全文获取类型
收费全文 | 229090篇 |
免费 | 17435篇 |
国内免费 | 9134篇 |
专业分类
电工技术 | 12453篇 |
技术理论 | 24篇 |
综合类 | 14144篇 |
化学工业 | 38778篇 |
金属工艺 | 13141篇 |
机械仪表 | 14515篇 |
建筑科学 | 17561篇 |
矿业工程 | 7499篇 |
能源动力 | 6420篇 |
轻工业 | 13440篇 |
水利工程 | 3585篇 |
石油天然气 | 16616篇 |
武器工业 | 1647篇 |
无线电 | 25121篇 |
一般工业技术 | 27326篇 |
冶金工业 | 13075篇 |
原子能技术 | 2247篇 |
自动化技术 | 28067篇 |
出版年
2024年 | 993篇 |
2023年 | 3800篇 |
2022年 | 6477篇 |
2021年 | 9100篇 |
2020年 | 7077篇 |
2019年 | 6012篇 |
2018年 | 6728篇 |
2017年 | 7535篇 |
2016年 | 6746篇 |
2015年 | 8855篇 |
2014年 | 11243篇 |
2013年 | 13266篇 |
2012年 | 14203篇 |
2011年 | 15441篇 |
2010年 | 13414篇 |
2009年 | 12678篇 |
2008年 | 12342篇 |
2007年 | 11844篇 |
2006年 | 12338篇 |
2005年 | 10745篇 |
2004年 | 7258篇 |
2003年 | 6224篇 |
2002年 | 5460篇 |
2001年 | 4884篇 |
2000年 | 5431篇 |
1999年 | 6447篇 |
1998年 | 5522篇 |
1997年 | 4500篇 |
1996年 | 4217篇 |
1995年 | 3515篇 |
1994年 | 2824篇 |
1993年 | 1975篇 |
1992年 | 1538篇 |
1991年 | 1226篇 |
1990年 | 933篇 |
1989年 | 740篇 |
1988年 | 540篇 |
1987年 | 339篇 |
1986年 | 284篇 |
1985年 | 197篇 |
1984年 | 139篇 |
1983年 | 115篇 |
1982年 | 124篇 |
1981年 | 100篇 |
1980年 | 73篇 |
1979年 | 36篇 |
1978年 | 28篇 |
1977年 | 29篇 |
1976年 | 53篇 |
1973年 | 13篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
11.
A distributed problem solving system can be characterized as a group of individual cooperating agents running to solve common problems. As dynamic application domains continue to grow in scale and complexity, it becomes more difficult to control the purposeful behavior of agents, especially when unexpected events may occur. This article presents an information and knowledge exchange framework to support distributed problem solving. From the application viewpoint the article concentrates on the stock trading domain; however, many presented solutions can be extended to other dynamic domains. It addresses two important issues: how individual agents should be interconnected so that their resources are efficiently used and their goals accomplished effectively; and how information and knowledge transfer should take place among the agents to allow them to respond successfully to user requests and unexpected external situations. The article introduces an architecture, the MASST system architecture, which supports dynamic information and knowledge exchange among the cooperating agents. The architecture uses a dynamic blackboard as an interagent communication paradigm to facilitate factual data, business rule, and command exchange between cooperating MASST agents. The critical components of the MASST architecture have been implemented and tested in the stock trading domain, and have proven to be a viable solution for distributed problem solving based on cooperating agents 相似文献
12.
13.
本文评价了塑料闪烁片用作软β核素探测器时的计数效率、β谱、本底谱和康普顿电子谱的特征。文中强调:采用胶合光导剂构成的系统是一种新型探测器(软β核素内部样品塑料闪烁探测器)。本文提出内部样品固体探测器、胶合光导剂和胶合闪烁光导剂的新概念。 相似文献
14.
在第一部分综合讨论的基础上对甘三酯立体专一分析方法作了初步探讨。以液体油(菜油)及固体脂(猪脂)为基质,系统地研究了这一分析方法,取得了经验并补充了一些具体验证方法。分析液体油的结果与文献数据相一致,分析猪脂的结果欠佳,还存在一些问题需待进一步研究。 相似文献
15.
16.
介绍了子午轮胎硫化的各种介质性能要求及介质供应工艺流程,分析了各种介质的质量要求.介绍了系统各参数的控制调节项目及运行技术管理的一些措施. 相似文献
18.
Xue‐Bing Zhao Lei Wang De‐Hua Liu 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2008,83(6):950-956
Previous work has shown that the enzymatic hydrolysis of sugarcane bagasse could be greatly enhanced by peracetic acid (PAA) pretreatment. There are several factors affecting the enzymatic digestibility of the biomass, including lignin and hemicelluloses content, cellulose crystallinity, acetyl group content, accessible surface area and so on. The objective of this work is to analyze the mechanism of the enhancement of enzymatic digestibility caused by PAA pretreatment. Delignification resulted in an increase of the surface area and reduction of the irreversible absorption of cellulase, which helped to increase the enzymatic digestibility. The Fourier transform infrared (FTIR) spectrum showed that the absorption peaks of aromatic skeletal vibrations were weakened or disappeared after PAA pretreatment. However, the infrared crystallization index (N.O'KI) was increased. X‐ray diffraction (XRD) analysis indicated that the crystallinity of PAA‐treated samples was increased owing to the partial removal of amorphous lignin and hemicelluloses and probable physical change of cellulose. The effect of acetyl group content on enzymatic digestibility is negligible compared with the degree of delignification and crystallinity. The results indicate that enhancement of enzymatic digestibility of sugarcane bagasse by PAA pretreatment is achieved mainly by delignification and an increase in the surface area and exposure of cellulose fibers. Copyright © 2008 Society of Chemical Industry 相似文献
19.
Oxide films were deposited on different substrates by laser molecular beam epitaxy. Reflection high-energy electron diffraction was performed to in situ investigate the change of growth mode and the lattice relaxation during the growth. An asymmetrical phenomenon was found in the two kinds of strain states, compressive stress and tensile stress of heterostructures with different lattice mismatch. In the case of BaTiO3/SrTiO3 (2.2%), 2D layer-by-layer growth mode without lattice relaxation can be maintained for a longer period for BTO films on STO with compressive stress, comparing to STO films on BTO with tensile stress. When MgO films were deposited on SrTiO3 with a large mismatch of 7.8%, compressive stress leads to rapid lattice relaxation with a very thin wet layer, and 3D strained island were observed. As a comparison, SrTiO3 films on MgO with tensile stress were configured. No RHEED patterns can be observed duo to a large tensile stress. 相似文献
20.