全文获取类型
收费全文 | 120437篇 |
免费 | 2388篇 |
国内免费 | 2390篇 |
出版年
2024年 | 39篇 |
2023年 | 305篇 |
2022年 | 762篇 |
2021年 | 1396篇 |
2020年 | 962篇 |
2019年 | 1193篇 |
2018年 | 12699篇 |
2017年 | 11232篇 |
2016年 | 8478篇 |
2015年 | 2465篇 |
2014年 | 2399篇 |
2013年 | 2571篇 |
2012年 | 6725篇 |
2011年 | 14841篇 |
2010年 | 13245篇 |
2009年 | 9335篇 |
2008年 | 11171篇 |
2007年 | 12564篇 |
2006年 | 1417篇 |
2005年 | 1475篇 |
2004年 | 1743篇 |
2003年 | 1701篇 |
2002年 | 1303篇 |
2001年 | 732篇 |
2000年 | 539篇 |
1999年 | 436篇 |
1998年 | 251篇 |
1997年 | 286篇 |
1996年 | 261篇 |
1995年 | 214篇 |
1994年 | 223篇 |
1993年 | 181篇 |
1992年 | 237篇 |
1991年 | 221篇 |
1990年 | 137篇 |
1989年 | 113篇 |
1988年 | 96篇 |
1987年 | 121篇 |
1986年 | 82篇 |
1985年 | 69篇 |
1984年 | 59篇 |
1983年 | 54篇 |
1982年 | 38篇 |
1981年 | 26篇 |
1979年 | 25篇 |
1975年 | 26篇 |
1972年 | 263篇 |
1971年 | 285篇 |
1965年 | 22篇 |
1962年 | 26篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
841.
Sui Xin He Xiao-yan Liu Ning-hua Dang Yan-ru Cha Qian-qian Sun Mei-ling Li Chun-yang Fu Hui-hui Song Xiao-yan Qin Qi-long Chen Xiu-lan Zhang Yu-zhong Su Hai-nan Zhang Xi-ying 《Antonie van Leeuwenhoek》2021,114(7):947-955
Antonie van Leeuwenhoek - A novel Gram-negative, rod-shaped, aerobic, oxidase-positive and catalase-negative bacterium, designated strain SM1970T, was isolated from a seawater sample collected from... 相似文献
842.
843.
844.
845.
846.
847.
848.
849.
Kathie Y Sun Daniel Oreper Sarah A Schoenrock Rachel McMullan Paola Giusti-Rodríguez Vasyl Zhabotynsky Darla R Miller Lisa M Tarantino Fernando Pardo-Manuel de Villena William Valdar 《Genetics》2021,218(1)
Female mammals are functional mosaics of their parental X-linked gene expression due to X chromosome inactivation (XCI). This process inactivates one copy of the X chromosome in each cell during embryogenesis and that state is maintained clonally through mitosis. In mice, the choice of which parental X chromosome remains active is determined by the X chromosome controlling element (Xce), which has been mapped to a 176-kb candidate interval. A series of functional Xce alleles has been characterized or inferred for classical inbred strains based on biased, or skewed, inactivation of the parental X chromosomes in crosses between strains. To further explore the function structure basis and location of the Xce, we measured allele-specific expression of X-linked genes in a large population of F1 females generated from Collaborative Cross (CC) strains. Using published sequence data and applying a Bayesian “Pólya urn” model of XCI skew, we report two major findings. First, inter-individual variability in XCI suggests mouse epiblasts contain on average 20–30 cells contributing to brain. Second, CC founder strain NOD/ShiLtJ has a novel and unique functional allele, Xceg, that is the weakest in the Xce allelic series. Despite phylogenetic analysis confirming that NOD/ShiLtJ carries a haplotype almost identical to the well-characterized C57BL/6J (Xceb), we observed unexpected patterns of XCI skewing in females carrying the NOD/ShiLtJ haplotype within the Xce. Copy number variation is common at the Xce locus and we conclude that the observed allelic series is a product of independent and recurring duplications shared between weak Xce alleles. 相似文献
850.
Chen Zhang Qisheng Zuo Man Wang Hao Chen Nana He Jing Jin Tingting Li Jingyi Jiang Xia Yuan Jiancheng Li Xiang Shi Ming Zhang Hao Bai Yang Zhang Qi Xu Hengmi Cui Guobin Chang Jiuzhou Song Hongyan Sun Yani Zhang Guohong Chen Bichun Li 《Journal of cellular physiology》2021,236(2):1391-1400
The development of primordial germ cells (PGCs) undergoes epigenetic modifications. The study of histone methylation in regulating PGCs is beneficial to understand the development and differentiation mechanism of germ stem cells. Notably, it provides a theoretical basis for directed induction and mass acquisition in vitro. However, little is known about the regulation of PGC formation by histone methylation. Here, we found the high enrichment of H3K4me2 in the blastoderm, genital ridges, and testis. Chromatin immunoprecipitation sequencing was performed and the results revealed that genomic H3K4me2 is dynamic in embryonic stem cells, PGCs, and spermatogonial stem cells. This trend was consistent with the H3K4me2 enrichment in the gene promoter region. Additionally, narrow region triggered PGC‐related genes (Bmp4, Wnt5a, and Tcf7l2) and signaling pathways (Wnt and transforming growth factor‐β). After knocking down histone methylase Mll2 in vitro and vivo, the level of H3K4me2 decreased, inhibiting Cvh and Blimp1 expression, then repressing the formation of PGCs. Taken together, our study revealed the whole genome map of H3K4me2 in the formation of PGCs, contributing to improve the epigenetic study in PGC formation and providing materials for bird gene editing and rescue of endangered birds. 相似文献