全文获取类型
收费全文 | 349篇 |
免费 | 27篇 |
出版年
2023年 | 4篇 |
2022年 | 2篇 |
2021年 | 10篇 |
2020年 | 12篇 |
2019年 | 7篇 |
2018年 | 15篇 |
2017年 | 12篇 |
2016年 | 17篇 |
2015年 | 22篇 |
2014年 | 19篇 |
2013年 | 30篇 |
2012年 | 39篇 |
2011年 | 19篇 |
2010年 | 17篇 |
2009年 | 13篇 |
2008年 | 20篇 |
2007年 | 22篇 |
2006年 | 8篇 |
2005年 | 10篇 |
2004年 | 15篇 |
2003年 | 13篇 |
2002年 | 12篇 |
2001年 | 4篇 |
1999年 | 2篇 |
1997年 | 1篇 |
1996年 | 1篇 |
1995年 | 1篇 |
1993年 | 1篇 |
1992年 | 2篇 |
1988年 | 2篇 |
1985年 | 1篇 |
1984年 | 2篇 |
1983年 | 3篇 |
1982年 | 5篇 |
1981年 | 3篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1976年 | 1篇 |
1970年 | 1篇 |
1969年 | 1篇 |
1966年 | 1篇 |
1965年 | 1篇 |
1964年 | 2篇 |
1963年 | 1篇 |
排序方式: 共有376条查询结果,搜索用时 171 毫秒
31.
Alexandra Castilho Laura Neumann Sasha Daskalova Hugh S. Mason Herta Steinkellner Friedrich Altmann Richard Strasser 《The Journal of biological chemistry》2012,287(43):36518-36526
Proper N- and O-glycosylation of recombinant proteins is important for their biological function. Although the N-glycan processing pathway of different expression hosts has been successfully modified in the past, comparatively little attention has been paid to the generation of customized O-linked glycans. Plants are attractive hosts for engineering of O-glycosylation steps, as they contain no endogenous glycosyltransferases that perform mammalian-type Ser/Thr glycosylation and could interfere with the production of defined O-glycans. Here, we produced mucin-type O-GalNAc and core 1 O-linked glycan structures on recombinant human erythropoietin fused to an IgG heavy chain fragment (EPO-Fc) by transient expression in Nicotiana benthamiana plants. Furthermore, for the generation of sialylated core 1 structures constructs encoding human polypeptide:N-acetylgalactosaminyltransferase 2, Drosophila melanogaster core 1 β1,3-galactosyltransferase, human α2,3-sialyltransferase, and Mus musculus α2,6-sialyltransferase were transiently co-expressed in N. benthamiana together with EPO-Fc and the machinery for sialylation of N-glycans. The formation of significant amounts of mono- and disialylated O-linked glycans was confirmed by liquid chromatography-electrospray ionization-mass spectrometry. Analysis of the three EPO glycopeptides carrying N-glycans revealed the presence of biantennary structures with terminal sialic acid residues. Our data demonstrate that N. benthamiana plants are amenable to engineering of the O-glycosylation pathway and can produce well defined human-type O- and N-linked glycans on recombinant therapeutics. 相似文献
32.
Q Qi A Gibson X Fu M Zheng R Kuehn Y Wang Y Wang S Navarro JA Morrell D Jiang G Simmons E Bell NB Ivleva AL McClerren P Loida TG Ruff ME Petracek SB Preuss 《The Journal of biological chemistry》2012,287(37):31482-31493
Previous studies have demonstrated that Arabidopsis thaliana BBX32 (AtBBX32) represses light signaling in A. thaliana and that expression of AtBBX32 in soybean increases grain yield in multiple locations and multiyear field trials. The BBX32 protein is a member of the B-box zinc finger family from A. thaliana and contains a single conserved Zn(2+)-binding B-box domain at the N terminus. Although the B-box domain is predicted to be involved in protein-protein interactions, the mechanism of interaction is poorly understood. Here, we provide in vitro and in vivo evidence demonstrating the physical and functional interactions of AtBBX32 with another B-box protein, soybean BBX62 (GmBBX62). Deletion analysis and characterization of the purified B-box domain indicate that the N-terminal B-box region of AtBBX32 interacts with GmBBX62. Computational modeling and site-directed mutagenesis of the AtBBX32 B-box region identified specific residues as critical for mediating the interaction between AtBBX32 and GmBBX62. This study defines the plant B-box as a protein interaction domain and offers novel insight into its role in mediating specific protein-protein interactions between different plant B-box proteins. 相似文献
33.
34.
Zbigniew S. Kolber Sasha Tozzi Jonathan P. Zehr David M. Karl 《Journal of phycology》2012,48(3):595-606
This study describes the relationships between dinitrogen (N2) fixation, dihydrogen (H2) production, and electron transport associated with photosynthesis and respiration in the marine cyanobacterium Trichodesmium erythraeum Ehrenb. strain IMS101. The ratio of H2 produced:N2 fixed (H2:N2) was controlled by the light intensity and by the light spectral composition and was affected by the growth irradiance level. For Trichodesmium cells grown at 50 μmol photons · m?2 · s?1, the rate of N2 fixation, as measured by acetylene reduction, saturated at light intensities of 200 μmol photons · m?2 · s?1. In contrast, net H2 production continued to increase with light levels up to 1,000 μmol photons · m?2 · s?1. The H2:N2 ratios increased monotonically with irradiance, and the variable fluorescence measured using a fast repetition rate fluorometer (FRRF) revealed that this increase was accompanied by a progressive reduction of the plastoquinone (PQ) pool. Additions of 2,5‐dibromo‐3‐methyl‐6‐isopropyl‐p‐benzoquinone (DBMIB), an inhibitor of electron transport from PQ pool to PSI, diminished both N2 fixation and net H2 production, while the H2:N2 ratio increased with increasing level of PQ pool reduction. In the presence of 3‐(3,4‐dichlorophenyl)‐1,1‐dimethylurea (DCMU), nitrogenase activity declined but could be prolonged by increasing the light intensity and by removing the oxygen supply. These results on the coupling of N2 fixation and H2 cycling in Trichodesmium indicate how light intensity and light spectral quality of the open ocean can influence the H2:N2 ratio and modulate net H2 production. 相似文献
35.
