全文获取类型
收费全文 | 750篇 |
免费 | 19篇 |
国内免费 | 22篇 |
学科分类
工业技术 | 791篇 |
出版年
2024年 | 1篇 |
2023年 | 6篇 |
2022年 | 12篇 |
2021年 | 15篇 |
2020年 | 8篇 |
2019年 | 11篇 |
2018年 | 10篇 |
2017年 | 29篇 |
2016年 | 24篇 |
2015年 | 30篇 |
2014年 | 48篇 |
2013年 | 44篇 |
2012年 | 37篇 |
2011年 | 65篇 |
2010年 | 51篇 |
2009年 | 53篇 |
2008年 | 46篇 |
2007年 | 59篇 |
2006年 | 40篇 |
2005年 | 26篇 |
2004年 | 21篇 |
2003年 | 21篇 |
2002年 | 25篇 |
2001年 | 15篇 |
2000年 | 21篇 |
1999年 | 10篇 |
1998年 | 8篇 |
1997年 | 14篇 |
1996年 | 8篇 |
1995年 | 6篇 |
1994年 | 5篇 |
1993年 | 8篇 |
1992年 | 4篇 |
1991年 | 2篇 |
1990年 | 3篇 |
1989年 | 1篇 |
1988年 | 2篇 |
1980年 | 2篇 |
排序方式: 共有791条查询结果,搜索用时 0 毫秒
41.
42.
Interactive voice browsers offer an alternative paradigm that affords ubiquitous mobile access to the WWW using a wide range
of consumer devices. This technology can facilitate a safe, “hands-free” browsing environment that is of importance both to
car drivers and various mobile and technical professionals. This paper describes the challenges of architecting an interactive
voice browser that combines digital audio with the features of a speech synthesizer to make structural elements of the document
explicit to the listener. The aesthetics of the audio rendition can simultaneously help reduce the monotony factor and enhance
comprehension. The evolution of the voice browser gave rise to a new conceptual model of the HTML document structure and its
mapping to a 3D audio space. A number of novel features are discussed for improving both the user’s comprehension of the HTML
document structure and their orientation within it. These factors, in turn, can improve the effectiveness of the browsing
experience. 相似文献
43.
大力提高机动性和可靠性已经并列成为现代军用地面雷达研制中的当务之急和关注热点。其机动性很大程度上受制于以越野汽车为主体的轮式运载系统,雷达装载设计的规范化因此当然受到重视。本文围绕雷达装载设计中的超载问题提出了自己的看法:首先从上装与载车的匹配关系着眼把可移式、机动式雷达归纳为公路运输型、一般越野型和高度越野型三个类别;继而实事求是地分析了超载现象,遵循“宁超勿偏”、“超而不过”原则分别对三类雷达车的超载程度进行了定量限制;最后提出了机动式雷达的基本特征和避免过度超载的有效途径。 相似文献
44.
Organic thin film transistors: Materials,processes and devices 总被引:1,自引:0,他引:1
B.?Chandar Shekar Jiyeon?Lee Shi-Woo?RheeEmail author 《Korean Journal of Chemical Engineering》2004,21(1):267-285
For the past ten years, organic materials have been extensively investigated as an electronic material for thin film transistor
(TFT) devices. Organic materials offer strong promise in terms of properties, processing and cost effectiveness and they can
be used in flat panel displays, imagers, smart cards, inventory tags and large area electronic applications. In this review,
we summarize the current status of the organic thin film transistors including substrate materials, electrodes, semiconducting
and dielectric layers; organic thin film preparation methods; morphological studies for organic thin films; electrical characterization
of gate dielectric layers and semiconducting active layers; and characterization of the OTFTs. Future prospects and investigations
required to improve the OTFT performance are also given.
This paper is dedicated to Professor Hyun-Ku Rhee on the occasion of his retirement from Seoul National University. 相似文献
45.
With more and more wireless devices being mobile, there is a constant challenge to provide reliable and high quality communication services among these devices. In this paper, we propose a link availability-based QoS-aware (LABQ) routing protocol for mobile ad hoc networks based on mobility prediction and link quality measurement, in addition to energy consumption estimate. The goal is to provide highly reliable and better communication links with energy-efficiency. The proposed routing algorithm has been verified by NS-2 simulations. The results have shown that LABQ outperforms existing algorithms by significantly reducing link breakages and thereby reducing the overheads in reconnection and retransmission. It also reduces the average end-to-end delay for data transfer and enhances the lifetime of nodes by making energy-efficient routing decisions. 相似文献
46.
