全文获取类型
收费全文 | 961篇 |
免费 | 3篇 |
专业分类
化学工业 | 4篇 |
金属工艺 | 1篇 |
轻工业 | 24篇 |
石油天然气 | 2篇 |
一般工业技术 | 4篇 |
冶金工业 | 929篇 |
出版年
2016年 | 1篇 |
2015年 | 1篇 |
2014年 | 1篇 |
2013年 | 1篇 |
2012年 | 3篇 |
2011年 | 4篇 |
2009年 | 1篇 |
2008年 | 1篇 |
2007年 | 3篇 |
2006年 | 2篇 |
2005年 | 4篇 |
2004年 | 2篇 |
2003年 | 3篇 |
2001年 | 1篇 |
2000年 | 1篇 |
1999年 | 24篇 |
1998年 | 282篇 |
1997年 | 121篇 |
1996年 | 126篇 |
1995年 | 68篇 |
1994年 | 55篇 |
1993年 | 43篇 |
1992年 | 6篇 |
1991年 | 22篇 |
1990年 | 10篇 |
1989年 | 22篇 |
1988年 | 11篇 |
1987年 | 14篇 |
1986年 | 13篇 |
1985年 | 17篇 |
1982年 | 6篇 |
1981年 | 5篇 |
1980年 | 7篇 |
1978年 | 5篇 |
1977年 | 24篇 |
1976年 | 52篇 |
1975年 | 2篇 |
排序方式: 共有964条查询结果,搜索用时 15 毫秒
51.
52.
53.
54.
55.
56.
The effects of different organic acids on Alternaria alternata growth and tenuazonic acid production (TeA) were evaluated. Both TeA pure toxin solution and TeA production in solid medium were considered. Sodium benzoate, potassium sorbate and sodium propionate, all preservatives commonly used by food industry in Argentina, were tested. TeA was stable as pure toxin solution when was treated with the salts of organic acids used. A differential effect was observed when the preservatives were evaluated in relation to A. alternata growth and TeA production in solid medium. L evels above 10mg/kg of sodium benzoate and potassium sorbate produced a total inhibition of fungal development and toxin biosynthesis. Sodium propionate produced a 59% decrease in A. alternata growth and total inhibition of TeA production only at the highest concentration of preservatives used. 相似文献
57.
The effect of Evans blue (EB) on large-conductance Ca2+-activated K+ (BKCa) channels was investigated in cultured endothelial cells of human umbilical veins. In whole-cell configuration, EB (50 microM) reversibly increased the amplitude of K+ outward currents (IK). When the patch pipettes were filled with 10 mM EGTA, its stimulatory effect on IK was unaltered. Further application of EB in the presence of suramin, a blocker of P2-purinergic receptor, or AOPCP, an inhibitor of 5'-nucleotidase, still increased IK. However, charybdotoxin (100 nM) suppressed EB-induced increase in IK. In inside-out configuration, bath application of EB (50 microM) did not change single channel conductance but significantly increased the activity of BKCa channels. The EB-induced increase in the activity of BKCa channels was independent on internal Ca2+. EB (50 microM) shifted the activation curve of BKCa channels to less positive membrane potentials by approximately 20 mV. The change in the kinetic behavior of BKCa channels caused by EB in these cells is due to an increase in mean open time and a decrease in mean closed time. These results indicate that EB can stimulate the activity of BKCa channel in endothelial cells. This effect is unrelated to its blockade of P2-purinergic receptors or inhibition of 5'-nucleotidase. The direct stimulation of these ionic channels by EB may contribute to its effect on capillary permeability. 相似文献
58.
P69 is an isozyme of the medium size class of human 2'-5' oligoadenylate synthetases. In this study, recombinant P69 was expressed and used for enzymological and structural investigations. Bacterially expressed P69 was inactive whereas the same protein expressed in insect cells was highly active. Whether this difference could be due to differential post-translational modifications of the protein was investigated. Mutations of appropriate residues showed that myristoylation of the protein was not necessary for enzyme activity. In contrast, inhibition of glycosylation of P69, by tunicamycin treatment of the insect cells, produced an enzymatically inactive protein. Recombinant P69 produced in insect cells was purified by affinity chromatography. It was a dimeric glycoprotein, very stable and completely dependent on double stranded (ds) RNA for activity. The enzyme catalyzed the non-processive synthesis of 2'-5'-linked oligoadenylate products containing up to 30 residues. 2'-O-Methylated dsRNA was incapable of activating P69 and a 25-base pair dsRNA was as effective as larger dsRNA. This expression system will be useful for large scale production of P69 and its mutants for structural studies. 相似文献
59.
60.