全文获取类型
收费全文 | 5128篇 |
免费 | 336篇 |
国内免费 | 373篇 |
专业分类
5837篇 |
出版年
2024年 | 6篇 |
2023年 | 75篇 |
2022年 | 177篇 |
2021年 | 270篇 |
2020年 | 180篇 |
2019年 | 206篇 |
2018年 | 205篇 |
2017年 | 156篇 |
2016年 | 229篇 |
2015年 | 301篇 |
2014年 | 380篇 |
2013年 | 405篇 |
2012年 | 467篇 |
2011年 | 375篇 |
2010年 | 244篇 |
2009年 | 226篇 |
2008年 | 252篇 |
2007年 | 190篇 |
2006年 | 178篇 |
2005年 | 165篇 |
2004年 | 165篇 |
2003年 | 148篇 |
2002年 | 108篇 |
2001年 | 123篇 |
2000年 | 87篇 |
1999年 | 100篇 |
1998年 | 49篇 |
1997年 | 34篇 |
1996年 | 37篇 |
1995年 | 41篇 |
1994年 | 31篇 |
1993年 | 22篇 |
1992年 | 29篇 |
1991年 | 24篇 |
1990年 | 31篇 |
1989年 | 8篇 |
1988年 | 17篇 |
1987年 | 12篇 |
1986年 | 9篇 |
1985年 | 8篇 |
1984年 | 10篇 |
1983年 | 8篇 |
1982年 | 7篇 |
1981年 | 5篇 |
1980年 | 6篇 |
1979年 | 3篇 |
1978年 | 3篇 |
1977年 | 3篇 |
1975年 | 6篇 |
1974年 | 3篇 |
排序方式: 共有5837条查询结果,搜索用时 0 毫秒
71.
Haiping Zhang Bailian Cai Anke Geng Huanyin Tang Wenjun Zhang Sheng Li Ying Jiang Rong Tan Xiaoping Wan Zhiyong Mao 《Aging cell》2020,19(2)
The decline in DNA repair capacity contributes to the age‐associated decrease in genome integrity in somatic cells of different species. However, due to the lack of clinical samples and appropriate tools for studying DNA repair, whether and how age‐associated changes in DNA repair result in a loss of genome integrity of human adult stem cells remains incompletely characterized. Here, we isolated 20 eyelid adipose‐derived stem cell (ADSC) lines from healthy individuals (young: 10 donors with ages ranging 17–25 years; old: 10 donors with ages ranging 50–59 years). Using these cell lines, we systematically compared the efficiency of base excision repair (BER) and two DNA double‐strand break (DSB) repair pathways—nonhomologous end joining (NHEJ) and homologous recombination (HR)—between the young and old groups. Surprisingly, we found that the efficiency of BER but not NHEJ or HR is impaired in aged human ADSCs, which is in contrast to previous findings that DSB repair declines with age in human fibroblasts. We also demonstrated that BER efficiency is negatively associated with tail moment, which reflects a loss of genome integrity in human ADSCs. Mechanistic studies indicated that at the protein level XRCC1, but not other BER factors, exhibited age‐associated decline. Overexpression of XRCC1 reversed the decline of BER efficiency and genome integrity, indicating that XRCC1 is a potential therapeutic target for stabilizing genomes in aged ADSCs. 相似文献
72.
