首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   439篇
  免费   32篇
  国内免费   20篇
电工技术   181篇
综合类   43篇
化学工业   18篇
金属工艺   16篇
机械仪表   17篇
建筑科学   15篇
矿业工程   11篇
能源动力   13篇
轻工业   5篇
水利工程   8篇
石油天然气   1篇
武器工业   8篇
无线电   45篇
一般工业技术   18篇
冶金工业   14篇
原子能技术   4篇
自动化技术   74篇
  2024年   1篇
  2023年   2篇
  2022年   4篇
  2021年   9篇
  2020年   8篇
  2019年   5篇
  2018年   9篇
  2017年   3篇
  2016年   9篇
  2015年   19篇
  2014年   26篇
  2013年   23篇
  2012年   32篇
  2011年   28篇
  2010年   34篇
  2009年   36篇
  2008年   19篇
  2007年   33篇
  2006年   37篇
  2005年   20篇
  2004年   14篇
  2003年   19篇
  2002年   17篇
  2001年   14篇
  2000年   16篇
  1999年   9篇
  1998年   6篇
  1997年   6篇
  1996年   4篇
  1995年   5篇
  1994年   4篇
  1993年   6篇
  1992年   6篇
  1991年   1篇
  1987年   1篇
  1985年   1篇
  1983年   1篇
  1982年   1篇
  1981年   2篇
  1980年   1篇
排序方式: 共有491条查询结果,搜索用时 15 毫秒
1.
A series of experiments introduced interruptions to the execution phase of simple Tower of London problems and found that the opportunity for preparation before the break in task reduced the time cost at resumption. Retrieval of the suspended goal was facilitated when participants were given the opportunity to encode retrieval cues during an "interruption lag" (the brief time before engaging in the interrupting task) but was impeded when these visual cues were subsequently altered following interruption. The results provide useful support for the goal-activation model (E. M. Altmann & G. J. Trafton, 2002), which assumes that context--at the points of both goal suspension and goal retrieval--is critical to efficient interruption recovery. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
2.
The aggregation pheromone produced by maleIps paraconfusus (Coleoptera: Scolytidae) tunneling in Monterey pine,Pinus radiata, logs was trapped on Porapak Q. A concentration of an extract of trapped volatiles that attracted beetles was determined in the laboratory through a concentration–response analysis of walking behavior of males and females. The interruptant effects of four concentrations of verbenone on response to a constant concentration of this naturally produced aggregation pheromone were tested with males and females. Independent of its enantiomeric composition [99.5% (S)-(–), 93.1 % (S)-(–), and 98.3% (R)-(+)], verbenone significantly reduced the percentage of females (but not males) reaching the attractant source. However, when the time required for beetles of both sexes taken together to reach the attractant source was considered, verbenone of higher enantiomeric purity had a greater effect on beetle behavior. Solutions of 99.5% (S)-(–)- and 98.3% (R)-(+)-verbenone increased the time required for beetles to reach the attractive source when compared to 93.1% (S)-(–)-verbenone. When pooled across enantiomeric blends, increasing concentrations of verbenone resulted in slower responses in beetles that reached the attractant source within 2 min. Males and females did not respond to verbenone alone.  相似文献   
3.
网络通信的普及和发展使得对网络协议尤其是安全协议的需求日益增长,同时安全要求及攻击方式的多样化对网络安全协议的效率和准确性提出了更高的要求。通过对各种协议安全性分析方法进行研究,采用串空间方法对DTLS协议进行形式化建模,进而采用认证测试方法进行协议认证性证明,用简明清晰的方式验证DTLS协议的认证性,保障了数据传输的安全。  相似文献   
4.
讨论了Windows操作系统下硬件中断产生的方法,使用硬件DIO输出卡对设计的中断服务程序作了多种时序下试验,做了Windows系统下中断服务工作时的干扰试验,在中断线程和工作线程内部提出了多种试验方法,深入研究了Windows系统下的内核级调度执行相关代码段所需的时间,测试了多种时钟的精确度,设计了工程实用的中断服务程序。  相似文献   
5.
AlGaAs/GaAs multi-quantum well (MQW) was prepared by molecular beam epitaxy(MBE) with growth-interrupted heterointerface (GIH) method and continuous growth (CG) method, respectively. The microstructures Of the MQWs were characterized by double-crystal X-ray rocking curve (DCRC) and atomic force microscopy (AFM), and the photoluminescence (PL) properties of the MQWs were also studied. The MQWs grown with GIH method show that higher order satellite peaks of Pendelloesung fiinges are observed in DCRC, the roughness of surface is much reduced in AFM, and the full width at half maximum (FWHM) of exciton line is much narrower in PL. The results indicate that the GIH method reduces the monolayer growth step density at the heterointerface due to the migration of surface atomsfor a few minutes grower interruption, and substantially improves the quality of AlGaAs/GaAs MQWs.  相似文献   
6.
