全文获取类型
收费全文 | 822篇 |
免费 | 64篇 |
国内免费 | 40篇 |
专业分类
电工技术 | 55篇 |
综合类 | 58篇 |
化学工业 | 96篇 |
金属工艺 | 24篇 |
机械仪表 | 28篇 |
建筑科学 | 65篇 |
矿业工程 | 56篇 |
能源动力 | 27篇 |
轻工业 | 49篇 |
水利工程 | 168篇 |
石油天然气 | 2篇 |
武器工业 | 1篇 |
无线电 | 38篇 |
一般工业技术 | 29篇 |
冶金工业 | 125篇 |
自动化技术 | 105篇 |
出版年
2024年 | 2篇 |
2023年 | 8篇 |
2022年 | 32篇 |
2021年 | 51篇 |
2020年 | 46篇 |
2019年 | 35篇 |
2018年 | 23篇 |
2017年 | 17篇 |
2016年 | 20篇 |
2015年 | 24篇 |
2014年 | 50篇 |
2013年 | 87篇 |
2012年 | 130篇 |
2011年 | 88篇 |
2010年 | 73篇 |
2009年 | 64篇 |
2008年 | 23篇 |
2007年 | 47篇 |
2006年 | 46篇 |
2005年 | 14篇 |
2004年 | 3篇 |
2003年 | 8篇 |
2002年 | 5篇 |
2001年 | 5篇 |
2000年 | 7篇 |
1999年 | 9篇 |
1998年 | 1篇 |
1997年 | 1篇 |
1996年 | 3篇 |
1994年 | 1篇 |
1992年 | 1篇 |
1987年 | 1篇 |
1986年 | 1篇 |
排序方式: 共有926条查询结果,搜索用时 15 毫秒
71.
72.
针对传统互补型带隙基准电压源在只有N型有源器件工艺中的局限性,采用运放反馈的闭环控制方法来产生基准电压,设计了一种可以集成于只有N型有源器件和无源元件工艺中的基准电压源产生电路。为只存在N型MOS或者NPN型晶体管、没有P型器件、难以用传统的带隙电压源结构来产生精确参考电压的特定工艺,提供了一种具有良好的电源抑制比特性和有效地补偿N型器件结压降变化的负温度系数的基准电压源电路;并提出了提高反馈回路稳定性的措施。 相似文献
73.
74.
《Signal Processing: Image Communication》2009,24(7):587-597
Fragile digital watermarking has been applied for authentication and alteration detection in images. Utilizing the cosine and Hartley transforms over finite fields, a new transform domain fragile watermarking scheme is introduced. A watermark is embedded into a host image via a blockwise application of two-dimensional finite field cosine or Hartley transforms. Additionally, the considered finite field transforms are adjusted to be number theoretic transforms, appropriate for error-free calculation. The employed technique can provide invisible fragile watermarking for authentication systems with tamper location capability. It is shown that the choice of the finite field characteristic is pivotal to obtain perceptually invisible watermarked images. It is also shown that the generated watermarked images can be used as publicly available signature data for authentication purposes. 相似文献
75.
基于水布垭面板坝的现场大型承载试验成果,采用基于IGA的反演方法,研究了栖霞组灰岩、茅口组灰岩两种原级配筑坝堆石料的邓肯E–B模型参数。结果表明:在相同应力加载路径条件下,现场原级配堆石料比经过缩尺后的室内三轴试验试样具有更大的体积变形和更高的切线弹性模量,两者的力学性状存在较大差别。对栖霞组原级配灰岩堆石料的回弹模量参数反演分析得到K ur约为K值的2倍,而nu r远大于邓肯建议的直接引用加载时的弹性模量指数n值。宜加强现场原级配粗粒堆石料的力学性质研究,为超高堆石坝的建设提供更为可靠的理论依据。 相似文献
76.
77.
电磁波层析成像是在电磁波法基础上发展起来的一种高分辨地球物理勘探手段,以获得孔间电磁吸收系数或电导率分布图像为主要工作内容,从而达到探明孔间物性分布、确定异常区之目的.本文简要介绍了钻孔电磁波层析成像技术基本的方法原理,通过实例,描述了其在岩溶工程勘察中的作用和较好的应用效果. 相似文献
78.
移动通信直放站的种类、选型与工程安装 总被引:1,自引:0,他引:1
移动通信直放站是解决基站覆盖不足而存在信号盲区的一种方式。根据直放站系列产品的特点和移动通信网络的需求,不同的地理环境及应用场合,系统的解决方案是不同的。文中对移动通信直放站的种类、选型和安装三个方面进行了详细的论述,旨在对建设一个性能优良、经济可靠的移动通信直放站提供参考。 相似文献
79.
《Graphical Models》2002,64(3-4):169-182
In general, mesh smoothing is performed by minimizing the discrete energy function for the surface. One of the major problems in mesh smoothing is to prevent the mesh from shrinking. In this paper, we propose a novel volume constraint to address the shrinking problem in mesh smoothing. Our key observation is that the mesh can be efficiently smoothed patch by patch in a signal processing manner, and then a local volume preserving constraint can be easily imposed to the energy minimization problem associated with the small patch, called the smoothing stencil, so as to effectively avoid the mesh shrinkage. In our implementation, the smoothing stencil is the 1-ring neighboring region of an edge or a triangle. And the constrained minimization problem is solved by a 2-step approximation method for efficiency. A series of examples demonstrate that the proposed smoothing method can be applied to remove noise from a mesh or remove rough detail from an original mesh to generate a smooth model in object reconstruction and geometry modeling. 相似文献
80.
Additive manufacturing,quasi-static and dynamic compressive behaviours of ceramic lattice structures
《Journal of the European Ceramic Society》2022,42(15):7102-7112
Ceramic lattice structures (CLSs) are used for construction in common and extreme environments because of the extraordinary properties of ceramics. In this study, we designed and additively manufactured CLSs with distinct structural parameters to explore their quasi-static and dynamic compressive behaviours in detail. It was demonstrated that both the relative density (?ρ) and inclination angle (ω) had a significant impact on the quasi-static and dynamic mechanical properties of the CLSs. Furthermore, the mathematical relationships between the quasi-static compressive properties, including quasi-static compressive strength (QS), quasi-static Young’s modulus (QY), and quasi-static energy absorption (QE), versus ?ρ and ω obeyed the Gibson–Ashby and Deshpande and Fleck models, respectively. It was revealed by experiment and simulation that as the stiffness increased, the quasi-static failure mode of the CLSs changed from a parallel-vertical-inclined mixed mode to a parallel-vertical mode. In addition, the relationship between the dynamic mechanical properties of the CLSs versus ?ρ and ω also followed the Gibson–Ashby and Deshpande and Fleck models. The exceptional dynamic increase factor indicated that CLSs are highly suitable for extreme environments. These findings will aid in the research and development of customised additively manufactured CLSs. 相似文献