全文获取类型
收费全文 | 914篇 |
免费 | 68篇 |
国内免费 | 2篇 |
出版年
2021年 | 6篇 |
2020年 | 8篇 |
2019年 | 6篇 |
2018年 | 11篇 |
2016年 | 7篇 |
2015年 | 20篇 |
2014年 | 28篇 |
2013年 | 38篇 |
2012年 | 57篇 |
2011年 | 36篇 |
2010年 | 25篇 |
2009年 | 36篇 |
2008年 | 48篇 |
2007年 | 34篇 |
2006年 | 32篇 |
2005年 | 32篇 |
2004年 | 25篇 |
2003年 | 23篇 |
2002年 | 28篇 |
2001年 | 29篇 |
2000年 | 14篇 |
1999年 | 16篇 |
1998年 | 9篇 |
1996年 | 9篇 |
1995年 | 10篇 |
1994年 | 8篇 |
1993年 | 9篇 |
1992年 | 6篇 |
1991年 | 16篇 |
1990年 | 15篇 |
1989年 | 11篇 |
1988年 | 9篇 |
1987年 | 13篇 |
1986年 | 7篇 |
1985年 | 13篇 |
1984年 | 17篇 |
1983年 | 16篇 |
1982年 | 15篇 |
1981年 | 10篇 |
1980年 | 11篇 |
1979年 | 20篇 |
1978年 | 14篇 |
1977年 | 8篇 |
1976年 | 9篇 |
1975年 | 11篇 |
1974年 | 13篇 |
1973年 | 15篇 |
1971年 | 6篇 |
1968年 | 10篇 |
1964年 | 6篇 |
排序方式: 共有984条查询结果,搜索用时 15 毫秒
921.
922.
Helene S. Smith Lewis I. Pizer Laird Pylkas Seymour Lederberg 《Journal of virology》1969,4(2):162-168
We have investigated some of the biochemical events that accompany the abortive infection by T2 of Shigella dysenteriae lysogenized with the temperate phage P2. After infection with T2, protein and RNA synthesis continued for 3 to 5 min. The virus-induced enzyme, deoxycytidylate hydroxymethylase was produced in reduced amounts (15% of normal), and the extent of deoxyribonucleic acid (DNA) synthesis was 0.1% of that found with a nonlysogenic strain. Measurements of the production of acid-soluble fragments and sedimentation analyses failed to detect enzymatic degradation of the infecting viral DNA which could be specifically related to the presence of the prophage P2. Each interaction between T2 and a bacterium resulted in the death of the cell. This observation is consistent with results obtained with other types of bacteria which show that only when a nucleolytic attack occurs on T2 DNA does the cell have an increased capacity to survive after adsorption of T2. 相似文献
923.
David S. Goldstein Si-Houn Hahn Courtney Holmes †Cynthia Tifft Judith Harvey-White ‡Sheldon Milstein ‡Seymour Kaufman 《Journal of neurochemistry》1995,64(6):2810-2813
Abstract: Plasma and CSF concentrations of endogenous l -DOPA, catecholamines, and metabolites of monoamines were assayed in a patient with atypical phenylketonuria due to absent dihydropteridine reductase (DHPR), before and during treatment with folinic acid, Sinemet, and 5-hydroxytryptophan. The patient had low but detectable levels of l -DOPA, 3,4-dihydroxyphenylacetic acid (DOPAC), and 3,4-dihydroxyphenylglycol (DHPG) in plasma and low but detectable levels of these compounds and of homovanillic acid (HVA) and 5-hydroxyindoleacetic acid (5-HIAA) in CSF, with approximately normal plasma and CSF levels of norepinephrine [noradrenaline (NA)]. Folinic acid treatment approximately doubled plasma levels of l -DOPA, NA, DOPAC, and DHPG, compared with values during dietary phenylalanine restriction alone. Detection of l -DOPA, catecholamines, and monoamine metabolites in this patient indicates that monoamine synthesis in humans does not absolutely require DHPR. The results are consistent with the existence of an alternative biochemical pathway, with folinic acid treatment augmenting activity along this pathway. Low plasma levels of l -DOPA, DOPAC, and DHPG may reflect decreased catecholamine synthesis and turnover in sympathetic nerves, with compensatory increases in exocytotic release normalizing plasma NA levels. 相似文献
924.
925.
926.
927.
IL-4 can correct defective IgE production in SJA/9 mice. 总被引:3,自引:0,他引:3
H F Savelkoul B W Seymour L Sullivan R L Coffman 《Journal of immunology (Baltimore, Md. : 1950)》1991,146(6):1801-1805
SJA/9 mice are unable to produce significant serum IgE responses to either primary or secondary challenge with protein Ag or helminth parasites. Previous work has shown that this defect resides the T cell rather than with the B cells. These experiments test several possible explanations for the lack of IgE production in these mice. SJA/9 mice do not appear to overproduce IFN-gamma or any other antagonist of IL-4 function. Helminth parasite infection induces normal levels of IL-5-dependent eosinophilia, suggesting that there is not a complete absence of a Th2 response in these mice. The defect, however can be explained by a substantial reduction in IL-4 production in vivo and can be corrected by infusion with IL-4. The reason for this lack of IL-4 production is not yet clear and, paradoxically, SJA/9 T cells can be stimulated in vitro to produce IL-4 levels comparable to T cells from other strains. 相似文献
928.
Emanuela Taioli Annie Im Xia Xu Timothy D Veenstra Gretchen Ahrendt Seymour Garte 《Reproductive biology and endocrinology : RB&E》2010,8(1):93
Background
An important aspect of the link between estrogen and breast cancer is whether urinary estrogen levels are representative of the intra-tissue levels of bioavailable estrogens. 相似文献929.
930.