Bleavins K Perone P Naik M Rehman M Aslam MN Dame MK Meshinchi S Bhagavathula N Varani J 《Biological trace element research》2012,145(2):257-267
The purpose of this study was to assess insoluble salts containing gadolinium (Gd3+) for effects on human dermal fibroblasts. Responses to insoluble Gd3+ salts were compared to responses seen with Gd3+ solubilized with organic chelators, as in the Gd3+-based contrast agents (GBCAs) used for magnetic resonance imaging. Insoluble particles of either Gd3+ phosphate or Gd3+ carbonate rapidly attached to the fibroblast cell surface and stimulated proliferation. Growth was observed at Gd3+ concentrations between 12.5 and 125 μM, with toxicity at higher concentrations. Such a narrow window did not characterize
GBCA stimulation. Proliferation induced by insoluble Gd3+ salts was inhibited in the presence of antagonists of mitogen-activated protein kinase and phosphatidylinositol 3-kinase
signaling pathways (similar to chelated Gd3+) but was not blocked by an antibody to the platelet-derived growth factor receptor (different from chelated Gd3+). Finally, high concentrations of the insoluble Gd3+ salts failed to prevent fibroblast lysis under low-Ca2+ conditions, while similar concentrations of chelated Gd3+ were effective. In conclusion, while insoluble Gd3+ salts are capable of stimulating fibroblast proliferation, one should be cautious in assuming that GBCA dechelation must
occur in vivo to produce the profibrotic changes seen in association with GBCA exposure in the subset of renal failure patients
that develop nephrogenic systemic fibrosis. 相似文献
36.
AS Whiteley S Jenkins I Waite N Kresoje H Payne B Mullan R Allcock A O'Donnell 《Journal of microbiological methods》2012,91(1):80-88
Here we demonstrate a cost effective and scalable microbial ecology sequencing platform using the Ion Torrent Personal Genome Machine (PGM). We assessed both PCR amplified 16S rRNA and shotgun metagenomic approaches and generated 100,000+ to 1,000,000+ reads using 'post-light' based sequencing technology within different sized semi-conductor chips. Further development of Golay barcoded Ion Tags allowed multiplex analyses of microbial communities with substantially reduced costs compared with platforms such as 454/GS-FLX. Using these protocols we assessed the bacterial and archaeal dynamics within covered anaerobic digesters used to treat piggery wastes. Analysis of these sequence data showed that these novel methanogenic waste treatment systems are dominated by bacterial taxa, in particular Clostridium, Synergistia and Bacteroides that were maintained as a stable community over extended time periods. Archaeal community dynamics were more stochastic with the key methanogenic taxa more difficult to resolve, principally due to the poor congruence seen between community structures generated either by nested PCR or metagenomic approaches for archaeal analyses. Our results show that for microbial community structure and function analyses, the PGM platform provides a low cost, scalable and high throughput solution for both Tag sequencing and metagenomic analyses. 相似文献
37.
38.
The mechanisms that control the size and shape of membranes are not well understood, despite the importance of these structures in determining organelle and cell morphology. The prospore membrane, a double lipid bilayer that is synthesized de novo during sporulation in S. cerevisiae, grows to surround the four meiotic products. This membrane determines the shape of the newly formed spores and serves as the template for spore wall deposition. Ultimately, the inner leaflet of the prospore membrane will become the new plasma membrane of the cell upon germination. Here we show that Spo71, a pleckstrin homology domain protein whose expression is induced during sporulation, is critical for the appropriate growth of the prospore membrane. Without SPO71, prospore membranes surround the nuclei but are abnormally small, and spore wall deposition is disrupted. Sporulating spo71Δ cells have prospore membranes that properly localize components to their growing leading edges yet cannot properly localize septin structures. We also found that SPO71 genetically interacts with SPO1, a gene with homology to the phospholipase B gene that has been previously implicated in determining the shape of the prospore membrane. Together, these results show that SPO71 plays a critical role in prospore membrane development. 相似文献
39.
40.
Lesley Tilleman Sasha De Henau Martje Pauwels Nora Nagy Isabel Pintelon Bart P. Braeckman Karolien De Wael Sabine Van Doorslaer Dirk Adriaensen Jean-Pierre Timmermans Luc Moens Sylvia Dewilde 《PloS one》2012,7(12)
Globins occur in all kingdoms of life where they fulfill a wide variety of functions. In the past they used to be primarily characterized as oxygen transport/storage proteins, but since the discovery of new members of the globin family like neuroglobin and cytoglobin, more diverse and complex functions have been assigned to this heterogeneous family. Here we propose a function for a membrane-bound globin of C. elegans, GLB-26. This globin was predicted to be myristoylated at its N-terminus, a post-translational modification only recently described in the globin family. In vivo, this globin is found in the membrane of the head mesodermal cell and in the tail stomato-intestinal and anal depressor muscle cells. Since GLB-26 is almost directly oxidized when exposed to oxygen, we postulate a possible function as electron transfer protein. Phenotypical studies show that GLB-26 takes part in regulating the length of the defecation cycle in C. elegans under oxidative stress conditions. 相似文献