业技术   229篇
冶金工业   211篇
自动化技术   155篇
  2024年   1篇
  2023年   23篇
  2022年   71篇
  2021年   94篇
  2020年   45篇
  2019年   45篇
  2018年   35篇
  2017年   43篇
  2016年   40篇
  2015年   52篇
  2014年   40篇
  2013年   83篇
  2012年   82篇
  2011年   103篇
  2010年   84篇
  2009年   76篇
  2008年   90篇
  2007年   72篇
  2006年   61篇
  2005年   37篇
  2004年   44篇
  2003年   36篇
  2002年   30篇
  2001年   27篇
  2000年   20篇
  1999年   13篇
  1998年   18篇
  1997年   11篇
  1996年   9篇
  1995年   5篇
  1994年   2篇
  1993年   6篇
  1992年   1篇
  1991年   2篇
  1990年   1篇
  1989年   3篇
  1988年   7篇
  1987年   4篇
  1986年   2篇
  1985年   7篇
  1984年   1篇
  1983年   3篇
  1982年   2篇
  1981年   2篇
  1979年   1篇
  1977年   1篇
  1976年   3篇
  1975年   2篇
  1973年   1篇
排序方式: 共有1441条查询结果,搜索用时 31 毫秒
991.
Reviews the book, Helene Deutsch: A psychoanalyst's life by Paul Roazen (see record 1992-97543-000). In this biography of over 391 pages, Paul Roazen describes the life of Helene Deutsch, seen by many historians of psychology as one of Freud's best-known and favourite students and a major contributor to psychoanalysis in her own right. Each of the three sections in the book concentrates on a major episode and station in her life: Poland, Vienna, and finally Massachusetts. Roazen carefully describes Helene's family background, her circle of friends, her romance with Felix Deutsch, and of course her relationship with Freud. The book reads much like a shortened psychoanalysis of Helene Deutsch herself. A good biography should not only describe an individual's contribution to a profession, but also this contribution should become understandable as an outgrowth of the cultural heritage, the Zeitgeist, and the unique life history of the individual. Roazen has clearly succeeded in doing that. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
992.
Anisotropically conductive film (ACF) is a smart electronic packaging material that consumes minimal space for connecting integrated circuit (IC) chips to a liquid crystal display (LCD) panel or printed circuit board. It consists of an adhesive resin and fine conductive fillers such as metallic particles or metal-coated polymer balls. The fillers are compressed and maintain a certain elastic capability while conducted between electrodes. The size of the contact area and the shape of the fillers are important factors in determining conductivity. The process of applying ACF is modeled into three consecutive steps, and the stress and deformation states are studied by finite element analysis in each. In step 1 of the manufacturing process, external load is applied to compress the conductive particles at a temperature of 190°C so that the matrix resin is in a fluid condition. In step 2, an external load is maintained at this temperature to allow the matrix resin to solidify; then, the load is released and the particles spring back to create tensile stresses in the bonding resin matrix. The last step considers the bonded and conducting ACF cooling from 190°C to room temperature. The state of stress and deformation will be readjusted due to different contraction properties between the filler and matrix resin. The results presented in this paper show that changing the thickness of a coated nickel layer does not clearly affect the conductivity of ACF, and the deformation should be greater than 40% for the stability of conductivity.  相似文献   
993.
