全文获取类型
收费全文 | 323篇 |
免费 | 0篇 |
国内免费 | 1篇 |
专业分类
系统科学 | 4篇 |
教育与普及 | 1篇 |
现状及发展 | 46篇 |
研究方法 | 102篇 |
综合类 | 164篇 |
自然研究 | 7篇 |
出版年
2021年 | 4篇 |
2020年 | 1篇 |
2018年 | 7篇 |
2017年 | 6篇 |
2016年 | 3篇 |
2015年 | 2篇 |
2013年 | 5篇 |
2012年 | 41篇 |
2011年 | 49篇 |
2010年 | 14篇 |
2009年 | 2篇 |
2008年 | 23篇 |
2007年 | 31篇 |
2006年 | 34篇 |
2005年 | 30篇 |
2004年 | 23篇 |
2003年 | 19篇 |
2002年 | 23篇 |
1976年 | 1篇 |
1972年 | 2篇 |
1971年 | 1篇 |
1968年 | 1篇 |
1957年 | 1篇 |
1955年 | 1篇 |
排序方式: 共有324条查询结果,搜索用时 23 毫秒
81.
Reich PB Hobbie SE Lee T Ellsworth DS West JB Tilman D Knops JM Naeem S Trost J 《Nature》2006,440(7086):922-925
Enhanced plant biomass accumulation in response to elevated atmospheric CO2 concentration could dampen the future rate of increase in CO2 levels and associated climate warming. However, it is unknown whether CO2-induced stimulation of plant growth and biomass accumulation will be sustained or whether limited nitrogen (N) availability constrains greater plant growth in a CO2-enriched world. Here we show, after a six-year field study of perennial grassland species grown under ambient and elevated levels of CO2 and N, that low availability of N progressively suppresses the positive response of plant biomass to elevated CO2. Initially, the stimulation of total plant biomass by elevated CO2 was no greater at enriched than at ambient N supply. After four to six years, however, elevated CO2 stimulated plant biomass much less under ambient than enriched N supply. This response was consistent with the temporally divergent effects of elevated CO2 on soil and plant N dynamics at differing levels of N supply. Our results indicate that variability in availability of soil N and deposition of atmospheric N are both likely to influence the response of plant biomass accumulation to elevated atmospheric CO2. Given that limitations to productivity resulting from the insufficient availability of N are widespread in both unmanaged and managed vegetation, soil N supply is probably an important constraint on global terrestrial responses to elevated CO2. 相似文献
82.
83.
Rentel MC Lecourieux D Ouaked F Usher SL Petersen L Okamoto H Knight H Peck SC Grierson CS Hirt H Knight MR 《Nature》2004,427(6977):858-861
Active oxygen species (AOS) generated in response to stimuli and during development can function as signalling molecules in eukaryotes, leading to specific downstream responses. In plants these include such diverse processes as coping with stress (for example pathogen attack, wounding and oxygen deprivation), abscisic-acid-induced guard-cell closure, and cellular development (for example root hair growth). Despite the importance of signalling via AOS in eukaryotes, little is known about the protein components operating downstream of AOS that mediate any of these processes. Here we show that expression of an Arabidopsis thaliana gene (OXI1) encoding a serine/threonine kinase is induced in response to a wide range of H2O2-generating stimuli. OXI1 kinase activity is itself also induced by H2O2 in vivo. OXI1 is required for full activation of the mitogen-activated protein kinases (MAPKs) MPK3 and MPK6 after treatment with AOS or elicitor and is necessary for at least two very different AOS-mediated processes: basal resistance to Peronospora parasitica infection, and root hair growth. Thus, OXI1 is an essential part of the signal transduction pathway linking oxidative burst signals to diverse downstream responses. 相似文献
85.
