全文获取类型
收费全文 | 14453篇 |
免费 | 1213篇 |
国内免费 | 880篇 |
专业分类
电工技术 | 769篇 |
技术理论 | 1篇 |
综合类 | 1226篇 |
化学工业 | 989篇 |
金属工艺 | 928篇 |
机械仪表 | 1157篇 |
建筑科学 | 2049篇 |
矿业工程 | 1491篇 |
能源动力 | 422篇 |
轻工业 | 452篇 |
水利工程 | 290篇 |
石油天然气 | 571篇 |
武器工业 | 101篇 |
无线电 | 1028篇 |
一般工业技术 | 746篇 |
冶金工业 | 1848篇 |
原子能技术 | 99篇 |
自动化技术 | 2379篇 |
出版年
2024年 | 31篇 |
2023年 | 144篇 |
2022年 | 478篇 |
2021年 | 424篇 |
2020年 | 488篇 |
2019年 | 344篇 |
2018年 | 261篇 |
2017年 | 282篇 |
2016年 | 340篇 |
2015年 | 369篇 |
2014年 | 937篇 |
2013年 | 824篇 |
2012年 | 1047篇 |
2011年 | 1111篇 |
2010年 | 847篇 |
2009年 | 1035篇 |
2008年 | 786篇 |
2007年 | 988篇 |
2006年 | 896篇 |
2005年 | 826篇 |
2004年 | 682篇 |
2003年 | 682篇 |
2002年 | 720篇 |
2001年 | 448篇 |
2000年 | 321篇 |
1999年 | 251篇 |
1998年 | 160篇 |
1997年 | 146篇 |
1996年 | 134篇 |
1995年 | 113篇 |
1994年 | 83篇 |
1993年 | 69篇 |
1992年 | 46篇 |
1991年 | 35篇 |
1990年 | 24篇 |
1989年 | 26篇 |
1988年 | 27篇 |
1987年 | 9篇 |
1986年 | 13篇 |
1985年 | 8篇 |
1984年 | 21篇 |
1983年 | 11篇 |
1982年 | 13篇 |
1981年 | 4篇 |
1980年 | 4篇 |
1979年 | 3篇 |
1975年 | 3篇 |
1966年 | 6篇 |
1957年 | 3篇 |
1955年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
Mingzhi Zhao Jianwei Cao Zhi Wang Guohua Li 《Journal of the European Ceramic Society》2019,39(7):2427-2435
The crystallization phenomena of spinel in CaO-MgO-Al2O3-SiO2-Fe2O3 glass have received much attention due to the particular role in preparation of glass-ceramic materials, which represent an effective option to manage hazardous waste. In this study, both preliminary spinel and secondary spinel were precipitated in the precursor glass. The formation of these spinel was meticulously assessed by a combination of X-ray diffractometry and scanning electron microscopy. The structure of the microenvironment in the precursor glass was characterized by Raman spectrums. These advanced techniques highlight the potential for one-step crystallization of the glass. The investigation, which focused on one-step crystallization, demonstrated the growth of pyroxene on spinel accompanying a migration of chromium. The results also show the microstructure of the obtained glass-ceramic was very dependent on the heat-treat temperature. This study not only unambiguously reveals the precipitation mechanisms of spinel but also provides more documentation for one-step crystallization in the glass-ceramics field. 相似文献
3.
This paper summarizes the basics of pulsed thermal nondestructive testing (TNDT) including theoretical solutions, data processing algorithms and practical implementation. Typical defects are discussed along with 1D analytical and multi-dimensional numerical solutions. Special emphasis is focused on defect characterization by the use of inverse solutions. A list of TNDT terms is provided. Applications of active TNDT, mainly in the aerospace industry, are discussed briefly, and some trends in the further development of this technique are described. 相似文献
4.
为解决21000工作面采空区及顶板涌水问题,根据工作面出水点的不同情况,采取了集水器导水、老塘设挡水堰截水、挖排水沟疏水等多项治水措施,经统计排水量达33~42m3/h,有效控制了水情,确保了工作面正常生产。 相似文献
5.
摘要:为了研究退火温度对镀锌DP980+Z烘烤硬化值的影响,退火温度控制在760~820℃之间,系统分析退火温度对烘烤硬化值的影响。通过准静态拉伸试验机测量烘烤硬化值及抗拉强度,采用lepara试剂对组织中的马氏体进行着色,利用金相显微镜及图像处理软件测量马氏体的体积分数;采用扫描电镜观察DP980+Z的双相组织特点,并且将组织图片通过CAD转化成有限元图进行网格划分,建立代表性体积单元(RVE),通过有限元分析铁素体、马氏体强度对烘烤硬化值的影响。在同样的变形量情况下,DP980+Z的原始屈服强度越高,烘烤硬化值越高。 相似文献
6.
Defects are often present in rolled products, such as wire rod. The market demand for wire rod without any defects has increased. In the final wire rod products, defects originating from steel making, casting, pre‐rolling of billets and during wire rod rolling can appear. In this work, artificial V‐shaped longitudinal surface cracks have been analysed experimentally and by means of FEM. The results indicate that the experiments and FEM calculations show the same tendency except in two cases, where instability due to fairly “round” false round bars disturbed the experiment. FE studies in combination with practical experiments are necessary in order to understand the behaviour of the material flows in the groove and to explain whether the crack will open up as a V‐shape or if it will be closed as an I‐shape. 相似文献
7.
The present study investigates the impact of different key solutions of mobile phones on users' effectiveness and efficiency using the devices. In the first experiment, 36 children (9 - 14 years) and in the second experiment 45 young adults (19 - 33 years) completed four common phone tasks twice consecutively on three simulated phones that had identical menus, but different key solutions. An approach was undertaken to quantify the complexity of keys in three models, incorporating different factors contributing to the keys' complexity (number of key options, number of modes and number of modes with a semantically dissimilar meaning), in order to predict users' performance decrements. As a further main factor, the degree of the users' locus of control (LOC) was measured and interactions with performance outcomes were studied. As dependent measures, the number of inefficient keystrokes, the number of tasks solved and the processing time were determined. Results showed a significant effect of control key solutions on users' efficiency and effectiveness for both children and young adults. Moreover, children's LOC values significantly interacted with performance: children with low LOC values showed the lowest performance and no learnability, especially when using keys with a high complexity. From the three factors contributing to the complexity of keys, keys exerting different functions with semantically inconsistent meanings had the worst effect on performance. It is concluded that in mobile user interface design keys with semantically inconsistent meanings should be generally avoided. 相似文献
8.
迷宫螺旋泵和密封工作特性研究 总被引:1,自引:1,他引:0
介绍了一种实测迷宫螺旋泵和密封工作特性的实验方法,通过该方法可以测得迷宫螺旋泵的泵送特性曲线、迷宫螺旋端面组合密封的最大密封压力以及端面开启的开始转速,具有一定的实用价值。 相似文献
9.
地理空间信息网格调度技术,要比传统的高性能计算中的调度技术复杂,原因是如果将全部网格资源作为一个应用程序的调度和执行目标,必将导致通信延迟、成本昂贵、执行低效等。为此,综合考虑应用程序特性、机器特性等,研究设计了地理空间信息网格高性能调度技术中的应用程序调度模型,包括地理空间信息网格应用程序分析;资源特性分析;应用程序分解;性能预测;资源调度;机器选择;任务映射;任务调度;任务调度器和调度器管理模块。以实现为不同的应用程序匹配不同的计算资源,提高计算资源的利用率和应用程序的执行效率。 相似文献
10.