全文获取类型
收费全文 | 5549篇 |
免费 | 597篇 |
出版年
2021年 | 82篇 |
2020年 | 39篇 |
2019年 | 59篇 |
2018年 | 65篇 |
2017年 | 76篇 |
2016年 | 99篇 |
2015年 | 175篇 |
2014年 | 207篇 |
2013年 | 240篇 |
2012年 | 303篇 |
2011年 | 272篇 |
2010年 | 199篇 |
2009年 | 201篇 |
2008年 | 287篇 |
2007年 | 293篇 |
2006年 | 248篇 |
2005年 | 253篇 |
2004年 | 217篇 |
2003年 | 206篇 |
2002年 | 179篇 |
2001年 | 138篇 |
2000年 | 116篇 |
1999年 | 94篇 |
1998年 | 78篇 |
1997年 | 63篇 |
1996年 | 59篇 |
1995年 | 56篇 |
1994年 | 35篇 |
1993年 | 64篇 |
1992年 | 99篇 |
1991年 | 96篇 |
1990年 | 100篇 |
1989年 | 73篇 |
1988年 | 80篇 |
1987年 | 80篇 |
1986年 | 67篇 |
1985年 | 76篇 |
1984年 | 65篇 |
1983年 | 43篇 |
1982年 | 46篇 |
1981年 | 51篇 |
1979年 | 59篇 |
1978年 | 69篇 |
1977年 | 39篇 |
1976年 | 40篇 |
1975年 | 35篇 |
1974年 | 40篇 |
1973年 | 34篇 |
1972年 | 48篇 |
1971年 | 47篇 |
排序方式: 共有6146条查询结果,搜索用时 15 毫秒
991.
Lynn B. Jorde Michael Bamshad Alan R. Rogers 《BioEssays : news and reviews in molecular, cellular and developmental biology》1998,20(2):126-136
Molecular genetic data have greatly improved our ability to test hypotheses about human evolution. During the past decade, a large amount of nuclear and mitochondrial data have been collected from diverse human populations. Taken together, these data indicate that modern humans are a relatively young species. African populations show the largest amount of genetic diversity, and they are the most genetically divergent population. Modern human populations expanded in size first on the African continent. These findings support a recent African origin of modern humans, but this conclusion should be tempered by the possible effects of factors such as gene flow, population size differences, and natural selection. BioEssays 20:126–136, 1998. © 1998 John Wiley & Sons, Inc. 相似文献
992.
Alisha G. Lewis Robert Caldwell Jason V. Rogers Maria Ingaramo Rebecca Y. Wang Ilya Soifer David G. Hendrickson R. Scott McIsaac David Botstein Patrick A. Gibney 《Molecular biology of the cell》2021,32(22)
The electron transport chain (ETC) is a well-studied and highly conserved metabolic pathway that produces ATP through generation of a proton gradient across the inner mitochondrial membrane coupled to oxidative phosphorylation. ETC mutations are associated with a wide array of human disease conditions and to aging-related phenotypes in a number of different organisms. In this study, we sought to better understand the role of the ETC in aging using a yeast model. A panel of ETC mutant strains that fail to survive starvation was used to isolate suppressor mutants that survive. These suppressors tend to fall into major nutrient sensing and signaling pathways, suggesting that the ETC is involved in proper starvation signaling to these pathways in yeast. These suppressors also partially restore ETC-associated gene expression and pH homeostasis defects, though it remains unclear whether these phenotypes directly cause the suppression or are simply effects. This work further highlights the complex cellular network connections between metabolic pathways and signaling events in the cell and their potential roles in aging and age-related diseases. 相似文献
993.
Nicolas Rabas Sarah Palmer Louise Mitchell Shehab Ismail Andrea Gohlke Joel S. Riley Stephen W.G. Tait Payam Gammage Leandro Lemgruber Soares Iain R. Macpherson Jim C. Norman 《The Journal of cell biology》2021,220(12)
The cystine-glutamate antiporter, xCT, supports a glutathione synthesis program enabling cancer cells to cope with metabolically stressful microenvironments. Up-regulated xCT, in combination with glutaminolysis, leads to increased extracellular glutamate, which promotes invasive behavior by activating metabotropic glutamate receptor 3 (mGluR3). Here we show that activation of mGluR3 in breast cancer cells activates Rab27-dependent release of extracellular vesicles (EVs), which can transfer invasive characteristics to “recipient” tumor cells. These EVs contain mitochondrial DNA (mtDNA), which is packaged via a PINK1-dependent mechanism. We highlight mtDNA as a key EV cargo necessary and sufficient for intercellular transfer of invasive behavior by activating Toll-like receptor 9 in recipient cells, and this involves increased endosomal trafficking of pro-invasive receptors. We propose that an EV-mediated mechanism, through which altered cellular metabolism in one cell influences endosomal trafficking in other cells, is key to generation and dissemination of pro-invasive microenvironments during mammary carcinoma progression. 相似文献
994.
