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   8308篇
  免费   1254篇
  国内免费   827篇
电工技术   377篇
综合类   821篇
化学工业   304篇
金属工艺   145篇
机械仪表   476篇
建筑科学   456篇
矿业工程   140篇
能源动力   48篇
轻工业   390篇
水利工程   90篇
石油天然气   146篇
武器工业   85篇
无线电   1046篇
一般工业技术   868篇
冶金工业   1551篇
原子能技术   84篇
自动化技术   3362篇
  2024年   80篇
  2023年   217篇
  2022年   295篇
  2021年   368篇
  2020年   377篇
  2019年   323篇
  2018年   301篇
  2017年   263篇
  2016年   356篇
  2015年   324篇
  2014年   446篇
  2013年   502篇
  2012年   544篇
  2011年   623篇
  2010年   583篇
  2009年   556篇
  2008年   547篇
  2007年   557篇
  2006年   509篇
  2005年   428篇
  2004年   385篇
  2003年   318篇
  2002年   286篇
  2001年   247篇
  2000年   147篇
  1999年   122篇
  1998年   79篇
  1997年   63篇
  1996年   69篇
  1995年   42篇
  1994年   39篇
  1993年   27篇
  1992年   24篇
  1991年   17篇
  1990年   22篇
  1989年   28篇
  1988年   14篇
  1985年   18篇
  1984年   19篇
  1983年   9篇
  1975年   9篇
  1966年   12篇
  1965年   17篇
  1964年   23篇
  1963年   10篇
  1959年   9篇
  1958年   10篇
  1957年   10篇
  1956年   13篇
  1955年   19篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
Through two experiments, the study sought to emphasize the usefulness of the visual and kinesthetic imagery in mental practice. In Experiment 1, it was hypothesized that when the task to be learned through mental practice necessitates the reproduction of a form by drawing, the visual image, which provides a wide span of apprehension, is more suitable than the kinesthetic image. On the other hand, the kinesthetic image that supplies inputs from the muscles' positions and movements should be more appropriate for the acquisition of the duration of the drawing. In Experiment 2, it was hypothesized that the task, transformed into a motor task necessitating minute coordination of the two hands, would benefit more from kinesthetic imagery. To have optimal control over what was actually experienced during mental practice, the participants' imagery skills were measured. The participants also benefited from prior imagery training. The results demonstrate that when using mental practice to initially acquire a task, visual imagery is better for tasks that emphasize form while kinesthetic imagery is better for those tasks that emphasize timing or minute coordination of the two hands. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
32.
The primary visual sources of depth and size information are binocular cues and motion parallax. Here, the authors determine the efficacy of these cues to control prehension by presenting them in isolation from other visual cues. When only binocular cues were available, reaches showed normal scaling of the transport and grasp components with object distance and size. However, when only motion parallax was available, only the transpont component scaled reliably. No additional increase in scaling was found when both cues were available simultaneously. Therefore, although equivalent information is available from binocular and motion parallax information, the latter may be of relatively limited use for the control of the grasp. Binocular disparity appears selectively important for the control of the grasp. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
33.
Martha J. Farah.     
Recognizes Martha J. Farah for rigorous empirical and theoretical analysis of visual cognition, in which understanding of normal function and analysis of neurological deficits illuminate and strengthen one another. Applying diverse experimental techniques within an integrated approach to the study of mind and brain, she has sharpened and helped to answer fundamental questions about how humans generate and manipulate visual images, recognize objects, and attend to positions in space. Along with a citation, a biography is presented for Farah, as well as a bibliography of her works. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
34.
Reviews the book, Basic Processes in Reading Visual Word Recognition by Derek Besner and Glyn W. Humphreys (see record 1990-99017-000). While there has been an increase in the amount of work on many different aspects of reading, as Besner and Humphreys point out in the overview to their book, the vast majority of the research on the topic of reading in the past twenty years has been concerned with the processes involved in word recognition. For this reason, Besner and Humphreys have attempted to bring together studies on topics which are both relevant to current debates in the field of word recognition, and which are likely to be important for future developments in the field. They have compiled an edited volume consisting of their overview and eight additional chapters. The editors have attempted to span the continuum of processes involved in word recognition and thus have included chapters which cover topics ranging from the visual analysis of words, to those on the influence of semantic factors on word recognition. The authors of these chapters comprise an impressive list of researchers in the field of word recognition, with the majority of chapters being authored by leading researchers on the topic. Given the stature of the authors and the range of topics covered, in theory this volume should provide a very thorough overview of current theory and research on reading. There is no question that each of the chapters is interesting and important in its own right. However, in practice the volume as a whole fell somewhat short of my expectations. The different tacts taken by different authors has resulted in a very uneven coverage of the current debates in the field. Notwithstanding these criticisms, I am sure that the majority of researchers in this field will consider this volume to be an important contribution. The book would provide a very useful addition to graduate courses in cognitive sciences and as a supplemental text for an undergraduate course on the psychology of reading. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
35.
