全文获取类型
收费全文 | 6723篇 |
免费 | 1034篇 |
国内免费 | 721篇 |
专业分类
电工技术 | 272篇 |
综合类 | 688篇 |
化学工业 | 170篇 |
金属工艺 | 123篇 |
机械仪表 | 417篇 |
建筑科学 | 391篇 |
矿业工程 | 94篇 |
能源动力 | 32篇 |
轻工业 | 194篇 |
水利工程 | 45篇 |
石油天然气 | 60篇 |
武器工业 | 67篇 |
无线电 | 849篇 |
一般工业技术 | 796篇 |
冶金工业 | 1161篇 |
原子能技术 | 18篇 |
自动化技术 | 3101篇 |
出版年
2024年 | 73篇 |
2023年 | 194篇 |
2022年 | 269篇 |
2021年 | 313篇 |
2020年 | 318篇 |
2019年 | 275篇 |
2018年 | 254篇 |
2017年 | 225篇 |
2016年 | 305篇 |
2015年 | 269篇 |
2014年 | 372篇 |
2013年 | 403篇 |
2012年 | 454篇 |
2011年 | 505篇 |
2010年 | 468篇 |
2009年 | 458篇 |
2008年 | 443篇 |
2007年 | 456篇 |
2006年 | 396篇 |
2005年 | 362篇 |
2004年 | 315篇 |
2003年 | 247篇 |
2002年 | 228篇 |
2001年 | 199篇 |
2000年 | 129篇 |
1999年 | 91篇 |
1998年 | 57篇 |
1997年 | 43篇 |
1996年 | 52篇 |
1995年 | 27篇 |
1994年 | 27篇 |
1993年 | 18篇 |
1992年 | 15篇 |
1991年 | 13篇 |
1990年 | 13篇 |
1989年 | 13篇 |
1988年 | 9篇 |
1985年 | 14篇 |
1984年 | 13篇 |
1975年 | 7篇 |
1966年 | 9篇 |
1965年 | 8篇 |
1964年 | 16篇 |
1963年 | 7篇 |
1962年 | 6篇 |
1961年 | 6篇 |
1958年 | 10篇 |
1956年 | 9篇 |
1955年 | 15篇 |
1954年 | 7篇 |
排序方式: 共有8478条查询结果,搜索用时 0 毫秒
991.
Studies of anxiety suggest that threat stimuli can be identified preattentively, but this conclusion is questionable because of possible low-level perceptual confounds. Two experiments used visual search tasks in which abstract shapes were conditioned to carry neutral or negative valence. Experiment 1 found generally faster responses to threat-associated abstract stimuli but no evidence that they were detected preattentively, irrespective of trait anxiety level. A similar pattern was found in Experiment 2, in which individuals high in snake or spider fear showed no evidence of preattentive detection of abstract stimuli associated with their feared object. In contrast, implicit behavioral measures showed significant effects of conditioning, demonstrating that targets associated with threat were negatively evaluated in these experiments. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
992.
993.
Eight experiments examined the conditions under which a color singleton that is presented for the 1st time without prior announcement captures attention. The main hypothesis is that an unannounced singleton captures attention to the extent that it deviates from expectations. This hypothesis was tested within a visual-search paradigm in which set-size effects were used to infer attentional capture. The results showed that attentional capture by an unannounced color singleton was due to a mismatch with expectations concerning the color of the object and not due to its being a singleton. Thus, the results imply that theories of attention have to consider expectation discrepancy as a determinant of attention shifts. (PsycINFO Database Record (c) 2011 APA, all rights reserved) 相似文献
994.
Two studies investigated the effects of conditioning to masked stimuli on visuospatial attention. During the conditioning phase, masked snakes and spiders were paired with a burst of white noise, or paired with an innocuous tone, in the conditioned stimulus (CS)+ and CS- conditions, respectively. Attentional allocation to the CSs was then assessed with a visual probe task, in which the CSs were presented unmasked (Experiment 1) or both unmasked and masked (Experiment 2), together with fear-irrelevant control stimuli (flowers and mushrooms). In Experiment 1, participants preferentially allocated attention to CS+ relative to control stimuli. Experiment 2 suggested that this attentional bias depended on the perceived aversiveness of the unconditioned stimulus and did not require conscious recognition of the CSs during both acquisition and expression. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
995.
