全文获取类型
收费全文 | 1844篇 |
免费 | 2篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 2篇 |
化学工业 | 26篇 |
金属工艺 | 1篇 |
机械仪表 | 3篇 |
建筑科学 | 1篇 |
能源动力 | 28篇 |
轻工业 | 8篇 |
无线电 | 6篇 |
一般工业技术 | 13篇 |
冶金工业 | 1747篇 |
原子能技术 | 1篇 |
自动化技术 | 11篇 |
出版年
2021年 | 4篇 |
2016年 | 2篇 |
2015年 | 1篇 |
2014年 | 1篇 |
2013年 | 2篇 |
2012年 | 2篇 |
2011年 | 2篇 |
2010年 | 3篇 |
2009年 | 6篇 |
2008年 | 1篇 |
2007年 | 6篇 |
2006年 | 4篇 |
2005年 | 5篇 |
2004年 | 4篇 |
2003年 | 3篇 |
2002年 | 6篇 |
2001年 | 2篇 |
2000年 | 4篇 |
1999年 | 57篇 |
1998年 | 583篇 |
1997年 | 300篇 |
1996年 | 203篇 |
1995年 | 88篇 |
1994年 | 86篇 |
1993年 | 96篇 |
1992年 | 11篇 |
1991年 | 30篇 |
1990年 | 22篇 |
1989年 | 26篇 |
1988年 | 21篇 |
1987年 | 26篇 |
1986年 | 22篇 |
1985年 | 28篇 |
1984年 | 1篇 |
1983年 | 6篇 |
1982年 | 6篇 |
1981年 | 10篇 |
1980年 | 19篇 |
1979年 | 1篇 |
1978年 | 6篇 |
1977年 | 39篇 |
1976年 | 87篇 |
1975年 | 4篇 |
1973年 | 1篇 |
1972年 | 1篇 |
1971年 | 1篇 |
1968年 | 1篇 |
1962年 | 1篇 |
1955年 | 1篇 |
1938年 | 1篇 |
排序方式: 共有1847条查询结果,搜索用时 15 毫秒
91.
The effects of feeding diest containing either cholesterol (0.24% w/w) or cholestyramine (2.5% w/w) and of fasting on sterol synthesis in the liver, ileum, and lung of both male and female guinea pigs have been studied by measuring the incorporation by tissue slices of 14C-labeled acetate into total digitoninpredipitable sterols. Cholesterol feeding significantly decreased (P less than 0.05) sterol synthesis in the liver, ileum, and lung of the males and in the ileum of females. Cholestyramine feeding stimulated the rate of hepatic sterol synthesis 13-fold but did not significantly affect sterologenesis in the ileum. Sterol synthesis in the lung was significantly increased (P less than 0.05) but to a much lesser extent than in the liver. Fatty acid synthesis in the liver, ileum, and lung was not significantly affected by either cholesterol or cholestyramine feeding. In guinea pigs fasted for 24 hr, sterol synthesis was inhibited in all three tissues, the most pronounced effect occurring in the liver. Only in the lung was fatty acid synthesis significantly decreased (P less than 0.001) by fasting. Cholesterol feeding resulted in increased concentrations of cholesterol in the plasma and liver. Cholestyramine feeding reduced plasma cholesterol concentration by 81% in females and by 64% in males. However, it did not significantly change the tissue cholesterol concentrations. Fasting resulted in a significant increase (P less than 0.05) in plasma cholesterol concentration but did not effect the concentration of cholesterol in the tissues. It was concluded that in the normal guinea pig, the feedback inhibition produced by both cholesterol and also possibly by bile acids suppresses sterol synthesis in the liver to very low rates compared to those in the small intestine, where sterologenesis is not only less sensitive to the cholesterol negative feedback system than that in the liver, but also is not subject to regulation by the bile acid negative feedback system. 相似文献
92.
Two cases of perforated diverticula of the terminal ileum are presented with a discussion of the literature. Primary resection is the treatment of choice. Asymptomatic diverticula discovered on routine contrast studies should not be managed surgically. 相似文献
93.
We compare the vibrational entropy changes of proteins calculated using a full and a number of approximate normal modes analysis methods. The vibrational entropy differences for three conformational changes and three protein binding interactions were computed. In general, the approximate methods yield good estimates of the vibrational entropy change in a fraction of the time required by full normal modes analysis. The absolute entropies are either overestimated or greatly underestimated, but the difference is sufficiently accurate for some methods. This indicates that some of the approximate methods can give reasonable estimates of the associated vibrational entropy changes, making them suitable for inclusion in free energy calculations. 相似文献
94.
Jejunal villous changes associated with farmer's lung 总被引:1,自引:0,他引:1
TJ Robinson SD Nelson M Haire D Middleton SA McMillan JP Evans 《Canadian Metallurgical Quarterly》1981,57(673):697-701
95.
96.
97.
98.
SD Kevan 《Canadian Metallurgical Quarterly》1986,34(10):6713-6718
99.
100.