全文获取类型
收费全文 | 356267篇 |
免费 | 32851篇 |
国内免费 | 23092篇 |
专业分类
电工技术 | 50401篇 |
技术理论 | 44篇 |
综合类 | 40696篇 |
化学工业 | 15688篇 |
金属工艺 | 9833篇 |
机械仪表 | 24883篇 |
建筑科学 | 33344篇 |
矿业工程 | 13343篇 |
能源动力 | 11484篇 |
轻工业 | 7554篇 |
水利工程 | 11532篇 |
石油天然气 | 9625篇 |
武器工业 | 4792篇 |
无线电 | 43850篇 |
一般工业技术 | 17878篇 |
冶金工业 | 12525篇 |
原子能技术 | 2889篇 |
自动化技术 | 101849篇 |
出版年
2024年 | 1605篇 |
2023年 | 4342篇 |
2022年 | 8514篇 |
2021年 | 10072篇 |
2020年 | 10588篇 |
2019年 | 7607篇 |
2018年 | 6752篇 |
2017年 | 8853篇 |
2016年 | 10225篇 |
2015年 | 11834篇 |
2014年 | 23948篇 |
2013年 | 20240篇 |
2012年 | 26304篇 |
2011年 | 27867篇 |
2010年 | 21405篇 |
2009年 | 21933篇 |
2008年 | 22422篇 |
2007年 | 27479篇 |
2006年 | 24113篇 |
2005年 | 21390篇 |
2004年 | 17647篇 |
2003年 | 15823篇 |
2002年 | 12174篇 |
2001年 | 10069篇 |
2000年 | 8188篇 |
1999年 | 6623篇 |
1998年 | 4848篇 |
1997年 | 3903篇 |
1996年 | 3358篇 |
1995年 | 2785篇 |
1994年 | 2237篇 |
1993年 | 1549篇 |
1992年 | 1225篇 |
1991年 | 882篇 |
1990年 | 689篇 |
1989年 | 613篇 |
1988年 | 436篇 |
1987年 | 239篇 |
1986年 | 208篇 |
1985年 | 218篇 |
1984年 | 189篇 |
1983年 | 189篇 |
1982年 | 115篇 |
1981年 | 86篇 |
1980年 | 63篇 |
1979年 | 65篇 |
1978年 | 40篇 |
1977年 | 41篇 |
1976年 | 26篇 |
1959年 | 33篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
应用人工神经网络处理部分广东地区煤质分析数据,建立网络模型,预测出煤的发热量,经实测值与预测值比较,在一定的煤种范围内预测值与实测值比较接近。 相似文献
62.
Efficient multicast search under delay and bandwidth constraints 总被引:1,自引:0,他引:1
The issue of a multicast search for a group of users is discussed in this study. Given the condition that the search is over
only after all the users in the group are found, this problem is called the Conference Call Search (CCS) problem. The goal
is to design efficient CCS strategies under delay and bandwidth constraints. While the problem of tracking a single user has
been addressed by many studies, to the best of our knowledge, this study is one of the first attempts to reduce the search
cost for multiple users. Moreover, as oppose to the single user tracking, for which one can always reduce the expected search
delay by increasing the expected search cost, for a multicast search the dependency between the delay and the search cost
is more complicated, as demonstrated in this study. We identify the key factors affecting the search efficiency, and the dependency
between them and the search delay. Our analysis shows that under tight bandwidth constraints, the CCS problem is NP-hard.
We therefore propose a search method that is not optimal, but has a low computational complexity. In addition, the proposed
strategy yields a low search delay as well as a low search cost. The performance of the proposed search strategy is superior
to the implementation of an optimal single user search on a group of users.
Amotz Bar-Noy received the B.Sc. degree in 1981 in Mathematics and Computer Science and the Ph.D. degree in 1987 in Computer Science, both
from the Hebrew University, Israel. From October 1987 to September 1989 he was a post-doc fellow in Stanford University, California.
