全文获取类型
收费全文 | 9622篇 |
免费 | 693篇 |
国内免费 | 306篇 |
专业分类
电工技术 | 361篇 |
综合类 | 381篇 |
化学工业 | 1576篇 |
金属工艺 | 522篇 |
机械仪表 | 614篇 |
建筑科学 | 501篇 |
矿业工程 | 171篇 |
能源动力 | 313篇 |
轻工业 | 458篇 |
水利工程 | 149篇 |
石油天然气 | 298篇 |
武器工业 | 30篇 |
无线电 | 1434篇 |
一般工业技术 | 1566篇 |
冶金工业 | 885篇 |
原子能技术 | 92篇 |
自动化技术 | 1270篇 |
出版年
2024年 | 42篇 |
2023年 | 131篇 |
2022年 | 250篇 |
2021年 | 332篇 |
2020年 | 266篇 |
2019年 | 271篇 |
2018年 | 264篇 |
2017年 | 260篇 |
2016年 | 256篇 |
2015年 | 343篇 |
2014年 | 407篇 |
2013年 | 592篇 |
2012年 | 546篇 |
2011年 | 592篇 |
2010年 | 491篇 |
2009年 | 515篇 |
2008年 | 459篇 |
2007年 | 455篇 |
2006年 | 414篇 |
2005年 | 397篇 |
2004年 | 271篇 |
2003年 | 267篇 |
2002年 | 258篇 |
2001年 | 249篇 |
2000年 | 211篇 |
1999年 | 260篇 |
1998年 | 268篇 |
1997年 | 217篇 |
1996年 | 181篇 |
1995年 | 162篇 |
1994年 | 135篇 |
1993年 | 105篇 |
1992年 | 94篇 |
1991年 | 80篇 |
1990年 | 62篇 |
1989年 | 67篇 |
1988年 | 58篇 |
1987年 | 46篇 |
1986年 | 38篇 |
1985年 | 42篇 |
1984年 | 31篇 |
1983年 | 22篇 |
1982年 | 35篇 |
1981年 | 26篇 |
1980年 | 17篇 |
1979年 | 14篇 |
1977年 | 20篇 |
1976年 | 19篇 |
1974年 | 19篇 |
1973年 | 14篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
101.
This paper is concerned with identification of linear parameter varying (LPV) systems in an input-output setting with Box-Jenkins (BJ) model structure. Classical linear time invariant prediction error method (PEM) is extended to the LPV PEM. Under the new LPV framework, identification of two types of input-output LPV models is considered: one is based on parameter interpolation and the other is based on model interpolation. The effectiveness of the proposed solution is validated by comparison with other existing LPV identification approaches through simulation examples and demonstrated by experiment studies. 相似文献
102.
Yufei Huang Feng Chu Chengbin Chu Yingluo Wang 《Journal of Intelligent Manufacturing》2012,23(1):73-89
This paper develops a new quantitative model to find the optimal number of new employees with a Newsvendor model in a pull
production system. This model allows learning, forgetting and variable wage. This paper also provides numerical results on
sensitivity analysis, and compares the numerical results in three different situations: the situation with both learning and
forgetting effect, that with learning effect but without forgetting effect and the situation with neither learning nor forgetting
effect. The conclusions drawn from the comparison may offer theoretical insight for human resource managers to make appropriate
employment decisions. 相似文献
103.
R. L. Meng T. H. Lin M. K. Wu C. W. Chu S. Z. Huang 《Journal of Low Temperature Physics》1982,48(5-6):383-388
High-pressure study has been made both resistively and magnetically on Eu1.2Mo6(S1–x
Se
x
)8. Superconductivity was detected at a lower pressure in samples forx0 than forx=0 in spite of the larger unit cell volume of the former. The superconductivity observed remains non-bulk up to 20 kbar. The maximum onset temperature of the superconductivity transition decreases withx.On leave from the Physics Institute, Chinese Academy of Sciences, Peking, China. 相似文献
104.
105.
106.
107.
108.
人工自然环境通过调节温度、湿度、光照度等参数,模拟各种自然环境。为提高产品的安全等级,本文提出了一种新的设计方案,在采用分级控制及硬件冗余结构的基础上,对关键电路采取了故障-安全保障措施,提高了系统安全性;针对温湿度之间存在较强耦合,控制精度难于提高的问题,提出了一种新的控制算法,即采用模糊自整定PID算法实现温度控制,采用模糊前馈-PID反馈复合算法实现湿度控制。结果表明,本文提出的控制算法有效地改善了系统控制品质。 相似文献
109.
110.
The degree of consolidation is usually used as one of the criteria for assessing the effectiveness of soil improvement work using the fill surcharge or vacuum preloading method. It is also often used as a design specification in a soil improvement contract. Degree of consolidation is normally calculated using settlement data. However, as the effect of vacuum preloading is controlled largely by pore water pressure changes, it is necessary to analyze the pore water pressure variations and to assess the degree of consolidation using pore water pressures. In this paper, the problems involved in the estimation of degree of consolidation using settlement data are discussed. A method to estimate the average degree of consolidation using pore water pressure data is suggested. Two case studies are presented to examine the characteristics of the pore water pressure variation of soil under vacuum loading. The degree of consolidation achieved in each of the two cases is assessed using pore water pressure data and compared with that estimated using settlement data. Factors affecting the degree of consolidation assessment are discussed. 相似文献