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排序方式: 共有132条查询结果,搜索用时 125 毫秒
1.
Characterization of a novel murine T cell-activating factor 总被引:8,自引:0,他引:8
Purified resting peripheral lymph node T cells can be activated to produce interleukin 2 (IL 2) and to proliferate in the presence of Concanavalin A (Con A) and an apparently novel lymphokine that we call T cell activating factor (TAF). TAF is biochemically distinct from IL 1, IL 2, IL 3, and other colony stimulating factors, IL 4 (BSF-1) and interferons. Furthermore, of the recombinant and natural cytokines tested, only IL 2 and TAF are active in the TAF assay. In the presence of Con A, TAF stimulates an increase in the steady-state level of IL 2 mRNA in T cells, the secretion of active IL 2 into the culture medium, and the proliferation of the T cells. We propose that TAF is a previously undescribed molecule the function of which is to stimulate IL 2 production by T cells that have encountered antigen, and we propose that TAF has an important role in primary T cell immune responses. 相似文献
2.
Crystal and solution structures of the oligonucleotide d(ATGCGCAT)2: a combined X-ray and NMR study. 总被引:4,自引:1,他引:3
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G R Clark D G Brown M R Sanderson T Chwalinski S Neidle J M Veal R L Jones W D Wilson G Zon E Garman 《Nucleic acids research》1990,18(18):5521-5528
A combined crystal-structure determination and NMR analysis of the octanucleotide d(ATGCGCAT)2 is reported. The X-ray analysis shows that the structure is A-form duplex in crystal state. The NMR study shows that in solution this sequence is B-type. The conformational results from each technique are presented in detail. The implications of these findings in terms of conformational flexibility and ligand binding are discussed. 相似文献
3.
Crystal structure of a berenil-dodecanucleotide complex: the role of water in sequence-specific ligand binding. 总被引:8,自引:1,他引:7
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D G Brown M R Sanderson J V Skelly T C Jenkins T Brown E Garman D I Stuart S Neidle 《The EMBO journal》1990,9(4):1329-1334
The three-dimensional structure of a complex between the dodecanucleotide d(CGCGAATTCGCG) and the anti-trypanocidal drug berenil, has been determined to a resolution of 2.5 A. The structure has been solved by molecular replacement and refined to an R factor of 0.177. A total of 49 water molecules have been located. The drug is bound at the 5'-AAT-3' region of the oligonucleotide. At one end of the drug the amidinium group is in hydrogen-bonded contact with N3 of the adenine base complementary to the thymine of the AAT. The other amidinium group does not make direct interactions with the DNA. Instead, a water molecule mediates between them. This is in hydrogen-bonded contact with an amidinium nitrogen atom, N3 of the 5' end adenine base and the ring oxygen atom of an adjacent deoxyribose. Molecular mechanics calculations have been performed on this complex, with the drug at various positions along the sequence. These show that the observed position is only 0.8 kcal/mol higher in energy than the best position. It is suggested that there is a broad energy well in the AATT region for this drug, and that water molecules as well as the neighbouring sequence, will determine precise positioning. More general aspects of minor groove binding are discussed. 相似文献
4.
The nanH genes of Vibrio cholerae and Salmonella typhimurium LT2 coding neuraminidase were cloned separately in Escherichia coli, and the expression products purified. Single crystals of the V. cholerae neuraminidase were obtained using the hanging drop vapour diffusion method with polyethylene glycol as precipitant at pH 7.2. The crystals belong to the orthorhombic space group P2(1)2(1)2(1), with unit cell dimensions a = 71.9 A, b = 79.0 A, c = 165.7 A, and with one molecule in the asymmetric unit. Diffraction extends to at least 2.5 A. Single crystals of the S. typhimurium neuraminidase were obtained by hanging drop with potassium phosphate as precipitant at pH 7.2. The crystals also belong to the orthorhombic space group P2(1)2(1)2(1), with unit cell dimensions a = 47.4 A, b = 82.8 A, c = 92.4 A, and with one molecule in the asymmetric unit. Diffraction extends to at least 1.8 A. 相似文献
5.
