全文获取类型
收费全文 | 157578篇 |
免费 | 14753篇 |
国内免费 | 8297篇 |
专业分类
电工技术 | 10598篇 |
技术理论 | 13篇 |
综合类 | 12868篇 |
化学工业 | 24638篇 |
金属工艺 | 9223篇 |
机械仪表 | 10243篇 |
建筑科学 | 12162篇 |
矿业工程 | 4537篇 |
能源动力 | 4477篇 |
轻工业 | 14369篇 |
水利工程 | 3245篇 |
石油天然气 | 7968篇 |
武器工业 | 1570篇 |
无线电 | 17119篇 |
一般工业技术 | 17221篇 |
冶金工业 | 6472篇 |
原子能技术 | 1905篇 |
自动化技术 | 22000篇 |
出版年
2024年 | 754篇 |
2023年 | 2677篇 |
2022年 | 5132篇 |
2021年 | 6778篇 |
2020年 | 5129篇 |
2019年 | 4192篇 |
2018年 | 4587篇 |
2017年 | 5224篇 |
2016年 | 4683篇 |
2015年 | 6673篇 |
2014年 | 8469篇 |
2013年 | 9768篇 |
2012年 | 11434篇 |
2011年 | 12322篇 |
2010年 | 10968篇 |
2009年 | 10412篇 |
2008年 | 10199篇 |
2007年 | 9547篇 |
2006年 | 9081篇 |
2005年 | 7342篇 |
2004年 | 5315篇 |
2003年 | 4611篇 |
2002年 | 4711篇 |
2001年 | 4013篇 |
2000年 | 3308篇 |
1999年 | 2985篇 |
1998年 | 2122篇 |
1997年 | 1643篇 |
1996年 | 1489篇 |
1995年 | 1189篇 |
1994年 | 921篇 |
1993年 | 693篇 |
1992年 | 564篇 |
1991年 | 418篇 |
1990年 | 301篇 |
1989年 | 225篇 |
1988年 | 191篇 |
1987年 | 121篇 |
1986年 | 117篇 |
1985年 | 57篇 |
1984年 | 41篇 |
1983年 | 40篇 |
1982年 | 37篇 |
1981年 | 31篇 |
1980年 | 37篇 |
1979年 | 19篇 |
1977年 | 8篇 |
1970年 | 7篇 |
1959年 | 8篇 |
1951年 | 6篇 |
排序方式: 共有10000条查询结果,搜索用时 999 毫秒
41.
Dong Zhang 《Korean Journal of Chemical Engineering》2008,25(5):1205-1207
Ceria-zirconia solid particles have been recognized as a key material of the automotive exhaust catalysts since they can release
and uptake oxygen owing to the rapid reversible oxidation states of cerium between Ce3+ and Ce4+. Several methods have recently been described to prepare the CeO2-ZrO2 solid particles used in the catalysts. In this paper, a new coprecipitation method is used to prepare the CeO2-ZrO2 solid particles. The Ce-Zr alcogel is dried and calcined in flowing N2 not in flowing air under atmospheric pressure. The results show that the ceria-zirconia sample calcined at 650 °C has high
surface area over 90 m2g−1, which drops to 40 m2g−1 following treatment at 900°C. 相似文献
42.
Bingyong Yan Zuohua Tian Songjiao Shi 《International Journal of Electrical Power & Energy Systems》2008,30(5):343-360
In this paper, we propose a novel distributed robust fault detection and identification (RFDI) scheme for a class of nonlinear systems. Firstly, a detection and identification estimator—robust fault tracking approximator (RFTA) is designed for online health monitoring. A novel feature of the RFTA is that it can simultaneously detect and accurately identify the shape and magnitude of the fault and disturbance. Moreover, it takes less online training time compared with the traditional neural network based fault diagnosis schemes. For some distributed systems, a network of distributed estimators is constructed where the RFTA is embedded into each estimator. Then we use consensus filter to filter the outputs of each estimator. One of the most important merits of the consensus filter is that its outputs can dramatically improve the accuracy of fault detection and identification. Next, the stability of the distributed RFDI scheme is rigorously investigated. Finally, two numerical examples are given to illustrate the feasibility and effectiveness of the proposed approach. 相似文献
43.
44.
45.
46.
Fixed point theorem-based iterative learning control for LTV systems with input singularity 总被引:1,自引:0,他引:1
In this paper, we address a challenging and open problem: how to design a suitable iterative learning control (ILC) system in the presence of input singularity, which is incurred by the singularities of the system direct feed-through term. Considering two typical types of input singularities, we first revise the ILC operators accordingly by adding a forgetting factor and incorporating a time-varying learning gain, in the sequel guarantee ILC operators to be contractible. Next, using the Banach fixed-point theorem, we demonstrate that the output sequence can either enter and remains ultimately in a designated neighborhood of the target trajectory, or is bounded by a class K function. Finally, an illustrative example is presented. 相似文献
47.
48.
实现水电厂电量快速微机巡回检测,温度采集较其它信号更为困难,本文着重讨论温度信号转换及与微机系统的连接。且介绍某水电厂微机控系统中非电量检测装置的硬件结构和软件编制。 相似文献
49.
50.