全文获取类型
收费全文 | 7598篇 |
免费 | 662篇 |
国内免费 | 3篇 |
专业分类
8263篇 |
出版年
2024年 | 12篇 |
2023年 | 44篇 |
2022年 | 118篇 |
2021年 | 220篇 |
2020年 | 94篇 |
2019年 | 124篇 |
2018年 | 163篇 |
2017年 | 142篇 |
2016年 | 248篇 |
2015年 | 474篇 |
2014年 | 509篇 |
2013年 | 501篇 |
2012年 | 707篇 |
2011年 | 685篇 |
2010年 | 389篇 |
2009年 | 327篇 |
2008年 | 512篇 |
2007年 | 477篇 |
2006年 | 429篇 |
2005年 | 390篇 |
2004年 | 353篇 |
2003年 | 372篇 |
2002年 | 307篇 |
2001年 | 58篇 |
2000年 | 51篇 |
1999年 | 81篇 |
1998年 | 71篇 |
1997年 | 48篇 |
1996年 | 43篇 |
1995年 | 39篇 |
1994年 | 25篇 |
1993年 | 34篇 |
1992年 | 27篇 |
1991年 | 26篇 |
1990年 | 23篇 |
1989年 | 9篇 |
1988年 | 17篇 |
1987年 | 15篇 |
1986年 | 17篇 |
1985年 | 16篇 |
1984年 | 9篇 |
1983年 | 3篇 |
1982年 | 4篇 |
1981年 | 8篇 |
1980年 | 9篇 |
1979年 | 3篇 |
1978年 | 7篇 |
1977年 | 5篇 |
1976年 | 5篇 |
1974年 | 4篇 |
排序方式: 共有8263条查询结果,搜索用时 15 毫秒
101.
102.
The TEL-Syk fusion protein was isolated from a patient with myelodysplasia with megakaryocyte blasts. Expression of TEL-Syk transforms interleukin-3 (IL-3)-dependent Ba/F3 cells in vitro by deregulating STAT5-mediated signal transduction pathways. In vivo, TEL-Syk expression in pre-B cells blocks B cell differentiation, leading to lymphoid leukemia. Here, we demonstrate that TEL-Syk introduced into fetal liver hematopoietic cells, which are then adoptively transferred into lethally irradiated recipients, leads to an aggressive myelodysplasia with myelofibrosis that is lethal in mice by 60–75 days. Expression of TEL-Syk induces a short-lived myeloexpansion that is rapidly followed by bone marrow failure and extreme splenic/hepatic fibrosis accompanied by extensive apoptosis. The disease is dependent on Syk kinase activity. Analysis of serum from TEL-Syk mice reveals an inflammatory cytokine signature reminiscent of that found in the sera from patients and mouse models of myeloproliferative neoplasms. TEL-Syk expressing cells showed constitutive STAT5 phosphorylation, which was resistant to JAK inhibition, consistent with deregulated cytokine signaling. These data indicate that expression of TEL-Syk in fetal liver hematopoietic cells results in JAK-independent STAT5 phosphorylation ultimately leading to a uniquely aggressive and lethal form of myelofibrosis. 相似文献
103.
104.
105.
Aim: To determine whether assessing the penetration of solutions with different concentrations of ethanol (alcohol percentage test: APT) on fungal surfaces is effective in characterization of hydrophobicity on fungal surfaces. Methods and Results: APT and contact angle (CA) measurements were conducted on nine hydrophobic and two hydrophilic fungal strains from the phyla of Ascomycota, Basidiomycota and Zygomycota. There was a strong positive correlation (R2 = 0·95) between the APT and CA measurements from eight of the nine hydrophobic stains (four pathogenic and mycotoxigenic Fusarium taxa, one melanosporaceous biotrophic taxon, Alternaria sp, Penicillium aurantiogriseum and Cladosporium cladosporioides). Hydrophilic control strains, Mortierella hyalina and Laccaria laccata, had CAs <90° and no measurable degree of hydrophobicity using the APT method. Conclusions: The APT method was effective in measuring the degree of hydrophobicity and can be conducted on different zones of fungal growth. Significance and Impact of the Study: Characterization of fungal surface hydrophobicity is important for understanding of its particular role and function in fungal morphogenesis and pathogenesis. APT is a simple method that can be utilized for fungal hydrophobicity measurements when CA cannot be measured because of obscured view from aerial mycelia growth. 相似文献
106.
107.
108.