Roberto?H?Higa Roberto?C?Togawa Arnaldo?J?Montagner Juliana?CF?Palandrani Igor?KS?Okimoto Paula?R?Kuser Michel?EB?Yamagishi Adauto?L?Mancini Goran?NeshichEmail author 《BMC bioinformatics》2004,5(1):107
Background
The integration of many aspects of protein/DNA structure analysis is an important requirement for software products in general area of structural bioinformatics. In fact, there are too few software packages on the internet which can be described as successful in this respect. We might say that what is still missing is publicly available, web based software for interactive analysis of the sequence/structure/function of proteins and their complexes with DNA and ligands. Some of existing software packages do have certain level of integration and do offer analysis of several structure related parameters, however not to the extent generally demanded by a user. 相似文献6.
Vanamee ES Hsieh Pc Zhu Z Yates D Garman E Xu Sy Aggarwal AK 《Journal of molecular biology》2003,334(3):595-603
BslI restriction endonuclease cleaves the symmetric sequence CCN(7)GG (where N=A, C, G or T). The enzyme is composed of two subunits, alpha and beta, that form a heterotetramer (alpha(2)beta(2)) in solution. The alpha subunit is believed to be responsible for DNA recognition, while the beta subunit is thought to mediate cleavage. Here, for the first time, we provide experimental evidence that BslI binds Zn(II). Specifically, using X-ray absorption spectroscopic analysis we show that the alpha subunit of BslI contains two Zn(Cys)(4)-type zinc motifs similar to those in the DNA-binding domain of the glucocorticoid receptor. This conclusion is supported by genetic analysis of the zinc-binding motifs, whereby amino acid substitutions in the zinc finger motifs are demonstrated to abolish or impair cleavage activity. An additional putative zinc-binding motif was identified in the beta subunit, consistent with the X-ray absorption data. These data were corroborated by proton induced X-ray emission measurements showing that full BslI contains at least three fully occupied Zn sites per alpha/beta heterodimer. On the basis of these data, we propose a role for the BslI Zn motifs in protein-DNA as well as protein-protein interactions. 相似文献
7.
Recent investigations into the nutrient cycling of coastal ecosystems have suggested that migratory or anadromous fish could
be important vectors of marine nutrients. Anadromous fish have assimilated marine nutrients that would contribute to the nutrient
budgets of freshwater systems by excretion, gamete release, or the decay of post-reproductive carcasses. However, the extent
to which freshwater predators utilize marine material is not well understood. In systems where anadromous fish temporarily
constitute a major portion of the fish community, they may contribute substantially to the diet of piscivorous fish and other
predators. Here we show the contribution of anadromous blueback herring, shad, and alewife (Alosa) to diets of large, non-indigenous piscivorous catfish (Ictalurus furcatus) using δ34S and δ13C. The spawning anadromous Alosa, captured in tidal freshwater, had enriched δ34S and δ13C values compared to resident, native freshwater species. As a result of consuming the anadromous Alosa, the I. furcatus isotope signature shifted towards the marine signal. The isotope analysis revealed that anadromous fish contribute substantially
to the diet of most captured I. furcatus. The percentage of anadromous Alosa carbon and sulfur that was incorporated into I. furcatus (≥38 cm total length) ranged from 0 to 84% and 10 to 69%, and had means (±SD) of 42 (±24) and 43 (±16)%, respectively. Although
the δ15N signal of marine-derived biomass is enriched by approximately 3‰ relative to terrestrial or freshwater biomass, it was not
as useful as δ34S and δ13C for nutrient source owing to trophic fractionation. This study demonstrates that anadromous fish may be a significant source
of nutrients to tidal freshwater apex predators.
Received: 19 March 1999 / Accepted: 26 October 1999 相似文献
8.
Bevan KS Chung Suresh Selvarasu Andrea Camattari Jimyoung Ryu Hyeokweon Lee Jungoh Ahn Hongweon Lee Dong-Yup Lee 《Microbial cell factories》2010,9(1):50
Background
Pichia pastoris has been recognized as an effective host for recombinant protein production. A number of studies have been reported for improving this expression system. However, its physiology and cellular metabolism still remained largely uncharacterized. Thus, it is highly desirable to establish a systems biotechnological framework, in which a comprehensive in silico model of P. pastoris can be employed together with high throughput experimental data analysis, for better understanding of the methylotrophic yeast's metabolism. 相似文献9.
10.
Anders CK Acharya CR Hsu DS Broadwater G Garman K Foekens JA Zhang Y Wang Y Marcom K Marks JR Mukherjee S Nevins JR Blackwell KL Potti A 《PloS one》2008,3(1):e1373