全文获取类型
收费全文 | 78803篇 |
免费 | 4620篇 |
国内免费 | 2209篇 |
专业分类
电工技术 | 3215篇 |
技术理论 | 2篇 |
综合类 | 3186篇 |
化学工业 | 10742篇 |
金属工艺 | 2214篇 |
机械仪表 | 2694篇 |
建筑科学 | 3968篇 |
矿业工程 | 1410篇 |
能源动力 | 1381篇 |
轻工业 | 5753篇 |
水利工程 | 1304篇 |
石油天然气 | 1604篇 |
武器工业 | 337篇 |
无线电 | 6038篇 |
一般工业技术 | 7774篇 |
冶金工业 | 22640篇 |
原子能技术 | 661篇 |
自动化技术 | 10709篇 |
出版年
2024年 | 229篇 |
2023年 | 907篇 |
2022年 | 1476篇 |
2021年 | 1869篇 |
2020年 | 1446篇 |
2019年 | 1137篇 |
2018年 | 1729篇 |
2017年 | 1983篇 |
2016年 | 2247篇 |
2015年 | 2375篇 |
2014年 | 2454篇 |
2013年 | 2848篇 |
2012年 | 4856篇 |
2011年 | 5309篇 |
2010年 | 3011篇 |
2009年 | 2929篇 |
2008年 | 2691篇 |
2007年 | 2548篇 |
2006年 | 2390篇 |
2005年 | 4801篇 |
2004年 | 3554篇 |
2003年 | 2884篇 |
2002年 | 1622篇 |
2001年 | 1402篇 |
2000年 | 1010篇 |
1999年 | 1278篇 |
1998年 | 6674篇 |
1997年 | 4252篇 |
1996年 | 2925篇 |
1995年 | 1780篇 |
1994年 | 1379篇 |
1993年 | 1319篇 |
1992年 | 444篇 |
1991年 | 458篇 |
1990年 | 419篇 |
1989年 | 388篇 |
1988年 | 357篇 |
1987年 | 271篇 |
1986年 | 241篇 |
1985年 | 211篇 |
1984年 | 93篇 |
1983年 | 101篇 |
1982年 | 158篇 |
1981年 | 195篇 |
1980年 | 212篇 |
1979年 | 74篇 |
1978年 | 105篇 |
1977年 | 618篇 |
1976年 | 1330篇 |
1975年 | 104篇 |
排序方式: 共有10000条查询结果,搜索用时 828 毫秒
32.
BDI模型能够很好地解决在特定环境下的Agent的推理和决策问题,但在动态和不确定环境下缺少决策和学习的能力。强化学习解决了Agent在未知环境下的决策问题,却缺少BDI模型中的规则描述和逻辑推理。针对BDI在未知和动态环境下的策略规划问题,提出基于强化学习Q-learning算法来实现BDI Agent学习和规划的方法,并针对BDI的实现模型ASL的决策机制做出了改进,最后在ASL的仿真平台Jason上建立了迷宫的仿真,仿真实验表明,在加入Q-learning学习机制后的新的ASL系统中,Agent在不确定环境下依然可以完成任务。 相似文献
33.
35.
From an experimental and theoretical investigation of the continuity of influent inorganic suspended solids (ISS) along the links connecting the primary settling tank (PST), fully aerobic or N removal activated sludge (AS) and anaerobic and aerobic sludge digestion unit operations, it was found that the influent wastewater (fixed) ISS concentration is conserved through primary sludge anaerobic digestion, activated sludge and aerobic digestion unit operations. However, the measured ISS flux at different stages through a series of wastewater treatment plant (WWTP) unit operations is not equal to the influent ISS flux, because the ordinary heterotrophic organisms (OHO) biomass contributes to the ISS flux by differing amounts depending on the active fraction of the VSS solids at that stage. 相似文献
36.
Role stress has received a lot of research attention in psychological, sociological, and organizational studies over the last several decades. Based on a literature review of about 300 journal articles, this article examines prominent consequences of role stress. Specific focus is on researching differences in relationships between facets of role stress (i.e., role ambiguity, role conflict, and role overload) and frequently cited consequences using techniques of meta-analysis. Findings indicate that each role stress facet has a different relationship with the eight consequences studied. Role stress research can benefit from looking at each facet individually in addition to role stress generally. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
37.
A set of poly[N‐oligo(ethylene oxide)yl 4‐vinylpyridinium tosylate] (P4VOEOOTs) has been prepared by spontaneous polymerization of 4‐vinylpyridine. This method gives a grafted polyelectrolyte having a positive charge on every backbone pyridinic moiety. The P4VP15Ts, P4VP164Ts, P4VP350Ts and P4VP750Ts aqueous solution conductivities were determined in the concentration range from 6 × 10?4 to 10?2 M at 25 °C. The variation of the conductivity versus concentration of the investigated system exhibits typical polyelectrolyte behaviour. The polyelectrolyte mobility was found to be dependent on the oligo(ethylene oxide) (OEO) side‐chain length. Manning's rod‐like model fails to describe these results. A simple steric effect is proposed to explain the influence of the OEO length. Copyright © 2003 Society of Chemical Industry 相似文献
38.
易前 《水利水电工程设计》2006,25(4):12-13
镜面混凝土是水电工程建设中新兴的一门施工技术,在乌江索风营水电站地下厂房岩锚梁混凝土施工中采用了镜面混凝土,这在技术上是一次大胆的尝试和创新,既满足了功能上的要求,同时也达到了美观和装饰地下厂房的效果,为今后水电工程施工中广泛采用镜面混凝土技术提供了样本和宝贵经验。 相似文献
39.
40.
The objective of this study was to compare methane production and characteristics of digested material in anaerobic digestion concepts according to the Animal By-Products Regulation (ABP-Regulation) of the EC (hygienisation of biowaste for 1 hour at 70 degrees C, particle size < 12 mm) and Finnish national regulations (treatment temperature 55 degrees C, feeding interval 24 h, hydraulic retention time (HRT) 20 d, particle size < 40 mm) and with small variations in treatment methods for treating manure and biowaste. Moreover, the survival of three different salmonella bacteria in these processes was studied. Hygienisation of biowaste prior to digestion at 35 degrees C enhanced methane production by 14-18% compared to similar treatment without hygienisation. The differences in treatment temperature, HRT and hygienisation of biowaste prior to digestion did not significantly affect the characteristics of digested material. The concepts according to the ABP-Regulation and Finnish national regulations were effective in destroying salmonella bacteria to an undetectable level. 相似文献