全文获取类型
收费全文 | 2303篇 |
免费 | 212篇 |
国内免费 | 2篇 |
出版年
2023年 | 7篇 |
2022年 | 10篇 |
2021年 | 58篇 |
2020年 | 22篇 |
2019年 | 39篇 |
2018年 | 48篇 |
2017年 | 31篇 |
2016年 | 66篇 |
2015年 | 117篇 |
2014年 | 139篇 |
2013年 | 171篇 |
2012年 | 196篇 |
2011年 | 196篇 |
2010年 | 118篇 |
2009年 | 113篇 |
2008年 | 140篇 |
2007年 | 151篇 |
2006年 | 125篇 |
2005年 | 135篇 |
2004年 | 109篇 |
2003年 | 104篇 |
2002年 | 117篇 |
2001年 | 23篇 |
2000年 | 17篇 |
1999年 | 22篇 |
1998年 | 20篇 |
1997年 | 16篇 |
1996年 | 12篇 |
1995年 | 17篇 |
1994年 | 10篇 |
1993年 | 11篇 |
1992年 | 11篇 |
1991年 | 11篇 |
1990年 | 11篇 |
1989年 | 10篇 |
1988年 | 5篇 |
1987年 | 10篇 |
1986年 | 8篇 |
1985年 | 7篇 |
1984年 | 5篇 |
1982年 | 7篇 |
1980年 | 4篇 |
1979年 | 5篇 |
1978年 | 6篇 |
1977年 | 5篇 |
1975年 | 6篇 |
1974年 | 7篇 |
1973年 | 4篇 |
1972年 | 4篇 |
1970年 | 4篇 |
排序方式: 共有2517条查询结果,搜索用时 15 毫秒
941.
Natural variation in CBF gene sequence,gene expression and freezing tolerance in the Versailles core collection of Arabidopsis thaliana 总被引:1,自引:0,他引:1
942.
The auxin influx carrier LAX3 promotes lateral root emergence 总被引:1,自引:0,他引:1
Swarup K Benková E Swarup R Casimiro I Péret B Yang Y Parry G Nielsen E De Smet I Vanneste S Levesque MP Carrier D James N Calvo V Ljung K Kramer E Roberts R Graham N Marillonnet S Patel K Jones JD Taylor CG Schachtman DP May S Sandberg G Benfey P Friml J Kerr I Beeckman T Laplaze L Bennett MJ 《Nature cell biology》2008,10(8):946-954
Lateral roots originate deep within the parental root from a small number of founder cells at the periphery of vascular tissues and must emerge through intervening layers of tissues. We describe how the hormone auxin, which originates from the developing lateral root, acts as a local inductive signal which re-programmes adjacent cells. Auxin induces the expression of a previously uncharacterized auxin influx carrier LAX3 in cortical and epidermal cells directly overlaying new primordia. Increased LAX3 activity reinforces the auxin-dependent induction of a selection of cell-wall-remodelling enzymes, which are likely to promote cell separation in advance of developing lateral root primordia. 相似文献
943.
Xiaoyu Jiang Naoki Nariai Martin Steffen Simon Kasif Eric D Kolaczyk 《BMC bioinformatics》2008,9(1):350
Background
In the current climate of high-throughput computational biology, the inference of a protein's function from related measurements, such as protein-protein interaction relations, has become a canonical task. Most existing technologies pursue this task as a classification problem, on a term-by-term basis, for each term in a database, such as the Gene Ontology (GO) database, a popular rigorous vocabulary for biological functions. However, ontology structures are essentially hierarchies, with certain top to bottom annotation rules which protein function predictions should in principle follow. Currently, the most common approach to imposing these hierarchical constraints on network-based classifiers is through the use of transitive closure to predictions. 相似文献944.
Background
Liquid chromatography coupled to mass spectrometry (LC-MS) has become a prominent tool for the analysis of complex proteomics and metabolomics samples. In many applications multiple LC-MS measurements need to be compared, e. g. to improve reliability or to combine results from different samples in a statistical comparative analysis. As in all physical experiments, LC-MS data are affected by uncertainties, and variability of retention time is encountered in all data sets. It is therefore necessary to estimate and correct the underlying distortions of the retention time axis to search for corresponding compounds in different samples. To this end, a variety of so-called LC-MS map alignment algorithms have been developed during the last four years. Most of these approaches are well documented, but they are usually evaluated on very specific samples only. So far, no publication has been assessing different alignment algorithms using a standard LC-MS sample along with commonly used quality criteria. 相似文献945.