Christine A. Byrd John T. Jones Joseph M. Quattro Matthew E. Rogers Peter C. Brunjes Richard G. Vogt 《Developmental neurobiology》1996,29(4):445-458
We cloned three putative odorant receptor (OR) genes from the zebrafish to use as in situ hybridization probes to follow the temporal patterns of neurons expressing OR genes through a developmental progression from embryo (12 h postfertilization) to adult. The identification of these genes is supported by sequence homology to previously reported ORs and by the morphology and location of labeled cells in in situ hybridization experiments. Cells expressing OR mRNA were first observed in the olfactory placodes between 31 and 38 h after fertilization (fish reared at 26°C). Initially, only single cells were observed to hybridize the probe; the number of labeled cells increased throughout the remainder of embryogenesis and through postembryonic growth and morphogenesis of the olfactory organ. At all ages, the positively hybridizing cells were scattered throughout the olfactory epithelium but not in the nonsensory epithelium of the olfactory organ. © 1996 John Wiley & Sons, Inc. 相似文献
995.
996.
Transposable elements (TEs) contribute to stress‐related long intergenic noncoding RNAs in plants
下载免费PDF全文
![点击此处可从《The Plant journal : for cell and molecular biology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
997.
Iain J. Davidson-Hunt C. Julían Idrobo Katherine L. Turner 《Human ecology: an interdisciplinary journal》2017,45(5):601-612
We introduce everyday creativity as an approach to understanding the role of agency in resilience thinking and as a conceptual lens through which to view the ways that people respond to globalized change. Our focus is on the use of biodiversity in crafting responses within food systems of rural and remote communities. We propose a conceptual framework to understand the flow of biological materials across five phases of a food system and how benefits map to actors. This allows us to locate disruptions that arise from globalized change and the factors that enable and constrain responses. We then present an application of the conceptual framework using a case study from the Atlantic Forest Coast of Brazil, that demonstrates that in a world characterized by globalized change our understanding of resilient food systems requires more analysis of the factors that limit everyday creativity at different phases of the food system. 相似文献
998.
Rogers Brubaker 《Ethnic and racial studies》2017,40(8):1330-1336
999.
Nichollas E Scott Lindsay D Rogers Anna Prudova Nat F Brown Nikolaus Fortelny Christopher M Overall Leonard J Foster 《Molecular systems biology》2017,13(1)
Protein–protein interaction networks (interactomes) define the functionality of all biological systems. In apoptosis, proteolysis by caspases is thought to initiate disassembly of protein complexes and cell death. Here we used a quantitative proteomics approach, protein correlation profiling (PCP), to explore changes in cytoplasmic and mitochondrial interactomes in response to apoptosis initiation as a function of caspase activity. We measured the response to initiation of Fas‐mediated apoptosis in 17,991 interactions among 2,779 proteins, comprising the largest dynamic interactome to date. The majority of interactions were unaffected early in apoptosis, but multiple complexes containing known caspase targets were disassembled. Nonetheless, proteome‐wide analysis of proteolytic processing by terminal amine isotopic labeling of substrates (TAILS) revealed little correlation between proteolytic and interactome changes. Our findings show that, in apoptosis, significant interactome alterations occur before and independently of caspase activity. Thus, apoptosis initiation includes a tight program of interactome rearrangement, leading to disassembly of relatively few, select complexes. These early interactome alterations occur independently of cleavage of these protein by caspases. 相似文献
1000.
Radiation capture and conversion efficiencies of Miscanthus sacchariflorus,M. sinensis and their naturally occurring hybrid M. × giganteus
下载免费PDF全文
![点击此处可从《Global Change Biology Bioenergy》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Christopher Lyndon Davey Laurence Edmund Jones Michael Squance Sarah Jane Purdy Anne Louise Maddison Jennifer Cunniff Iain Donnison John Clifton‐Brown 《Global Change Biology Bioenergy》2017,9(2):385-399
Miscanthus is a rhizomatous C4 grass of great interest as a biofuel crop because it has the potential to produce high yields over a wide geographical area with low agricultural inputs on marginal land less suitable for food production. At the moment, a clonal interspecific hybrid Miscanthus × giganteus is the most widely cultivated and studied in Europe and the United States, but breeding programmes are developing newer more productive varieties. Here, we quantified the physiological processes relating to whole season yield in a replicated plot trial in Wales, UK. Light capture and conversion efficiency were parameterized for four carefully selected genotypes (M. sinensis, M. sacchariflorus and Miscanthus × giganteus). Differences in the canopy architecture in mature stands as measured by the extinction coefficient (k) were small (0.55–0.65). Sensitivity analysis on a mathematical model of Miscanthus was performed to quantify the accumulative intercepted photosynthetically active radiation (iPAR) in the growing season using (i) k, (ii) variation in the thermal responses of leaf expansion rate, (iii) base temperature for degree days and (iv) date start of canopy expansion. A 10% increase in k or leaf area per degree day both had a minimal effect on iPAR (3%). Decreasing base temperature from 10 to 9 °C gave an 8% increase in iPAR. If the starting date for canopy expansion was the same as shoot emergence date, then the iPAR increases by 12.5%. In M. × giganteus, the whole season above ground and total (including below ground) radiation‐use efficiency (RUE) ranged from 45% to 37% higher than the noninterspecific hybrid genotypes. The greater yields in the interspecific hybrid M. × giganteus are explained by the higher RUE and not by differences in iPAR or partitioning effects. Studying the mechanisms underlying this complex trait could have wide benefits for both fuel and food production. 相似文献