Reboul J Vaglio P Rual JF Lamesch P Martinez M Armstrong CM Li S Jacotot L Bertin N Janky R Moore T Hudson JR Hartley JL Brasch MA Vandenhaute J Boulton S Endress GA Jenna S Chevet E Papasotiropoulos V Tolias PP Ptacek J Snyder M Huang R Chance MR Lee H Doucette-Stamm L Hill DE Vidal M 《Nature genetics》2003,34(1):35-41
To verify the genome annotation and to create a resource to functionally characterize the proteome, we attempted to Gateway-clone all predicted protein-encoding open reading frames (ORFs), or the 'ORFeome,' of Caenorhabditis elegans. We successfully cloned approximately 12,000 ORFs (ORFeome 1.1), of which roughly 4,000 correspond to genes that are untouched by any cDNA or expressed-sequence tag (EST). More than 50% of predicted genes needed corrections in their intron-exon structures. Notably, approximately 11,000 C. elegans proteins can now be expressed under many conditions and characterized using various high-throughput strategies, including large-scale interactome mapping. We suggest that similar ORFeome projects will be valuable for other organisms, including humans. 相似文献
86.
Pinyopich A Ditta GS Savidge B Liljegren SJ Baumann E Wisman E Yanofsky MF 《Nature》2003,424(6944):85-88
Carpels are essential for sexual plant reproduction because they house the ovules and subsequently develop into fruits that protect, nourish and ultimately disperse the seeds. The AGAMOUS (AG) gene is necessary for plant sexual reproduction because stamens and carpels are absent from ag mutant flowers. However, the fact that sepals are converted into carpelloid organs in certain mutant backgrounds even in the absence of AG activity indicates that an AG-independent carpel-development pathway exists. AG is a member of a monophyletic clade of MADS-box genes that includes SHATTERPROOF1 (SHP1), SHP2 and SEEDSTICK (STK), indicating that these four genes might share partly redundant activities. Here we show that the SHP genes are responsible for AG-independent carpel development. We also show that the STK gene is required for normal development of the funiculus, an umbilical-cord-like structure that connects the developing seed to the fruit, and for dispersal of the seeds when the fruit matures. We further show that all four members of the AG clade are required for specifying the identity of ovules, the landmark invention during the course of vascular plant evolution that enabled seed plants to become the most successful group of land plants. 相似文献
87.
Albert Lee Stephanie L. Rayner Serene S. L. Gwee Alana De Luca Hamideh Shahheydari Vinod Sundaramoorthy Audrey Ragagnin Marco Morsch Rowan Radford Jasmin Galper Sarah Freckleton Bingyang Shi Adam K. Walker Emily K. Don Nicholas J. Cole Shu Yang Kelly L. Williams Justin J. Yerbury Ian P. Blair Julie D. Atkin Mark P. Molloy Roger S. Chung 《Cellular and molecular life sciences : CMLS》2018,75(2):335-354
Amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) are fatal neurodegenerative disorders that have common molecular and pathogenic characteristics, such as aberrant accumulation and ubiquitylation of TDP-43; however, the mechanisms that drive this process remain poorly understood. We have recently identified CCNF mutations in familial and sporadic ALS and FTD patients. CCNF encodes cyclin F, a component of an E3 ubiquitin–protein ligase (SCFcyclin F) complex that is responsible for ubiquitylating proteins for degradation by the ubiquitin–proteasome system. In this study, we examined the ALS/FTD-causing p.Ser621Gly (p.S621G) mutation in cyclin F and its effect upon downstream Lys48-specific ubiquitylation in transfected Neuro-2A and SH-SY5Y cells. Expression of mutant cyclin FS621G caused increased Lys48-specific ubiquitylation of proteins in neuronal cells compared to cyclin FWT. Proteomic analysis of immunoprecipitated Lys48-ubiquitylated proteins from mutant cyclin FS621G-expressing cells identified proteins that clustered within the autophagy pathway, including sequestosome-1 (p62/SQSTM1), heat shock proteins, and chaperonin complex components. Examination of autophagy markers p62, LC3, and lysosome-associated membrane protein 2 (Lamp2) in cells expressing mutant cyclin FS621G revealed defects in the autophagy pathway specifically resulting in impairment in autophagosomal–lysosome fusion. This finding highlights a potential mechanism by which cyclin F interacts with p62, the receptor responsible for transporting ubiquitylated substrates for autophagic degradation. These findings demonstrate that ALS/FTD-causing mutant cyclin FS621G disrupts Lys48-specific ubiquitylation, leading to accumulation of substrates and defects in the autophagic machinery. This study also demonstrates that a single missense mutation in cyclin F causes hyper-ubiquitylation of proteins that can indirectly impair the autophagy degradation pathway, which is implicated in ALS pathogenesis. 相似文献
88.
