全文获取类型
收费全文 | 4279篇 |
免费 | 384篇 |
国内免费 | 154篇 |
专业分类
电工技术 | 351篇 |
综合类 | 364篇 |
化学工业 | 733篇 |
金属工艺 | 145篇 |
机械仪表 | 274篇 |
建筑科学 | 301篇 |
矿业工程 | 171篇 |
能源动力 | 198篇 |
轻工业 | 267篇 |
水利工程 | 149篇 |
石油天然气 | 260篇 |
武器工业 | 27篇 |
无线电 | 348篇 |
一般工业技术 | 580篇 |
冶金工业 | 144篇 |
原子能技术 | 71篇 |
自动化技术 | 434篇 |
出版年
2024年 | 19篇 |
2023年 | 72篇 |
2022年 | 72篇 |
2021年 | 115篇 |
2020年 | 147篇 |
2019年 | 140篇 |
2018年 | 115篇 |
2017年 | 150篇 |
2016年 | 157篇 |
2015年 | 204篇 |
2014年 | 273篇 |
2013年 | 340篇 |
2012年 | 300篇 |
2011年 | 332篇 |
2010年 | 241篇 |
2009年 | 250篇 |
2008年 | 207篇 |
2007年 | 266篇 |
2006年 | 249篇 |
2005年 | 169篇 |
2004年 | 140篇 |
2003年 | 131篇 |
2002年 | 126篇 |
2001年 | 92篇 |
2000年 | 73篇 |
1999年 | 64篇 |
1998年 | 52篇 |
1997年 | 49篇 |
1996年 | 44篇 |
1995年 | 38篇 |
1994年 | 33篇 |
1993年 | 20篇 |
1992年 | 17篇 |
1991年 | 20篇 |
1990年 | 13篇 |
1989年 | 12篇 |
1988年 | 12篇 |
1987年 | 8篇 |
1986年 | 5篇 |
1985年 | 6篇 |
1984年 | 3篇 |
1983年 | 6篇 |
1981年 | 3篇 |
1980年 | 3篇 |
1964年 | 3篇 |
1962年 | 2篇 |
1960年 | 2篇 |
1959年 | 2篇 |
1957年 | 3篇 |
1956年 | 3篇 |
排序方式: 共有4817条查询结果,搜索用时 31 毫秒
11.
12.
In air-compression systems, instabilities occur during operation close to their peak pressure-rise capability. However, the
peak efficiency of a compression system lies close to this region of instability. A surge is a violent mode of instability
where there is total breakdown of flow in the system and pressure-rise capability is lost drastically. Generally, all compression
systems operate with a margin defined as the ‘surge margin’, and, consequently, system operational efficiency is lower. It
is of interest to study compression-system surge to understand its dynamics in order to operate compression systems close
to the instability for achieving high efficiency safely without encountering surge. Unsteady pressure data from a compression
system, captured during surge oscillations, reveal many aspects of flow physics and are analysed to understand the surge dynamics
of the system. A set of controlled experiments was conducted with a simple desktop experimental test set-up and essential
aspects of surge dynamics have been characterised. 相似文献
13.
14.
15.
The Error-in-Variables Model (EVM) applies to a large class of problems in parameter estimation in which there is error in all the variables. This property makes it of more general applicability than the widely used technique of ordinary Least Squares. While there is a voluminous literature on EVM there is nothing on a general method for designing experiments when EVM applies. In this paper we present an extension of the concept of D-optimality to provide such a general method. It is illustrated by applying it to the estimation of copolymer reactivity ratios and to fitting an ellipse. 相似文献
16.
17.
Hari B. Goyal M. O. Garg K. R. Rao R. D. Srivastava 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》1985,35(2):49-56
The kinetics of the reaction of acetic acid and acetylene over zinc acetate-activated carbon catalyst was investigated over a wide range of process variables in a pilot reactor. Although various catalytic reaction mechanisms were postulated, the rate of reaction was most satisfactorily correlated by a mechanism of surface reaction between charged adsorbed acetic acid and acetylene, which assumes that the rate controlling step was the irreversible charged adsorption of acetylene and acetic acid. 相似文献
18.
19.
20.