全文获取类型
收费全文 | 61628篇 |
免费 | 4939篇 |
国内免费 | 4803篇 |
出版年
2024年 | 147篇 |
2023年 | 836篇 |
2022年 | 1970篇 |
2021年 | 3205篇 |
2020年 | 2194篇 |
2019年 | 2690篇 |
2018年 | 2491篇 |
2017年 | 1924篇 |
2016年 | 2688篇 |
2015年 | 3864篇 |
2014年 | 4641篇 |
2013年 | 4722篇 |
2012年 | 5648篇 |
2011年 | 5136篇 |
2010年 | 3083篇 |
2009年 | 2770篇 |
2008年 | 3127篇 |
2007年 | 2818篇 |
2006年 | 2434篇 |
2005年 | 2019篇 |
2004年 | 1621篇 |
2003年 | 1519篇 |
2002年 | 1155篇 |
2001年 | 981篇 |
2000年 | 932篇 |
1999年 | 864篇 |
1998年 | 535篇 |
1997年 | 494篇 |
1996年 | 519篇 |
1995年 | 448篇 |
1994年 | 446篇 |
1993年 | 338篇 |
1992年 | 469篇 |
1991年 | 345篇 |
1990年 | 300篇 |
1989年 | 271篇 |
1988年 | 221篇 |
1987年 | 208篇 |
1986年 | 183篇 |
1985年 | 169篇 |
1984年 | 115篇 |
1983年 | 122篇 |
1982年 | 81篇 |
1981年 | 46篇 |
1980年 | 52篇 |
1979年 | 64篇 |
1976年 | 50篇 |
1974年 | 57篇 |
1973年 | 49篇 |
1972年 | 59篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
992.
993.
Xiaohui Yang Yu Yang Jian Ling Jiantao Guan Xiao Guo Daofeng Dong Liping Jin Sanwen Huang Jun Liu Guangcun Li 《Plant biotechnology journal》2020,18(2):364-372
Traditional approaches for sequencing insertion ends of bacterial artificial chromosome (BAC) libraries are laborious and expensive, which are currently some of the bottlenecks limiting a better understanding of the genomic features of auto‐ or allopolyploid species. Here, we developed a highly efficient and low‐cost BAC end analysis protocol, named BAC‐anchor, to identify paired‐end reads containing large internal gaps. Our approach mainly focused on the identification of high‐throughput sequencing reads carrying restriction enzyme cutting sites and searching for large internal gaps based on the mapping locations of both ends of the reads. We sequenced and analysed eight libraries containing over 3 200 000 BAC end clones derived from the BAC library of the tetraploid potato cultivar C88 digested with two restriction enzymes, Cla I and Mlu I. About 25% of the BAC end reads carrying cutting sites generated a 60–100 kb internal gap in the potato DM reference genome, which was consistent with the mapping results of Sanger sequencing of the BAC end clones and indicated large differences between autotetraploid and haploid genotypes in potato. A total of 5341 Cla I‐ and 165 Mlu I‐derived unique reads were distributed on different chromosomes of the DM reference genome and could be used to establish a physical map of target regions and assemble the C88 genome. The reads that matched different chromosomes are especially significant for the further assembly of complex polyploid genomes. Our study provides an example of analysing high‐coverage BAC end libraries with low sequencing cost and is a resource for further genome sequencing studies. 相似文献
994.
Genome assembly provides insights into the genome evolution and flowering regulation of orchardgrass
995.
996.
997.
998.
Yao Dang Yongpan An Jinzhao He Boyue Huang Jie Zhu Miaomiao Gao Shun Zhang Xin Wang Baoxue Yang Zhengwei Xie 《Aging cell》2020,19(1)
Although aging and senescence have been extensively studied in the past few decades, however, there is lack of clinical treatment available for anti‐aging. This study presents the effects of berberine (BBR) on the aging process resulting in a promising extension of lifespan in model organisms. BBR extended the replicative lifespan, improved the morphology, and boosted rejuvenation markers of replicative senescence in human fetal lung diploid fibroblasts (2BS and WI38). BBR also rescued senescent cells with late population doubling (PD). Furthermore, the senescence‐associated β‐galactosidase (SA‐β‐gal)‐positive cell rates of late PD cells grown in the BBR‐containing medium were ~72% lower than those of control cells, and its morphology resembled that of young cells. Mechanistically, BBR improved cell growth and proliferation by promoting entry of cell cycles from the G0 or G1 phase to S/G2‐M phase. Most importantly, BBR extended the lifespan of chemotherapy‐treated mice and naturally aged mice by ~52% and ~16.49%, respectively. The residual lifespan of the naturally aged mice was extended by 80%, from 85.5 days to 154 days. The oral administration of BBR in mice resulted in significantly improved health span, fur density, and behavioral activity. Therefore, BBR may be an ideal candidate for the development of an anti‐aging medicine. 相似文献
999.
Gemma Aragonès Kalavathi Dasuri Opeoluwa Olukorede Sarah G. Francisco Carol Renneburg Caroline Kumsta Malene Hansen Shun Kageyama Masaaki Komatsu Sheldon Rowan Jonathan Volkin Michael Workman Wenxin Yang Paula Daza Diego Ruano Helena Dominguez‐Martín José Antonio Rodríguez‐Navarro Xue‐Liang Du Michael A. Brownlee Eloy Bejarano Allen Taylor 《Aging cell》2020,19(11)
1000.
Oyundari Amartuvshin Chi‐Hung Lin Shao‐Chun Hsu Shih‐Han Kao Alvin Chen Wei‐Chun Tang Han‐Lin Chou Dong‐Lin Chang Yen‐Yang Hsu Bai‐Shiou Hsiao Elham Rastegari Kun‐Yang Lin Yu‐Ting Wang Chi‐Kuang Yao Guang‐Chao Chen Bi‐Chang Chen Hwei‐Jan Hsu 《Aging cell》2020,19(8)
Changes in mitochondrial dynamics (fusion and fission) are known to occur during stem cell differentiation; however, the role of this phenomenon in tissue aging remains unclear. Here, we report that mitochondrial dynamics are shifted toward fission during aging of Drosophila ovarian germline stem cells (GSCs), and this shift contributes to aging‐related GSC loss. We found that as GSCs age, mitochondrial fragmentation and expression of the mitochondrial fission regulator, Dynamin‐related protein (Drp1), are both increased, while mitochondrial membrane potential is reduced. Moreover, preventing mitochondrial fusion in GSCs results in highly fragmented depolarized mitochondria, decreased BMP stemness signaling, impaired fatty acid metabolism, and GSC loss. Conversely, forcing mitochondrial elongation promotes GSC attachment to the niche. Importantly, maintenance of aging GSCs can be enhanced by suppressing Drp1 expression to prevent mitochondrial fission or treating with rapamycin, which is known to promote autophagy via TOR inhibition. Overall, our results show that mitochondrial dynamics are altered during physiological aging, affecting stem cell homeostasis via coordinated changes in stemness signaling, niche contact, and cellular metabolism. Such effects may also be highly relevant to other stem cell types and aging‐induced tissue degeneration. 相似文献