全文获取类型
收费全文 | 698篇 |
免费 | 120篇 |
国内免费 | 1篇 |
出版年
2021年 | 6篇 |
2020年 | 7篇 |
2019年 | 5篇 |
2018年 | 8篇 |
2017年 | 8篇 |
2016年 | 16篇 |
2015年 | 29篇 |
2014年 | 30篇 |
2013年 | 38篇 |
2012年 | 38篇 |
2011年 | 35篇 |
2010年 | 26篇 |
2009年 | 11篇 |
2008年 | 24篇 |
2007年 | 31篇 |
2006年 | 23篇 |
2005年 | 35篇 |
2004年 | 41篇 |
2003年 | 30篇 |
2002年 | 32篇 |
2001年 | 15篇 |
2000年 | 19篇 |
1999年 | 20篇 |
1998年 | 10篇 |
1997年 | 14篇 |
1996年 | 7篇 |
1995年 | 8篇 |
1994年 | 7篇 |
1993年 | 13篇 |
1992年 | 17篇 |
1991年 | 15篇 |
1990年 | 9篇 |
1989年 | 14篇 |
1988年 | 11篇 |
1987年 | 8篇 |
1986年 | 10篇 |
1985年 | 10篇 |
1984年 | 12篇 |
1983年 | 11篇 |
1982年 | 7篇 |
1981年 | 11篇 |
1980年 | 11篇 |
1979年 | 8篇 |
1978年 | 8篇 |
1977年 | 7篇 |
1975年 | 6篇 |
1974年 | 8篇 |
1973年 | 8篇 |
1972年 | 6篇 |
1970年 | 5篇 |
排序方式: 共有819条查询结果,搜索用时 15 毫秒
81.
Effects of clothianidin on Bombus impatiens (Hymenoptera: Apidae) colony health and foraging ability
We conducted laboratory experiments to investigate the lethal and sublethal effects of clothianidin on bumble bee, Bombus impatiens Cresson, colony health and foraging ability. Bumble bee colonies were exposed to 6 ppb clothianidin, representing the highest residue levels found in field studies on pollen, and a higher dose of 36 ppb clothianidin in pollen. Clothianidin did not effect pollen consumption, newly emerged worker weights, amount of brood or the number of workers, males, and queens at either dose. The foraging ability of worker bees tested on an artificial array of complex flowers also did not differ among treatments. These results suggest that clothianidin residues found in seed-treated canola and possibly other crops will not adversely affect the health of bumble bee colonies or the foraging ability of workers. 相似文献
82.
83.
Wet electron microscopy (EM) is a new imaging method with the potential to allow higher spatial resolution of samples. In contrast to most EM methods, it requires little time to perform and does not require complicated equipment or difficult steps. We used this method on a common murine macrophage cell line, IC-21, in combination with various stains and preparations, to collect high resolution images of the actin cytoskeleton. Most importantly, we demonstrated the use of quantum dots in conjunction with this technique to perform light/electron correlation microscopy. We found that wet EM is a useful tool that fits into a niche between the simplicity of light microscopy and the high spatial resolution of EM. 相似文献
84.
We applied a micro-cDNA-based subtraction method to identify genes expressed in the regenerating sensory epithelia (SE) of the chicken inner ear. Sensory hair cells in the avian utricle SE are in a constant state of turnover, where dying hair cells are replaced by new ones derived from supporting cells. In contrast, hair cells in the cochlea remain quiescent unless damaged. We used this difference to enrich for utricle-specific genes, using reiterative cDNA subtraction and demonstrate enrichment for utricle-specific sequences. A total of 1710 cDNA sequence reads revealed the presence of many cDNAs encoding known structural components of the SE (for example, Harmonin and beta-tectorin), proteins involved in cellular proliferation, such as P311, HIPK2, and SPALT1, among many others of unknown function. These libraries are the first of their kind and should prove useful for the discovery of candidate genes for hearing disorders, regenerative and apoptotic pathways, and novel chicken ESTs. 相似文献
85.
Hoover SE Higo HA Winston ML 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》2006,176(1):55-63
We examined the effect of larval and adult nutrition on worker honey bee (Apis mellifera L.) ovary development. Workers were fed high or low-pollen diets as larvae, and high or low-protein diets as adults. Workers
fed low-protein diets at both life stages had the lowest levels of ovary development, followed by those fed high-protein diets
as larvae and low- quality diets as adults, and then those fed diets poor in protein as larvae but high as adults. Workers
fed high-protein diets at both life stages had the highest levels of ovary development. The increases in ovary development
due to improved dietary protein in the larval and adult life stages were additive. Adult diet also had an effect on body mass.