In this paper, we consider a discrete-time queuing system with head-of-line non-preemptive priority scheduling and a single server subjected to server interruptions. We model the server interruptions by a correlated Markovian on/off process with geometrically distributed on and off periods. Two classes of traffic are considered, namely high-priority and low-priority traffic. In the first part of the paper, we derive an expression for the functional equation describing the transient evolution of this priority queuing system. This functional equation is then manipulated and transformed into a mathematical tractable form. This allows us to derive the joint probability generating function (pgf) of the system contents. From this pgf, closed-form expressions for various performance measures, such as mean and variance of system contents and customer delay can be derived. Finally, we illustrate our solution technique with some numerical examples, whereby we demonstrate the negative effect of correlation in the interruption process on the performance of both classes. Some numerical results illustrating the impact of second-order characteristics of the arrival process on mean delays are also presented. The proposed approach which is purely based on pgfs is entirely analytical and enables the derivation of not only steady-state but transient performance measures, as well. The paper presents new insights into the performance analysis of discrete-time queues with service interruption and it also covers some previously published results as a special case.

Scope and purpose

In this contribution, we consider a practical queuing model, with HOL priority scheduling, two classes of traffic, and a server which is subjected to a correlated Markovian interruption process. We first derive a non-linear functional equation relating the joint pgf of the system state vector between two consecutive slots. Then we outline a solution technique to solve for this functional equation. This allows us to derive the joint pgf of the system contents of both classes, from which various performance measures related to mean system contents and customer delays are derived. We also demonstrate how the proposed approach allows for derivation of transient performance measures, as well. It should be noted that detailed coverage of the transient analysis of the system is beyond the scope of this paper.To our best knowledge, this is the first initiative that aims to explore the performance of queuing systems with priority scheduling when the shared server is subjected to service interruption. The paper also generalizes the results of Walraevens et al. (Analysis of a single-server ATM queue with priority scheduling, Computers & Operations Research 2003;30(12):1807–30) by incorporating service interruption into their original queuing model. By means of numerical results, the paper also demonstrates the effect of correlation in the service interruption process on the performance of both classes of customers. The impact of second-order characteristics of the arrival process on mean delays is also investigated.  相似文献   
7.
提出了一种采用软件扩展中断技术的简易实时多任务调度程序设计方法,详细介绍了1个调度程序和4个系统调用即软中断触发调用、硬中断进入调度、硬中断退出调用及陷阱调用的实现,并给出了相应的程序框图。该软中断单片机抢占式实时多任务处理方法具有核心程序短、效率高、使用简单等优点,适合于单片机级的应用。  相似文献   
8.
Nowadays, the microgrid cluster is an important application scenario for energy trading. In trading, one of the most important research directions is the issue of pricing. To determine reasonable pricing for the microgrid cluster, data communication is used to create the cyber-physical system (CPS), which can improve the observability of microgrids. Then, the following works are carried out in the CPS. In the physical layer: 1) Regarding trading between microgrids and the load, based on the generalized game theory, an optimal pricing strategy is proposed, which takes into account the interactive relationships among microgrids and transforms the pricing problem into a Nikaido-Isoda function to obtain the optimal prices conveniently; 2) Regarding peer-to-peer trading between two microgrids, based on evolutionary game theory and the penalty mechanism, the optimal sale price of the seller is selected with boundary rationality. In the cyber layer, regarding the communication interruption issue existing in pricing (i.e., the game process), based on the principle of matching the performance of the path with the importance degree of the data, a dynamic regulating method of paths is proposed, i.e., adopting a new path to re-transmit the interrupted data to the destination. Finally, the effect of the proposed strategies is verified by case studies.   相似文献   
9.
针对目前国内常规配电自动化技术方案存在的故障隔离与供电恢复完全依赖主站、故障隔离与供电恢复时间较长、可靠性较差、任一点故障都有可能导致同一供电区全部停电从而导致供电公司和电力用户蒙受不应有损失等问题,提出了一种配电网超高速故障隔离与供电恢复的技术方案,不仅彻底解决了这些问题,而且能够自动屏蔽那些发生故障的FTU,使故障隔离区在当时条件下达到最小,既可与传统配调中心配合构成常规的配电网自动化系统,也可独立实现超高速故障隔离与恢复供电。此外,还介绍了该技术方案的原理并举例分析了各种情况下的故障隔离与供电恢复过程。经实验室测试、实际工程实施和运行实践证明,该方案能够满足超高速故障隔离与供电恢复的要求,技术先进,价格合理,具有很强的通用性和实用性。  相似文献   
10.
一种电力用户停电损失函数估算方法   总被引:3,自引:0,他引:3       下载免费PDF全文
电力用户停电损失函数对电力系统规划、运行和电力市场下的安全费用计算等具有重要意义。但求取停电损失函数需要区分不同电力用户的用电性质,也需要大量统计数据资料作为停电损失函数的分析依据,从而使其成为当前电力市场研究工作的一个难点。本文在目前研究成果的基础上,提出一种参考其它地区停电损失函数、根据所研究地区电力用户消耗每kW h电力的平均效益估算用户停电损失函数的方法。该方法避免了大量数据统计工作,对不同性质电力用户的停电损失函数进行快速简单分析。用加拿大停电损失函数近似估算了天津市电力用户停电损失函数,实例表明所提方法可行。  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号