Dingqian Wu Xiaoxiao Fu Yuanyuan Zhang Qiang Li Ligang Ye Shu Han Mao Zhang 《Experimental biology and medicine (Maywood, N.J.)》2020,245(18):1683
C16 peptide and angiopoietin-1 (Ang-1) have been found to have anti-inflammatory activity in various inflammation-related diseases. However, their combined role in acute respiratory distress syndrome (ARDS) has not been investigated yet. The objective of this study was to investigate the effects of C16 peptide and Ang-1 in combination with lipopolysaccharide (LPS)-induced inflammatory insult in vitro and in vivo. Human pulmonary microvascular endothelial cells and human pulmonary alveolar epithelial cells were used as cell culture systems, and an ARDS rodent model was used for in vivo studies. Our results demonstrated that C16 and Ang-1 in combination significantly suppressed inflammatory cell transmigration by 33% in comparison with the vehicle alone, and decreased the lung tissue wet-to-dry lung weight ratio to a maximum of 1.53, compared to 3.55 in the vehicle group in ARDS rats. Moreover, C + A treatment reduced the histology injury score to 60% of the vehicle control, enhanced arterial oxygen saturation (SO2), decreased arterial carbon dioxide partial pressure (PCO2), and increased oxygen partial pressure (PO2) in ARDS rats, while also improving the survival rate from 47% (7/15) to 80% (12/15) and diminishing fibrosis, necrosis, and apoptosis in lung tissue. Furthermore, when C + A therapy was administered 4 h following LPS injection, the treatment showed significant alleviating effects on pulmonary inflammatory cell infiltration 24 h postinsult. In conclusion, our in vitro and in vivo studies show that C16 and Ang-1 exert protective effects against LPS-induced inflammatory insult. C16 and Ang-1 hold promise as a novel agent against LPS-induced ARDS. Further studies are needed to determine the potential for C16 and Ang-1 in combination in treating inflammatory lung diseases. 相似文献
73.
Wetlands Ecology and Management - Little is known about the effect of woody plant expansion on decomposition of root mixtures in grass-dominant temperate wetlands. Here, we collected fine roots... 相似文献
74.
Jialiang Li Richard I. Milne Dafu Ru Jibin Miao Wenjing Tao Lei Zhang Jingjing Xu Jianquan Liu Kangshan Mao 《Molecular ecology》2020,29(7):1250-1266
Having a comprehensive understanding of population structure, genetic differentiation and demographic history is important for the conservation and management of threatened species. High‐throughput sequencing (HTS) provides exciting opportunities to address a wide range of factors for conservation genetics. Here, we generated HTS data and identified 266,884 high‐quality single nucleotide polymorphisms from 82 individuals of Cupressus chengiana, to assess population genomics across the species' full range, comprising the Daduhe River (DDH), Minjiang River (MJR) and Bailongjiang River (BLJ) catchments in western China. admixture , principal components analysis and phylogenetic analyses indicated that each region contains a distinct lineage, with high levels of differentiation between them (DDH, MJR and BLJ lineages). MJR was newly distinguished compared to previous surveys, and evidence including coalescent simulations supported a hybrid origin of MJR during the Quaternary. Each of these three lineages should be recognized as an evolutionarily significant unit (ESU), due to isolation, differing genetic adaptations and different demographic history. Currently, each ESU faces distinct threats, and will require different conservation strategies. Our work shows that population genomic approaches using HTS can reconstruct the complex evolutionary history of threatened species in mountainous regions, and hence inform conservation efforts, and contribute to the understanding of high biodiversity in mountains. 相似文献
75.
Plant and Soil - Graminoid-dominated wetlands have been subjected to widespread shrub encroachment, yet the effect of this shift in species composition on litter decomposition remains unclear,... 相似文献
76.
Chen Chong-Juan Liu Xue-Yan Wang Xian-Wei Hu Chao-Chen Xu Shi-Qi Mao Rong Bu Zhao-Jun Fang Yun-Ting Koba Keisuke 《Plant and Soil》2021,467(1-2):345-357
Plant and Soil - Plant carbon (C), nitrogen (N), phosphorus (P) levels and their stoichiometry and N uptake strategies are important aspects influencing vegetation composition and C dynamics in... 相似文献
77.
Shi Yu Mao Xudong Cai Mingcheng Hu Shenqiang Lai Xiulan Chen Shiyi Jia Xianbo Wang Jie Lai Songjia 《Molecular and cellular biochemistry》2021,476(1):425-433
Molecular and Cellular Biochemistry - Skeletal muscle satellite cells (SMSCs), also known as a multipotential stem cell population, play a crucial role during muscle growth and regeneration. In... 相似文献
78.
Wu Ying Jiang Lisha Zhang Lingling Liu Xia Yan Lina Luan Ting Rui Can Mao Zhiyuan Fan Chong Liu Yu Li Ping Zeng Xin 《Mycopathologia》2021,186(2):177-188
Mycopathologia - Vulvovaginal candidiasis (VVC) caused by Candida spp. affects 70–75% of women at least once during their lives. We aim to elucidate the potential mechanism of VVC and... 相似文献
79.
80.