全文获取类型
收费全文 | 71580篇 |
免费 | 4016篇 |
国内免费 | 2775篇 |
专业分类
电工技术 | 5639篇 |
技术理论 | 19篇 |
综合类 | 8117篇 |
化学工业 | 2399篇 |
金属工艺 | 837篇 |
机械仪表 | 2986篇 |
建筑科学 | 13165篇 |
矿业工程 | 3050篇 |
能源动力 | 1895篇 |
轻工业 | 1873篇 |
水利工程 | 4248篇 |
石油天然气 | 1766篇 |
武器工业 | 304篇 |
无线电 | 6082篇 |
一般工业技术 | 3546篇 |
冶金工业 | 5000篇 |
原子能技术 | 456篇 |
自动化技术 | 16989篇 |
出版年
2024年 | 114篇 |
2023年 | 479篇 |
2022年 | 986篇 |
2021年 | 1369篇 |
2020年 | 1523篇 |
2019年 | 1062篇 |
2018年 | 992篇 |
2017年 | 1347篇 |
2016年 | 1719篇 |
2015年 | 1940篇 |
2014年 | 5904篇 |
2013年 | 4698篇 |
2012年 | 5270篇 |
2011年 | 5643篇 |
2010年 | 4385篇 |
2009年 | 4683篇 |
2008年 | 4690篇 |
2007年 | 5659篇 |
2006年 | 4859篇 |
2005年 | 4121篇 |
2004年 | 3550篇 |
2003年 | 3157篇 |
2002年 | 2489篇 |
2001年 | 1815篇 |
2000年 | 1402篇 |
1999年 | 1047篇 |
1998年 | 718篇 |
1997年 | 536篇 |
1996年 | 423篇 |
1995年 | 360篇 |
1994年 | 267篇 |
1993年 | 198篇 |
1992年 | 134篇 |
1991年 | 106篇 |
1990年 | 68篇 |
1989年 | 94篇 |
1988年 | 72篇 |
1987年 | 35篇 |
1986年 | 68篇 |
1985年 | 73篇 |
1984年 | 74篇 |
1983年 | 82篇 |
1982年 | 24篇 |
1981年 | 19篇 |
1980年 | 11篇 |
1979年 | 13篇 |
1977年 | 14篇 |
1961年 | 7篇 |
1960年 | 7篇 |
1959年 | 9篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
961.
962.
本文对搭建RSS网络文摘管理系统网站进行了简要的介绍。它主要实现用户管理、网摘管理、网摘分类管理、信息恢复、网摘加入RSS、修改密码等功能;并对数据库结构进行了较详细的分析。 相似文献
963.
随着高校网络信息化的不断发展,网络安全问题开始日益突出,如何建立一套安全可行的校园网络安全系统,是所有高校校园网络管理者所需要解决的问题。 相似文献
964.
谷权峰 《计算机工程与科学》2010,32(4):146-150
"中美合作百万册数字图书馆计划"(简称CADAL)已建成了含有100万册电子图书、数据信息量达到150Tbytes的数字图书馆,具有很高的科学参考价值。本文围绕数字图书馆的海量信息管理这一课题,逐步探讨了电子图书数据查重、电子图书精确管理和数字图书馆系统容灾快速恢复等急待解决的研究课题,根据项目引用的数字图书馆标准,对CADAL电子书查重、CADAL图书元数据入数据库、CADAL数字图书馆数据库设计、CADAL数字图书馆的备份等系统需求进行了软件实现。研究成果直接应用在CADAL项目中,有力地支持了CADAL生产和发布系统的平稳运行,保障了CADAL图书馆提供内容丰富的知识服务。 相似文献
965.
内容管理系统是目前企业信息管理领域的研究热点。该文介绍了企业内容管理系统的意义和技术发展趋势,并分析了现在企业系统中存在的问题。针对中小企事业单位的需求,设计和实现了易特内容管理系统,尤其在安全性上的改进,保障了企业各类信息的安全可靠。其实现思路对于提高内容管理系统在企业的应用提供了很好的参考价值。 相似文献
966.