Iman Azimi Alice H. Bong Greta X. H. Poo Kaela Armitage Dawn Lok Sarah J. Roberts-Thomson Gregory R. Monteith 《Cellular and molecular life sciences : CMLS》2018,75(24):4525-4537
Store-operated Ca2+ entry is a pathway that is remodelled in a variety of cancers, and altered expression of the components of store-operated Ca2+ entry is a feature of breast cancer cells of the basal molecular subtype. Studies of store-operated Ca2+ entry in breast cancer cells have used non-specific pharmacological inhibitors, complete depletion of intracellular Ca2+ stores and have mostly focused on MDA-MB-231 cells (a basal B breast cancer cell line). These studies compared the effects of the selective store-operated Ca2+ entry inhibitors Synta66 and YM58483 (also known as BTP2) on global cytosolic free Ca2+ ([Ca2+]CYT) changes induced by physiological stimuli in a different breast cancer basal cell line model, MDA-MB-468. The effects of these agents on proliferation as well as serum and epidermal growth factor (EGF) induced migration were also assessed. Activation with the purinergic receptor activator adenosine triphosphate, produced a sustained increase in [Ca2+]CYT that was entirely dependent on store-operated Ca2+ entry. The protease activated receptor 2 activator, trypsin, and EGF also produced Ca2+ influx that was sensitive to both Synta66 and YM58483. Serum-activated migration of MDA-MB-468 breast cancer cells was sensitive to both store-operated Ca2+ inhibitors. However, proliferation and EGF-activated migration was differentially affected by Synta66 and YM58483. These studies highlight the need to define the exact mechanisms of action of different store-operated calcium entry inhibitors and the impact of such differences in the control of tumour progression pathways. 相似文献
89.
Sarah Hayton Garth L. Maker Ian Mullaney Robert D. Trengove 《Cellular and molecular life sciences : CMLS》2017,74(24):4421-4441
Metabolomics is an analytical technique that investigates the small biochemical molecules present within a biological sample isolated from a plant, animal, or cultured cells. It can be an extremely powerful tool in elucidating the specific metabolic changes within a biological system in response to an environmental challenge such as disease, infection, drugs, or toxins. A historically difficult step in the metabolomics pipeline is in data interpretation to a meaningful biological context, for such high-variability biological samples and in untargeted metabolomics studies that are hypothesis-generating by design. One way to achieve stronger biological context of metabolomic data is via the use of cultured cell models, particularly for mammalian biological systems. The benefits of in vitro metabolomics include a much greater control of external variables and no ethical concerns. The current concerns are with inconsistencies in experimental procedures and level of reporting standards between different studies. This review discusses some of these discrepancies between recent studies, such as metabolite extraction and data normalisation. The aim of this review is to highlight the importance of a standardised experimental approach to any cultured cell metabolomics study and suggests an example procedure fully inclusive of information that should be disclosed in regard to the cell type/s used and their culture conditions. Metabolomics of cultured cells has the potential to uncover previously unknown information about cell biology, functions and response mechanisms, and so the accurate biological interpretation of the data produced and its ability to be compared to other studies should be considered vitally important. 相似文献
90.
Correction to: The role of connexin proteins and their channels in radiation-induced atherosclerosis
Ramadan Raghda Baatout Sarah Aerts An Leybaert Luc 《Cellular and molecular life sciences : CMLS》2021,78(10):4847-4847
Cellular and Molecular Life Sciences - A correction to this paper has been published: https://doi.org/10.1007/s00018-021-03811-z 相似文献