全文获取类型
收费全文 | 6783篇 |
免费 | 579篇 |
国内免费 | 292篇 |
专业分类
电工技术 | 311篇 |
综合类 | 423篇 |
化学工业 | 1194篇 |
金属工艺 | 272篇 |
机械仪表 | 477篇 |
建筑科学 | 649篇 |
矿业工程 | 200篇 |
能源动力 | 188篇 |
轻工业 | 487篇 |
水利工程 | 164篇 |
石油天然气 | 355篇 |
武器工业 | 46篇 |
无线电 | 792篇 |
一般工业技术 | 800篇 |
冶金工业 | 345篇 |
原子能技术 | 112篇 |
自动化技术 | 839篇 |
出版年
2024年 | 27篇 |
2023年 | 106篇 |
2022年 | 218篇 |
2021年 | 243篇 |
2020年 | 201篇 |
2019年 | 168篇 |
2018年 | 188篇 |
2017年 | 225篇 |
2016年 | 198篇 |
2015年 | 275篇 |
2014年 | 362篇 |
2013年 | 397篇 |
2012年 | 419篇 |
2011年 | 467篇 |
2010年 | 407篇 |
2009年 | 443篇 |
2008年 | 376篇 |
2007年 | 377篇 |
2006年 | 396篇 |
2005年 | 307篇 |
2004年 | 208篇 |
2003年 | 179篇 |
2002年 | 206篇 |
2001年 | 168篇 |
2000年 | 164篇 |
1999年 | 194篇 |
1998年 | 142篇 |
1997年 | 102篇 |
1996年 | 107篇 |
1995年 | 72篇 |
1994年 | 72篇 |
1993年 | 37篇 |
1992年 | 37篇 |
1991年 | 34篇 |
1990年 | 23篇 |
1989年 | 20篇 |
1988年 | 9篇 |
1987年 | 9篇 |
1986年 | 11篇 |
1985年 | 11篇 |
1984年 | 4篇 |
1983年 | 4篇 |
1981年 | 2篇 |
1980年 | 3篇 |
1979年 | 4篇 |
1978年 | 4篇 |
1977年 | 6篇 |
1976年 | 8篇 |
1973年 | 2篇 |
1959年 | 2篇 |
排序方式: 共有7654条查询结果,搜索用时 0 毫秒
11.
This paper presents a novel matrix unit cell scheduler (MUCS) for input-buffered asynchronous transfer mode (ATM) switches. The MUCS concept originates from a heuristic strategy that leads to an optimal solution for cell scheduling. Numerical analysis indicates that input-buffered ATM switches scheduled by MUCS can utilize nearly 100% of the available link bandwidth. A transistor-level MUCS circuit has been designed and verified using HSPICE. The circuit features a regular structure, minimal interconnects, and a low transistor count. HSPICE simulation indicates that using 2-μm CMOS technology, the MUCS circuit can operate at clock frequency of 100 MHz 相似文献
12.
液相添加剂对PTCR陶瓷电性能的影响 总被引:3,自引:2,他引:1
液相添加剂AST(Al2O3+SiO2+TiO2)对BaTiO3陶瓷材料电性能的影响很大,随着Al2O3含量的增加,材料的电性能降低;SiO2、TiO2的物理特性对材料电性能影响较大;过量TiO2对材料PTC效应有重要影响,适当过量TiO2含量,可得到性能优良的PTCR陶瓷。 相似文献
13.
A mathematical model for the development of a segregated layer of exudated droplets during DC casting of aluminum ingots is established. The model accounts for the metallostatic pressure driven interdendritic melt flow through the mushy zone by a Darcy type equation, the surface segregation due to this melt flow, and the decrease of the total solute concentration in different positions of the mush as a result of the exudation. The solution domain for the governing differential equations is constituted by the mushy zone of the cast. The main physical phenomena included in the model have been studied in a simple one dimensional case study. 相似文献
14.
历史中心区复兴中的地域性问题与对策 总被引:2,自引:0,他引:2
本文以上海思南路47~48街坊改造为例,探讨城市形态更新与居民外迁问题,并期待相关地域性社会对策的出现。 相似文献
15.
16.
This paper presents experimental and analytical results of four scaled prestressed concrete box-girder bridges with corrugated steel webs. The location of prestressing strands at both ends of the specimens and the thickness of end diaphragms are the two major parameters. Based on the experimental results of all four specimens, their seismic behavior is critically examined, including hysteretic loops, ductility factor, dissipated energy, and failure mode, etc. It was found that both the thickness of end diaphragms and the location of prestressing strands at both ends of the specimens are insignificant when the specimens failed at the mid-span due to concrete crushing, and the proposed analytical model can be used to predict the load-displacement relationship of such bridges. 相似文献
17.
莫灿林 《浙江理工大学学报》1992,(1)
根据空间RSCR四杆机构出现特殊位置的几何特征,运用旋转变换把空间问题转换为平面问题,对实现两特殊位置运动的空间RSCR曲柄摇杆机构的图解综合法进行了探讨。 相似文献
18.
网络通信技术正在迅猛地发展,各种各样的高速通信技术如雨后春笋,其中ATM作为一种信元换技术,具有以兆或千兆级速率传送话音、数据和图象的能力,它在网络通信技术中占有特别重要的地位。本文介绍了ATM技术的产生、基本特点、体系结构、在BISDN中的作用、存在的问题以及发展前景。 相似文献
19.
The effect of DC flux on the core loss is examined for the practical range of power and frequency. Relevant core loss equations are derived and applied to an optimization algorithm to determine the minimum core loss at a given ratio of s (DC flux density to AC peak flux density). It has been found that the curves of hysteresis loss density versus the ratio of s exhibit a peak at a critical ratio. Below or above this critical ratio, the loss density decreases drastically. On the other hand, the curves of eddy-current loss density versus the ratio of s exhibits a minimum point at a critical ratio. Below or above this critical ratio, the loss density increases gradually 相似文献
20.
Mo Yang Cengiz S. Ozkan Huajian Gao 《Journal of The Association for Laboratory Automation》2003,8(2):86-89
A method has been developed for fabricating polymer microstructures based on electric field induced self assembly and pattern formation. A dielectric fluid placed in between two conductive plates experience a force in an applied electric field gradient across the plates, which can induce a diffusive surface instability and self construction of the fluid surface. This process is exploited for the fabrication of self assembled polymer microstructures as well as replicated patterns through the use of pre-patterned plates or electrodes. FEM simulation is used to decide the minimum wavelength and electric gradient distribution of polymer structures. A variety of structures in the micron and nanometer scales including bio-fluidic MEMS, polymer optoelectronic devices can be fabricated using this method. 相似文献