全文获取类型
收费全文 | 716篇 |
免费 | 2篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 7篇 |
综合类 | 4篇 |
化学工业 | 74篇 |
金属工艺 | 1篇 |
机械仪表 | 34篇 |
建筑科学 | 40篇 |
矿业工程 | 6篇 |
能源动力 | 1篇 |
轻工业 | 194篇 |
水利工程 | 6篇 |
石油天然气 | 14篇 |
武器工业 | 1篇 |
无线电 | 23篇 |
一般工业技术 | 287篇 |
冶金工业 | 2篇 |
自动化技术 | 25篇 |
出版年
2020年 | 1篇 |
2019年 | 7篇 |
2018年 | 7篇 |
2017年 | 4篇 |
2016年 | 1篇 |
2015年 | 1篇 |
2014年 | 2篇 |
2013年 | 3篇 |
2012年 | 70篇 |
2011年 | 123篇 |
2010年 | 27篇 |
2009年 | 13篇 |
2008年 | 70篇 |
2007年 | 67篇 |
2006年 | 57篇 |
2005年 | 43篇 |
2004年 | 25篇 |
2003年 | 32篇 |
2002年 | 24篇 |
2001年 | 21篇 |
2000年 | 31篇 |
1999年 | 12篇 |
1998年 | 12篇 |
1997年 | 2篇 |
1996年 | 5篇 |
1995年 | 7篇 |
1994年 | 7篇 |
1993年 | 5篇 |
1992年 | 4篇 |
1991年 | 6篇 |
1990年 | 6篇 |
1989年 | 1篇 |
1988年 | 3篇 |
1987年 | 1篇 |
1986年 | 3篇 |
1985年 | 3篇 |
1984年 | 2篇 |
1983年 | 7篇 |
1982年 | 1篇 |
1979年 | 2篇 |
1967年 | 1篇 |
排序方式: 共有719条查询结果,搜索用时 46 毫秒
1.
2.
3.
4.
5.
This study was designed to evaluate the incidence of the PSE/DFD status in a Portuguese pig slaughterhouse, covering two seasons of the year (spring and summer) in order to find out if the proportions of those poor meat quality categories were sufficient to concern the meat industry. Meat quality classification was based on the measurements of the pH(60), pH(24), drip losses and colour (L, a, b) in the longissimus dorsi muscle (between the last third and fourth ribs) of 380 pigs randomly chosen from the line. The high global incidence of PSE and likely PSE (30%) as well as DFD (10%) carcasses and the enormous variation of the meat quality between the different days of analysis proves that the pig population presents a great variation of halothane genotype and that handling procedures have to be optimized in order to decrease stress and glycogen store depletion. The percentage of PSE carcasses during the summer season was double that found in the spring, probably due to a higher environmental temperature and relative humidity. 相似文献
6.
Estimates of the scintillation index, fractional fade time, expected number of fades, and mean duration of fade time associated with a propagating Gaussian-beam wave are developed for uplink and downlink laser satellite-communication channels. Estimates for the spot size of the beam at the satellite or the ground or airborne receiver are also provided. Weak-fluctuation theory based on the log-normal model is applicable for intensity fluctuations near the optical axis of the beam provided that the zenith angle is not too large, generally not exceeding 60°. However, there is an increase in scintillations that occurs with increasing pointing error at any zenith angle, particularly for uplink channels. Large off-axis scintillations are of particular significance because they imply that small pointing errors can cause serious degradation in the communication-channel reliability. Off-axis scintillations increase more rapidly for larger-diameter beams and, in some cases, can lead to a radial saturation effect for pointing errors less than 1 μrad off the optical beam axis. 相似文献
7.
Feng D Ho D Chen K Wu LC Wang JK Liu RS Yeh SH 《IEEE transactions on medical imaging》1995,14(4):697-710
Measurement of the local cerebral metabolic rate of glucose (LCMRGlc) and the individual rate constant parameters of the [(18 )F]2-fluoro-2-deoxy-D-glucose (FDG) model can provide a clearer understanding and insight to the physiological processes in the human brain, and a quicker and more accurate means of diagnosis in clinical applications. A systematic study using simulated and clinical tissue time activity data is presented to evaluate several existing and newly developed major algorithms used for determining LCMRGlc and the individual rate constants from positron emission tomography dynamic data. The computational and statistical properties of the autoradiographic approach, weighted and unweighted nonlinear least squares methods, Patlak graphic approach, weighted integration method, linear least squares and generalized linear least squares methods are investigated and discussed in this paper. 相似文献
8.
9.
10.