In the past, equine color vision was tested with stimuli composed either of painted cards or photographic slides or through physiological testing using electroretinogram flicker photometry. Some studies produced similar results, but others did not, demonstrating that there was not yet a definitive answer regarding color vision in horses (Equus caballus). In this study, a pseudoisochromatic plate test--which is highly effective in testing color vision both in small children and in adult humans--was used for the first time on a nonhuman animal. Stimuli consisted of different colored dotted circles set against backgrounds of varying dots. The coloration of the circles corresponded to the visual capabilities of different types of color deficiencies (anomalous trichromacy and dichromacy). Four horses were tested on a 2-choice discrimination task. All horses successfully reached criterion for gray circles and demonstration circles. None of the horses were able to discriminate the protan-deutan plate or the individual protan or deutan plates. However, all were able to discriminate the tritan plate. The results suggest that horses are dichromats with color vision capabilities similar to those of humans with red-green color deficiencies. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
36.
Participants' usage of informational variables in learning visual relative-mass discrimination in collisions was tracked by means of PROBIT correlations. Four groups received feedback that was true or accorded with either of three nonspecificational cue variables. A majority in each group adopted the feedback, but several participants defied the false feedback. Unlike in previous research, the fit to data of the relative-mass invariant could not be bettered by post hoc linear combinations of the cues. Discriminability was lower in the use of the invariant. Analytic complexity was rejected as an explanation for discriminability differences. A "smart mechanism" for pickup of the relative-mass invariant was developed as an extension of G. Johansson's (1950/1994) vector model. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
37.
介绍了一种基于时序特征的电能量计量计费系统(TMR)的旁路代自动识别和代入算法。首先分析了现有TMR中的旁路代处理方式,指出这些处理方式的缺陷;然后通过分析TMR旁路代发生前后电量的时序特征,提出了一种基于电量时序特征的自动旁路代算法,此算法能在旁路代事件开始时即做出正确判断,并在适当的延时后开始完成旁路电量的自动代入。该算法在江苏省电力公司TMR中获得了很好的实验效果。  相似文献   
38.
Organic molecular scintillating crystals are noted for their good timing and particle discrimination process. Trans-stilbene is one such candidate noted for its good particle detection characteristics for the past five decades. Progressive strengthening of detection characteristics of trans-stilbene has been attempted by improving crystal perfection. A series of timing resolution studies have been carried out for the Bridgman grown trans-stilbene crystals under different experimental conditions. The results were compared with the previously reported values. Pulse shape discrimination process has been carried out for 241Am and 252Cf sources and good discrimination has been obtained for gamma-alpha and gamma-neutron sources from the grown organic phosphor crystal. Electronic Publication  相似文献   
39.
Development environments based on ActiveX controls and JavaBeans are marketed as ‘visual programming’ platforms; in practice their visual dimension is limited to the design and implementation of an application's graphical user interface (GUI). The availability of sophisticated GUI development environments and visual component development frameworks is now providing viable platforms for implementing visual programming within general‐purpose platforms, i.e. for the specification of non‐GUI program functionality using visual representations. We describe how specially designed reflective components can be used in an industry‐standard visual programming environment to graphically specify sophisticated data transformation pipelines that interact with GUI elements. The components are based on Unix‐style filters repackaged as ActiveX controls. Their visual layout on the development environment canvas is used to specify the connection topology of the resultant pipeline. The process of converting filter‐style programs into visual controls is automated using a domain‐specific language. We demonstrate the approach through the design and the visual implementation of a GUI‐based spell‐checker. Copyright © 2001 John Wiley & Sons, Ltd.  相似文献   
40.
刘文贵 《质谱学报》2002,23(2):120-120
测量准确度是热电离质谱 ( TIMS)的重要指标 ,对于使用年限较长的 TIMS,造成准确度下降的因素很多 ,分析判断更复杂。为了准确、系统地了解其中的主要原因 ,本文从 TIMS的基本工作原理出发 ,对影响测量准确度的主要因素 ,如离子束的角分散、能量分散、电磁场稳定性、多接收器的形变和位移、电子倍增器的衰老和放大器增益的差异等及相应的解决办法作了较深入的探讨  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