全文获取类型
收费全文 | 190篇 |
免费 | 0篇 |
国内免费 | 2篇 |
专业分类
系统科学 | 21篇 |
教育与普及 | 3篇 |
理论与方法论 | 2篇 |
现状及发展 | 13篇 |
研究方法 | 31篇 |
综合类 | 117篇 |
自然研究 | 5篇 |
出版年
2019年 | 1篇 |
2018年 | 2篇 |
2015年 | 2篇 |
2014年 | 2篇 |
2012年 | 14篇 |
2011年 | 22篇 |
2010年 | 9篇 |
2009年 | 4篇 |
2008年 | 13篇 |
2007年 | 14篇 |
2006年 | 16篇 |
2005年 | 21篇 |
2004年 | 18篇 |
2003年 | 24篇 |
2002年 | 18篇 |
2001年 | 1篇 |
1999年 | 4篇 |
1998年 | 2篇 |
1997年 | 1篇 |
1996年 | 1篇 |
1995年 | 1篇 |
1994年 | 2篇 |
排序方式: 共有192条查询结果,搜索用时 0 毫秒
111.
This article examines how strong the association is between the obtaining of higher educational qualifications and later entry to motherhood, and how these are associated with levels and pace of second and subsequent childbearing. Data from the ONS Longitudinal Study are used to estimate these associations for women born in England and Wales between 1954 and 1958. Average age of entry to motherhood is found to be five years later for women with higher qualifications than for those without. Increasing age of motherhood is always associated with a lower likelihood of going on to have another child, but the decline with age is less pronounced for women with a higher qualification. Moreover, for any given age of childbearing, mothers with a higher qualification are more likely than those without to have another child, and are more likely to do so quickly. 相似文献
112.
113.
Auwerx J Avner P Baldock R Ballabio A Balling R Barbacid M Berns A Bradley A Brown S Carmeliet P Chambon P Cox R Davidson D Davies K Duboule D Forejt J Granucci F Hastie N de Angelis MH Jackson I Kioussis D Kollias G Lathrop M Lendahl U Malumbres M von Melchner H Müller W Partanen J Ricciardi-Castagnoli P Rigby P Rosen B Rosenthal N Skarnes B Stewart AF Thornton J Tocchini-Valentini G Wagner E Wahli W Wurst W 《Nature genetics》2004,36(9):925-927
The European Mouse Mutagenesis Consortium is the European initiative contributing to the international effort on functional annotation of the mouse genome. Its objectives are to establish and integrate mutagenesis platforms, gene expression resources, phenotyping units, storage and distribution centers and bioinformatics resources. The combined efforts will accelerate our understanding of gene function and of human health and disease. 相似文献
114.
Postcopulatory sperm competition is a key aspect of sexual selection and is believed to drive the rapid evolution of both reproductive physiology and reproduction-related genes. It is well-established that mating behavior determines the intensity of sperm competition, with polyandry (i.e., female promiscuity) leading to fiercer sperm competition than monandry. Studies in mammals, particularly primates, showed that, owing to greater sperm competition, polyandrous taxa generally have physiological traits that make them better adapted for fertilization than monandrous species, including bigger testes, larger seminal vesicles, higher sperm counts, richer mitochondrial loading in sperm and more prominent semen coagulation. Here, we show that the degree of polyandry can also impact the dynamics of molecular evolution. Specifically, we show that the evolution of SEMG2, the gene encoding semenogelin II, a main structural component of semen coagulum, is accelerated in polyandrous primates relative to monandrous primates. Our study showcases the intimate relationship between sexual selection and the molecular evolution of reproductive genes. 相似文献
115.
116.
117.
118.
119.
The DNA sequence and comparative analysis of human chromosome 5 总被引:1,自引:0,他引:1
Schmutz J Martin J Terry A Couronne O Grimwood J Lowry S Gordon LA Scott D Xie G Huang W Hellsten U Tran-Gyamfi M She X Prabhakar S Aerts A Altherr M Bajorek E Black S Branscomb E Caoile C Challacombe JF Chan YM Denys M Detter JC Escobar J Flowers D Fotopulos D Glavina T Gomez M Gonzales E Goodstein D Grigoriev I Groza M Hammon N Hawkins T Haydu L Israni S Jett J Kadner K Kimball H Kobayashi A Lopez F Lou Y Martinez D Medina C Morgan J Nandkeshwar R Noonan JP Pitluck S Pollard M Predki P 《Nature》2004,431(7006):268-274
Chromosome 5 is one of the largest human chromosomes and contains numerous intrachromosomal duplications, yet it has one of the lowest gene densities. This is partially explained by numerous gene-poor regions that display a remarkable degree of noncoding conservation with non-mammalian vertebrates, suggesting that they are functionally constrained. In total, we compiled 177.7 million base pairs of highly accurate finished sequence containing 923 manually curated protein-coding genes including the protocadherin and interleukin gene families. We also completely sequenced versions of the large chromosome-5-specific internal duplications. These duplications are very recent evolutionary events and probably have a mechanistic role in human physiological variation, as deletions in these regions are the cause of debilitating disorders including spinal muscular atrophy. 相似文献
120.