全文获取类型
收费全文 | 1022篇 |
免费 | 0篇 |
专业分类
化学工业 | 3篇 |
轻工业 | 1篇 |
一般工业技术 | 4篇 |
冶金工业 | 1013篇 |
自动化技术 | 1篇 |
出版年
2008年 | 1篇 |
2003年 | 2篇 |
2000年 | 1篇 |
1999年 | 21篇 |
1998年 | 312篇 |
1997年 | 152篇 |
1996年 | 116篇 |
1995年 | 62篇 |
1994年 | 68篇 |
1993年 | 68篇 |
1992年 | 7篇 |
1991年 | 20篇 |
1990年 | 15篇 |
1989年 | 16篇 |
1988年 | 18篇 |
1987年 | 12篇 |
1986年 | 9篇 |
1985年 | 11篇 |
1983年 | 1篇 |
1982年 | 7篇 |
1981年 | 5篇 |
1980年 | 12篇 |
1979年 | 2篇 |
1978年 | 5篇 |
1977年 | 26篇 |
1976年 | 48篇 |
1975年 | 2篇 |
1971年 | 1篇 |
1964年 | 1篇 |
1955年 | 1篇 |
排序方式: 共有1022条查询结果,搜索用时 15 毫秒
61.
62.
AA Morris JW Taanman J Blake JM Cooper BD Lake M Malone S Love PT Clayton JV Leonard AH Schapira 《Canadian Metallurgical Quarterly》1998,28(4):556-563
BACKGROUND/AIMS: Liver failure in infancy can result from several disorders of the mitochondrial respiratory chain. In some patients, levels of mitochondrial DNA are markedly reduced, a phenomenon referred to as mitochondrial DNA depletion. To facilitate diagnosis of this condition, we have reviewed the clinical and pathological features in five patients with mitochondrial DNA depletion. METHODS: Cases were identified by preparing Southern blots of DNA from muscle and liver, hybridising with appropriate probes and quantifying mitochondrial DNA relative to nuclear DNA. RESULTS: All our patients with mitochondrial DNA depletion died of liver failure. Other problems included hypotonia, hypoglycaemia, neurological abnormalities (including Leigh syndrome) and cataracts. Liver histology showed geographic areas of fatty change, bile duct proliferation, collapse of liver architecture and fibrosis; some cells showed decreased cytochrome oxidase activity. Muscle from three patients showed mitochondrial proliferation, with loss of cytochrome oxidase activity in some fibres but not in others; in these cases, muscle mitochondrial DNA levels were less than 5% of the median control value. The remaining two patients (from a single pedigree) had normal muscle histology and histochemistry associated with less severe depletion of mitochondrial DNA in muscle. CONCLUSIONS: Liver failure is common in patients with mitochondrial DNA depletion. Associated clinical features often include neuromuscular disease. Liver and muscle histology can be helpful in making the diagnosis. Mitochondrial DNA levels should be measured whenever liver failure is thought to have resulted from respiratory chain disease. 相似文献
63.
64.
65.
66.
67.
68.
BC Bonning VK Ward MM van Meer TF Booth BD Hammock 《Canadian Metallurgical Quarterly》1997,94(12):6007-6012
Juvenile hormone esterase (JHE; EC 3.1.1.1), which is intrinsically involved in regulation of development of some insect larvae, is rapidly removed from the hemolymph by the pericardial cells. Lys-29 and Lys-524, which are implicated in the degradation of JHE, were mutated to Arg. Neither the half-life of the modified JHE in the hemolymph nor the catalytic parameters were changed significantly, but when combined, these mutations resulted in apparent failure of lysosomal targeting in the pericardial cell complex. A hypothesis for the mechanism of reduced efficiency of lysosomal targeting is presented. Infection of larvae with a recombinant baculovirus expressing the modified JHE resulted in a 50% reduction in feeding damage compared with larvae infected with the wild-type virus, thus demonstrating improved properties as a biological insecticide. These data demonstrate that alteration of specific residues of JHE that disrupted lysosomal targeting, dramatically increased the insecticidal activity of this protein. 相似文献
69.
70.
JS Sadeh D Rudikoff ML Gordon J Bowden BD Goldman M Lebwohl 《Canadian Metallurgical Quarterly》1997,133(6):747-750
To investigate the mechanisms of the hypolipidemic effect of monatepil, a new class of calcium antagonists with alpha 1-adrenergic blocking activity, we examined the effects of the drug on low-density lipoprotein (LDL) receptor activity and the level of LDL receptor mRNA present in cultured human skin fibroblasts. At concentrations of 2 x 10(-5) M, monatepil increased the binding (248 +/- 43%; mean +/- SD), internalization (374 +/- 18%), and degradation (145 +/- 2%) of 125I-LDL in human skin fibroblasts (n = 3, p < 0.05). Treatment of human skin fibroblasts with 2 x 10(-5) M of monatepil for 6 hours resulted in an increase in LDL receptor mRNA to 163% of the control level (n = 2), as shown by Northern blot analysis. Our results suggest that the hypolipidemic clinical effects of monatepil may be due to increased LDL receptor activity. 相似文献