全文获取类型
收费全文 | 6885篇 |
免费 | 1170篇 |
国内免费 | 1036篇 |
专业分类
电工技术 | 197篇 |
综合类 | 700篇 |
化学工业 | 35篇 |
金属工艺 | 3篇 |
机械仪表 | 148篇 |
建筑科学 | 21篇 |
矿业工程 | 33篇 |
能源动力 | 36篇 |
轻工业 | 9篇 |
水利工程 | 156篇 |
石油天然气 | 10篇 |
武器工业 | 27篇 |
无线电 | 2407篇 |
一般工业技术 | 243篇 |
冶金工业 | 33篇 |
原子能技术 | 2篇 |
自动化技术 | 5031篇 |
出版年
2024年 | 29篇 |
2023年 | 87篇 |
2022年 | 117篇 |
2021年 | 132篇 |
2020年 | 203篇 |
2019年 | 138篇 |
2018年 | 165篇 |
2017年 | 240篇 |
2016年 | 282篇 |
2015年 | 394篇 |
2014年 | 495篇 |
2013年 | 559篇 |
2012年 | 629篇 |
2011年 | 670篇 |
2010年 | 583篇 |
2009年 | 634篇 |
2008年 | 642篇 |
2007年 | 655篇 |
2006年 | 506篇 |
2005年 | 442篇 |
2004年 | 364篇 |
2003年 | 281篇 |
2002年 | 207篇 |
2001年 | 192篇 |
2000年 | 114篇 |
1999年 | 70篇 |
1998年 | 58篇 |
1997年 | 39篇 |
1996年 | 32篇 |
1995年 | 26篇 |
1994年 | 23篇 |
1993年 | 20篇 |
1992年 | 16篇 |
1991年 | 13篇 |
1990年 | 4篇 |
1989年 | 3篇 |
1988年 | 1篇 |
1987年 | 7篇 |
1986年 | 7篇 |
1985年 | 3篇 |
1984年 | 4篇 |
1983年 | 2篇 |
1980年 | 3篇 |
排序方式: 共有9091条查询结果,搜索用时 15 毫秒
1.
2.
The Vehicle Routing Problem with Simultaneous Pickup and Delivery (VRPSPD) is an extension to the classical Vehicle Routing Problem (VRP), where customers may both receive and send goods simultaneously. The Vehicle Routing Problem with Mixed Pickup and Delivery (VRPMPD) differs from the VRPSPD in that the customers may have either pickup or delivery demand. However, the solution approaches proposed for the VRPSPD can be directly applied to the VRPMPD. In this study, an adaptive local search solution approach is developed for both the VRPSPD and the VRPMPD, which hybridizes a Simulated Annealing inspired algorithm with Variable Neighborhood Descent. The algorithm uses an adaptive threshold function that makes the algorithm self-tuning. The proposed approach is tested on well-known VRPSPD and VRPMPD benchmark instances derived from the literature. The computational results indicate that the proposed algorithm is effective in solving the problems in reasonable computation time. 相似文献
3.
陈国龙 《计算机辅助设计与图形学学报》1994,6(2):136-142
本文介绍了一种在微机上实现的印制板自动布线方法──多级线探索法及其编程方法。这种方法是基于完备布线算法的概念,通过分析李氏算法和传统线探索法的不足之处而得到的。虽然它也是一种线探索法,但有较传统线探索法更强的探索能力,不需要结合李氏算法而能单独完成布线任务,是一种较理想的算法,通过实验获得了较为满意的效果。 相似文献
4.
一种支持QoS的拓扑自适应动态组播路由算法 总被引:3,自引:0,他引:3
YAM、QoSMIC、DSDMR等一类支持QoS的动态组播路由算法允许组播成员动态地加入和离开,同时为接收方提供多个可选择的组播接入路径,以满足不同应用的QoS需求。但这些算法普遍存在控制信令开销大和结点加入时延长,可扩展性不好等问题。本文在分析这些算法的基础上,提出改进的支持QoS的动态组播路由算法,即拓扑自适应动态组播路由(Topology Adaptive Dynamic Multicast Routing,TADMR)算法。该算法避免了以往算法中大部分盲目的路径搜索,并使结点加入时延不再受限于固定的等待时钟,而与网络拓扑相自适应。性能分析和仿真结果表明,该算法具有较低的控制信令开销和结点加入时延,适用于各种网络规模和群组规模,具有良好的可扩展性。 相似文献
5.
自动交换光网络的概念一经提出即受到业界的广泛关注,运营商尤其对其寄予了厚望。本文首先概要地介绍了ASON的优点,然后重点论述了ASON的信令与路由功能,包括对它们的要求以及标准化工作。 相似文献
6.
We consider the switchbox routing problem of two-terminal nets in the case when all thek nets lie on two adjacent sides of the rectangle. Our routing model is the standard two-layer model. We develop an optimal algorithm that routes all the nets whenever a routing exists. The routing obtained uses the fewest possible number of vias. A more general version of this problem (adjacent staircase) is also optimally solved.This research was supported in part by NSA Contract No. MDA-904-85H-0015, NSF Grant No. DCR-86-00378, and by NSF Engineering Research Centers Program NSFD CDR 88003012. 相似文献
7.
8.
Recent technological advances have made it possible to support long lifetime and large volume streaming data transmissions
in sensor networks. A major challenge is to maximize the lifetime of battery-powered sensors to support such transmissions.
Battery, as the power provider of the sensors, therefore emerges as the key factor for achieving high performance in such
applications. Recent study in battery technology reveals that the behavior of battery discharging is more complex than we
used to think. Battery powered sensors might waste a huge amount of energy if we do not carefully schedule and budget their
discharging. In this paper we study the effect of battery behavior on routing for streaming data transmissions in wireless
sensor networks. We first give an on-line computable energy model to mathematically model battery discharge behavior. We show
that the model can capture and describe battery behavior accurately at low computational complexity and thus is suitable for
on-line battery capacity computation. Based on this battery model we then present a battery-aware routing (BAR) protocol to
schedule the routing in wireless sensor networks. The routing protocol is sensitive to the battery status of routing nodes
and avoids energy loss. We use the battery data from actual sensors to evaluate the performance of our protocol. The results
show that the battery-aware protocol proposed in this paper performs well and can save a significant amount of energy compared
to existing routing protocols for streaming data transmissions. Network lifetime is also prolonged with maximum data throughput.
As far as we know, this is the first work considering battery-awareness with an accurate analytical on-line computable battery
model in sensor network routing. We believe the battery model can be used to explore other energy efficient schemes for wireless
networks as well. 相似文献
9.
分布存储多机系统中的消息传递技术 总被引:9,自引:1,他引:8
本文回顾了分布存储多机系统中消息传递技术几十年来的发展,介绍了现阶段消息传递技术的主要研究成果,例如wormhole寻径技术,虚通道流控制技术等。最后,对消息传递技术今后的研究方向作出了一些设想。 相似文献
10.