全文获取类型
收费全文 | 42801篇 |
免费 | 2841篇 |
国内免费 | 1174篇 |
专业分类
电工技术 | 1681篇 |
综合类 | 1742篇 |
化学工业 | 6502篇 |
金属工艺 | 1265篇 |
机械仪表 | 1509篇 |
建筑科学 | 2546篇 |
矿业工程 | 492篇 |
能源动力 | 946篇 |
轻工业 | 5149篇 |
水利工程 | 804篇 |
石油天然气 | 656篇 |
武器工业 | 142篇 |
无线电 | 4122篇 |
一般工业技术 | 5240篇 |
冶金工业 | 6971篇 |
原子能技术 | 452篇 |
自动化技术 | 6597篇 |
出版年
2024年 | 127篇 |
2023年 | 469篇 |
2022年 | 957篇 |
2021年 | 1319篇 |
2020年 | 955篇 |
2019年 | 948篇 |
2018年 | 1005篇 |
2017年 | 1127篇 |
2016年 | 1068篇 |
2015年 | 1391篇 |
2014年 | 1752篇 |
2013年 | 2309篇 |
2012年 | 2496篇 |
2011年 | 2823篇 |
2010年 | 2287篇 |
2009年 | 2223篇 |
2008年 | 2219篇 |
2007年 | 2036篇 |
2006年 | 1780篇 |
2005年 | 1529篇 |
2004年 | 1168篇 |
2003年 | 947篇 |
2002年 | 818篇 |
2001年 | 696篇 |
2000年 | 620篇 |
1999年 | 697篇 |
1998年 | 2291篇 |
1997年 | 1427篇 |
1996年 | 988篇 |
1995年 | 629篇 |
1994年 | 603篇 |
1993年 | 574篇 |
1992年 | 308篇 |
1991年 | 262篇 |
1990年 | 267篇 |
1989年 | 258篇 |
1988年 | 258篇 |
1987年 | 175篇 |
1986年 | 183篇 |
1985年 | 234篇 |
1984年 | 207篇 |
1983年 | 155篇 |
1982年 | 161篇 |
1981年 | 152篇 |
1980年 | 147篇 |
1979年 | 145篇 |
1978年 | 118篇 |
1977年 | 181篇 |
1976年 | 210篇 |
1975年 | 127篇 |
排序方式: 共有10000条查询结果,搜索用时 859 毫秒
1.
2.
3.
Dan Ye Kaiyu Wang Haijiao Yang Xingang Zhao 《International Journal of Adaptive Control and Signal Processing》2020,34(11):1677-1696
In this article, an adaptive fuzzy output feedback control method is presented for nonlinear time-delay systems with time-varying full state constraints and input saturation. To overcome the problem of time-varying constraints, the integral barrier Lyapunov functions (IBLFs) integrating with dynamic surface control (DSC) are applied for the first time to keep the state from violating constraints. The effects of unknown time delays can be removed by using designed Lyapunov-Krasovskii functions (LKFs). An auxiliary design system is introduced to solve the problem of input saturation. The unknown nonlinear functions are approximated by the fuzzy logic systems (FLS), and the unmeasured states are estimated by a designed fuzzy observer. The novel controller can guarantee that all signals remain semiglobally uniformly ultimately bounded and satisfactory tracking performance is achieved. Finally, two simulation examples illustrate the effectiveness of the presented control methods. 相似文献
4.
5.
采用ETAG 004:2013《外墙外保温薄抹灰系统欧洲技术认证指南》中规定的静态泡沫块法,测试在单位面积上使用不同数量锚栓的岩棉板外保温系统的抗风压性能。通过试验可以得出:在混凝土墙体上单纯采用敲击式锚栓锚固岩棉板外保温系统时,拉伸强度可达12.9 k Pa;单位面积增加锚栓的使用量可以提高系统的抗拉承载力,但在不同条件下增加相同数量锚栓对系统抗风载能力提高的程度不同;在普通混凝土墙中,单纯锚固岩棉板保温系统破坏时,单个锚栓承载力平均值的最大值约为其拉拔承载力的50.3%。 相似文献
6.
