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   1524篇
  免费   159篇
  国内免费   353篇
  2024年   4篇
  2023年   20篇
  2022年   36篇
  2021年   65篇
  2020年   64篇
  2019年   43篇
  2018年   75篇
  2017年   69篇
  2016年   71篇
  2015年   50篇
  2014年   61篇
  2013年   137篇
  2012年   96篇
  2011年   113篇
  2010年   106篇
  2009年   107篇
  2008年   125篇
  2007年   154篇
  2006年   154篇
  2005年   109篇
  2004年   77篇
  2003年   57篇
  2002年   42篇
  2001年   23篇
  2000年   25篇
  1999年   23篇
  1998年   25篇
  1997年   15篇
  1996年   9篇
  1995年   11篇
  1994年   4篇
  1993年   5篇
  1992年   8篇
  1991年   4篇
  1990年   1篇
  1989年   10篇
  1988年   6篇
  1987年   5篇
  1986年   5篇
  1985年   2篇
  1984年   5篇
  1983年   1篇
  1982年   2篇
  1981年   3篇
  1980年   3篇
  1979年   3篇
  1973年   1篇
  1970年   1篇
  1966年   1篇
排序方式: 共有2036条查询结果,搜索用时 15 毫秒
831.
Work function (WF) can be measured using the Kelvin probe (KP) technique to characterize surface behavior of micro/nanostructures grown on substrates such as metals or semiconductors. However, for such micro/nanostructures, substrates with different WF can strongly affect the measurements if they are exposed directly to face the Kevin probe tip. In this article, a model is proposed to investigate the WF of sparse ZnO nanorods grown on an Si substrate. It is demonstrated that theoretical results from the model are consistent with experimental observations performed using a KP system.  相似文献   
832.
Transformation and misfit dislocations are used to describe the motion of glissile interfaces with one set of misfit dislocations in the framework of the Frank?Bilby equation. The sweep of these glissile interfaces brings about an invariant-plane-strain type shape deformation. Our approach explains the glissile motion of martensitic interfaces and small-angle symmetrical tilt grain boundaries. It is consistent with the phenomenological theory of martensite crystallography but more flexible.  相似文献   
833.
The effect of chamber gas pressure on the amorphicity of Al85Ni5Y10 alloy was studied for the melt-spinning process. The amorphicity of as-quenched ribbons was characterized by X-ray diffraction (XRD) and differential scanning calorimetry (DSC). The chamber atmosphere pressure is crucial to the cooling rate of melt spinning. At high vacuum, at pressure less than 0.001?atm, fully crystalline fragments are obtained. Monolithic amorphous ribbons were only obtained at a gas pressure of 0.1?atm, 0.2?atm or higher. The extended contact length between ribbons and the copper wheel contributes to the high cooling rate of melt spinning in Al-based glass forming alloys; that is supported by images recorded by a high-speed camera. Higher chamber pressure increases contact length between ribbons and the wheel, which is qualitatively elucidated by Bernoulli's equation.  相似文献   
834.

The alpha -> beta polytypic transformation in SiC was observed during ball milling at room temperature. Microstructural evolution was characterized on an atomic scale by high-resolution electron microscopy (HREM). HREM observations showed that partial dislocations play an important role in the transformation under the complicated conditions during ball milling.  相似文献   
835.
杨泽波 《哲学研究》2013,(1):37-43,127,128
在建构道德存有论的过程中,牟宗三非常重视"觉他"的思维方式问题,认为这种思维方式即是康德所说的智的直觉。康德不承认人类可以有智的直觉,儒家则承认人完全可以有这种能力,所以儒家超越了康德。牟宗三这一观点在学界影响很大,人们一般都是从正面理解,目前尚无人系统而明  相似文献   
836.