基于SOA的科技项目管理系统平台的研究 总被引:3,自引:0,他引:3
为了实现可动态重构、能快速适应业务需求变化的科技项目管理系统,论文在分析面向服务架构(SOA)的思想和科技项目管理领域需求的基础上,提出了基于面向服务架构的科技项目管理系统平台的设计框架,该框架主要包含了可重用的服务仓库和业务流程服务集成引擎。论文详细阐述框架中主要构件模块和业务流程服务引擎。通过项目实践表明,在该框架指导下能有效解决目前科技项目管理系统中存在的问题。 相似文献
967.
968.
Stephen J. Walsh Amy L. McCleary Carlos F. Mena Yang Shao Julie P. Tuttle Augusto Gonzlez Rachel Atkinson 《Remote sensing of environment》2008,112(5):291-1941
In the Galapagos Islands of Ecuador, one of the greatest threats to the terrestrial ecosystem is the increasing number and areal extent of invasive species. Increased human presence on the islands has hastened the introduction of plant and animal species that threaten the native and endemic flora and fauna. Considerable research on invasive species in the Galapagos Islands has been conducted by the Charles Darwin Foundation. We complement that work through a spatially- and spectrally-explicit satellite assessment of an important invasive plant species (Psidium guajava — guava) on Isabela Island that integrates diverse remote sensing systems, data types, spatial and spectral resolutions, and analytical and image processing approaches. QuickBird and Hyperion satellite data are processed to characterize the areal extent and spatial structure of guava through the following approaches: (1) QuickBird data are classified through a traditional pixel-based approach (i.e., an unsupervised classification approach using the ISODATA algorithm), as well as an Object-Based Image Analysis (OBIA) approach; (2) multiple approaches for spectral “unmixing” of the Hyperion hyper-spectral data are assessed to construct spectral end-members from QuickBird data using linear and non-linear mixture modeling approaches; and (3) landscape pattern metrics are calculated and compared for the pixel-based, object-based, and spectral unmixing approaches. The spectral–spatial characteristics of guava are interpreted relative to management strategies for the control of guava and the restoration of natural ecosystems in the Galapagos National Park. 相似文献
969.
The vulnerability of structures to unforeseen events 总被引:2,自引:0,他引:2
A structure is vulnerable to an unforeseen event if it is not sufficiently robust. One insight into the lack of robustness is gained through the vulnerability of a structure to disproportionate collapse. In this paper, the importance of assessing the vulnerability of a structure to unforeseen events is highlighted and the nature of unforeseen events examined. A theory of structural vulnerability which examines the form of the structure to determine the most vulnerable sequence of failure events is briefly described. The potential for damage to propagate through a structure is examined through a new measure of hazard potential and vertical pushover analysis. An analysis of an example structure shows that such an approach is able to capture the weaknesses in a structure either due to form or external actions. 相似文献
970.
Mesh networks are a potential solution for providing communication infrastructure in an emergency. They can be rapidly deployed by first responders in the wake of a major disaster to augment an existing wireless or wired network. We imagine a mesh node with multiple radios embedded in each emergency vehicle arriving at the site to form the backbone of a mobile wireless mesh. The ability of such a mesh network to monitor itself, diagnose faults and anticipate problems are essential features for its sustainable operation. Typical SNMP-based centralized solutions introduce a single point of failure and are unsuitable for managing such a network. Mesh-Mon is a decentralized monitoring and management system designed for such a mobile, rapidly deployed, unplanned mesh network and works independently of the underlying mesh routing protocol. Mesh-Mon nodes are designed to actively cooperate and use localized algorithms to predict, detect, diagnose and resolve network problems in a scalable manner. Mesh-Mon is independent of the underlying routing protocol and can operate even if the mesh routing protocol completely fails. One novel aspect of our approach is that we employ mobile users of the mesh, running software called Mesh-Mon-Ami, to ferry management packets between physically-disconnected partitions in a delay-tolerant-network manner. The main contributions of this paper are the design, implementation and evaluation of a comprehensive monitoring and management architecture that helps a network administrator proactively identify, diagnose and resolve a range of issues that can occur in a dynamic mesh network. In experiments on Dart-Mesh, our 16-node indoor mesh testbed, we found Mesh-Mon to be effective in quickly diagnosing and resolving a variety of problems with high accuracy, without adding significant management overhead. 相似文献