There are many potential causes of corrosion in animal buildings. Animals exhale large quantities of moisture into the air creating high relative humidity in the building if the moisture is not properly vented. High humidity increases the potential for condensation. In addition, ammonia may be found in large quantities in animal buildings. Ammonia is released from manure and urine. In addition, ammonium chloride is used as a nitrogen source in fertilisers. In this study, the atmospheric corrosion of hot-dip-galvanised steel and zinc alloy-coated steel such as zinc–aluminium and zinc–aluminium–magnesium has been studied in atmospheres containing different levels of ammonia. Investigations have also been conducted at different levels of ammonium chloride. The results are discussed in view of the mechanisms of corrosion of zinc and zinc alloy-coated steel in ammonia and ammonium chloride-containing environments. 相似文献
7.
Production planning and control (PPC) systems that employ aspects from both make-to-order (MTO) and make-to-stock (MTS) production control are known as hybrid MTS/MTO systems. While both MTO and MTS separately have been studied extensively, their combined use has received less attention. However, the literature on this topic is growing and this paper shows that the review performed in this paper is an important addition to the field. We categorise relevant literature according to a novel taxonomy and show that hybrid MTS/MTO production control can be used in different contexts. In addition, an overview of the modelling techniques and methods used in these papers is provided. Based on the reviewed literature, relevant research questions and directions for future research are identified. Finally, it is shown that hybrid MTS/MTO production control is prevalent in practice by discussing research with industrial applications. The paper contains an overview of research on hybrid MTS/MTO production control to be used as reference for researchers active in the field, and provides managerial insights and directions for future research on this topic. 相似文献
8.
欺骗式干扰通过发射与真实卫星信号相似的信号误导接收机产生错误的定位结果,具有极大的危害。该文针对转发式欺骗干扰,提出一种基于信号重构的单天线欺骗干扰抑制方法。该方法首先通过参数估计方法估计出欺骗信号载波频率和码相位,然后构建欺骗信号子空间正交投影矩阵以抑制干扰。仿真实验结果表明该方法对欺骗干扰具有良好的抑制效果,能够保障接收机在干扰环境中实现有效定位,并具有较低的运算复杂度。 相似文献
9.
Shouguang Wang Mengdi Gan Mengchu Zhou Dan You 《IEEE/CAA Journal of Automatica Sinica》2015,2(4):345-352
As a powerful analysis tool of Petri nets, reachability trees are fundamental for systematically investigating many characteristics such as boundedness, liveness and reversibility. This work proposes a method to generate a reachability tree, called ωRT for short, for a class of unbounded generalized nets called ω-independent nets based on new modified reachability trees (NMRTs). ωRT can effectively decrease the number of nodes by removing duplicate and ω-duplicate nodes in the tree, and verify properties such as reachability, liveness and deadlocks. Two examples are provided to show its superiority over NMRTs in terms of tree size. 相似文献
10.
Elucidation of colour development and microstructural characteristics of Allium sativum fumigated with acetic acid 下载免费PDF全文
Li Li Dan Wang Xihong Li Yu Wang Xiaofeng Ju 《International Journal of Food Science & Technology》2015,50(5):1083-1088
It has been well known that the greening of Allium sativum cloves could be formed after immersed in acetic acid solution. Nonetheless, no investigation was reported on colour development of A. sativum in response to acetic acid vapour until now. In this study, the brief exposure of A. sativum to acetic acid vapour (200–400 ppm) was combined with controlled atmosphere (5%, 20% and 80% CO2) packaging storage to break cell membrane and green garlic. The garlic bulbs were fumigated with acetic acid before controlled CO2 atmosphere packaging for 25 days at 4 °C. Fumigation with 200 ppm acetic acid followed by high CO2 atmosphere packaging (80% CO2) facilitated the garlic greening. It was also verified that γ‐glutamyl transpeptidase was involved in garlic greening in present study, and the compromise of glacial acetic acid vapour fumigation and CO2 gas atmosphere in package stored at low temperature could result in garlic greening as well. 相似文献