全文获取类型
收费全文 | 85820篇 |
免费 | 6579篇 |
国内免费 | 2882篇 |
专业分类
电工技术 | 5828篇 |
技术理论 | 9篇 |
综合类 | 8055篇 |
化学工业 | 7195篇 |
金属工艺 | 2427篇 |
机械仪表 | 3136篇 |
建筑科学 | 15909篇 |
矿业工程 | 2911篇 |
能源动力 | 2611篇 |
轻工业 | 15855篇 |
水利工程 | 5374篇 |
石油天然气 | 2868篇 |
武器工业 | 627篇 |
无线电 | 4163篇 |
一般工业技术 | 5122篇 |
冶金工业 | 5094篇 |
原子能技术 | 621篇 |
自动化技术 | 7476篇 |
出版年
2024年 | 471篇 |
2023年 | 1317篇 |
2022年 | 2234篇 |
2021年 | 2867篇 |
2020年 | 2889篇 |
2019年 | 2344篇 |
2018年 | 2204篇 |
2017年 | 2481篇 |
2016年 | 2824篇 |
2015年 | 2921篇 |
2014年 | 6183篇 |
2013年 | 5439篇 |
2012年 | 6127篇 |
2011年 | 6591篇 |
2010年 | 5162篇 |
2009年 | 5294篇 |
2008年 | 4693篇 |
2007年 | 5645篇 |
2006年 | 5085篇 |
2005年 | 4089篇 |
2004年 | 3499篇 |
2003年 | 3060篇 |
2002年 | 2677篇 |
2001年 | 1962篇 |
2000年 | 1588篇 |
1999年 | 1243篇 |
1998年 | 847篇 |
1997年 | 654篇 |
1996年 | 568篇 |
1995年 | 473篇 |
1994年 | 367篇 |
1993年 | 259篇 |
1992年 | 229篇 |
1991年 | 157篇 |
1990年 | 123篇 |
1989年 | 122篇 |
1988年 | 102篇 |
1987年 | 85篇 |
1986年 | 57篇 |
1985年 | 54篇 |
1984年 | 44篇 |
1983年 | 35篇 |
1982年 | 45篇 |
1981年 | 17篇 |
1980年 | 31篇 |
1979年 | 12篇 |
1977年 | 10篇 |
1965年 | 19篇 |
1964年 | 8篇 |
1959年 | 12篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
221.
Floc architecture of bioflocculation sediment by ESEM and CLSM 总被引:1,自引:0,他引:1
Sediment flocculation is a critical component for the understanding of cohesive sediment dynamics. Traditionally, the referred study has largely been devoted to forming mechanism, influencing factors and physicochemical sediment conditions of all kinds of organic-flocculation and inorganic-flocculation. However, during the last decade, the bioflocculation of sediment by biological activity has been given increasing attention. But most studies have focused on the interrelations between biological and sedimentological variables. With the assistance of a newly developed field kit and correlative microscopy (which includes environmental scanning electron microscopy and confocal laser scanning microscopy), this article begins to bridge the resolution gap between sediment particles and biological activities as well as its metabolic products biofilm, in order to better understand the role of polymeric material biofilm in floc ultrastructure and outward floc behavior of bioflocculation sediment. Results have demonstrated that bioflocculation sediment was observed to be composed of complex networks of biofilm and appeared to be of complicated physical floc structures. The biofilm was found to embed particles and permeate the void space, representing the dominant physical bridging mechanism of the flocs and contributed to the extensive surface area, architecture characteristics, and mechanical properties of bioflocculation sediment. 相似文献
222.
Oracle数据库应用是一门实践性很强的课程,本文首先阐述了课程改革的思路,并从课程内容设置、教学模式、教学方法、考核方式、课程资料建设等方面进行了深入的研究与实践,提高了课程的教学质量和教学效果。 相似文献
223.
刘永辉 《网络安全技术与应用》2013,(10):68-68,78
现阶段我国高校网络教育学院发展速度和规模都在不断的加速、扩大.2013年教育部公示我国共有68所网络教育院校具有招生资格.面对着高校扩招的步伐逐步扩大,各网络教育学院为了得到进一步的发展也在不断的进行着各种的招生宣传, “211重点院校”、“在家上名牌大学”等成为一些高校网络远程教育学院高呼的口号.但是招生宣的各种招式对于网络教育学院的长久发展来说只是临渊慕鱼.保证教学质量才是高校网络教育学院的长久发展之道.本文从高校网络教育学院远程教学的质量保证体系方面进行阐述,旨在探讨保证高校网络教育学院长久、健康发展的方法. 相似文献
224.
Although client satisfaction surveys can assess client satisfaction with IT service quality, they cannot easily be used to pinpoint how internal IT behaviors influence client satisfaction and prescribe solutions. This research fills the gap by introducing a concept— IT Service Climate—and a validated ten-item instrument that significantly explained client ratings of IT service quality. We recommend this measure as an effective diagnostic tool for managers aiming to improve quality and client satisfaction. 相似文献
225.
《国际互联网参考资料服务季刊》2013,18(4):57-76
Abstract The World Wide Web offers a large and ever-expanding number of resources in the fields of psychology and sociology. Growth of the Web has been so fast that it has been difficult to keep track of all the new resources that are rapidly becoming available. With so many new Web sites cropping up, there is a growing need to sort through these resources and determine which sites are the most valuable for research in these subject areas. This study first discusses some criteria for assessing the quality of Web sites, and then applies these criteria to the Web sites currently available in an effort to determine which sites are the best for these two fields. 相似文献
226.
本文介绍了锦屏二级水电站3#引水隧洞有盖重防渗固结灌浆试验的施工方法和试验参数。通过防渗固结灌浆试验,总结出在灌浆施工中应及时采集的相关信息和采取的施工工艺,既保证了施工质量又保证了施工速度 相似文献
227.
228.
混凝土生产工艺流程复杂,控制工序多,生产过程除易受系统因素影响外,还受随机因素的干扰较大,生产质量不易控制,本文应用统计过程控制(SPC)在龙滩水电站混凝土生产中的质量控制实践来谈点初浅的认识. 相似文献
229.
毛丹丹 《河北水利水电技术》2011,(4):19-21
自武汉城市圈被评为两型社会综合配套改革实验区以来,面对水环境呈现多样性和复杂性的现状,将武汉城市圈建设成为富有滨水特色的现代化生态城市圈是两型社会建设主题中应有之义,也是推动城市圈生态化发展的必由之路。针对武汉城市圈水生态保护与建设的问题,在阐述了其必然性的基础上,对理论支撑及基本原则作了细致具体的分析,希望能对武汉城市圈水生态保护与建设的实践问题等相关研究有所帮助。 相似文献
230.
Gigabit home networks represent a key technology to make the Future Internet success a reality. Consumers will require networks to be simple to install, without the need of any new wire and with green consideration. To make this network ubiquitous, seamless and robust, a technology independent MAC layer will ensure its global control and provide connectivities to any number of devices the user wishes to connect to it in any room. In order to make this vision comes true, substantial progress is required in the fields of protocol design and in systems architectures. For this goal, we introduce a new convergence layer denoted inter-MAC, which provides a common infrastructure to the home network, Among the inter-MAC functionalities, we focused the interest on the path selection mechanism including the green aspect. To improve quality of service, reduce energy consumption and radiofrequency devices number, we define a new path selection protocol based on several metrics. We present some preliminary results obtained on an experimental test bed. 相似文献