全文获取类型
收费全文 | 759篇 |
免费 | 77篇 |
国内免费 | 1篇 |
出版年
2022年 | 11篇 |
2021年 | 13篇 |
2019年 | 3篇 |
2018年 | 11篇 |
2017年 | 14篇 |
2016年 | 13篇 |
2015年 | 34篇 |
2014年 | 21篇 |
2013年 | 30篇 |
2012年 | 64篇 |
2011年 | 55篇 |
2010年 | 30篇 |
2009年 | 24篇 |
2008年 | 43篇 |
2007年 | 55篇 |
2006年 | 46篇 |
2005年 | 49篇 |
2004年 | 33篇 |
2003年 | 32篇 |
2002年 | 36篇 |
2001年 | 12篇 |
2000年 | 11篇 |
1999年 | 14篇 |
1998年 | 8篇 |
1997年 | 7篇 |
1996年 | 3篇 |
1995年 | 7篇 |
1994年 | 4篇 |
1993年 | 4篇 |
1992年 | 13篇 |
1991年 | 12篇 |
1990年 | 13篇 |
1989年 | 6篇 |
1988年 | 10篇 |
1986年 | 6篇 |
1985年 | 6篇 |
1984年 | 7篇 |
1983年 | 7篇 |
1982年 | 6篇 |
1981年 | 11篇 |
1980年 | 6篇 |
1977年 | 6篇 |
1974年 | 5篇 |
1973年 | 5篇 |
1970年 | 2篇 |
1969年 | 2篇 |
1968年 | 2篇 |
1967年 | 3篇 |
1966年 | 4篇 |
1965年 | 3篇 |
排序方式: 共有837条查询结果,搜索用时 46 毫秒
1.
2.
3.
Donald R. McCarty Christian B. Carson Mark Lazar S. Caprice Simonds 《Genesis (New York, N.Y. : 2000)》1989,10(6):473-481
The viviparous-1 (vp1) locus in maize is a developmental gene that controls diverse aspects of the maturation phase of seed development. Mutations of vp1 alter embryo sensitivity to the hormone abscisic acid and block formation of anthocyanin pigment. Molecular cloning of a Robertson Mutator-induced mutant allele, vp1-mum-1, by transposable element tagging has allowed analysis of several transposon-induced vp1 mutants. In the vp1-Mc mutation, the gene is disrupted by 4.0 kbp insertion, which results in expression of a 3′ truncated mRNA. Phenotypically, this allele is at least partially functional in causing embryo dormancy, but is ineffective in controlling anthocyanin expression. This result suggests that disruption of the C-terminal domain of the Vp1 protein specifically affects regulation of the anthocyanin pathway. A second Mutator- derived allele, vp1-mum2, exhibits an unusual form of somatic mutability in which endosperm cells revert from wild-type vp1 expression to a mutant condition. The vp1-mum2 allele contains a 1.5 kbp Insertion that has no detectable homology to known Mu elements. This element is retained In wild-type germinal revertants derived from vp1-mum2 An apparent DNA modification affecting cleavage at an internal Sstl restriction site in the element correlates with vp1-mum2 states that exhibit wild-type Vp1 expression. A model involving mitotic assortment of modified and unmodified DNA strands during development is proposed for vp1-mum2 somatic mutation. 相似文献
4.
5.
6.
Ligand-induced endocytosis of the EGF receptor is blocked by mutational inactivation and by microinjection of anti-phosphotyrosine antibodies 总被引:29,自引:0,他引:29
Early events in ligand-induced endocytosis of the EGF receptor have been examined. A mutant EGF receptor devoid of intrinsic protein-tyrosine kinase activity bound EGF and dimerized normally yet failed to undergo ligand-induced internalization. Immunofluorescence microscopy revealed that receptors lacking kinase activity failed to undergo the ligand-induced internalization characteristic of receptors with kinase activity. Monoclonal anti-phosphotyrosine antibodies effectively inhibited phosphorylation of exogenous substrates in vitro and, when microinjected into cells containing active EGF receptors, prevented internalization of the receptor when cells were subsequently challenged with EGF. These results point to a crucial role for the kinase activity of the EGF receptor in the process of ligand-induced endocytosis of receptors, and imply that a phosphorylated substrate(s) is required. 相似文献
7.
Cholinesterases in Single Nerve Cells Isolated from the Locus Ceruleus and from Nucleus of the Facial Nerve of the Rat: A Microgasometric Study 总被引:2,自引:2,他引:0
Cholinesterase activity in single nerve cell bodies isolated from the locus ceruleus and nucleus of the facial nerve of the rat was analyzed by the microgasometric method. Acetylcholinesterase activity is about the same in both types of cells. Nonspecific cholinesterase is present in noradrenergic cells of the locus ceruleus but not in the cholinergic cells of the nucleus of the facial nerve. The total activity of cholinesterases and the activity of acetylcholinesterase in nerve cell bodies isolated from the locus ceruleus remains practically unchanged from the tenth postnatal day until the age of 24 months. Depletion of noradrenaline by a high dose of reserpine does not influence the total activity of cholinesterases in nerve cell bodies of locus ceruleus. 相似文献
8.
9.
10.