全文获取类型
收费全文 | 7160篇 |
免费 | 404篇 |
国内免费 | 441篇 |
专业分类
电工技术 | 105篇 |
技术理论 | 1篇 |
综合类 | 266篇 |
化学工业 | 37篇 |
金属工艺 | 142篇 |
机械仪表 | 383篇 |
建筑科学 | 112篇 |
矿业工程 | 37篇 |
能源动力 | 31篇 |
轻工业 | 29篇 |
水利工程 | 9篇 |
石油天然气 | 9篇 |
武器工业 | 53篇 |
无线电 | 1741篇 |
一般工业技术 | 255篇 |
冶金工业 | 27篇 |
原子能技术 | 14篇 |
自动化技术 | 4754篇 |
出版年
2024年 | 24篇 |
2023年 | 116篇 |
2022年 | 127篇 |
2021年 | 170篇 |
2020年 | 184篇 |
2019年 | 142篇 |
2018年 | 143篇 |
2017年 | 216篇 |
2016年 | 260篇 |
2015年 | 253篇 |
2014年 | 441篇 |
2013年 | 407篇 |
2012年 | 384篇 |
2011年 | 467篇 |
2010年 | 341篇 |
2009年 | 384篇 |
2008年 | 457篇 |
2007年 | 501篇 |
2006年 | 507篇 |
2005年 | 442篇 |
2004年 | 372篇 |
2003年 | 386篇 |
2002年 | 296篇 |
2001年 | 222篇 |
2000年 | 169篇 |
1999年 | 147篇 |
1998年 | 120篇 |
1997年 | 69篇 |
1996年 | 49篇 |
1995年 | 60篇 |
1994年 | 34篇 |
1993年 | 34篇 |
1992年 | 18篇 |
1991年 | 14篇 |
1990年 | 9篇 |
1989年 | 13篇 |
1988年 | 6篇 |
1987年 | 3篇 |
1986年 | 2篇 |
1985年 | 1篇 |
1984年 | 7篇 |
1983年 | 4篇 |
1982年 | 2篇 |
1981年 | 1篇 |
1978年 | 1篇 |
排序方式: 共有8005条查询结果,搜索用时 15 毫秒
81.
水下船体表面清刷和检测为爬壁机器人开辟了新的应用领域,其特点是机械本体稳定地吸附在水下船体表面上,同时能够灵活地完成移动、转向、越障等行走功能,进而完成针对船体表面的检测、清刷等作业。文中重点介绍了几种水下船体作业的爬壁爬行机器人,并对机器人的吸附和行走两个关键技术进行了分析,总结了水下船体作业机器人研究中的一些难点问题及其发展趋势。 相似文献
82.
为解决移动业务数据日稽核、监控物资发放情况等问题,设计并实现了基于BOSS的移动营业操作系统。通过对BOSS克隆数据库中自动抽取业务数据与营业操作系统中业务数据的对比实现了业务稽核功能,满足了公司精细化管理的要求。实践表明,该系统有效提高了工作效率,减少了员工工作量,节约了大量的人力成本。 相似文献
83.
为了把移动雷达实时数据传输到北京市气象局,通过对比多种无线通信方式以及卫星通信的优缺点等方法建立了一套卫星通信系统。结果表明:本系统在应急、网络速率、安全等方面都能满足移动雷达系统对数据通信的要求。这套系统的设计将对应急系统的建立具有一定的指导意义。 相似文献
84.
本文以我们自主研发的移动通信系统为例,针对突发性高密度话务量,以及抢险救灾和突发事件和任务的应急通讯需求,探讨和研究了多功能车载机动式移动通信系统以及有关关键技术。主要包括了系统构建、组成、基于动中通的伺服系统设计、主要应用模式分析以及和常规通信组网方式的分析和比较。 相似文献
85.
86.
Multicast routing in mobile ad hoc networks (MANETs) poses several challenges due to inherent characteristics of the network such as node mobility, reliability, scarce resources, etc. This paper proposes an Agent Based Multicast Routing Scheme (ABMRS) in MANETs, which uses a set of static and mobile agents. Five types of agents are used in the scheme: Route manager static agent, Network initiation mobile agent, Network management static agent, Multicast initiation mobile agent and Multicast management static agent. The scheme operates in the following steps: (1) to identify reliable nodes; (2) to connect reliable nodes through intermediate nodes; (3) to construct a backbone for multicasting using reliable nodes and intermediate nodes; (4) to join multicast group members to the backbone; (5) to perform backbone and group members management in case of mobility. The scheme has been simulated in various network scenarios to test operation effectiveness in terms of performance parameters such as packet delivery ratio, control overheads and group reliability. Also, a comparison of proposed scheme with MAODV (Multicast Ad hoc on-demand Distance Vector) protocol is presented. ABMRS performs better than MAODV as observed from the simulation. ABMRS offers flexible and adaptable multicast services and also supports component based software development. 相似文献
87.
Windson Viana 《Journal of Systems and Software》2008,81(3):382-394
Ubiquitous Computing promises seamless access to information anytime, anywhere with different and heterogeneous devices. This kind of environment imposes new challenges to software development. For example, information and user interface should be adapted according to contextual characteristics such as user, environment, and access device. In case of device adaptation, the development challenge is related to the heterogeneity of the devices, which requires software engineers to create different versions for each type of device and every platform. This paper proposes a MB-UID (model-based user interface development) approach for semi-automatic generation of adaptive applications for mobile devices. An environment, called XMobile, offers a device-independent user interface framework and a code generation tool for providing fast development of multi-platform and adaptive applications according to device and platform features. A case study is also presented to illustrate how the environment can be used for constructing an application for heterogeneous devices with different network connectivity modes. 相似文献
88.
This paper reports on a case study of a teacher from a technical education institution who explored the educational affordances of PDA technology over a period of six months. Based on this teacher’s perspectives, the study was designed to inform our own understanding of educational affordances of this new and emerging technology. Understanding of educational affordances is important in the context of planning a suitable intervention to support pedagogically effective integration of PDA technology. The study explicated a set of five affordances of PDA technology: as a multimedia-access tool, connectivity tool, capture tool, representational tool and analytical tool. We call on further research to expand this set into a more comprehensive collage of educational affordances of PDA technology. 相似文献
89.
Data services via wireless networks and mobile devices have experienced rapid growth worldwide. We investigated the factors influencing adoption of wireless mobile data services (WMDS) in China and tested our model for explaining adoption intentions there. We argued that individuals form their intention to adopt WMDS under the influence of wireless mobile technology, the social environment, personal innovativeness of IT, trust awareness, and the facilitating conditions. We examined the simultaneous effects of these five influences on beliefs in the context of wireless Internet data services via mobile phones. Survey data were collected from 1432 participants in several metro cities across China. The findings suggest that WMDS adoption intention in China is determined by consumers’ perceived usefulness and perceived ease of use of WMDS. Theoretical and practical implications are included in our paper. 相似文献
90.
This paper proposes a method to reduce the cost of a core-based group-shared multicast tree, where the cost is evaluated by the total bandwidth consumption of multicasting packets among all group members. Due to the broadcast nature of radio transmissions, we find that the challenge of determining minimum cost multicast tree can be approximated by finding the multicast tree with a minimum number of non-leaves (the minimum non-leaf multicast tree problem). However, we also find that the minimum non-leaf multicast tree problem is NP-complete. Thus, a method is proposed to dynamically reduce the number of non-leaves in an existing multicast tree. Experimental results show that our method reduces the cost of the multicast tree in both geometrically and randomly distributed network models and the random waypoint mobility model. 相似文献