全文获取类型
收费全文 | 2090篇 |
免费 | 46篇 |
国内免费 | 68篇 |
出版年
2024年 | 2篇 |
2023年 | 29篇 |
2022年 | 51篇 |
2021年 | 44篇 |
2020年 | 26篇 |
2019年 | 81篇 |
2018年 | 94篇 |
2017年 | 64篇 |
2016年 | 56篇 |
2015年 | 92篇 |
2014年 | 130篇 |
2013年 | 194篇 |
2012年 | 133篇 |
2011年 | 125篇 |
2010年 | 104篇 |
2009年 | 92篇 |
2008年 | 85篇 |
2007年 | 111篇 |
2006年 | 95篇 |
2005年 | 107篇 |
2004年 | 39篇 |
2003年 | 40篇 |
2002年 | 38篇 |
2001年 | 24篇 |
2000年 | 29篇 |
1999年 | 31篇 |
1998年 | 21篇 |
1997年 | 17篇 |
1996年 | 16篇 |
1995年 | 13篇 |
1994年 | 9篇 |
1993年 | 11篇 |
1992年 | 25篇 |
1991年 | 11篇 |
1990年 | 3篇 |
1989年 | 14篇 |
1988年 | 13篇 |
1987年 | 7篇 |
1986年 | 6篇 |
1985年 | 12篇 |
1984年 | 25篇 |
1983年 | 9篇 |
1982年 | 15篇 |
1981年 | 12篇 |
1980年 | 11篇 |
1979年 | 17篇 |
1978年 | 12篇 |
1977年 | 3篇 |
1976年 | 4篇 |
1971年 | 1篇 |
排序方式: 共有2204条查询结果,搜索用时 15 毫秒
1.
Annette Graham 《Free radical research》1998,28(6):611-621
Compelling evidence suggests that low-density lipoprotein (LDL) is oxidized by cells within the arterial intima and that, once oxidized, it is profoundly atherogenic. The precise mechanism(s) by which cells promote the oxidation of LDL in vivo are not known; in vitro, however, oxidation of LDL can be enhanced by a number of differing mechanisms, including reaction with free and protein-bound metal ions, thiols, reactive oxygen species, lipoxygenase, myeloperoxidase and peroxynitrite. This review is concerned with the mechanisms by which cells enhance the oxidation of LDL in the presence of transition metals; in particular, the regulation, pro- and anti-oxidant consequences, and mechanism of action of cellular thiol production are examined, and contrasted with thiol-independent oxidation of LDL in the presence of transition metals. 相似文献
2.
3.
The mechanism of hypercholesterolemia effect of Cu2+ deficiency was studied in rats. There was increased activity of hepatic hydroxymethylglutaryl-coenzyme A reductase and increased
incorporation of labelled acetate into free cholesterol of liver in the Cu2+ deficient rats. Incorporation of label into ester cholesterol was however decreased in the liver. Concentration of bile acids
in the liver was not significantly altered. Increase in the incorporation of labelled acetate into serum cholesterol and increase
in the concentration of cholesterol and apo B in the low density lipoproteins + very low density lipoproteins fractions were
observed. Activity of lipoprotein lipase of the extrahepatic tissues decreased in the Cu2+ deficient rats. 相似文献
4.
Three compounds capsaicin, curcumin and ferulic acid showing hypolipidemic activity have been tested in adult Wistar rats
fed high fat diets. Capsaicin (0.20 mg%) fed to female rats along with a 30% saturated fat diet lowered the rate of weight
gain, liver and serum triglycerides. In male rats it lowered only the liver and serum total and very low density and low density
lipoprotein triglycerides whether fed continuously for 13 or 8 weeks after interchanging the control and test diets from the
5th week onwards. Capsaicin fed to female rats in 30% mixed fat diet increased the rate of weight gain, lowered liver and
serum triglycerides, lowered adipose tissue lipoprotein lipase, elevated the hormone sensitive lipase and serum free fatty
acids. Capsaicin in 30% saturated fat diet lowered both the enzyme activities to a much lesser extent. Curcumin and ferulic
acid (both at 25 mg%) in 30% saturated fat diet tended to lower the rate of weight gain, liver total lipids and serum triglycerides.
It is of significance that a common dietary compound ‘capsaicin’ in the range of human intake triggers lipid lowering action
in rats fed high fat diets.
This paper was presented at the 55th Annual Meeting of the Society of Biological Chemists (India) held at Trivandrum during
December 15–17th, 1986. 相似文献
5.
