全文获取类型
收费全文 | 10240篇 |
免费 | 1391篇 |
国内免费 | 1086篇 |
专业分类
电工技术 | 897篇 |
技术理论 | 1篇 |
综合类 | 1081篇 |
化学工业 | 131篇 |
金属工艺 | 60篇 |
机械仪表 | 433篇 |
建筑科学 | 402篇 |
矿业工程 | 104篇 |
能源动力 | 202篇 |
轻工业 | 72篇 |
水利工程 | 679篇 |
石油天然气 | 126篇 |
武器工业 | 127篇 |
无线电 | 2090篇 |
一般工业技术 | 584篇 |
冶金工业 | 919篇 |
原子能技术 | 18篇 |
自动化技术 | 4791篇 |
出版年
2024年 | 68篇 |
2023年 | 211篇 |
2022年 | 326篇 |
2021年 | 368篇 |
2020年 | 383篇 |
2019年 | 346篇 |
2018年 | 313篇 |
2017年 | 400篇 |
2016年 | 453篇 |
2015年 | 524篇 |
2014年 | 769篇 |
2013年 | 756篇 |
2012年 | 892篇 |
2011年 | 893篇 |
2010年 | 667篇 |
2009年 | 673篇 |
2008年 | 682篇 |
2007年 | 713篇 |
2006年 | 542篇 |
2005年 | 492篇 |
2004年 | 424篇 |
2003年 | 372篇 |
2002年 | 274篇 |
2001年 | 214篇 |
2000年 | 144篇 |
1999年 | 115篇 |
1998年 | 115篇 |
1997年 | 84篇 |
1996年 | 65篇 |
1995年 | 58篇 |
1994年 | 39篇 |
1993年 | 40篇 |
1992年 | 26篇 |
1991年 | 19篇 |
1990年 | 16篇 |
1989年 | 19篇 |
1988年 | 12篇 |
1987年 | 7篇 |
1986年 | 12篇 |
1985年 | 15篇 |
1983年 | 8篇 |
1980年 | 8篇 |
1966年 | 10篇 |
1965年 | 8篇 |
1964年 | 17篇 |
1963年 | 18篇 |
1962年 | 9篇 |
1961年 | 8篇 |
1959年 | 12篇 |
1956年 | 12篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
22.
Four experiments investigated the effect of recent selective practice on the cost of switching between 2 tasks afforded by letter-digit pairs: alphabet arithmetic and shape comparison. Experiments 1 and 2 found a greater cost associated with switching to the more recently practiced task: evidence that task-set inertia contributes to switching costs. Experiment 3 found this effect to be limited to trials on which a recently trained stimulus followed another such stimulus: a result problematic for all current theories of task-set priming. Experiment 4 showed that the effect of recent practice was eliminated by active preparation for a task switch: It appears that endogenous task-set preparation reduces the effects of task-set inertia. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
23.
Hovius Marjolijn; Kellenbach Marion L.; Graham Kim S.; Hodges John R.; Patterson Karalyn 《Canadian Metallurgical Quarterly》2003,17(1):100
The authors investigated the impact of semantic knowledge on visual object analysis by assessing the performance of patients with semantic dementia on a different-views object matching test and on 2 object decision tests differing, for example, in whether the nonreal items were nonsense objects or chimeras of 2 real objects. On average, the patients scored normally on both the object matching and the object decision test including nonsense objects but were impaired on the object decision test including chimeras; this latter was also the only visual object test that correlated significantly with degree of semantic impairment. These findings demonstrate that object decision is not a single task or ability and that it is not necessarily independent of conceptual knowledge. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
24.
陈恒庆 《冶金标准化与质量》2004,42(1):54-57
根据美国国家标准学会 (ANSI)理事会主席、ISO现任主席OliverR .Smoot在日本东京召开的国际标准化协议会上的讲演整理。 相似文献
25.
A task-switching paradigm with a 2:1 mapping between cues and tasks was used to separate cue-switching processes (indexed through pure cue-switch costs) from actual task-switching processes (indexed through additional costs in case of cue and task changes). A large portion of total switch costs was due to cue changes (Experiments 1 and 2), and cue-switch costs but not task-switch costs were sensitive to effects of practice (Experiment 1) and preparation (Experiment 2). In contrast, task-switch costs were particularly sensitive to response-priming effects (Experiments 1 and 2) and task-set inhibition (Experiment 3). Results suggest two processing stages relevant during task-set selection: cue-driven retrieval of task rules from long-term memory and the automatic application of rules to a particular stimulus situation. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
26.
随着无线网络所支持的业务种类的增加和具有弹性服务质量要求的业务的大量出现,与服务质量保证密切相关的呼叫接纳控制问题成了近年来无线网络研究的热点之一。本文研究了基于准马尔可夫决策过程方法的多业务最优呼叫接纳控制问题。根据业务的特点,首先引入了带宽分配满意度函数和收益率函数,在此基础上,提出了基于带宽分配满意度的最优带宽分配算法和基于准马尔可夫决策过程方法的最优呼叫接纳控制策略。计算结果表明,本文方案能够在对各类业务的呼叫阻塞率进行适当权衡的前提下,进一步提高网络的期望收益率和期望带宽利用率,同时满足了各类业务的最低服务质量要求。 相似文献
27.
28.
29.
Jules Sadefo Kamdem 《Computing and Visualization in Science》2007,10(4):197-210
In this paper, we generalize the Linear VaR method from portfolios with normally distributed risk factors to portfolios with
mixture of elliptically distributed ones. We treat both the Expected Shortfall and the Value-at-Risk of such portfolios. Special
attention is given to the particular case of a mixture of multivariate t-distributions.
This is a part of J. SADEFO-KAMDEM PhD Thesis[12] of the Université de Reims, France . It has been presented at the workshop
on modelling and computation in Financial Engineering at Bad Herrenalb, Germany May 6-8, 2003. The author is an associate
professor at the Department of mathematics, université d’Evry Val d’Essonne. 相似文献
30.
This study examined whether objects are attended in serial or in parallel during a demanding visual search task. A component of the event-related potential waveform, the N2pc wave, was used as a continuous measure of the allocation of attention to possible targets in the search arrays. Experiment 1 demonstrated that the relative allocation of attention shifts rapidly, favoring one item and then another. In Experiment 2, a paradigm was used that made it possible to track the absolute allocation of attention to individual items. This experiment showed that attention was allocated to one object for 100-150 ms before attention began to be allocated to the next object. These findings support models of attention that posit serial processing in demanding visual search tasks. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献