A novel effect is reported in which serial recall of visual digits was disrupted to a greater degree by the presence of the same set of digits presented as an irrelevant auditory sequence than by the presence of irrelevant auditory consonants, but only when the order of the irrelevant digits was incongruent with that of the to-be-remembered digits (Experiment 1). Experiment 2 replicated this order-incongruence effect and showed also that disruption was dictated by the number of order-incongruent transitions but not by the number of novel tokens contained within the irrelevant sequence. The results favor an interference-by- process approach to the disruption of serial memory by irrelevant sound over approaches based on notions of interference by content and/or interference by depletion of attentional resources. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
996.
Madden David J.; Whiting Wythe L.; Spaniol Julia; Bucur Barbara 《Canadian Metallurgical Quarterly》2005,20(2):317
Two experiments investigated adult age differences in the explicit (knowledge-based) and implicit (repetition priming) components of top-down attentional guidance during discrimination of a target singleton. Experiment 1 demonstrated an additional contribution of explicit top-down attention, relative to the implicit effect of repetition priming, which was similar in magnitude for younger and older adults. Experiment 2 examined repetition priming of target activation and distractor inhibition independently. The additional contribution of explicit top-down attention, relative to the repetition priming of distractor inhibition, was greater for older adults than for younger adults. The results suggest that some forms of top-down attentional control are preserved as a function of adult age and may operate in a compensatory manner. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
997.
Grounding language in perception 总被引:1,自引:0,他引:1
Jeffrey Mark Siskind 《Artificial Intelligence Review》1994,8(5-6):371-391
This paper describes an implemented computer program that recognizes the occurrence of simple spatial motion events in simulated video input. The program receives an animated line-drawing as input and produces as output a semantic representation of the events occurring in that animation. This paper suggests that the notions ofsupport, contact, andattachment are crucial to specifying many simple spatial motion event types and presents a logical notation for describing classes of events that incorporates such notions as primitives. It then suggests that the truth values of such primitives can be recovered from perceptual input by a process of counterfactual simulation, predicting the effect of hypothetical changes to the world on the immediate future. Finally, it suggests that such counterfactual simulation is performed using knowledge of naive physical constraints such assubstantiality, continuity, gravity, andground plane. This paper describes the algorithms that incorporate these ideas in the program and illustrates the operation of the program on sample input. 相似文献
998.
水利水电工程土石方开挖可视化设计方法初探 总被引:6,自引:0,他引:6
土石方开挖是施工组织设计中的重要组成部分,它对土石方工程的概预算、施工的进度安排以及土石方工程填挖平衡的设计都有很大的影响。传统的土石方设计方法由于平面地形图可视性差以及求各网格点高程值的烦琐性,使得这项工作量很大,并且有时会因为网格划分的不合理,而产生较大的误差。为此,本提出土石方开挖的可视化设计方法,该方法弥补了传统方法的不足,能够很好地满足设计需要;同时,计算结果提供的土石方开挖后形态仿真图,能够呈现不同项目、开挖部位及断面特征(坡度),可以为组织开挖工程设计提供可视化决策信息。 相似文献
999.
Neglect is an acquired cognitive disorder characterized by a lack of processing of one side of a stimulus or representational space. There are hemispheric asymmetries in its cause and in its effects, but implemented computational models of neglect have tended not to incorporate this fact. The authors report a series of neural network simulations of the line-bisection task. They test the hypothesis that simple, neuroanatomically realistic principles of connectivity in the nervous system can produce emergent behaviors that capture a wide range of quantitative and qualitative data observed in neglect patients presenting with general visuospatial neglect. They demonstrate that exploring low-level architectural principles in implemented computational models is both a productive avenue of research and offers the most parsimonious explanations of behaviors observed in patients. (PsycINFO Database Record (c) 2011 APA, all rights reserved) 相似文献
1000.
Miltner Wolfgang H. R.; Krieschel Silke; Hecht Holger; Trippe Ralf; Weiss Thomas 《Canadian Metallurgical Quarterly》2004,4(4):323
Spider-phobic and nonphobic subjects searched for a feared/fear-relevant (spider) or neutral target (mushroom) presented in visual matrices of neutral objects (flowers). In half of the displays, the mushroom target was paired with a spider distractor, or a spider target was paired with a mushroom distractor. Although all subjects responded faster to the neutral target than to the feared/fear-relevant target, phobics were slower to respond than nonphobics when a mushroom target was presented with a spider distractor. Their eyes appeared to be drawn to the feared distractor before fixating neutral targets. A further experiment indicated no group differences when subjects merely judged the homogeneity of matrices. Thus, threat seems to capture the attention of phobics only when it is part of a background that subjects are explicitly instructed to ignore. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献