946.
947.
Boyko AR Williamson SH Indap AR Degenhardt JD Hernandez RD Lohmueller KE Adams MD Schmidt S Sninsky JJ Sunyaev SR White TJ Nielsen R Clark AG Bustamante CD 《PLoS genetics》2008,4(5):e1000083
Quantifying the distribution of fitness effects among newly arising mutations in the human genome is key to resolving important debates in medical and evolutionary genetics. Here, we present a method for inferring this distribution using Single Nucleotide Polymorphism (SNP) data from a population with non-stationary demographic history (such as that of modern humans). Application of our method to 47,576 coding SNPs found by direct resequencing of 11,404 protein coding-genes in 35 individuals (20 European Americans and 15 African Americans) allows us to assess the relative contribution of demographic and selective effects to patterning amino acid variation in the human genome. We find evidence of an ancient population expansion in the sample with African ancestry and a relatively recent bottleneck in the sample with European ancestry. After accounting for these demographic effects, we find strong evidence for great variability in the selective effects of new amino acid replacing mutations. In both populations, the patterns of variation are consistent with a leptokurtic distribution of selection coefficients (e.g., gamma or log-normal) peaked near neutrality. Specifically, we predict 27–29% of amino acid changing (nonsynonymous) mutations are neutral or nearly neutral (|s|<0.01%), 30–42% are moderately deleterious (0.01%<|s|<1%), and nearly all the remainder are highly deleterious or lethal (|s|>1%). Our results are consistent with 10–20% of amino acid differences between humans and chimpanzees having been fixed by positive selection with the remainder of differences being neutral or nearly neutral. Our analysis also predicts that many of the alleles identified via whole-genome association mapping may be selectively neutral or (formerly) positively selected, implying that deleterious genetic variation affecting disease phenotype may be missed by this widely used approach for mapping genes underlying complex traits. 相似文献
948.
949.
The clinical outcome of Helicobacter pylori infection is determined by a complex scenario of interactions between the bacterium and the host. The main bacterial factors associated with colonization and pathogenicity comprise outer membrane proteins including BabA, SabA, OipA, AlpA/B, as well as the virulence factors CagA in the cag pathogenicity island ( cag PAI) and the vacuolating cytotoxin VacA. The multitude of these proteins and allelic variation makes it extremely difficult to test the contribution of each individual factor. Much effort has been put into identifying the mechanism associated with H. pylori -associated carcinogenesis. Interaction between bacterial factors such as CagA and host signal transduction pathways seems to be critical for mediating the induction of membrane dynamics, actin-cytoskeletal rearrangements and the disruption of cell-to-cell junctions as well as proliferative, pro-inflammatory and antiapoptotic nuclear responses. An animal model using the Mongolian gerbil is a useful system to study the gastric pathology of H. pylori infection. 相似文献
950.
Tipsmark CK Luckenbach JA Madsen SS Kiilerich P Borski RJ 《Comparative biochemistry and physiology. Part A, Molecular & integrative physiology》2008,150(3):265-273
The southern flounder is a euryhaline teleost that inhabits ocean, estuarine, and riverine environments. We investigated the osmoregulatory strategy of juvenile flounder by examining the time-course of homeostatic responses, hormone levels, and gill Na(+),K(+)-ATPase and Na(+),K(+),2Cl(-) cotransporter protein expression after salinity challenge. Transfer of freshwater (FW)-acclimated flounder to sea water (SW) induced an increase in plasma osmolality and cortisol and a decrease in muscle water content, plasma insulin-like growth factor I (IGF-I) and hepatic IGF-I mRNA, all returning to control levels after 4 days. Gill Na(+),K(+)-ATPase and Na(+),K(+),2Cl(-) cotransporter protein levels were elevated in response to SW after 4 days. Transfer of SW-acclimated flounder to FW reduced gill Na(+),K(+)-ATPase and Na(+),K(+),2Cl(-) cotransporter protein, increased plasma IGF-I, but did not alter hepatic IGF-I mRNA or plasma cortisol levels. Gill claudin-3 and claudin-4 immunoreactive proteins were elevated in FW versus SW acclimated flounder. The study demonstrates that successful acclimation of southern flounder to SW or FW occurs after an initial crisis period and that the salinity adaptation process is associated with changes in branchial expression of ion transport and putative tight junction claudin proteins known to regulate epithelial permeability in mammalian vertebrates. 相似文献