全文获取类型
收费全文 | 51494篇 |
免费 | 3898篇 |
国内免费 | 3446篇 |
出版年
2024年 | 87篇 |
2023年 | 513篇 |
2022年 | 1260篇 |
2021年 | 2253篇 |
2020年 | 1527篇 |
2019年 | 1940篇 |
2018年 | 2086篇 |
2017年 | 1710篇 |
2016年 | 2222篇 |
2015年 | 2590篇 |
2014年 | 3312篇 |
2013年 | 3681篇 |
2012年 | 4107篇 |
2011年 | 3864篇 |
2010年 | 2715篇 |
2009年 | 2379篇 |
2008年 | 2787篇 |
2007年 | 2510篇 |
2006年 | 2200篇 |
2005年 | 1856篇 |
2004年 | 1747篇 |
2003年 | 1662篇 |
2002年 | 1381篇 |
2001年 | 1141篇 |
2000年 | 967篇 |
1999年 | 738篇 |
1998年 | 437篇 |
1997年 | 363篇 |
1996年 | 352篇 |
1995年 | 373篇 |
1994年 | 327篇 |
1993年 | 262篇 |
1992年 | 388篇 |
1991年 | 331篇 |
1990年 | 283篇 |
1989年 | 258篇 |
1988年 | 196篇 |
1987年 | 244篇 |
1986年 | 197篇 |
1985年 | 176篇 |
1984年 | 139篇 |
1983年 | 134篇 |
1982年 | 117篇 |
1981年 | 106篇 |
1979年 | 89篇 |
1978年 | 98篇 |
1977年 | 72篇 |
1976年 | 74篇 |
1975年 | 76篇 |
1973年 | 83篇 |
排序方式: 共有10000条查询结果,搜索用时 265 毫秒
941.
Nan Zhang Jiyun Yang Anfei Fang Jiyang Wang Dayong Li Yuejiao Li Shanzhi Wang Fuhao Cui Junjie Yu Yongfeng Liu You-Liang Peng Wenxian Sun 《Molecular Plant Pathology》2020,21(4):445-459
The biotrophic fungal pathogen Ustilaginoidea virens causes rice false smut, a newly emerging plant disease that has become epidemic worldwide in recent years. The U. virens genome encodes many putative effector proteins that, based on the study of other pathosystems, could play an essential role in fungal virulence. However, few studies have been reported on virulence functions of individual U. virens effectors. Here, we report our identification and characterization of the secreted cysteine-rich protein SCRE1, which is an essential virulence effector in U. virens. When SCRE1 was heterologously expressed in Magnaporthe oryzae, the protein was secreted and translocated into plant cells during infection. SCRE1 suppresses the immunity-associated hypersensitive response in the nonhost plant Nicotiana benthamiana. Induced expression of SCRE1 in rice also inhibits pattern-triggered immunity and enhances disease susceptibility to rice bacterial and fungal pathogens. The immunosuppressive activity is localized to a small peptide region that contains an important ‘cysteine-proline-alanine-arginine-serine’ motif. Furthermore, the scre1 knockout mutant generated using the CRISPR/Cas9 system is attenuated in U. virens virulence to rice, which is greatly complemented by the full-length SCRE1 gene. Collectively, this study indicates that the effector SCRE1 is able to inhibit host immunity and is required for full virulence of U. virens. 相似文献
942.
Yingfan Cai Xiaoyan Cai Qinglian Wang Ping Wang Yu Zhang Chaowei Cai Yanchao Xu Kunbo Wang Zhongli Zhou Chenxiao Wang Shuaipeng Geng Bo Li Qi Dong Yuqing Hou Heng Wang Peng Ai Zhen Liu Feifei Yi Minshan Sun Guoyong An Jieru Cheng Yuanyuan Zhang Qian Shi Yuanhui Xie Xinying Shi Ying Chang Feifei Huang Yun Chen Shimiao Hong Lingyu Mi Quan Sun Lin Zhang Baoliang Zhou Renhai Peng Xiao Zhang Fang Liu 《Plant biotechnology journal》2020,18(3):814-828
943.