The results demonstrate that both carry-over of larval reserves and nutrients acquired in the adult life stage are important
to ovary development in worker honey bees. Carry-over from larval development, however, appears to be less important to adult
fecundity than is adult nutrition. Seasonal trends in worker ovary development and mass were examined throughout the brood
rearing season. Worker ovary development was lowest in spring, highest in mid-summer, and intermediate in fall. 相似文献
86.
Computational disease gene identification: a concert of methods prioritizes type 2 diabetes and obesity candidate genes 总被引:4,自引:1,他引:3
Tiffin N Adie E Turner F Brunner HG van Driel MA Oti M Lopez-Bigas N Ouzounis C Perez-Iratxeta C Andrade-Navarro MA Adeyemo A Patti ME Semple CA Hide W 《Nucleic acids research》2006,34(10):3067-3081
Genome-wide experimental methods to identify disease genes, such as linkage analysis and association studies, generate increasingly large candidate gene sets for which comprehensive empirical analysis is impractical. Computational methods employ data from a variety of sources to identify the most likely candidate disease genes from these gene sets. Here, we review seven independent computational disease gene prioritization methods, and then apply them in concert to the analysis of 9556 positional candidate genes for type 2 diabetes (T2D) and the related trait obesity. We generate and analyse a list of nine primary candidate genes for T2D genes and five for obesity. Two genes, LPL and BCKDHA, are common to these two sets. We also present a set of secondary candidates for T2D (94 genes) and for obesity (116 genes) with 58 genes in common to both diseases. 相似文献
87.
88.
Morales Quinones M Winston JT Stromhaug PE 《The Journal of biological chemistry》2012,287(13):10121-10133
Misfolded protein aggregation causes disease and aging; autophagy counteracts this by eliminating damaged components, enabling cells to survive starvation. The cytoplasm-to-vacuole targeting pathway in yeast encompasses the aggregation of the premature form of aminopeptidase 1 (prApe1) in cytosol and its sequestration by autophagic proteins into a vesicle for vacuolar transport. We show that the propeptide of Ape1 is important for aggregation and vesicle formation and that it is sufficient for binding to prApe1 and Atg19. Defective aggregation disrupts vacuolar transport, suggesting that aggregate shape is important in vesicle formation, whereas Atg19 binding is not sufficient for vacuolar transport. Aggregation involves hydrophobicity, whereas Atg19 binding requires additional electrostatic interactions. Ape1 dodecamerization may cluster propeptides into trimeric structures, with sufficient affinity to form propeptide hexamers by binding to other dodecamers, causing aggregation. We show that Ape1 aggregates bind Atg19 and Atg8 in vitro; this could be used as a scaffold for an in vitro assay of autophagosome formation to elucidate the mechanisms of autophagy. 相似文献
89.
Fournier B Andargachew R Robin AZ Laur O Voelker DR Lee WY Weber D Parkos CA 《The Journal of biological chemistry》2012,287(23):19386-19398
Signal regulatory protein α (SIRPα), a highly glycosylated type-1 transmembrane protein, is composed of three immunoglobulin-like extracellular loops as well as a cytoplasmic tail containing three classical tyrosine-based inhibitory motifs. Previous reports indicate that SIRPα binds to humoral pattern recognition molecules in the collectin family, namely surfactant proteins D and A (Sp-D and Sp-A, respectively), which are heavily expressed in the lung and constitute one of the first lines of innate immune defense against pathogens. However, little is known about molecular details of the structural interaction of Sp-D with SIRPs. In the present work, we examined the molecular basis of Sp-D binding to SIRPα using domain-deleted mutant proteins. We report that Sp-D binds to the membrane-proximal Ig domain (D3) of SIRPα in a calcium- and carbohydrate-dependent manner. Mutation of predicted N-glycosylation sites on SIRPα indicates that Sp-D binding is dependent on interactions with specific N-glycosylated residues on the membrane-proximal D3 domain of SIRPα. Given the remarkable sequence similarity of SIRPα to SIRPβ and the lack of known ligands for the latter, we examined Sp-D binding to SIRPβ. Here, we report specific binding of Sp-D to the membrane-proximal D3 domain of SIRPβ. Further studies confirmed that Sp-D binds to SIRPα expressed on human neutrophils and differentiated neutrophil-like cells. Because the other known ligand of SIRPα, CD47, binds to the membrane-distal domain D1, these findings indicate that multiple, distinct, functional ligand binding sites are present on SIRPα that may afford differential regulation of receptor function. 相似文献
90.