全文获取类型
收费全文 | 257篇 |
免费 | 10篇 |
专业分类
电工技术 | 3篇 |
化学工业 | 69篇 |
机械仪表 | 4篇 |
建筑科学 | 11篇 |
能源动力 | 13篇 |
轻工业 | 10篇 |
水利工程 | 3篇 |
无线电 | 14篇 |
一般工业技术 | 26篇 |
冶金工业 | 82篇 |
原子能技术 | 2篇 |
自动化技术 | 30篇 |
出版年
2023年 | 2篇 |
2019年 | 2篇 |
2018年 | 3篇 |
2017年 | 3篇 |
2016年 | 3篇 |
2015年 | 5篇 |
2013年 | 14篇 |
2012年 | 3篇 |
2011年 | 15篇 |
2010年 | 7篇 |
2009年 | 6篇 |
2008年 | 14篇 |
2007年 | 8篇 |
2006年 | 8篇 |
2005年 | 3篇 |
2004年 | 8篇 |
2003年 | 6篇 |
2002年 | 7篇 |
2001年 | 5篇 |
2000年 | 7篇 |
1999年 | 7篇 |
1998年 | 21篇 |
1997年 | 16篇 |
1996年 | 9篇 |
1995年 | 7篇 |
1994年 | 8篇 |
1993年 | 7篇 |
1992年 | 3篇 |
1991年 | 2篇 |
1990年 | 9篇 |
1989年 | 3篇 |
1988年 | 4篇 |
1985年 | 2篇 |
1984年 | 2篇 |
1982年 | 2篇 |
1981年 | 5篇 |
1979年 | 1篇 |
1977年 | 5篇 |
1976年 | 4篇 |
1975年 | 2篇 |
1974年 | 1篇 |
1970年 | 3篇 |
1968年 | 1篇 |
1966年 | 1篇 |
1957年 | 1篇 |
1944年 | 1篇 |
1941年 | 1篇 |
1940年 | 2篇 |
1938年 | 1篇 |
1928年 | 1篇 |
排序方式: 共有267条查询结果,搜索用时 500 毫秒
1.
To meet the criteria of role accountability, nursing competence and ongoing staff development, an improved peer-evaluation system was designed to continuously monitor these new roles. This peer-evaluation process converts evaluation input into data, giving staff a visual picture of how their performance compares within their peer group. This peer-evaluation process was designed as a tool to assist in staff growth and development, not as a punitive system. 相似文献
2.
3.
4.
The selective reduction of nitrogen oxides by hydrocarbons on a Pt catalyst has been investigated. Some variations are observed between different reductants. However, the most significant result is the observation that no N2O is observed as a by-product when toluene is used as a reductant. 相似文献
5.
The supply and return piping of passive solar domestic hot water systems (SDHWS) is typically exposed to ambient weather conditions, and damaging pipe freeze is a major concern. This paper presents a pipe-freeze model that accounts for hot water draws and uses 30 years of actual weather data. The simulation results are cast in terms of pipe-freeze probabilities. Using contour maps of the continental United States, the pipe-freeze probabilities for residential, commercial, and seasonal passive SDHWS are presented for various pipe and insulation geometries. 相似文献
6.
7.
Frequency-domain studies of time-dependent light propagation in tissuelike phantoms that contain optical heterogeneities are described. Specifically the phase shift and amplitude modulation of reemergent light were measured when illuminated by an amplitude-modulated light source. Changes in the phase angle and the extent of modulation revealed the presence of a light-absorbing object. Furthermore the magnitude and direction of these changes were sensitive to the absorber depth and the light modulation frequency in a manner that could be used to infer the location of the heterogeneity. These data suggest the feasibility of optical imaging by frequency-domain methods. 相似文献
8.
We investigated the risk factors of outsourced software development. Our first objective was to create empirically generated lists of risk factors for both domestically- and offshore-outsourced projects. Our second objective was to compare these two contexts: how do the risk factors change and which ones are most important in each. To address these objectives, we conducted two Delphi surveys to identify the important risk factors from a client perspective, in domestic and offshore settings. We qualitatively compared the results of the surveys to identify similarities and differences across their risk profiles. We identified three types of risks: those that appeared in both contexts; those that appeared in both but were exacerbated in the offshore context; and those that were unique to the offshore context. Our findings suggested that traditional project management risks were important in both contexts; however, the offshore context seemed to be more vulnerable to some traditional risks as well as factors that were unique to it. 相似文献
9.
We present the technique of bideposition to realize thin-film helicoidal bianisotropic mediums (TFHBM's) that exhibit high optical activity. We show, by experiment as well as by simulation, that the optical rotation produced by these chiral sculptured thin films is roughly proportional to the square of the local linear birefringence. Experimental measurements on bideposited TFHBM's of titanium oxide yield a typical value of 5 degrees /mum for the effective specific rotation in the short-wavelength regime; the corresponding value determined for the standard unideposited TFHBM's is 1 degrees /mum. Both types of TFHBM's are highly optically active in comparison with quartz, fluorite films, and cholesteric liquid crystals. Bideposited TFHBM's will lend themselves to many different types of optical devices. 相似文献
10.