全文获取类型
收费全文 | 7359篇 |
免费 | 803篇 |
国内免费 | 393篇 |
学科分类
工业技术 | 8555篇 |
出版年
2024年 | 25篇 |
2023年 | 97篇 |
2022年 | 140篇 |
2021年 | 195篇 |
2020年 | 210篇 |
2019年 | 200篇 |
2018年 | 165篇 |
2017年 | 221篇 |
2016年 | 264篇 |
2015年 | 263篇 |
2014年 | 441篇 |
2013年 | 462篇 |
2012年 | 556篇 |
2011年 | 523篇 |
2010年 | 369篇 |
2009年 | 427篇 |
2008年 | 373篇 |
2007年 | 521篇 |
2006年 | 422篇 |
2005年 | 364篇 |
2004年 | 313篇 |
2003年 | 307篇 |
2002年 | 314篇 |
2001年 | 272篇 |
2000年 | 194篇 |
1999年 | 158篇 |
1998年 | 109篇 |
1997年 | 106篇 |
1996年 | 92篇 |
1995年 | 78篇 |
1994年 | 84篇 |
1993年 | 56篇 |
1992年 | 44篇 |
1991年 | 45篇 |
1990年 | 38篇 |
1989年 | 26篇 |
1988年 | 20篇 |
1987年 | 16篇 |
1986年 | 8篇 |
1985年 | 2篇 |
1984年 | 10篇 |
1983年 | 2篇 |
1982年 | 3篇 |
1981年 | 2篇 |
1980年 | 7篇 |
1975年 | 2篇 |
1963年 | 2篇 |
1961年 | 1篇 |
1959年 | 1篇 |
1955年 | 1篇 |
排序方式: 共有8555条查询结果,搜索用时 0 毫秒
1.
Beebe-Frankenberger Margaret; Bocian Kathleen M.; MacMillan Donald L.; Gresham Frank M. 《Canadian Metallurgical Quarterly》2004,96(2):204
A cohort of 2nd-grade students provided comparisons of academic and social competence based on school retention/promotion decisions. Sample groups were (a) retained, (b) at risk for retention, (c) special education, and (d) promoted. Findings suggested most children with academic deficiencies are identified by schools early and are sorted into educational treatments differing in intensity that represent a continuum of competence. The authors provide empirical evidence counter to the assumptions that retained students have the requisite ability to catch up and have more problem behaviors than other low-achieving students. The relevance of high-stakes test scores for promotion/retention decisions and the parallels between schools' implementation of retention policy and implementation of regulations for identifying children with disabilities are included in the discussion. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
3.
4.
The acquisition of new skills over a life span is a remarkable human ability. This ability, however, is constrained by age of acquisition (AoA); that is, the age at which learning occurs significantly affects the outcome. This is most clearly reflected in domains such as language, music, and athletics. This article provides a perspective on the neural and computational mechanisms underlying AoA in language acquisition. The authors show how AoA modulates both monolingual lexical processing and bilingual language acquisition. They consider the conditions under which syntactic processing and semantic processing may be differentially sensitive to AoA effects in second-language acquisition. The authors conclude that AoA effects are pervasive and that the neural and computational mechanisms underlying learning and sensorimotor integration provide a general account of these effects. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
5.
6.
介绍了二次盐水及离子膜电解工序的主要设备和流程,对二次盐水及离子膜电解工序运行中出现的问题进行了分析,并提出了解决措施。 相似文献
7.
Braithwaite Jason J.; Humphreys Glyn W.; Hodsoll John 《Canadian Metallurgical Quarterly》2003,29(4):758
Five experiments addressed the role of color grouping in preview search (D. G. Watson & G. W. Humphreys, 1997). Experiment 1 used opposite color ratios of distractors in preview and second search displays, creating equal numbers of distractors in each color group in the final display. There was selective slowing for new targets carrying the majority color of the old items. This effect held when there was no bias in the preview and only the second search set had an uneven color ratio (Experiment 2). In Experiment 3, participants had foreknowledge of the target color, and effects were shown over and above those due to color biases. Experiment 4 demonstrated negative color carryover even when previews changed color. Experiment 5 showed reduced color carryover effects when previews were presented more briefly. Collectively, the results provide evidence for inhibitory carryover effects in preview search based on feature grouping. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
8.
9.
城市二次加压供水设施污染的防治与对策 总被引:2,自引:2,他引:0
从设计、施工、管理等方面,分析了城市二次加压设施污染的原因,提出设计及施工中的防治对策及二次加压设施管理上的对策,以确保城市安全供水。 相似文献
10.
Learning a sequence of target locations when the sequence is uncorrelated with a sequence of responses and target location is not the response dimension (pure perceptual-based sequence learning) was examined. Using probabilistic sequences of target locations, the author shows that such learning can be implicit, is unaffected by distance between target locations, and is mostly limited to first-order transition probabilities. Moreover, the mechanism underlying learning affords processing of information at anticipated target locations and appears to be attention based. Implications for hypotheses of implicit sequence learning are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献