全文获取类型
收费全文 | 2333篇 |
免费 | 207篇 |
国内免费 | 1篇 |
出版年
2024年 | 6篇 |
2023年 | 10篇 |
2022年 | 23篇 |
2021年 | 49篇 |
2020年 | 22篇 |
2019年 | 33篇 |
2018年 | 35篇 |
2017年 | 48篇 |
2016年 | 60篇 |
2015年 | 103篇 |
2014年 | 126篇 |
2013年 | 134篇 |
2012年 | 182篇 |
2011年 | 164篇 |
2010年 | 116篇 |
2009年 | 89篇 |
2008年 | 154篇 |
2007年 | 166篇 |
2006年 | 142篇 |
2005年 | 146篇 |
2004年 | 126篇 |
2003年 | 103篇 |
2002年 | 118篇 |
2001年 | 31篇 |
2000年 | 23篇 |
1999年 | 38篇 |
1998年 | 34篇 |
1997年 | 24篇 |
1996年 | 18篇 |
1995年 | 18篇 |
1994年 | 20篇 |
1993年 | 12篇 |
1992年 | 16篇 |
1991年 | 14篇 |
1990年 | 11篇 |
1989年 | 9篇 |
1988年 | 13篇 |
1987年 | 6篇 |
1986年 | 6篇 |
1985年 | 14篇 |
1984年 | 5篇 |
1983年 | 7篇 |
1981年 | 6篇 |
1980年 | 7篇 |
1979年 | 6篇 |
1978年 | 4篇 |
1977年 | 9篇 |
1975年 | 4篇 |
1973年 | 3篇 |
1972年 | 3篇 |
排序方式: 共有2541条查询结果,搜索用时 218 毫秒
101.
While much has been learned in recent years about the movement of soluble transport factors across the nuclear pore complex (NPC), comparatively little is known about intranuclear trafficking. We isolated the previously identified Saccharomyces protein Mlp1p (myosin-like protein) by an assay designed to find nuclear envelope (NE) associated proteins that are not nucleoporins. We localized both Mlp1p and a closely related protein that we termed Mlp2p to filamentous structures stretching from the nucleoplasmic face of the NE into the nucleoplasm, similar to the homologous vertebrate and Drosophila Tpr proteins. Mlp1p can be imported into the nucleus by virtue of a nuclear localization sequence (NLS) within its COOH-terminal domain. Overexpression experiments indicate that Mlp1p can form large structures within the nucleus which exclude chromatin but appear highly permeable to proteins. Remarkably, cells harboring a double deletion of MLP1 and MLP2 were viable, although they showed a slower net rate of active nuclear import and faster passive efflux of a reporter protein. Our data indicate that the Tpr homologues are not merely NPC-associated proteins but that they can be part of NPC-independent, peripheral intranuclear structures. In addition, we suggest that the Tpr filaments could provide chromatin-free conduits or tracks to guide the efficient translocation of macromolecules between the nucleoplasm and the NPC. 相似文献
102.
Faithful segregation of sister chromatids during cell division requires properly regulated cohesion between the sister centromeres.
The sister chromatids are attached along their lengths, but particularly tightly in the centromeric regions. Therefore specific
cohesion proteins may be needed at the centromere. Here we show that Drosophila MEI-S332 protein localizes to mitotic metaphase centromeres. Both overexpression and mutation of MEI-S332 increase the number
of apoptotic cells. In mei-S332 mutants the ratio of metaphase to anaphase figures is lower than wild type, but it is higher if MEI-S332 is overexpressed.
In chromosomal squashes centromeric attachments appear weaker in mei-S332 mutants than wild type and tighter when MEI-S332 is overexpressed. These results are consistent with MEI-S332 contributing
to centromeric sister-chromatid cohesion in a dose-dependent manner. MEI-S332 is the first member identified of a predicted
class of centromeric proteins that maintain centromeric cohesion.
Received: 11 December 1998; in revised form: 4 August 1999 / Accepted: 13 August 1999 相似文献
103.
104.
Lewis RA Kress TL Cote CA Gautreau D Rokop ME Mowry KL 《Mechanisms of development》2004,121(1):101-109
Although it is widely regarded that the targeting of RNA molecules to subcellular destinations depends upon the recognition of cis-elements found within their 3' untranslated regions (UTR), relatively little is known about the specific features of these cis-sequences that underlie their function. Interaction between specific repeated motifs within the 3' UTR and RNA-binding proteins has been proposed as a critical step in the localization of Vg1 RNA to the vegetal pole of Xenopus oocytes. To understand the relative contributions of repeated localization element (LE) sequences, we used comparative functional analysis of Vg1 LEs from two frog species, Xenopus laevis and Xenopus borealis. We show that clusters of repeated VM1 and E2 motifs are required for efficient localization. However, groups of either site alone are not sufficient for localization. In addition, we present evidence that the X. borealis Vg1 LE is recognized by the same set of RNA-binding proteins as the X. laevis Vg1 LE and is capable of productive interactions with the X. laevis transport machinery as it is sufficient to direct vegetal localization in X. laevis oocytes. These results suggest that clustered sets of cis-acting sites within the LE direct vegetal transport through specific interactions with the localization machinery. 相似文献
105.
106.
107.
Christopher?A?BidwellEmail author Lauren?N?Kramer Allison?C?Perkins Tracy?S?Hadfield Diane?E?Moody Noelle?E?Cockett 《BMC biology》2004,2(1):17
Background
The callipyge mutation is located within an imprinted gene cluster on ovine chromosome 18. The callipyge trait exhibits polar overdominant inheritance due to the fact that only heterozygotes inheriting a mutant paternal allele (paternal heterozygotes) have a phenotype of muscle hypertrophy, reduced fat and a more compact skeleton. The mutation is a single A to G transition in an intergenic region that results in the increased expression of several genes within the imprinted cluster without changing their parent-of-origin allele-specific expression. 相似文献108.
By comparing two fully sequenced genomes of Chlamydia trachomatis using competitive hybridization on DNA microarrays, a logarithmic correlation was demonstrated between the signal ratio of the arrays and the 75-99% range of nucleotide identities of the genes. Variable genes within 14 uncharacterized strains of C. trachomatis were identified by array analysis and verified by DNA sequencing. These genes may be crucial for understanding chlamydial virulence and pathogenesis. 相似文献
109.
110.
A balanced psychology and a full life 总被引:3,自引:0,他引:3
Seligman ME Parks AC Steen T 《Philosophical transactions of the Royal Society of London. Series B, Biological sciences》2004,359(1449):1379-1381
Psychology since World War II has been largely devoted to repairing weakness and understanding suffering. Towards that end, we have made considerable gains. We have a classification of mental illness that allows international collaboration, and through this collaboration we have developed effective psychotherapeutic or pharmacological treatments for 14 major mental disorders. However, while building a strong science and practice of treating mental illness, we largely forgot about everyday well-being. Is the absence of mental illness and suffering sufficient to let individuals and communities flourish? Were all disabling conditions to disappear, what would make life worth living? Those committed to a science of positive psychology can draw on the effective research methods developed to understand and treat mental illness. Results from a new randomized, placebo-controlled study demonstrate that people are happier and less depressed three months after completing exercises targeting positive emotion. The ultimate goal of positive psychology is to make people happier by understanding and building positive emotion, gratification and meaning. Towards this end, we must supplement what we know about treating illness and repairing damage with knowledge about nurturing well-being in individuals and communities. 相似文献