Amy E. Zanne Kessy Abarenkov Michelle E. Afkhami Carlos A. Aguilar‐Trigueros Scott Bates Jennifer M. Bhatnagar Posy E. Busby Natalie Christian William K. Cornwell Thomas W. Crowther Habacuc Flores‐Moreno Dimitrios Floudas Romina Gazis David Hibbett Peter Kennedy Daniel L. Lindner Daniel S. Maynard Amy M. Milo Rolf Henrik Nilsson Jeff Powell Mark Schildhauer Jonathan Schilling Kathleen K. Treseder 《Biological reviews of the Cambridge Philosophical Society》2020,95(2):409-433
Fungi play many essential roles in ecosystems. They facilitate plant access to nutrients and water, serve as decay agents that cycle carbon and nutrients through the soil, water and atmosphere, and are major regulators of macro‐organismal populations. Although technological advances are improving the detection and identification of fungi, there still exist key gaps in our ecological knowledge of this kingdom, especially related to function . Trait‐based approaches have been instrumental in strengthening our understanding of plant functional ecology and, as such, provide excellent models for deepening our understanding of fungal functional ecology in ways that complement insights gained from traditional and ‐omics‐based techniques. In this review, we synthesize current knowledge of fungal functional ecology, taxonomy and systematics and introduce a novel database of fungal functional traits (FunFun). FunFun is built to interface with other databases to explore and predict how fungal functional diversity varies by taxonomy, guild, and other evolutionary or ecological grouping variables. To highlight how a quantitative trait‐based approach can provide new insights, we describe multiple targeted examples and end by suggesting next steps in the rapidly growing field of fungal functional ecology. 相似文献
109.
Fatemeh Adelnia Ceereena Ubaida‐Mohien Ruin Moaddel Michelle Shardell Alexey Lyashkov Kenneth W. Fishbein Miguel A. Aon Richard G. Spencer Luigi Ferrucci 《Aging cell》2020,19(4)
Adequate support of energy for biological activities and during fluctuation of energetic demand is crucial for healthy aging; however, mechanisms for energy decline as well as compensatory mechanisms that counteract such decline remain unclear. We conducted a discovery proteomic study of skeletal muscle in 57 healthy adults (22 women and 35 men; aged 23–87 years) to identify proteins overrepresented and underrepresented with better muscle oxidative capacity, a robust measure of in vivo mitochondrial function, independent of age, sex, and physical activity. Muscle oxidative capacity was assessed by 31P magnetic resonance spectroscopy postexercise phosphocreatine (PCr) recovery time (τPCr) in the vastus lateralis muscle, with smaller τPCr values reflecting better oxidative capacity. Of the 4,300 proteins quantified by LC‐MS in muscle biopsies, 253 were significantly overrepresented with better muscle oxidative capacity. Enrichment analysis revealed three major protein clusters: (a) proteins involved in key energetic mitochondrial functions especially complex I of the electron transport chain, tricarboxylic acid (TCA) cycle, fatty acid oxidation, and mitochondrial ABC transporters; (b) spliceosome proteins that regulate mRNA alternative splicing machinery, and (c) proteins involved in translation within mitochondria. Our findings suggest that alternative splicing and mechanisms that modulate mitochondrial protein synthesis are central features of the molecular mechanisms aimed at maintaining mitochondrial function in the face of impairment. Whether these mechanisms are compensatory attempt to counteract the effect of aging on mitochondrial function should be further tested in longitudinal studies. 相似文献
110.
Rene M. van der Zande Michelle Achlatis Dorothea Bender‐Champ Andreas Kubicek Sophie Dove Ove Hoegh‐Guldberg 《Global Change Biology》2020,26(4):2203-2219
Despite recent efforts to curtail greenhouse gas emissions, current global emission trajectories are still following the business‐as‐usual representative concentration pathway (RCP) 8.5 emission pathway. The resulting ocean warming and acidification have transformative impacts on coral reef ecosystems, detrimentally affecting coral physiology and health, and these impacts are predicted to worsen in the near future. In this study, we kept fragments of the symbiotic corals Acropora intermedia (thermally sensitive) and Porites lobata (thermally tolerant) for 7 weeks under an orthogonal design of predicted end‐of‐century RCP8.5 conditions for temperature and pCO2 (3.5°C and 570 ppm above present‐day, respectively) to unravel how temperature and acidification, individually or interactively, influence metabolic and physiological performance. Our results pinpoint thermal stress as the dominant driver of deteriorating health in both species because of its propensity to destabilize coral–dinoflagellate symbiosis (bleaching). Acidification had no influence on metabolism but had a significant negative effect on skeleton growth, particularly when photosynthesis was absent such as in bleached corals or under dark conditions. Total loss of photosynthesis after bleaching caused an exhaustion of protein and lipid stores and collapse of calcification that ultimately led to A. intermedia mortality. Despite complete loss of symbionts from its tissue, P. lobata maintained small amounts of photosynthesis and experienced a weaker decline in lipid and protein reserves that presumably contributed to higher survival of this species. Our results indicate that ocean warming and acidification under business‐as‐usual CO2 emission scenarios will likely extirpate thermally sensitive coral species before the end of the century, while slowing the recovery of more thermally tolerant species from increasingly severe mass coral bleaching and mortality. This could ultimately lead to the gradual disappearance of tropical coral reefs globally, and a shift on surviving reefs to only the most resilient coral species. 相似文献