944.
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
945.
946.
947.
James V. McCann Steven R. Bischoff Yu Zhang Dale O. Cowley Veronica Sanchez‐Gonzalez George D. Daaboul Andrew C. Dudley 《Genesis (New York, N.Y. : 2000)》2020,58(7)
Extracellular vesicles (EVs) are abundant, lipid‐enclosed vectors that contain nucleic acids and proteins, they can be secreted from donor cells and freely circulate, and they can be engulfed by recipient cells thus enabling systemic communication between heterotypic cell types. However, genetic tools for labeling, isolating, and auditing cell type‐specific EVs in vivo, without prior in vitro manipulation, are lacking. We have used CRISPR‐Cas9‐mediated genome editing to generate mice bearing a CD63‐emGFPloxP/stop/loxP knock‐in cassette that enables the specific labeling of circulating CD63+ vesicles from any cell type when crossed with lineage‐specific Cre recombinase driver mice. As proof‐of‐principle, we have crossed these mice with Cdh5‐CreERT2 mice to generate CD63emGFP+ vasculature. Using these mice, we show that developing vasculature is marked with emerald GFP (emGFP) following tamoxifen administration to pregnant females. In adult mice, quiescent vasculature and angiogenic vasculature (in tumors) is also marked with emGFP. Moreover, whole plasma‐purified EVs contain a subpopulation of emGFP+ vesicles that are derived from the endothelium, co‐express additional EV (e.g., CD9 and CD81) and endothelial cell (e.g., CD105) markers, and they harbor specific miRNAs (e.g., miR‐126, miR‐30c, and miR‐125b). This new mouse strain should be a useful genetic tool for generating cell type‐specific, CD63+ EVs that freely circulate in serum and can subsequently be isolated and characterized using standard methodologies. 相似文献
948.
949.
Jason D. Roh Nicholas Houstis Andy Yu Bliss Chang Ashish Yeri Haobo Li Ryan Hobson Carolin Lerchenmüller Ana Vujic Vinita Chaudhari Federico Damilano Colin Platt Daniel Zlotoff Richard T. Lee Ravi Shah Michael Jerosch‐Herold Anthony Rosenzweig 《Aging cell》2020,19(6)
Heart failure with preserved ejection fraction (HFpEF) is the most common type of HF in older adults. Although no pharmacological therapy has yet improved survival in HFpEF, exercise training (ExT) has emerged as the most effective intervention to improving functional outcomes in this age‐related disease. The molecular mechanisms by which ExT induces its beneficial effects in HFpEF, however, remain largely unknown. Given the strong association between aging and HFpEF, we hypothesized that ExT might reverse cardiac aging phenotypes that contribute to HFpEF pathophysiology and additionally provide a platform for novel mechanistic and therapeutic discovery. Here, we show that aged (24–30 months) C57BL/6 male mice recapitulate many of the hallmark features of HFpEF, including preserved left ventricular ejection fraction, subclinical systolic dysfunction, diastolic dysfunction, impaired cardiac reserves, exercise intolerance, and pathologic cardiac hypertrophy. Similar to older humans, ExT in old mice improved exercise capacity, diastolic function, and contractile reserves, while reducing pulmonary congestion. Interestingly, RNAseq of explanted hearts showed that ExT did not significantly modulate biological pathways targeted by conventional HF medications. However, it reversed multiple age‐related pathways, including the global downregulation of cell cycle pathways seen in aged hearts, which was associated with increased capillary density, but no effects on cardiac mass or fibrosis. Taken together, these data demonstrate that the aged C57BL/6 male mouse is a valuable model for studying the role of aging biology in HFpEF pathophysiology, and provide a molecular framework for how ExT potentially reverses cardiac aging phenotypes in HFpEF. 相似文献
950.
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