From October 1989 to August 1996 he was a Research Staff Member with IBM T. J. Watson Research Center, New York. From February
1995 to September 2001 he was an associate Professor with the Electrical Engineering-Systems department of Tel Aviv University,
Israel. From September 1999 to December 2001 he was with AT research labs in New Jersey. Since February 2002 he is a Professor
with the Computer and Information Science Department of Brooklyn College - CUNY, Brooklyn New York.
Zohar Naor received the Ph.D. degree in Computer Science from Tel Aviv University, Tel Aviv, Israel, in 2000. Since 2003 he is with
the University of Haifa, Israel. His areas of interests include wireless networks, resource management of computer networks,
mobility, search strategies, and multiple access protocols. 相似文献
63.
为实现电源设备乃至通信机房的少人或无人值守和集中维护,必须建立一套完善的电信局动力环境集中监控系统。文中结合番禺区电信局的实际,讨论了提高系统运行可靠性的几点措施,包括硬件方面与软件方面的手段,关键在于加强系统的运行管理。 相似文献
64.
65.
66.
DSP--数字化时代的基因芯片 总被引:3,自引:0,他引:3
DSP是当今发展最为迅速的和最有发展前景的技术之一。与普通CPU和MCU相比 ,DSP在数字信号处理方面有着无可比拟的优势 ,特别适合网络、通信、控制等需要进行大量数字信号处理的应用场合。今天DSP已经成为通信、计算机、网络、工业控制以及家用电器等电子产品中不可或缺的基础器件 ,DSP在通信、计算机、网络、工业控制以及消费类电子产品等领域有着非常广泛的应用 ,本文阐述了DSP的特点、应用和市场以及DSP技术的发展前景。 相似文献
67.
M. J. O’Sullivan C. G. Walker M. L. O’Sullivan T. D. Thompson A. B. Philpott 《Telecommunication Systems》2006,33(4):353-376
The problem of designing fibre-optic networks for local-access telecommunications generates (at least) three non-trivial subproblems.
In the first of these subproblems one must determine how many fibre-optic cables (fibres) are required at either end of a
street. In the next subproblem a minimum-cost network must be designed to support the fibres. The network must also provide
distinct paths from either end of the street to the central exchange(s). Finally, the fibre-optic cables must be placed in
protective covers. These covers are available in a number of different sizes, allowing some flexibility when covering each
section of the network. In this paper we describe a dynamic programming (DP) formulation for finding a minimum-cost (protective)
covering for the network (the third of the subproblems). This problem is a generalised set covering problem with side constraints
and is further complicated by the introduction of fixed and variable welding costs. The DP formulation selects covers along
each arc (in the network), but cannot exactly model the fixed costs and so does not guarantee optimality. We also describe
an integer programming (IP) formulation for assessing the quality of the DP solutions. The cost of the networks constructed
by the IP model is less than those designed using the DP model, but the saving is not significant for the problems examined
(less than 0.1%). This indicates that the DP model will generally give very good solutions. Furthermore, as the problem dimensions
grow, DP gives significantly better solution times than IP. 相似文献
68.
多协议标记交换(MPLS)技术是综合利用网络第二层交换技术的有效性和第三层IP路由的灵活性等优点而产生的多层交换技术。通过在传统的IP包里加入标记,使路由转发依赖于标记,大大地提高IP包的转发速度,同时可使传统IP网络具有服务质量(QoS)能力。现主要分析MPLS体系结构,指出MPLS的一些应用。 相似文献
69.
动力环境网络监控精细管理 总被引:1,自引:0,他引:1
叙述动力环境运行质量分析管理,包括故障管理,性能管理和专题分析管理,以动力环境网络监控细致八微、言之有据的月度分析管理实例展现了其精细管理的效果。 相似文献
70.
在通信供电系统中,与直流供电系统相比,从设计、设备技术,到运行维护管理,交流供电系统都有所滞后。借鉴直流供电系统经验,通过应用N X并联逆变器模块热插拔技术,实行分散式供电,进而改变传统的以UPS为核心的集中供电模式,则可在很大程度上解决一直困扰着我们的交流供电系统成本高和可靠性低的难题。 相似文献