Despite the increased use of sensor technologies, including unmanned vehicles, the vast majority of improvised explosive device (IED) detections are made by human vision. Thus, TRAC-Monterey developed a simulation-based training prototype called the perceptual learning trainer (PLT). Fourteen novice and 5 expert IED detectors participated in human-in-the-loop experiments in which all participants were trained using the PLT tool while their eye-movement and IED detection performance were tracked in real-time. A series of 100 IED images with various degrees of difficulty was used for the training session. Pre- and posttraining assessments were conducted. Both speed and accuracy improved after just 1 session of the PLT training: RT decreased by 3.7 s for novices (p < .001) and 3.4 s for experts (p = .031), and detection probability increased by 5.9% for novices (p = .001). The PLT tool improved IED detection performance more in novice IED detectors than in experts. Novices and experts showed different visual scan patterns.  相似文献   
837.
This fMRI study explores how nonlinguistic cues modulate lexical activation in the bilingual brain. We examined the influence of face race on bilingual language production in a picture-naming paradigm. Chinese–English bilinguals were presented with pictures of objects and images of faces (Asian or Caucasian). Participants named the picture in their first or second language (Chinese or English) in separate blocks. Face race and naming language were either congruent (e.g., naming in Chinese when seeing an Asian face) or incongruent (e.g., naming in English when seeing an Asian face). Our results revealed that face cues facilitate naming when the socio-cultural identity of the face is congruent with the naming language. The congruence effects are reflected as effective integration of lexical and facial cues in key brain regions including IFG, MFG, ACC, and caudate. Implications of the findings in light of theories of language processing and cultural priming are discussed.  相似文献   
838.
Five experiments were conducted to investigate infants’ ability to transfer actions learned via imitation to new objects and to examine what components of the original context are critical to such transfer. Infants of 15 months observed an experimenter perform an action with one or two toys and then were offered a novel toy that was not demonstrated for them. In all experiments, infants performed target actions with the novel toy more frequently than infants who were offered the same toy but had seen no prior demonstrations. Infants exhibited transfer even when the specific part to be manipulated looked different across the toys, even when they had not performed the actions with the demonstration toys themselves, even when the actions produced no effects on the demonstrations, and even when the actions were demonstrated with only a single exemplar toy. Transfer was especially robust when infants not only observed but also practiced the target actions on the demonstration trials. Learning action affordances (“means”) seems to be a central aspect of human imitation, and the propensity to apply these learned action affordances in new object contexts may be an important basis for technological innovation and invention.  相似文献   
839.
In this paper, we aimed to verify the emotional facilitation effect in the picture–word interference task using event-related potentials. Twenty-one healthy subjects were asked to categorize the emotional valences of pictures accompanied by emotionally congruent, either centrally or laterally positioned Chinese words. For both the foveal and lateral word presentations, the reaction times were faster compared to the picture-only presentation. Compared to the picture-only presentation, P200 amplitude increased under the foveal word presentation condition and decreased under the lateral word presentation condition, indicating that more attentional resources were required when an accompanying word was in the center of a picture than when the word was in the lateral position. Latency of P300 was shorter in response to picture–word stimuli irrespective of word position, indicating that an emotionally congruent word facilitated the emotional processing of the target picture, which verified the emotional facilitation effect and was consistent with the results in psychology. The late positive component was more positive when the picture–word stimuli were more positive, which reflected the feature of positivity offset. The findings suggest that the time window for an emotional facilitation effect may be limited to processing aspects associated with P300 (i.e., affective evaluation).  相似文献   
840.
Judging similarities among objects, events, and experiences is one of the most basic cognitive abilities, allowing us to make predictions and generalizations. The main assumption in similarity judgment is that people selectively attend to salient features of stimuli and judge their similarities on the basis of the common and distinct features of the stimuli. However, it is unclear how people select features from stimuli and how they weigh features. Here, we present a computational method that helps address these questions. Our procedure combines image-processing techniques with a machine-learning algorithm and assesses feature weights that can account for both similarity and categorization judgment data. Our analysis suggests that a small number of local features are particularly important to explain our behavioral data.  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