全文获取类型
收费全文 | 8306篇 |
免费 | 770篇 |
国内免费 | 651篇 |
专业分类
电工技术 | 669篇 |
综合类 | 1054篇 |
化学工业 | 369篇 |
金属工艺 | 167篇 |
机械仪表 | 679篇 |
建筑科学 | 669篇 |
矿业工程 | 304篇 |
能源动力 | 159篇 |
轻工业 | 285篇 |
水利工程 | 183篇 |
石油天然气 | 204篇 |
武器工业 | 107篇 |
无线电 | 716篇 |
一般工业技术 | 396篇 |
冶金工业 | 201篇 |
原子能技术 | 26篇 |
自动化技术 | 3539篇 |
出版年
2024年 | 11篇 |
2023年 | 59篇 |
2022年 | 83篇 |
2021年 | 121篇 |
2020年 | 135篇 |
2019年 | 162篇 |
2018年 | 136篇 |
2017年 | 148篇 |
2016年 | 170篇 |
2015年 | 190篇 |
2014年 | 376篇 |
2013年 | 359篇 |
2012年 | 469篇 |
2011年 | 568篇 |
2010年 | 427篇 |
2009年 | 527篇 |
2008年 | 610篇 |
2007年 | 754篇 |
2006年 | 742篇 |
2005年 | 610篇 |
2004年 | 557篇 |
2003年 | 492篇 |
2002年 | 405篇 |
2001年 | 350篇 |
2000年 | 285篇 |
1999年 | 203篇 |
1998年 | 176篇 |
1997年 | 125篇 |
1996年 | 111篇 |
1995年 | 99篇 |
1994年 | 72篇 |
1993年 | 41篇 |
1992年 | 40篇 |
1991年 | 29篇 |
1990年 | 27篇 |
1989年 | 7篇 |
1988年 | 9篇 |
1987年 | 5篇 |
1986年 | 3篇 |
1985年 | 6篇 |
1984年 | 5篇 |
1983年 | 2篇 |
1981年 | 2篇 |
1980年 | 7篇 |
1979年 | 4篇 |
1977年 | 3篇 |
1975年 | 1篇 |
1973年 | 1篇 |
1961年 | 1篇 |
1957年 | 1篇 |
排序方式: 共有9727条查询结果,搜索用时 15 毫秒
11.
12.
13.
在普通圆纬机上编织彩横条织物时,彩横务循环单元受到一定限制。而在具有四色或六色调线装置的横务纹机上编织彩横条织物时,可扩大彩横条循环单元的横列数。文中举列说明了彩横条织物的设计与上机工艺的制定方法。 相似文献
14.
15.
Stochastic extensions to Petri nets have gained widespread acceptance as a method for describing the dynamic behavior of discrete-event
systems. Both simulation and analytic methods have been proposed to solve such models. This paper describes a set of efficient
procedures for simulating models that are represented as stochastic activity networks (SANs, a variant of stochastic Petri
nets) and composed SAN-based reward models (SBRMs). Composed SBRMs are a hierarchical representation for SANs, in which individual
SAN models can be replicated and joined together with other models, in an iterative fashion. The procedures exploit the hierarchical
structure and symmetries introduced by the replicate operation in a composed SBRM to reduce the cost of future event list
management. The procedures have been implemented as part of a larger performance-dependability modeling package known asUltraSAN, and have been applied to real, large-scale applications.
This work was supported in part by the Digital Equipment Corporation Faculty Program: Incentives for Excellence. 相似文献
16.
17.
采用封闭网络模型,按照电路元件参数,采用开路、短路和着色运算,将电路图逐层分解,得到网络展开图.给出网络展开图的概念和运算规则,指出网络展开图中从根到末稍每个路径的值就是网络行列式展开式中的一个有效项,从而由网络展开图得到符号网络函数.该方法直接对电路图进行运算,不需要建立任何形式的电路方程和行列式,适用于一般的有源电路,而且能生成各种类型的网络函数. 相似文献
18.
基于MAPINFO和VB的自来水管网信息系统的建立 总被引:2,自引:0,他引:2
介绍基于MapInfo平台,利用VB语言进行二次开发,建立自来水管网地理信息系统的关键技术及其注意的问题。 相似文献
19.
Hatto F. Jacobi 《国际钢铁研究》2003,74(11-12):667-678
Improvements of solidification processing in conventional or near net shape casting depend on sophisticated methods of macroscopic examination of central unsoundness and inhomogeneity of the cast material. As long as remarkable deviations referring to the quality features exist between the slab centre and the bulk material such methods should be looked after. Two semi‐macroscopic methods of segregation analysis are discussed in this paper: firstly, the potential of the emission spectral analysis combined with sectioning of a sample and secondly, the computer aided micro‐probe analysis. Both methods are restricted to small local areas. The proneness of elements and steel grades with respect to micro‐ and macrosegregation as well as distribution‐ and segregation coefficients are determined. The effect of a diffusion anneal on homogenisation of segregation is studied. Last not least the precipitation of sulphides, phosphides or carbonitrides is estimated. Ultrasonic detection of the central unsoundness of conventional slabs or thin slabs is a new approach towards a quantitative macroscopic examination. The sample size is 400 mm x 300 mm x 30 mm. To achieve a low ultrasonic noise using a 5 MHz‐transducer the samples are heat treated for grain refinement. “Dog bone porosity”, macroscopic topographical misfit between the upper and lower solidifying shells, periodical corner cracks or systematic transverse centre cracks are detected. Obviously, segregations do not reflect the ultrasonic beam. However, it can be presumed that an interrelation exists between porosity and segregation, although these might be locally apart from each other. This new ultrasonic test of the central unsoundness of continuous cast (c.c.) slabs gives valuable arguments to machine builders and maintenance people to decide on the right concepts for strand guidance, support rollers and secondary cooling. Soft reduction can be optimized and variations in casting speed counteracted by dynamic means. R&D service of this kind can help steelmakers when decisions are impending to build new casting machines or revamp old ones. 相似文献
20.
喷锚网支护可提高高且陡的边坡岩土结构强度和抗变形刚度,增强边坡的整体稳定性.根据公路路段的情况,路堑边坡采用喷锚网支护的形式,针对设计方案、材料要求、施工方法、技术措施,以及现场质量管理和检测问题进行探讨. 相似文献