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   5053篇
  免费   310篇
  国内免费   93篇
  2024年   11篇
  2023年   79篇
  2022年   88篇
  2021年   105篇
  2020年   167篇
  2019年   164篇
  2018年   292篇
  2017年   310篇
  2016年   262篇
  2015年   151篇
  2014年   182篇
  2013年   631篇
  2012年   372篇
  2011年   396篇
  2010年   258篇
  2009年   126篇
  2008年   325篇
  2007年   247篇
  2006年   269篇
  2005年   167篇
  2004年   138篇
  2003年   99篇
  2002年   96篇
  2001年   41篇
  2000年   68篇
  1999年   54篇
  1998年   31篇
  1997年   30篇
  1996年   21篇
  1995年   9篇
  1994年   26篇
  1993年   22篇
  1992年   22篇
  1991年   18篇
  1990年   17篇
  1989年   23篇
  1988年   12篇
  1987年   15篇
  1986年   5篇
  1985年   12篇
  1984年   8篇
  1983年   6篇
  1982年   5篇
  1981年   12篇
  1978年   6篇
  1974年   13篇
  1970年   4篇
  1968年   4篇
  1966年   4篇
  1965年   4篇
排序方式: 共有5456条查询结果,搜索用时 31 毫秒
41.
In this paper a method is outlined for measuring the diversity of the results of applied R&D with the use of IPC (International Patent Classification). The method has been tested in the contexts of the academic physical, engineering, and chemical institutes. The trend of applied research at a given institute increases both at the level of classes and subclasses, and at the IPC level. Inventions developed within specializations at each institute have a greater efficiency than other forms of inventive activity. The objective was to seek the optimal extent of diversification of applied R&D, which would simultaneously ensure the preservation of the scientific specialization of an institute, the high level of scientific research associated with developing innovations, and the high overall efficiency of each institute.  相似文献   
42.
Finland has followed the Scandinavian model of the welfare state in which the level of state activism is high, the economic pressures on the scientific activities are strong, and the left-wing parties and the Center Party have formulated the main ideas. In the 1970s welfare ideology was adopted in science policy by emphasizing the promotion of socially relevant scientific activities and the expansion of the university system as a means of effecting equal opportunity. Currently, the trend is toward a mixed welfare economy. Programs have been prepared in spite of the radical cut in government expenditure, and without a consideration of the long-term consequences.  相似文献   
43.
In the McGurk effect, visual information specifying a speaker’s articulatory movements can influence auditory judgments of speech. In the present study, we attempted to find an analogue of the McGurk effect by using nonspeech stimuli—the discrepant audiovisual tokens of plucks and bows on a cello. The results of an initial experiment revealed that subjects’ auditory judgments were influenced significantly by the visual pluck and bow stimuli. However, a second experiment in which speech syllables were used demonstrated that the visual influence on consonants was significantly greater than the visual influence observed for pluck-bow stimuli. This result could be interpreted to suggest that the nonspeech visual influence was not a true McGurk effect. In a third experiment, visual stimuli consisting of the wordspluck andbow were found to have no influence over auditory pluck and bow judgments. This result could suggest that the nonspeech effects found in Experiment 1 were based on the audio and visual information’s having an ostensive lawful relation to the specified event. These results are discussed in terms of motor-theory, ecological, and FLMP approaches to speech perception.  相似文献   
44.
When an observer views a moving scene binocularly, both motion parallax and binocular disparity provide depth information. In Experiments lA-1C, we measured sensitivity to surface curvature when these depth cues were available either individually or simultaneously. When the depth cues yielded comparable sensitivity to surface curvature, we found that curvature detection was easier with the cues present simultaneously, rather than individually. For 2 of the 6 subjects, this effect was stronger when the component of frontal translation of the surface was vertical, rather than horizontal. No such anisotropy was found for the 4 other subjects. If a moving object is observed binocularly, the patterns of optic flow are different on the left and right retinae. We have suggested elsewhere (Cornilleau-Pérès & Droulez, in press) that this motion disparity might be used as avisual cue for the perception of a 3-D structure. Our model consisted in deriving binocular disparity from the left and right distributions of vertical velocities, rather than from luminous intensities, as has been done in classical studies on stereoscopic vision. The model led to some predictions concerning the detection of surface curvature from motion disparity in the presence or absence of intensity-based disparity (classically termedbinocular disparity). In a second set of experiments, we attempted to test these predictions, and we failed to validate our theoretical scheme from a physiological point of view.  相似文献   
45.
The present research focused on power processes in a simulated organizational structure consisting of three hierarchical levels occupied by different numbers of mules and females. Subjects were presented with a chart showing the organizational hierarchy of which they were a member placed at the lowest level, and asked to nominate any person for the leader position vacated by the current incumbent. The results of Experiment I (n = 88 Dutch male and female university students) showed that male subjects strongly overnominated themselves, whereas a majority of the female subjects nominated either self or another female. Of the others that were nominated by both males and females, almost all were occupants of positions immediately below the leader position, indicating the normative influence of a bureaucratic rule of leader succession. Experiment 2 was a replicational study carried out in a different culture (n = lOl Polish male and female university students). Polish subjects adhered to the bureaucratic rule more strongly than their Dutch counterparts, and both females and males nominated mostly males. Results are discussed with reference to gender self-stereotypes and cultural differences.  相似文献   
46.
The Priestley duality for Wajsberg algebras   总被引:1,自引:1,他引:0  
The Priestley duality for Wajsberg algebras is developed. The Wajsberg space is a De Morgan space endowed with a family of functions that are obtained in rather natural way.As a first application of this duality, a theorem about unicity of the structure is given.  相似文献   
47.
Tested a 7-month, media-based, community intervention among Hispanics in San Francisco designed to change levels of information on the damaging effects of cigarette smoking and on the availability of culturally appropriate cessation services. Three community-wide surveys of Hispanics were conducted with independent random samples, two as baselines (n = 1,660 and 2,053) and one postintervention (n = 1,965). Results showed that changes in the level of awareness of cessation services had taken place after implementation of the intervention. Furthermore, those changes took place primarily among the less acculturated Spanish-speaking Hispanics who were the target of the intervention. The changes in information reported here demonstrate that a culturally appropriate information dissemination campaign that utilizes multiple channels can produce changes in a community's level of information even when the campaign is implemented for a relatively short period.  相似文献   
48.
49.
50.
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