全文获取类型
收费全文 | 19404篇 |
免费 | 1889篇 |
国内免费 | 1409篇 |
专业分类
电工技术 | 1484篇 |
综合类 | 1727篇 |
化学工业 | 1639篇 |
金属工艺 | 1571篇 |
机械仪表 | 1518篇 |
建筑科学 | 1029篇 |
矿业工程 | 336篇 |
能源动力 | 245篇 |
轻工业 | 266篇 |
水利工程 | 388篇 |
石油天然气 | 469篇 |
武器工业 | 246篇 |
无线电 | 3345篇 |
一般工业技术 | 2778篇 |
冶金工业 | 358篇 |
原子能技术 | 225篇 |
自动化技术 | 5078篇 |
出版年
2024年 | 71篇 |
2023年 | 302篇 |
2022年 | 373篇 |
2021年 | 476篇 |
2020年 | 476篇 |
2019年 | 462篇 |
2018年 | 405篇 |
2017年 | 516篇 |
2016年 | 520篇 |
2015年 | 667篇 |
2014年 | 1007篇 |
2013年 | 1115篇 |
2012年 | 1237篇 |
2011年 | 1308篇 |
2010年 | 1074篇 |
2009年 | 1109篇 |
2008年 | 1135篇 |
2007年 | 1412篇 |
2006年 | 1313篇 |
2005年 | 1215篇 |
2004年 | 1039篇 |
2003年 | 948篇 |
2002年 | 779篇 |
2001年 | 637篇 |
2000年 | 568篇 |
1999年 | 433篇 |
1998年 | 385篇 |
1997年 | 319篇 |
1996年 | 257篇 |
1995年 | 242篇 |
1994年 | 188篇 |
1993年 | 182篇 |
1992年 | 133篇 |
1991年 | 87篇 |
1990年 | 76篇 |
1989年 | 59篇 |
1988年 | 44篇 |
1987年 | 15篇 |
1986年 | 26篇 |
1985年 | 25篇 |
1984年 | 17篇 |
1983年 | 9篇 |
1982年 | 9篇 |
1981年 | 2篇 |
1980年 | 4篇 |
1979年 | 8篇 |
1978年 | 3篇 |
1976年 | 5篇 |
1975年 | 3篇 |
1951年 | 4篇 |
排序方式: 共有10000条查询结果,搜索用时 953 毫秒
131.
李红宇 《数字社区&智能家居》2007,(17)
介绍了在VC .net的运行环境下运用拆分窗口功能实现界面切换的步骤及具体实现方法,并给出了关键的实现函数与事例. 相似文献
132.
钻井工程固井胶结界面研究现状 总被引:8,自引:4,他引:4
固井质量问题在石油勘探开发中备受关注,对特殊工艺井钻井、油水井开采寿命和勘探开发效益有直接的影响。对固井胶结界面的研究是从根本上提高固井质量的一项基础性研究工作。为了推动固井胶结界面研究工作的开展,分析了国内外近年来有关固井界面研究的文献,阐述了开展固井胶结界面基础研究工作的意义,着重分析了这一研究领域目前所采用的研究方法,以及提高固井界面胶结强度的主要途径。在分析文献的基础上,提出今后深入开展固井界面研究工作的重点是:1)继续完善研究方法;2)重视动态研究;3)从胶结界面的微观结构和钻井工程整体系统的角度开展研究工作;4)注重改善胶结界面水化产物的微观结构和钻井工作液之间的协调增强作用。 相似文献
133.
DS2000-M1是高性能、开放式的LED控制系统,本文从软硬件两方面简述其设计原理。 相似文献
134.
An object design framework for structural engineering 总被引:1,自引:0,他引:1
Object-oriented principles have introduced several useful concepts for developing complex software systems. As a result, several methodologies have been suggested for the overall design of software systems based on these concepts. Methodologies and frameworks for designing objects that are to be part of the software systems are currently lacking. This paper proposes anobject design framework andmethodology, which utilizes the object-oriented concepts, for planning, organizing and designing structural engineering design objects. Design objects in an integrated structural engineering system are complex and often related to each other in various different ways. The paper also identifies several important relationships among structural engineering design objects. These relationships serve as communication channels through wich design objects send messages to and receive responses from each other. Several examples, drawn from reinforced concrete structures, will be presented to demonstrate the object design methodology and to illustrate how the framework is effective in reducing the complexity of design objects in an integrated structural engineering system. 相似文献
135.
PERFECT (Programming EnviRonment For Expert systems Constrained in reasoning Time) is aimed at providing the necessary engineering support in real-time knowledge-based system development. PERFECT bridges the gap between the traditional analysis and design methodologies, and the implementation tools for these systems. It does so by providing the means to construct a knowledge model and to choose a suitable inference strategy. Subsequently the properties of the knowledge model and inference strategy may be analysed. For instance, it may be checked whether the knowledge model contains sufficient knowledge to diagnose a fault in an industrial process. Moreover, it may be checked whether the inference engine is able to provide an answer to a certain problem in time. If not, the analyser of PERFECT proposes an alternative structure of the knowledge model. When the constructed knowledge model and the chosen inference strategy show the required time efficiency, the compiler of PERFECT may translate them to an actual real-time knowledge based system in COGSYS. In addition, guidelines are provided with respect to the design of the human-machine interface. The resulting system is an instrument—a source of information that can be used by the human operator during problem-solving, rather than a prosthesis—a device that solves the entire problem by itself and presents the outcome to the human operator. 相似文献
136.
A method has been developed, using a silicon-rubber-based sealant, which allows 2–3-mm-thick specimens to be maintained in a protected fluid environment for a number of months, without risk of dehydration. Following this, the specimen can be retrieved, stained, embedded and sectioned further. For example, 2-mm-thick sections of fixed unstained bone are easily examined by means of epi-illuminated polarized light and fluorescence microscopies using either conventional or confocal optics. The method could easily be extended to other tissues, for example brain tissue. 相似文献
137.
三维立体成像及其应用 总被引:3,自引:0,他引:3
本文首先介绍了三种传统的主要三维立体成像方法,即透镜板三维成像方法,投影式三维显示和全息照相术,其次,重点对于采用计算机产生的三维立体景象的方法进行了综述,其中包括人们近年来研究较多的自动立体成像技术等,最后给出了三维立体成像技术在航空航天,工业,教育,医学,军事等领域的应用实例,并预测了三维立体成像技术今后的主要发展方向。 相似文献
138.
Interfaces play an important role in determining the mechanical properties of composite materials. The interfaces established between a titanium-alloy matrix (Ti-6Al-4V) and uncoated and TiB2/C-coated SiC fibres are analysed by scanning electron microscopy, transmission electron microscopy and X-ray techniques. Emphasis is placed upon the interfacial morphology and microstructure, identification of reaction products, and the stability of the coating layer. Complex multi-reaction layers are observed frequently in the interfacial zones. Previous, often contradictory, reports about the interlayers are reviewed. Experimental observation demonstrates that the type and distribution of interlayers vary in a given system, due to prolonged treatment of the samples at temperature. The formation and distribution of the interlayers are discussed further, with respect to these and previous findings. Methods of reducing interfacial reactivity are discussed. 相似文献
139.
140.