Mobile Synchronizing Petri Nets (MSPN's) are a model for mobility and coordination based on coloured Petri Nets, in which systems are composed of a collection of (possibly mobile) hardware devices and mobile agents, both modelled homogenously. In this paper we approach their verification, for which we have chosen to code MSPN's into rewriting logic. In order to obtain a representation of MSPN systems by means of a rewrite theory, we develop a class of them, that we call ν-Abstract Petri nets (ν-APN's), which are easily representable in that framework. Moreover, the obtained representation provides a local mechanism for fresh name generation. Then we prove that, even if ν-APN's are a particular class of MSPN systems, they are strong enough to capture the behaviour of any MSPN system. We have chosen Maude to implement ν-APN's, as well as the translation from MSPN's to ν-APN's, for which we make intensive use of its reflective features. 相似文献
47.
移动通信中,终端的移动及管理是无线通信管理的基本组成部分和主要职能。集群通信的应急联动功能,也集中体现在对终端设备的管理和调度功能上,因此移动性管理成为集群通信系统中必不可少的逻辑功能实体。本文主要分析TETRA集群系统(V+D空中接口协议)移动性管理(Mobility Management)实体的功能,并用C语言编程实现。源程序可以在windows以及Linux等多种环境下运行。文中给出了基于ARM946ES内核的嵌入式系统平台上测试仿真结果及数据。 相似文献
48.
One critical issue in wireless sensor networks is how to gather sensed information in an energy-efficient way since the energy is a scarce resource in a sensor node. Cluster-based architecture is an effective architecture for data-gathering in wireless sensor networks. However, in a mobile environment, the dynamic topology poses the challenge to design an energy-efficient data-gathering protocol. In this paper, we consider the cluster-based architecture and provide distributed clustering algorithms for mobile sensor nodes which minimize the energy dissipation for data-gathering in a wireless mobile sensor network. There are two steps in the clustering algorithm: cluster-head election step and cluster formation step. We first propose two distributed algorithms for cluster-head election. Then, by considering the impact of node mobility, we provide a mechanism to have a sensor node select a proper cluster-head to join for cluster formation. Our clustering algorithms will achieve the following three objectives: (1) there is at least one cluster-head elected, (2) the number of cluster-heads generated is uniform, and (3) all the generated clusters have the same cluster size. Last, we validate our algorithms through an extensive experimental analysis with Random Walk Mobility (RWM) model, Random Direction Mobility (RDM) model, and a Simple Mobility (SM) model as well as present our findings. 相似文献
49.
Mobile IP has been developed by IETF to handle mobility of Internet hosts at the network layer. Mobile IP suffers from a number
of drawbacks, including low survivability due to single-point failure of Home Agents. Recently,
Seamless
IP diversity based
Generalized
Mobility
Architecture (SIGMA) was proposed to support low latency, low packet loss mobility of IP hosts. In this paper, we show that
the location management scheme used in SIGMA enhances the survivability of the SIGMA-based mobile network. We develop an analytical
model to evaluate and compare the survivability of SIGMA with that of Mobile IP. Numerical results show the improvement in
system response time and service blocking probability of SIGMA over Mobile IP in the presence of hardware failures and Distributed
Denial of Service (DDoS) attacks.
The research reported in this paper was funded by NASA Grants NAG3-2922 and NNX06AE44G 相似文献
50.
Dan Forsberg 《Wireless Personal Communications》2007,43(2):665-676
Handoffs must be fast for wireless mobile nodes (MN) without sacrificing security between the MN and the wireless access points
in the access networks. We describe and analyze our new secure Session Keys Context (SKC) scheme which has all the good features,
like mobility and security optimization, of the currently existing key distribution proposals, namely key-request, pre-authentication,
and pre-distribution. We analyze these solutions together, and provide some conclusions on possible co-operative scenarios
and on which level of the network to implement them. Finally before conclusions we provide some handoff delay simulation results
with SKC and key request schemes with corresponding example handoff scenarios with a next generation radio link layer. 相似文献