全文获取类型
收费全文 | 29417篇 |
免费 | 3226篇 |
国内免费 | 2181篇 |
专业分类
电工技术 | 1407篇 |
综合类 | 3405篇 |
化学工业 | 3038篇 |
金属工艺 | 2471篇 |
机械仪表 | 1676篇 |
建筑科学 | 5856篇 |
矿业工程 | 605篇 |
能源动力 | 421篇 |
轻工业 | 541篇 |
水利工程 | 1080篇 |
石油天然气 | 939篇 |
武器工业 | 314篇 |
无线电 | 3008篇 |
一般工业技术 | 4654篇 |
冶金工业 | 851篇 |
原子能技术 | 220篇 |
自动化技术 | 4338篇 |
出版年
2024年 | 147篇 |
2023年 | 474篇 |
2022年 | 687篇 |
2021年 | 855篇 |
2020年 | 905篇 |
2019年 | 892篇 |
2018年 | 882篇 |
2017年 | 1026篇 |
2016年 | 1001篇 |
2015年 | 1065篇 |
2014年 | 1704篇 |
2013年 | 1821篇 |
2012年 | 1946篇 |
2011年 | 2043篇 |
2010年 | 1554篇 |
2009年 | 1612篇 |
2008年 | 1650篇 |
2007年 | 1952篇 |
2006年 | 1846篇 |
2005年 | 1600篇 |
2004年 | 1357篇 |
2003年 | 1184篇 |
2002年 | 1022篇 |
2001年 | 900篇 |
2000年 | 802篇 |
1999年 | 677篇 |
1998年 | 581篇 |
1997年 | 482篇 |
1996年 | 391篇 |
1995年 | 356篇 |
1994年 | 294篇 |
1993年 | 272篇 |
1992年 | 217篇 |
1991年 | 137篇 |
1990年 | 108篇 |
1989年 | 104篇 |
1988年 | 66篇 |
1987年 | 41篇 |
1986年 | 33篇 |
1985年 | 35篇 |
1984年 | 16篇 |
1983年 | 16篇 |
1982年 | 15篇 |
1981年 | 2篇 |
1980年 | 16篇 |
1979年 | 20篇 |
1978年 | 3篇 |
1976年 | 4篇 |
1975年 | 3篇 |
1951年 | 5篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
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
82.
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
83.
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
84.
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
85.
86.
随着Deep Web数量和规模的快速增长,通过对其发起查询请求以得到存储在后台数据库中的相关信息,日渐成为用户获取信息的主要方式。为了方便用户有效地利用Deep Web中的信息,越来越多的研究者致力于这一领域的研究,重点之一是Deep Web后台数据库的数据集成。由于Deep Web后台数据库存储的主要是文本信息,使得从文本处理角度出发,针对Deep Web中存储的内容进行查询与检索的研究具有十分广阔的应用前景。本文对Deep Web的研究现状进行了较为详细的分析,同时对研究的发展方向进行了展望。 相似文献
87.
刘兵 《计算机光盘软件与应用》2012,(1):72+68
伴随计算机技术的不断发展进步,而各种不同的计算机软件由于开发商不同,其数据结构也各种各样,假如用户需要操作两套或者两套以上的软件,需要根据计算机提供对应的格式基础,按照计算机软件保留各种格式的数据结果,这样无形中就增加了用户的工作量,并且软件处理流程链也容易中断。而计算机软件的数据接口可以很好的解决这类问题。本文就针对计算机软件数据接口的应用进行分析研究。 相似文献
88.
目前反倾岩质边坡弯曲倾倒破坏分析方法仍以基于极限平衡理论的悬臂梁模型为主,但大多未考虑坡脚岩层的剪切破坏。为准确评价该类边坡的稳定性,建立考虑坡脚岩层剪切破坏的分析计算方法。首先,根据岩层变形破坏特征,将边坡分为后缘稳定区、中部弯曲倾倒区和前缘剪切区3个区域;其次,建立弯曲倾倒-剪切滑移破坏模式的稳定性分析方法;最后,通过工程实例验证,并进行参数分析。研究结果表明:提出的分析方法与工程实际符合性较好;边坡在倾角较陡、坡角较大时稳定性最差,坡角对边坡稳定性影响大于岩层倾角的影响;岩层厚度及层面内摩擦角增加有利于边坡稳定性,且会扩大坡脚剪切区范围。研究成果对反倾岩质边坡破坏的防治具有实践指导意义。 相似文献
89.
Thin-walled parts are widely used in the aerospace, shipbuilding, and automotive industry, but due to its unique structure and high accuracy requirements, which leads to an increase in scrapped parts, high cost in production, and a more extended period in the trial machining process. However, to adapt to fast production cycles and increase the efficiency of thin-walled parts machining, this paper presents a Digital Twin-driven thin-walled part manufacturing framework to allow the machine operator to manage the product changes, make the start-up phases faster and more accurate. The framework has three parts: preparation, machining, and measurement, driven by Digital Twin technologies in detail. By establishing and updating the workpiece Digital Twin under a different status, various manufacturing information and data can be integrated and available to machine operators and other Digital Twins. It can serve as a guideline for establishing the machine tool and workpiece Digital Twin and integrating them into the machining process. It provides the machine operator opportunities to interact with both the physical manufacturing process and its digital data in real-time. The digital representation of the physical process can support them to manage the trial machining from different aspects. In addition, a demonstrative case study is presented to explain the implementation of this framework in a real manufacturing environment. 相似文献
90.