全文获取类型
收费全文 | 504篇 |
免费 | 69篇 |
国内免费 | 41篇 |
专业分类
电工技术 | 45篇 |
综合类 | 36篇 |
化学工业 | 87篇 |
金属工艺 | 1篇 |
机械仪表 | 13篇 |
建筑科学 | 36篇 |
矿业工程 | 9篇 |
能源动力 | 5篇 |
轻工业 | 96篇 |
水利工程 | 6篇 |
石油天然气 | 30篇 |
武器工业 | 2篇 |
无线电 | 30篇 |
一般工业技术 | 42篇 |
冶金工业 | 7篇 |
原子能技术 | 4篇 |
自动化技术 | 165篇 |
出版年
2024年 | 2篇 |
2023年 | 5篇 |
2022年 | 13篇 |
2021年 | 12篇 |
2020年 | 16篇 |
2019年 | 17篇 |
2018年 | 7篇 |
2017年 | 22篇 |
2016年 | 26篇 |
2015年 | 25篇 |
2014年 | 31篇 |
2013年 | 40篇 |
2012年 | 38篇 |
2011年 | 37篇 |
2010年 | 20篇 |
2009年 | 30篇 |
2008年 | 28篇 |
2007年 | 36篇 |
2006年 | 35篇 |
2005年 | 22篇 |
2004年 | 16篇 |
2003年 | 29篇 |
2002年 | 19篇 |
2001年 | 20篇 |
2000年 | 16篇 |
1999年 | 15篇 |
1998年 | 11篇 |
1997年 | 4篇 |
1996年 | 5篇 |
1995年 | 2篇 |
1994年 | 2篇 |
1993年 | 4篇 |
1992年 | 2篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1989年 | 2篇 |
1986年 | 1篇 |
1983年 | 1篇 |
1959年 | 1篇 |
排序方式: 共有614条查询结果,搜索用时 15 毫秒
1.
Polarity Effect and Electromagnetic Radiation of Partial Discharge Accompanying Growth of Electrical Tree 下载免费PDF全文
Tatsuya Mutakamihigashi Yoshito Kuroishi Hideki Ueno 《Electrical Engineering in Japan》2015,192(3):19-26
We have investigated the characteristics of radiated electromagnetic (EM) waves from positive and negative partial discharges (PD) in epoxy resin and cross‐linked polyethylene. We found that there is a correlation among the EM level from PD, the positive PD current, and electrical trees. Therefore, the growth of an electrical tree produces a lot of positive PD. We have also investigated the characteristics of the frequency region of EM waves from PD in air, insulating oil, and liquid epoxy in addition to the above insulators. EM waves were detected in the frequency region of 40 MHz to 300 MHz from positive and negative PD in epoxy resin and cross‐linked polyethylene. EM waves were also detected in the frequency region of 40 MHz to 150 MHz from positive and negative PD in air. In the case of insulating oil and liquid epoxy, EM waves were detected in the frequency regions of 40 MHz to 150 MHz from positive PD, and 40 MHz to 250 MHz from negative PD. The frequency region differed depending on the material and the discharge polarity. Our investigation indicates that the cause is differences in electric field strength at the time of PD occurrence. 相似文献
2.
一种三叉树的存储结构及其基本操作的实现 总被引:3,自引:0,他引:3
本文在文献[1]所给出的有关三叉树有其相关概念的基础上,提出了一种新的三叉树存储结构,即“儿子-兄弟链表”方法,并在这种结构下,对三叉树的基本操作的实现算法进行了较详细的讨论。 相似文献
3.
孙涌 《计算机工程与科学》1997,19(1):37-41
本文提出一种新型的图形描述算法,该算法以各种规则图形作为图形的最小处理单位。利用本算法构造的图形管理系统可广泛用于环境实时监控、采样数据动态显示等领域 相似文献
4.
5.
6.
Aleksandra A. Ageeva Ilya M. Magin Alexander B. Doktorov Victor F. Plyusnin Polina S. Kuznetsova Alexander A. Stepanov Alexander A. Alekseev Nikolay E. Polyakov Tatyana V. Leshina 《International journal of molecular sciences》2021,22(12)
The study of the L- and D-amino acid properties in proteins and peptides has attracted considerable attention in recent years, as the replacement of even one L-amino acid by its D-analogue due to aging of the body is resulted in a number of pathological conditions, including Alzheimer’s and Parkinson’s diseases. A recent trend is using short model systems to study the peculiarities of proteins with D-amino acids. In this report, the comparison of the excited states quenching of L- and D-tryptophan (Trp) in a model donor–acceptor dyad with (R)- and (S)-ketoprofen (KP-Trp) was carried out by photochemically induced dynamic nuclear polarization (CIDNP) and fluorescence spectroscopy. Quenching of the Trp excited states, which occurs via two mechanisms: prevailing resonance energy transfer (RET) and electron transfer (ET), indeed demonstrates some peculiarities for all three studied configurations of the dyad: (R,S)-, (S,R)-, and (S,S)-. Thus, the ET efficiency is identical for (S,R)- and (R,S)-enantiomers, while RET differs by 1.6 times. For (S,S)-, the CIDNP coefficient is almost an order of magnitude greater than for (R,S)- and (S,R)-. To understand the source of this difference, hyperpolarization of (S,S)-and (R,S)- has been calculated using theory involving the electron dipole–dipole interaction in the secular equation. 相似文献
7.
针对于Petersen图P9进行研究,利用两个Petersen图K3,3,1与中间边组成的图的方法来形成petersen图中的P9,本文得到了一种带有纽结分支的内在链图H(93),并证明了该定理. 相似文献
8.
Anthony Corns 《New Review of Information Networking》2015,20(1-2):66-72
The EU co-funded project Advanced Research Infrastructure for Archaeological Dataset Networking in Europe (ARIADNE) aims to integrate data and services across Europe for the archaeological research community. The Discovery Programme has investigated data holdings and management practices in Irish archaeology, focusing on what information is available in physical and digital forms, approaches to preservation and accessibility, and the challenges and opportunities around dataset networking with Irish archaeological data. While significant work will be required to enable the accessibility expected by researchers now and in future, there is also an opportunity to approach the challenges of digital preservation as a community. 相似文献
9.
由二元关系导出的概念格是一种非常有用的形式化工具,也很适合于发现数据中潜在的概念。概念格的算法一直是数据挖掘领域研究的热点。本文根据需要对概念格的结构进行一定的修改,采用一个带头、尾指针的链表作为整个算法的数据结构,提出概念格的渐进式维护算法,该算法中包含两个算法,即渐进式构造算法和渐进式删除算法。最后,通过将该算法和其他算法进行比较,得出较好的时间和空间效率。 相似文献
10.