全文获取类型
收费全文 | 30616篇 |
免费 | 4714篇 |
国内免费 | 3564篇 |
专业分类
电工技术 | 2490篇 |
技术理论 | 4篇 |
综合类 | 3757篇 |
化学工业 | 2269篇 |
金属工艺 | 389篇 |
机械仪表 | 1208篇 |
建筑科学 | 2474篇 |
矿业工程 | 1315篇 |
能源动力 | 846篇 |
轻工业 | 2073篇 |
水利工程 | 1661篇 |
石油天然气 | 1369篇 |
武器工业 | 276篇 |
无线电 | 3226篇 |
一般工业技术 | 2133篇 |
冶金工业 | 1657篇 |
原子能技术 | 84篇 |
自动化技术 | 11663篇 |
出版年
2024年 | 190篇 |
2023年 | 572篇 |
2022年 | 1050篇 |
2021年 | 1202篇 |
2020年 | 1328篇 |
2019年 | 1163篇 |
2018年 | 1173篇 |
2017年 | 1317篇 |
2016年 | 1511篇 |
2015年 | 1536篇 |
2014年 | 2118篇 |
2013年 | 2146篇 |
2012年 | 2516篇 |
2011年 | 2786篇 |
2010年 | 2145篇 |
2009年 | 2042篇 |
2008年 | 2060篇 |
2007年 | 2286篇 |
2006年 | 1839篇 |
2005年 | 1514篇 |
2004年 | 1218篇 |
2003年 | 1000篇 |
2002年 | 791篇 |
2001年 | 613篇 |
2000年 | 453篇 |
1999年 | 425篇 |
1998年 | 314篇 |
1997年 | 263篇 |
1996年 | 228篇 |
1995年 | 197篇 |
1994年 | 167篇 |
1993年 | 119篇 |
1992年 | 71篇 |
1991年 | 78篇 |
1990年 | 69篇 |
1989年 | 52篇 |
1988年 | 49篇 |
1987年 | 28篇 |
1986年 | 27篇 |
1985年 | 17篇 |
1984年 | 26篇 |
1983年 | 18篇 |
1982年 | 13篇 |
1979年 | 10篇 |
1966年 | 10篇 |
1965年 | 9篇 |
1964年 | 11篇 |
1960年 | 13篇 |
1959年 | 13篇 |
1957年 | 9篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
11.
文章主要讨论了LonWorks现场总线技术在城市污水处理厂和气象指数预报中的应用。采用IPC和PLC控制结构对现场的各种设备实现控制和数据的采集,通过现场总线网络传输数据到中心控制室或远程终端,实现污水处理的自动控制和气象信息的实时采集和处理。 相似文献
12.
13.
Flame structure and NO emission characteristics in counterflow diffusion flame of blended fuel of H2/CO2/Ar have been numerically simulated with detailed chemistry. The combination of H2, CO2 and Ar as fuel is selected to clearly display the contribution of hydrocarbon products to flame structure and NO emission characteristics due to the breakdown of CO2. A radiative heat loss term is involved to correctly describe the flame dynamics especially at low strain rates. The detailed chemistry adopts the reaction mechanism of GRI 2.11, which consists of 49 species and 279 elementary reactions. All mechanisms including thermal, NO2, N2O and Fenimore are taken into account to separately evaluate the effects of CO2 addition on NO emission characteristics. The increase of added CO2 quantity causes flame temperature to fall since at high strain rates a diluent effect is prevailing and at low strain rates the breakdown of CO2 produces relatively populous hydrocarbon products and thus the existence of hydrocarbon products inhibits chain branching. It is also found that the contribution of NO production by N2O and NO2 mechanisms are negligible and that thermal mechanism is concentrated on only the reaction zone. As strain rate and CO2 quantity increase, NO production is remarkably augmented. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献
14.
对未知组成的样品进行紫外光谱扫描 ,根据扫描结果以及各种溴指数测定方法的适用范围 ,选择测定未知物溴指数的适宜方法 ,以提高测定准确度。 相似文献
16.
17.
J. L. Díez J. L. Navarro A. Sala 《Soft Computing - A Fusion of Foundations, Methodologies and Applications》2007,11(10):973-983
In this work, simple modifications on the cost index of particular local-model fuzzy clustering algorithms are proposed in
order to improve the readability of the resulting models. The final goal is simultaneously providing local linear models (reasonably
close to the plant’s Jacobian) and clustering in the input space so that desirable characteristics (regarding final model
accuracy, and convexity and smoothness of the cluster membership functions) are improved with respect to other proposals in
literature. Some examples illustrate the proposed approach. 相似文献
18.
19.
20.
Attempts have been made to extend SQL to work with multimedia databases. We are reserved on the representation ability of extended SQL to cope with the richness in content of multimedia data. In this paper we present an example of a multimedia database system, Computer Aided Facial Image Inference and Retrieval system (CAFIIR). The system stores and manages facial images and criminal records, providing necessary functions for crime identification. We would like to demonstrate some core techniques for multimedia database with CAFIIR system. Firstly, CAFIIR is a integrated system. Besides database management, there are image analysis, image composition, image aging, and report generation subsystems, providing means for problem solving. Secondly, the richness of multimedia data urges feature-based database for their management. CAFIIR is feature-based. A indexing mechanism,iconic index, has been proposed for indexing facial images using hierarchical self-organization neural network. The indexing method operates on complex feature measures and provides means for visual navigation. Thirdly, special retrieval methods for facial images have been developed, including visual browsing, similarity retrieval, free text retrieval and fuzzy retrieval. 相似文献