Genetic analysis of murine strains C57BL/6J and C3H/HeJ to confirm the map position ofAth-1, a gene determining atherosclerosis susceptibility 总被引:4,自引:0,他引:4
Beverly Paigen Deborah Albee Patricia A. Holmes Diane Mitchell 《Biochemical genetics》1987,25(7-8):501-511
Previous results suggested that strains C57BL/6J and C3H/HeJ differed in a single gene for atherosclerosis susceptibility, calledAth-1. Based on data from recombinant inbred strainsAth-1 was tentatively assigned to chromosome 1 linked toAlp-2. In this report, a cross between C57BL/6 and C3H/HeJ was carried out in order to test whether the tentative map position was correct. Parental strains and F1 and F2 progeny were examined. Susceptible alleles ofAth-1, found in C57BL/6, are associated with relatively low levels of high-density lipoprotein (HDL)-cholesterol in animals fed an atherogenic diet; resistant alleles ofAth-1 are associated with relatively high levels of HDL-cholesterol. F1 progeny have HDL levels that are intermediate between these of the two parental strains. Among the F2 progeny,Alp-2 andAth-1 cosegregated, providing confirmatory evidence thatAth-1 is linked toAlp-2 on chromosome 1. Three mice recombinant forAlp-2 andAth-1 were found among the 60 chromosomes tested, giving an estimated map distance between these two genes of 5.0±2.8 (SE) cM. The phenotypic characteristics ofAth-1 resemble a genetic trait in humans, hyperalphalipoproteinemia, which is characterized by elevated levels of HDL-cholesterol, reduced risk of heart disease, and increased longevity.This work was supported by Grant HL-32087 from the Heart, Lung, and Blood Institute, National Institutes of Health, Grant 1858 from the Council for Tobacco Research, Grant 86-1387 from the American Heart Association with funds contributed in part by the Alameda, Orange, and Santa Barbara County Chapters, and Grants 85-N132A and 85-N136A from the California Affiliate of the American Heart Association. 相似文献
6.
Cholesterol binding reserve of hyperlipemic rat serum lipoproteins in chronic ethanol administration
Chronic administration of ethanol in rats caused the reduction of serum cholesterol binding reserve. The very low density
and high density lipoproteins, main serum cholesterol binding reserves, were slightly increased with corresponding increases
in their lipid and protein components during initial stage of alcohol consumption. However, these capacities get deminished
during reversal of hyperlipemia induced by prolonged action of ethanol. This situation may be an early indicator for the initiation
of hepatic damage and a variety of secondary effects of ethanol. 相似文献
7.
Opacity factor from group A streptococci is an apoproteinase 总被引:7,自引:0,他引:7
Opacity factor (OF) is an enzyme, elaborated by certain serotypes of group A streptococci, which produces opalescence in mammalian sera. OF has been designated a lipoproteinase. Lipoproteins are complex structures and many enzymes are involved in their catalysis. We therefore set out to establish which of the many enzymes OF could be. Results showed that OF rendered high density lipoprotein (HDL) insoluble, accounting for the opalescence in serum, and altered its electrophoretic mobility. Electron microscopy revealed that OF caused an aggregation of HDL and an alteration in molecule shape. OF specifically split apoprotein AI of HDL into two fragments demonstrable by SDS-PAGE. We therefore designate OF as an apoproteinase. 相似文献
8.
To study the potential relationship between circulating triacylglycerol (TAG) levels and lipoprotein lipase (LPL) activity in the newborn rat liver, pups from undernourished or normal control mothers were nursed by normal dams, and studied at 0, 1, 15 or 30 days of age. Plasma TAG levels and liver TAG concentration increased more in pups from undernourished mothers than they did in controls. At birth, liver LPL activity was similarly high in both groups but, whereas in controls it decreased progressively after birth, in pups from undernourished mothers it remained stable until 15 days of age. Results suggest that the hypertriglyceridemia present in pups from undernourished mothers may be responsible for the sustained high LPL activity in their liver which may enhance the hepatic uptake of circulating TAG. 相似文献
9.
The effect of biotin deficiency on the metabolism of cholesterol was studied in rats fed cholesterol-free and cholesterol-containing
diet. Biotin deficiency induced by feeding raw egg-white resulted in higher cholesterol in the serum and aorta, and higher
high density lipoprotein cholesterol and low density lipoprotein + very low density lipoprotein cholesterol. In the liver,
cholesterol increased only in the cholesterol diet group but not in the cholesterol-free diet group. Levels of triglycerides
were lower in the biotindeficient, cholesterol-free diet group, but triglycerides were elevated in the cholesterol diet group.
Concentration of bile acids in the liver and activity of lipoprotein lipase in the heart and adipose tissue were significantly
decreased in the biotin-deficient rats. Release of lipoproteins into the circulation, incorporation of [1,2-14C] acetate into cholesterol, and activity of plasma lecithin: cholesterol acyl transferase were higher. 相似文献
10.
Egg yolk lipoprotein promoted growth of a wide variety of mammalian cell lines, including plasma-cytomas and epithelial cell lines, in serum-free medium. The lipoprotein was active for cell growth when used with insulin, transferrin, ethanolamine and selenite. The most active lipoprotein fraction (YLP-pI7.5) was purified to give a single peak by chromatofocusing and gel filtration, and was homogeneous on a 0.35% agarose gel electrophoretogram. The lipoprotein was characterised as a very low density lipoprotein with a protein content of only 1.3%. This lipoprotein had an optimal concentration of 300 g/ml (4 g protein/ml). It was easily separable from proteinous molecules secreted into the serum-free medium by the cells, since it floated on the surface of the medium after addition of ammonium sulfate, to precipitate protein, and centrifugation. An associated structure of lipid and protein seemed to be still necessary for the lipoprotein to exhibit a growth promoting activity. 相似文献