全文获取类型
收费全文 | 1065778篇 |
免费 | 127484篇 |
国内免费 | 632篇 |
出版年
2018年 | 8409篇 |
2016年 | 12213篇 |
2015年 | 18373篇 |
2014年 | 21096篇 |
2013年 | 29637篇 |
2012年 | 33794篇 |
2011年 | 33892篇 |
2010年 | 22825篇 |
2009年 | 21410篇 |
2008年 | 30536篇 |
2007年 | 31435篇 |
2006年 | 29099篇 |
2005年 | 28275篇 |
2004年 | 27818篇 |
2003年 | 26796篇 |
2002年 | 25938篇 |
2001年 | 45607篇 |
2000年 | 46053篇 |
1999年 | 37309篇 |
1998年 | 14514篇 |
1997年 | 15090篇 |
1996年 | 14507篇 |
1995年 | 13556篇 |
1994年 | 13431篇 |
1993年 | 13221篇 |
1992年 | 31062篇 |
1991年 | 30006篇 |
1990年 | 29496篇 |
1989年 | 28724篇 |
1988年 | 26387篇 |
1987年 | 25828篇 |
1986年 | 23728篇 |
1985年 | 23839篇 |
1984年 | 20031篇 |
1983年 | 17416篇 |
1982年 | 14013篇 |
1981年 | 12543篇 |
1980年 | 11881篇 |
1979年 | 19303篇 |
1978年 | 15386篇 |
1977年 | 14001篇 |
1976年 | 13252篇 |
1975年 | 14250篇 |
1974年 | 15398篇 |
1973年 | 15045篇 |
1972年 | 13576篇 |
1971年 | 12642篇 |
1970年 | 10799篇 |
1969年 | 10350篇 |
1968年 | 9210篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
921.
Jin Wei Mia Madel Alfajaro Peter C. DeWeirdt Ruth E. Hanna William J. Lu-Culligan Wesley L. Cai Madison S. Strine Shang-Min Zhang Vincent R. Graziano Cameron O. Schmitz Jennifer S. Chen Madeleine C. Mankowski Renata B. Filler Neal G. Ravindra Victor Gasque Fernando J. de Miguel Ajinkya Patil Huacui Chen Craig B. Wilen 《Cell》2021,184(1):76-91.e13
922.
923.
924.
Titrating the effects of mitochondrial complex I impairment in the cell physiology. 总被引:14,自引:0,他引:14
The mitochondrial oxidative phosphorylation system consists of five multimeric enzymes (complexes I-V). NADH dehydrogenase or complex I (CI) is affected in most of the mitochondrial diseases and in some neurodegenerative disorders. We have studied the physiological consequences of a partial CI inhibition at the cellular level. We used a genetic model (40% CI-inhibited human-ape xenomitochondrial cybrids) and a drug-induced model (0-100% CI-inhibited cells using different concentrations of rotenone). We observed a quantitative correlation between the level of CI impairment and cell respiration, cell growth, free radical production, lipid peroxidation, mitochondrial membrane potential, and apoptosis. We showed that cell death was quantitatively associated with free radical production rather than with a decrease in respiratory chain function. The results obtained with human xenomitochondrial cybrid cells were compatible with those observed in rotenone-induced 40% CI-inhibited cells. At high concentrations (5-6-fold higher than the concentration necessary for 100% CI inhibition), rotenone showed a second toxic effect at the level of microtubule assembly, which also led to apoptosis. The correlation found among all the parameters studied helped clarify the physiological consequences of partial CI inhibitions at the cellular level. 相似文献
925.
926.
927.
928.
929.
930.
J. M. Warren 《Journal of human evolution》1974,3(6):445-454
The experimental literature on learning by Primate and non-Primate mammals is reviewed, with the aim of identifying peculiarly Primate features of learning. The evidence indicates that quantitative comparisons of learning by Primates and other mammals are intrinsically equivocal and uninformative because of the impossibility of equating experimental conditions for members of different species. The comparative results of early learning set studies were seriously misleading because the test conditions discriminated against representatives of species in which vision is not a dominant modality.Analyses of transfer between different learning tasks strongly suggest that rhesus macaques differ qualitatively from non-Primates like cats in that they develop generalized, trans-situationally valid response strategies during training on a particular problem which can facilitate learning in other situations. Non-Primate mammals appear not to develop such strategies under the same circumstances. There is also evidence that monkeys are more able than cats to discard previously learned strategies when they are no longer maximally profitable. 相似文献