全文获取类型
收费全文 | 5183篇 |
免费 | 556篇 |
国内免费 | 183篇 |
专业分类
电工技术 | 135篇 |
技术理论 | 1篇 |
综合类 | 165篇 |
化学工业 | 1095篇 |
金属工艺 | 235篇 |
机械仪表 | 302篇 |
建筑科学 | 246篇 |
矿业工程 | 24篇 |
能源动力 | 538篇 |
轻工业 | 171篇 |
水利工程 | 21篇 |
石油天然气 | 40篇 |
武器工业 | 20篇 |
无线电 | 782篇 |
一般工业技术 | 831篇 |
冶金工业 | 56篇 |
原子能技术 | 54篇 |
自动化技术 | 1206篇 |
出版年
2024年 | 123篇 |
2023年 | 201篇 |
2022年 | 141篇 |
2021年 | 195篇 |
2020年 | 220篇 |
2019年 | 199篇 |
2018年 | 90篇 |
2017年 | 141篇 |
2016年 | 191篇 |
2015年 | 194篇 |
2014年 | 334篇 |
2013年 | 372篇 |
2012年 | 445篇 |
2011年 | 487篇 |
2010年 | 405篇 |
2009年 | 455篇 |
2008年 | 309篇 |
2007年 | 363篇 |
2006年 | 272篇 |
2005年 | 131篇 |
2004年 | 65篇 |
2003年 | 57篇 |
2002年 | 75篇 |
2001年 | 52篇 |
2000年 | 44篇 |
1999年 | 39篇 |
1998年 | 25篇 |
1997年 | 13篇 |
1996年 | 19篇 |
1995年 | 19篇 |
1994年 | 17篇 |
1993年 | 14篇 |
1992年 | 17篇 |
1991年 | 8篇 |
1990年 | 6篇 |
1989年 | 10篇 |
1988年 | 14篇 |
1987年 | 35篇 |
1986年 | 42篇 |
1985年 | 9篇 |
1984年 | 4篇 |
1973年 | 3篇 |
1972年 | 6篇 |
1971年 | 6篇 |
1970年 | 7篇 |
1969年 | 4篇 |
1967年 | 6篇 |
1966年 | 5篇 |
1965年 | 5篇 |
1962年 | 3篇 |
排序方式: 共有5922条查询结果,搜索用时 0 毫秒
1.
The study of collective user behaviours in social networking sites has become an increasing important topic in social media mining. Understanding such behaviours has its potential to extract actionable patterns that can be beneficial to develop effective marketing strategies, optimise user experiences and maximise website revenues. With the rapid development of micro-blogging, Twitter has become a richer source of intelligence that can be used to study collective user behaviour, due to its efficient and meaningful user-to-user interactions. However, the classical statistical methods have some drawbacks in bridging the gap between user-generated data and human analysts who mostly use linguistic terms to analyse data and model/summarise knowledge learned. To address this gap, this work proposes a new approach, which employs the mass assignment theory-based fuzzy association rules algorithm (MASS-FARM), for the first time, to extract useful interaction behaviour of Twitter users. The influential factors (including activity time, number of friends/followers and the number of tweets) are represented as fuzzy granules, and the associations amongst are studied by employing MASS-FARM. The collective user behaviours are analysed in the Reply category and the Non-Reply category, respectively. The applicability and usefulness of the proposed method are demonstrated via an empirical study on a collected Twitter data set. The derived results are also discussed and compared with existing works. 相似文献
2.
动漫广告具有病毒式传播的天然潜质。其独特鲜活的动漫形象是强有力的病原体,易吸附受众注意力;其核心受众是80、90后人群,他们注重感官消费、乐于信息分享,是典型的易感人群;网络、手机等新媒体日益成为动漫广告受众高度依赖的主流媒体,为动漫广告的病毒式传播提供了4A级的传播渠道;动漫文化本身具有强烈的感染力,能激发受众积极地分享动漫广告信息。鉴于病毒式传播高效的传播效果,动漫广告会在未来的广告营销中异军突起。 相似文献
3.
The Journal of Supercomputing - The topological structures of the interconnection networks of some parallel and distributed systems are designed as n-dimensional hypercube $$Q_n$$ or n-dimensional... 相似文献
4.
Let G1 and G2 be two connected graphs. The Kronecker product G1×G2 has vertex set V(G1×G2)=V(G1)×V(G2) and the edge set . In this paper, we show that if G is a bipartite graph with κ(G)=δ(G), then G×Kn(n?3) is super-κ. 相似文献
5.
