全文获取类型
收费全文 | 183895篇 |
免费 | 20053篇 |
国内免费 | 12431篇 |
专业分类
电工技术 | 14296篇 |
技术理论 | 9篇 |
综合类 | 23190篇 |
化学工业 | 19426篇 |
金属工艺 | 9722篇 |
机械仪表 | 14153篇 |
建筑科学 | 23463篇 |
矿业工程 | 9654篇 |
能源动力 | 8122篇 |
轻工业 | 8084篇 |
水利工程 | 9408篇 |
石油天然气 | 8811篇 |
武器工业 | 3348篇 |
无线电 | 12162篇 |
一般工业技术 | 21615篇 |
冶金工业 | 7056篇 |
原子能技术 | 2817篇 |
自动化技术 | 21043篇 |
出版年
2024年 | 693篇 |
2023年 | 2201篇 |
2022年 | 4572篇 |
2021年 | 5314篇 |
2020年 | 5783篇 |
2019年 | 4848篇 |
2018年 | 4642篇 |
2017年 | 5954篇 |
2016年 | 6785篇 |
2015年 | 7178篇 |
2014年 | 11498篇 |
2013年 | 10748篇 |
2012年 | 14623篇 |
2011年 | 14896篇 |
2010年 | 11492篇 |
2009年 | 11702篇 |
2008年 | 10741篇 |
2007年 | 13323篇 |
2006年 | 11698篇 |
2005年 | 9799篇 |
2004年 | 8058篇 |
2003年 | 6766篇 |
2002年 | 5517篇 |
2001年 | 4716篇 |
2000年 | 4047篇 |
1999年 | 3451篇 |
1998年 | 2690篇 |
1997年 | 2364篇 |
1996年 | 1958篇 |
1995年 | 1737篇 |
1994年 | 1458篇 |
1993年 | 1060篇 |
1992年 | 938篇 |
1991年 | 648篇 |
1990年 | 552篇 |
1989年 | 519篇 |
1988年 | 374篇 |
1987年 | 215篇 |
1986年 | 182篇 |
1985年 | 78篇 |
1984年 | 86篇 |
1983年 | 47篇 |
1982年 | 57篇 |
1981年 | 63篇 |
1980年 | 37篇 |
1979年 | 49篇 |
1978年 | 25篇 |
1975年 | 20篇 |
1959年 | 39篇 |
1951年 | 23篇 |
排序方式: 共有10000条查询结果,搜索用时 468 毫秒
161.
162.
163.
164.
165.
166.
Measurement Method of the Thickness Uniformity for Polymer Films 总被引:1,自引:0,他引:1
YANGHong-liang RENQuan FANYun-zheng 《半导体光子学与技术》2003,9(2):128-132
Several methods for investigating the thickness uniformity of polymer thin films are presented as well their measurement principles.A comparison of these experimental methods is given.The cylindrical lightwave feflection method is found to can obtain the thickness distribution along a certain direction.It is simple and suitable method to evaluate the film thickness uniformity. 相似文献
167.
微带型Wilkinson功分器设计与实现 总被引:2,自引:0,他引:2
小型低功耗器件是射频电路设计的研究热点,而微带技术具有小型化低功耗的优点,为此在介绍微带型Wilkin-son功分器工作原理的基础上,使用基于矩量法的ADS软件设计、仿真和优化计算相关数据参数,并制作了一个微带功分器实例,最后对加工的样品进行实测,获得与仿真值吻合较好的预期结果。 相似文献
168.
169.
Finite element piezothermoelasticity analysis and the active control of FGM plates with integrated piezoelectric sensors and actuators 总被引:3,自引:0,他引:3
An efficient finite element model is presented for the static and dynamic piezothermoelastic analysis and control of FGM
plates under temperature gradient environments using integrated piezoelectric sensor/actuator layers. The properties of an FGM plate are functionally graded in the thickness
direction according to a volume fraction power law distribution. A constant displacement-cum-velocity feedback control algorithm that couples the direct and inverse piezoelectric effects is applied to provide active feedback
control of the integrated FGM plate in a closed loop system. Numerical results for the static and dynamic control are presented
for the FGM plate, which consists of zirconia and aluminum. The effects of the constituent volume fractions and the influence
of feedback control gain on the static and dynamic responses of the FGM plates are examined.
Received: 13 March 2002 / Accepted: 5 March 2003
The work described in this paper was supported by a grant awarded by the Research Grants Council of the Hong Kong Special
Administrative Region, China (Project No. CityU 1024/01E). 相似文献
170.
P. A. Boucard L. Champaney 《International journal for numerical methods in engineering》2003,57(9):1259-1281
The aim of the present work is to develop an application of the LArge Time INcrement (LATIN) approach for the parametric analysis of static problems with multiple contacts. The methodology adopted was originally introduced to solve viscoplastic and large‐transformation problems. Here, the applications concern elastic, quasi‐static structural assemblies with local non‐linearities such as unilateral contact with friction. Our approach is based on a decomposition of the assembly into substructures and interfaces. The interfaces play the vital role of enabling the local non‐linearities, such as contact and friction, to be modelled easily and accurately. The problem on each substructure is solved by the finite element method and an iterative scheme based on the LATIN method is used for the global resolution. More specifically, the objective is to calculate a large number of design configurations. Each design configuration corresponds to a set of values of all the variable parameters (friction coefficients, prestress) which are introduced into the mechanical analysis. A full computation is needed for each set of parameters. Here we propose, as an alternative to carrying out these full computations, to use the capability of the LATIN method to re‐use the solution to a given problem (for one set of parameters) in order to solve similar problems (for the other sets of parameters). Copyright © 2003 John Wiley & Sons, Ltd. 相似文献