全文获取类型
收费全文 | 244340篇 |
免费 | 20287篇 |
国内免费 | 8192篇 |
专业分类
电工技术 | 37552篇 |
技术理论 | 30篇 |
综合类 | 26661篇 |
化学工业 | 11148篇 |
金属工艺 | 9399篇 |
机械仪表 | 22769篇 |
建筑科学 | 19658篇 |
矿业工程 | 10419篇 |
能源动力 | 9382篇 |
轻工业 | 5507篇 |
水利工程 | 6859篇 |
石油天然气 | 7239篇 |
武器工业 | 3985篇 |
无线电 | 23571篇 |
一般工业技术 | 12672篇 |
冶金工业 | 7334篇 |
原子能技术 | 2532篇 |
自动化技术 | 56102篇 |
出版年
2025年 | 1420篇 |
2024年 | 3738篇 |
2023年 | 3536篇 |
2022年 | 4970篇 |
2021年 | 5889篇 |
2020年 | 6403篇 |
2019年 | 4742篇 |
2018年 | 4223篇 |
2017年 | 5787篇 |
2016年 | 6948篇 |
2015年 | 7905篇 |
2014年 | 14632篇 |
2013年 | 12486篇 |
2012年 | 17052篇 |
2011年 | 17943篇 |
2010年 | 13670篇 |
2009年 | 13646篇 |
2008年 | 13905篇 |
2007年 | 17820篇 |
2006年 | 16071篇 |
2005年 | 14408篇 |
2004年 | 11808篇 |
2003年 | 10646篇 |
2002年 | 8122篇 |
2001年 | 6871篇 |
2000年 | 5643篇 |
1999年 | 4590篇 |
1998年 | 3435篇 |
1997年 | 2805篇 |
1996年 | 2466篇 |
1995年 | 2115篇 |
1994年 | 1750篇 |
1993年 | 1146篇 |
1992年 | 989篇 |
1991年 | 714篇 |
1990年 | 583篇 |
1989年 | 490篇 |
1988年 | 344篇 |
1987年 | 196篇 |
1986年 | 120篇 |
1985年 | 125篇 |
1984年 | 111篇 |
1983年 | 98篇 |
1982年 | 78篇 |
1981年 | 66篇 |
1980年 | 53篇 |
1979年 | 46篇 |
1978年 | 34篇 |
1977年 | 28篇 |
1976年 | 23篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
101.
周斌 《西华大学学报(自然科学版)》2012,(6):39-42
将P系统引入到图像阈值分割中,提出了一种基于P系统的图像阈值分割方法。采用一个两层膜的组织型P系统作为其计算框架,每个膜作为独立的并行计算单元,速度一位置模型作为进化规则,同时采用同向/反向转运规则交换和共享膜之间的对象。实验结果表明,这个基于P系统框架的阈值分割方法具有可用性和有效性,能为图像寻找最优的分割阈值。 相似文献
102.
103.
In recent years, educators and students are increasingly employing online collaboration applications such as Google Docs™ and PBWorks™ for group projects and assignments. Yet, the effectiveness of these emerging technologies has not been rigorously examined. Anchoring upon and informed by the existing literature, two design characteristics – sociability and visibility, and two human characteristics – gender and age, are focused on, which are salient in online collaboration applications. A field experiment was conducted to examine the direct and moderating effects of design and human characteristics on learning outcomes. The research found that sociability improved process satisfaction and positive social environment while visibility enhanced academic performance and solution satisfaction of learners. Males had higher solution satisfaction while older learners had higher academic performance. Moderating effects were also found. Both theoretical and practical implications are drawn. In particular, a rubric for online collaboration application selection for academic performance is conceived. This study provides empirical support for online collaboration application effectiveness in education which will augur well for future adoption, use and evolution. 相似文献
104.
Nguyen Quoc Dinh Author VitaeDong-Sung KimAuthor Vitae 《Computer Standards & Interfaces》2012,34(1):117-123
The International Society of Automation recently released ISA100.11a as an open standard for reliable wireless networks for industrial automation. ISA100.11a uses the TDMA scheme in the medium access layer to provide deterministic services. However, ISA100.11a adopts the CSMA-CA mechanism with priorities for retransmission from failure on dedicated links, sporadic data, and network configuration.This paper evaluates ISA100.11a CSMA-CA by simulation, considering the effects of backoff procedures and priority settings to probability of collision and successful use of slots. It's demonstrated that a high number of priority classes enable better network utilization resulting in less number of packets exceeding their lifetime. 相似文献
105.
《国际计算机数学杂志》2012,89(17):2374-2384
In this paper, we derive the piecewise linear system (PLS) associated with the bilateral obstacle problem and illustrate the equivalence between the linear system and finite-dimensional complementary problem. The existence and the uniqueness of the solution to the PLS are also demonstrated. Based on the PLS, a Picard iterative algorithm is proposed. The convergence analysis is given and examples are presented to verify the effectiveness of the method. 相似文献
106.
《国际计算机数学杂志》2012,89(11):2275-2284
The hypermeshes are a family of promising optical interconnection topologies for multiprocessor systems. In this paper, the conditional diagnosability of the hypermesh optical multiprocessor systems, under the PMC model, is determined. We derive that the conditional diagnosability of k n -hypermesh is 4n(k?1)?4k+1, where n≥3 and k≥5. This result shows that the hypermesh optical multiprocessor systems possess strong self-diagnosing abilities. 相似文献
107.
《Behaviour & Information Technology》2012,31(1):21-31
This paper presents a semiotic technique as a means of exploring meaning and understanding in interface design and use. This is examined through a study of the interaction between the ‘file’ metaphor and ‘save as’ command metaphor. The behaviour of these (from a functional or computational basis) do not exactly match, or map onto, the meaning of the metaphor. We examine both the denotation of a term to the user, i.e. its literal meaning to that person, and the term's connotations, i.e. any other meanings associated with the term. We suggest that the technique applied is useful in predicting future problems with understanding the use of metaphor at the interface and with designing appropriate signification for human-computer interaction. Variation in connotation was expected but a more fundamental difference in denotation was also uncovered. Moreover, the results clearly demonstrate that consistency in the denotation of a term is critical in achieving a good user understanding of the command. 相似文献
108.
为提高动力电池使用效率,提出了一种基于FPGA的动力电池检测系统的设计方案.采用AD转换芯片实现对电池电压、电流的采集,数字温度传感器对温度进行采集,再通过软件实现对数据的处理和实时显示.系统运行稳定,数据处理能力强,集成度高,易于扩展. 相似文献
109.
杨更 《湖南工业职业技术学院学报》2013,(6):20-22
本文为主要介绍,基于B/S结构,设计和开发网络版的读者问卷调查系统,此系统对调查问卷结果的分析和统计做出详细的描述,通过和图书馆其它系统的联合使用,形成特有的读者问卷调查反馈服务平台,本文参与“‘网络环境下高校用户信息行为实证研究”课题立项的研究。 相似文献
110.
水电站机电工程质量控制,对确保按照设计质量要求生产供货、按照规范标准安装试验、确保电站安全稳定运行、提高经济收益有着重要的意义。但是,质量控制是一个系统全面、不断进步的工作,需要我们不断探索,不断进步。 相似文献