Theoretical models of collaborative learning through online discussions presuppose that students generally attend to others’ posts. However, a succession of studies over the last decade has shown this assumption to be unwarranted. Instead, research indicates that learners attend to others’ posts in diverse and particular ways—an activity we have conceptualized as online “listening.” In this study, we take an important step forward in developing a robust theory of online listening by examining the relationship between how learners “listen” (access existing posts) and “speak” (contribute posts) in online discussions. Ten variables indexing four dimensions of students’ listening (breadth, depth, temporal contiguity and revisitation) and five variables indexing three dimensions of students’ speaking (discursiveness, depth of content and reflectivity) were calculated for 31 students participating in 6 week-long online discussions as part of an undergraduate educational psychology course. Multi-level mixed-model linear regressions indicated that responsiveness of students’ posts was positively predicted by how often they revisited previously read peer posts, and negatively related to a greater number of posts in the discussion overall. The depth of posts’ contents was predicted by the percentage of posts viewed that students actually read (as opposed to scanned). An exploratory follow-up analysis indicated that these listening-speaking relationships manifest differently over time for distinct subsets of learners (e.g., a decrease in variable pairs versus corresponding fluctuations around stable levels). Put together, results suggest that when students take the time to read and re-read their peers’ posts there are related benefits in the quality of the posts they contribute.  相似文献   
994.
995.
996.
[Correction Notice: An erratum for this article was reported in Vol 11(4) of Emotion (see record 2011-18271-002). There was an error in the title. The title of the article should read, “Can seeking happiness make people unhappy? Paradoxical effects of valuing happiness.” All versions of this article have been corrected.] Happiness is a key ingredient of well-being. It is thus reasonable to expect that valuing happiness will have beneficial outcomes. We argue that this may not always be the case. Instead, valuing happiness could be self-defeating, because the more people value happiness, the more likely they will feel disappointed. This should apply particularly in positive situations, in which people have every reason to be happy. Two studies support this hypothesis. In Study 1, female participants who valued happiness more (vs. less) reported lower happiness when under conditions of low, but not high, life stress. In Study 2, compared to a control group, female participants who were experimentally induced to value happiness reacted less positively to a happy, but not a sad, emotion induction. This effect was mediated by participants' disappointment at their own feelings. Paradoxically, therefore, valuing happiness may lead people to be less happy just when happiness is within reach. (PsycINFO Database Record (c) 2011 APA, all rights reserved)  相似文献   
997.
The messages and support that students receive regarding college preparation often varies by students' race/ethnicity, socioeconomic background, and generational status (Adelman, 2006; Freeman, 1997; McDonough, 2004; Venezia & Kirst, 2005; Wimberly, 2002). This investigation sought to understand the manner by which a social capital framework could help explain how information about postsecondary educational transitions was communicated to, and interpreted by, college-bound students in one large urban school district. African American college students retrospectively considered the people, both in school and out, who provided them with college preparatory information, support, and/or guidance. Data revealed that although students received encouragement from their social networks, there was a shortage of individualized, concrete, and comprehensive college planning. Findings suggest that college planning and preparation for students from traditionally underrepresented college populations must be more cohesive and focused toward providing access to academic, financial, and social information that is instrumental in the students' transitions to college. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
998.
999.
Extremely light (density ~1.46 g/cm3) and highly formable Mg-Li alloys have been drawing research interest; however, their relatively low strength is discouraging, and thus, an issue to be addressed. This paper processes and evaluates four Mg-Li alloys: the first, a basic alloy with a nominal composition of Mg-11%Li-1%Al-0.5%Zn; the second, an alloy with only Be added to the first; the third, an alloy with only Sc added to the first; and the fourth, with both Be and Sc added to the first. This research achieves a high strength of ~240 MPa for Mg-Li alloys using the processes of solid solution treatment plus 90% heavy rolling. A subsequent natural aging process proceeded spontaneously and resulted in strength decay. Room temperature softening behavior is uncommon, but offers a convenient route for studying age-softening characteristics of metallic alloys.  相似文献   
1000.
We propose an effective method for automatic writer recognition from unconstrained handwritten text images. Our method relies on two different aspects of writing: the presence of redundant patterns in the writing and its visual attributes. Analyzing small writing fragments, we seek to extract the patterns that an individual employs frequently as he writes. We also exploit two important visual attributes of writing, orientation and curvature, by computing a set of features from writing samples at different levels of observation. Finally we combine the two facets of handwriting to characterize the writer of a handwritten sample. The proposed methodology evaluated on two different data sets exhibits promising results on writer identification and verification.  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