全文获取类型
收费全文 | 42932篇 |
免费 | 3848篇 |
国内免费 | 2511篇 |
专业分类
电工技术 | 3427篇 |
技术理论 | 1篇 |
综合类 | 3832篇 |
化学工业 | 2607篇 |
金属工艺 | 4445篇 |
机械仪表 | 8453篇 |
建筑科学 | 1235篇 |
矿业工程 | 2900篇 |
能源动力 | 606篇 |
轻工业 | 3384篇 |
水利工程 | 404篇 |
石油天然气 | 580篇 |
武器工业 | 332篇 |
无线电 | 2546篇 |
一般工业技术 | 2706篇 |
冶金工业 | 2074篇 |
原子能技术 | 86篇 |
自动化技术 | 9673篇 |
出版年
2024年 | 259篇 |
2023年 | 807篇 |
2022年 | 1435篇 |
2021年 | 1542篇 |
2020年 | 1539篇 |
2019年 | 1133篇 |
2018年 | 1039篇 |
2017年 | 1309篇 |
2016年 | 1495篇 |
2015年 | 1642篇 |
2014年 | 2733篇 |
2013年 | 2185篇 |
2012年 | 3156篇 |
2011年 | 3282篇 |
2010年 | 2361篇 |
2009年 | 2371篇 |
2008年 | 2136篇 |
2007年 | 2907篇 |
2006年 | 2741篇 |
2005年 | 2335篇 |
2004年 | 1878篇 |
2003年 | 1622篇 |
2002年 | 1407篇 |
2001年 | 1231篇 |
2000年 | 990篇 |
1999年 | 756篇 |
1998年 | 588篇 |
1997年 | 474篇 |
1996年 | 384篇 |
1995年 | 341篇 |
1994年 | 299篇 |
1993年 | 203篇 |
1992年 | 144篇 |
1991年 | 114篇 |
1990年 | 95篇 |
1989年 | 104篇 |
1988年 | 80篇 |
1987年 | 31篇 |
1986年 | 31篇 |
1985年 | 14篇 |
1984年 | 8篇 |
1983年 | 16篇 |
1982年 | 14篇 |
1981年 | 6篇 |
1980年 | 6篇 |
1979年 | 8篇 |
1978年 | 6篇 |
1959年 | 4篇 |
1958年 | 3篇 |
1957年 | 3篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
71.
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
72.
73.
基于CPLD的系统硬件看门狗设计 总被引:1,自引:0,他引:1
基于以DSP芯片TMS320F2812为核心的数字伺服控制器,以国微电子公司的SM1032国产CPLD(兼容Lattice公司的ispLSI 1032)为载体,设计了专用的系统硬件看门狗模块,具备识别DSP软件初始化时序、自由定制看门狗时序等功能。通过对伺服控制器上电及工作运行时序的分析、仿真和实验验证,确定了硬件看门狗功能模块的设计方案,并给出了实验结果。 相似文献
74.
Fault detection and isolation in rotating machinery is very important from an industrial viewpoint as it can help in maintenance activities and significantly reduce the down-time of the machine, resulting in major cost savings. Traditional methods have been found to be not very accurate. Soft computing based methods are now being increasingly employed for the purpose. The proposed method is based on a genetic programming technique which is known as gene expression programming (GEP). GEP is somewhat a new member of the genetic programming family. The main objective of this paper is to compare the classification accuracy of the proposed evolutionary computing based method with other pattern classification approaches such as support vector machine (SVM), Wavelet-GEP, and proximal support vector machine (PSVM). For this purpose, six states viz., normal, bearing fault, impeller fault, seal fault, impeller and bearing fault together, cavitation are simulated on centrifugal pump. Decision tree algorithm is used to select the features. The results obtained using GEP is compared with the performance of Wavelet-GEP, support vector machine (SVM) and proximal support vector machine (PSVM) based classifiers. It is observed that both GEP and SVM equally outperform the other two classifiers (PSVM and Wavelet-GEP) considered in the present study. 相似文献
75.
A paradigm of scientific discovery is defined within a first-order logical framework. Within this paradigm, the concept of successful scientific inquiry is formalized and investigated. Among other results, it is shown that a simple method of scientific inquiry is universal in the sense that it leads to success on every problem for which success is in principle possible. 相似文献
76.
移动的用户能够方便地访问分布在普适计算环境中的传感器,进而获得情境信息,是情境感知系统的核心目标。本文提出了一种融合分布式P2P和Publish/Subscribe模式的混合式情境感知共享机制,基于抽象状态机对该机制的高鲁棒和可扩展的特性进行设计和规约,并采用AsmL测试工具生成有限状态机验证该机制的有效性和合理性,表明该机制可满足动态的分布式情境感知系统要求。 相似文献
77.
78.
79.
提高高铬白口铸铁磨球冲击抗力的技术关键 总被引:1,自引:1,他引:1
当高铬白口铸铁含铬量为18%~28%,Cr/C值是8 ̄9,铸铁的显微组织是回火马氏体 少量残余奥氏体(<5%) M7C3碳化物,则磨球具有高的冲击韧性和断裂韧性K1C,具有高的冲击抗力,表现出低的冲击剥落量。 相似文献
80.
阐述了200MW汽轮机焊接隔板变形这一在国内电站中多次出现的问题,以及由于隔板变形而对机组带来的危害.强调了在隔板发生严重变形时对隔板进行焊接加固的必要性,概述了隔板检查方法,包括隔板表面缺陷、内部缺陷、通流间隙、挠曲变形等的检查,以及隔板加固的工艺要点. 相似文献