开发可统计任意密码子用法的软件BestCodon 总被引:2,自引:2,他引:0
密码子偏好是自然现象,分析密码子的用法可以优化表达基因,即密码子优化,从而调节目的基因在特定宿主中的表达水平。现有密码子用法分析软件多数只限于单个密码子,适用于密码子对和密码子三联体的较少见。本文提出1种可统计任意密码子用法的软件结构,开发出1个密码子用法统计软件BestCodon,拥有序列检查和密码子用法统计2个模块。检查模块可代替人工校对,剔除输入序列中非规范字符,为后续分析提供正确的、符合规范的数据。统计模块根据用户指定的密码子组合类型,结果返回特定的密码子用法表。本文还探讨序列检查和密码子用法统计中计算机的运算特性,结果表明该软件检查1条长达150000 bp的序列仅耗时约0.2 s,而从中统计密码子十联体的用法仅耗时约0.1 s。 相似文献
6.
In (J. Comput. Phys. 229: 8105–8129, 2010), Li and Qiu investigated the hybrid weighted essentially non-oscillatory (WENO) schemes with different indicators for Euler
equations of gas dynamics. In this continuation paper, we extend the method to solve the one- and two-dimensional shallow
water equations with source term due to the non-flat bottom topography, with a goal of obtaining the same advantages of the
schemes for the Euler equations, such as the saving computational cost, essentially non-oscillatory property for general solution
with discontinuities, and the sharp shock transition. Extensive simulations in one- and two-dimensions are provided to illustrate
the behavior of this procedure. 相似文献
7.
L. ZhouC.P. Wang Y. YuX.J. Liu H. ChinenT. Omori I. OhnumaR. Kainuma K. Ishida 《Journal of Alloys and Compounds》2011,509(5):1554-1562
The isothermal sections of the Co-Nb-Ta ternary system at 900 °C, 1000 °C, 1100 °C, 1200 °C, 1300 °C have been experimentally determined by electron probe microanalysis (EPMA) and X-ray diffraction (XRD) techniques on the equilibrated alloys. On the basis of the experimental data investigated in the present work, the phase equilibria in the Co-Nb-Ta system has been thermodynamically assessed by using CALPHAD (CALculation of PHAse Diagrams) method, and a consistent set of the thermodynamic parameters leading to reasonable agreement between the calculated results and experimental data was obtained. 相似文献
8.
Uniformity of removal affects the finishing, and in some cases, the form accuracy of the polished surface. Tool paths are required for the automation of surface polishing. How the tool path may affect the removal of material in polishing is investigated in this paper. An analysis of how removal at a location due to polishing along adjacent path lines is presented. Four tool paths reportedly used in polishing are covered: scanning, bi-scanning, Hilbert and Peano paths. Removal in the inner surface as well as near the edges of surfaces is examined through simulations and analysis. The results show that, for the same path pitch, the peak-to-valley height (hpv) in the inner part of the removal map is the same for scanning, bi-scanning and Peano, while the texture of the removal maps can be quite different. The hpv values of Hilbert are more than double those of Peano, although both are fractal paths. Removal near the edges is particularly severe for scanning-type tool paths. The ratio of the edge peak height to the inner peak height is about 1.6 on average for scanning. The uniformity of removal further deteriorates as the ellipticity of the tool contact increases. When the contact direction is closely aligned with the path line direction, that ratio goes up to about 2.9 for contact ellipticity of 2. Polishing experiments have also been conducted. Both experiments and simulations point to the presence of edge effects in scanning paths and its absence in Peano paths. It is further proposed that, for more uniform removal of material: (1) changes in the tool path direction should be well distributed and (2) the direction of the path lines should be well balanced over the entire surface. 相似文献
9.
在现代网络中,越来越多的主机被部署在NAT和防火墙(FW)之后,这就要求VoIP、P2P等通信软件必须具备穿越NAT/FW的能力,才能实现端到端的数据传输.现有的STUN、TURN、ICE等方案虽然可以穿越大部分NAT/FW,但对有端口或协议限制的防火墙却无能为力.本文提出了将ICE和HTTP Tunnel技术相结合的穿越方案,设计并实现了可跨平台运行的HTTP Tunnel模块来配合ICE进行穿越.实验证明,在防火墙只开放80端口这种苛刻的条件下,该HTTP Tunnel模块也能够成功穿越大部分防火墙,实现数据流的稳定传输. 相似文献
10.
根据Fabry-Prot(F-P)腔的干涉原理,采用微机电系统(MEMS)工艺,研制出一种用于义齿压力检测的F-P腔光纤微型压力传感器。传感器膜片厚为6μm,膜片边长为100μm。在与义齿基托相同材料的树脂底基上,挖边长为1.2mm、深度为0.8mm平整的方形小坑,将传感器分布式埋植入底基,并用自制的施加压力的装置对传感器加压测试。用双波长方法解调干涉信号,用阵列波导光栅(AWG)复用传感器,从而实现对口腔义齿下方组织压力的分布式测量。测量结果表明,当义齿加载0~0.6MPa压力时,系统的相对反射率比值/压力可达0.020 1/MPa,测量结果具有良好的线性度,测量系统的复用能力强,且复用传感器之间没有串扰,适用于义齿对口腔下方组织压力的分布式测量。 相似文献