全文获取类型
收费全文 | 130篇 |
免费 | 12篇 |
出版年
2021年 | 3篇 |
2020年 | 1篇 |
2019年 | 2篇 |
2016年 | 3篇 |
2015年 | 6篇 |
2014年 | 7篇 |
2013年 | 14篇 |
2012年 | 7篇 |
2011年 | 6篇 |
2010年 | 4篇 |
2009年 | 2篇 |
2008年 | 6篇 |
2007年 | 5篇 |
2006年 | 7篇 |
2005年 | 8篇 |
2004年 | 7篇 |
2003年 | 3篇 |
2002年 | 2篇 |
2001年 | 1篇 |
2000年 | 3篇 |
1999年 | 4篇 |
1998年 | 2篇 |
1997年 | 2篇 |
1996年 | 1篇 |
1995年 | 1篇 |
1993年 | 3篇 |
1992年 | 1篇 |
1991年 | 2篇 |
1990年 | 3篇 |
1989年 | 1篇 |
1988年 | 2篇 |
1985年 | 5篇 |
1984年 | 1篇 |
1983年 | 5篇 |
1982年 | 1篇 |
1980年 | 2篇 |
1979年 | 2篇 |
1977年 | 1篇 |
1976年 | 2篇 |
1974年 | 1篇 |
1972年 | 1篇 |
1962年 | 2篇 |
排序方式: 共有142条查询结果,搜索用时 140 毫秒
1.
Sodium ions and an energized membrane required by Methanosarcina barkeri for the oxidation of methanol to the level of formaldehyde. 总被引:6,自引:3,他引:3 下载免费PDF全文
Methanogenesis from methanol by cell suspensions of Methanosarcina barkeri was inhibited by the uncoupler tetrachlorosalicylanilide. This inhibition was reversed by the addition of formaldehyde. 14C labeling experiments revealed that methanol served exclusively as the electron acceptor, whereas formaldehyde was mainly oxidized to CO2 under these conditions. These data support the hypothesis (M. Blaut and G. Gottschalk, Eur. J. Biochem. 141: 217-222, 1984) that the first step in methanol oxidation depends on the proton motive force or a product thereof. Cell extracts of M. barkeri converted methanol and formaldehyde to methane under an H2 atmosphere. Under an N2 atmosphere, however, formaldehyde was disproportionated to CH4 and CO2, whereas methanol was metabolized to a very small extent only, irrespective of the presence of ATP. It was concluded that cell extracts of M. barkeri are not able to oxidize methanol. In further experiments, the sodium dependence of methanogenesis and ATP formation by whole cells was investigated. Methane formation from methanol alone and the corresponding increase in the intracellular ATP content were strictly dependent on Na+. If, in contrast, methanol was utilized together with H2, methane and ATP were synthesized in the absence of Na+. The same is true for the disproportionation of formaldehyde to methane and carbon dioxide. From these experiments, it is concluded that in M. barkeri, Na+ is involved not in the process of ATP synthesis but in the first step of methanol oxidation. 相似文献
2.
3.
K. A. Dill S. Bromberg K. Yue K. M. Fiebig D. P. Yee P. D. Thomas H. S. Chan 《Protein science : a publication of the Protein Society》1995,4(4):561-602
General principles of protein structure, stability, and folding kinetics have recently been explored in computer simulations of simple exact lattice models. These models represent protein chains at a rudimentary level, but they involve few parameters, approximations, or implicit biases, and they allow complete explorations of conformational and sequence spaces. Such simulations have resulted in testable predictions that are sometimes unanticipated: The folding code is mainly binary and delocalized throughout the amino acid sequence. The secondary and tertiary structures of a protein are specified mainly by the sequence of polar and nonpolar monomers. More specific interactions may refine the structure, rather than dominate the folding code. Simple exact models can account for the properties that characterize protein folding: two-state cooperativity, secondary and tertiary structures, and multistage folding kinetics--fast hydrophobic collapse followed by slower annealing. These studies suggest the possibility of creating "foldable" chain molecules other than proteins. The encoding of a unique compact chain conformation may not require amino acids; it may require only the ability to synthesize specific monomer sequences in which at least one monomer type is solvent-averse. 相似文献
4.
Molecular size and polypeptide chain composition of cell membrane immunoglobulin (mIg) on lymphocytes of carp were studied using lactopreoxidase-catalysed surface radioiodination and SDS-polyacrylamide gel electrophoresis. Carp lymphocytes prepared from pronephros, blood and thymus carry mIgM in relatively high quantity. That means about 5-10% of the radiolabelled macromolecular cell surface material precipitates as IgM. Cell surface IgM on carp lymphocytes is present as monomeric IgM (m.w. 220000-260000) and HL subunit (m.w. 110000). There are differences among molecular weights of mIg monomers of pronephric lymphocytes (m.w. 220000) and thymocytes (m.w. 260000), whereas blood lymphocytes show both components. Following reduction and alkylation H and L chains were observed. Additional thymocytic mIg possesses two unidentified components with m.w. 35000-40000 and 110000. 相似文献
5.
Teresa Fiebig Giovanna Figueiredo Hanne Boll Hans Ulrich Kerl Ingo S. Noelte Alex Forster Christoph Groden Martin Kramer Marc A. Brockmann 《PloS one》2013,8(6)
Purpose
Small injection ports for mice are increasingly used for drug testing or when administering contrast agents. Commercially available mini-ports are expensive single-use items that cause imaging-artifacts. We developed and tested an artifact-free, low-cost, vascular access mini-port (VAMP) for mice.Procedures
Leakage testing of the VAMP was conducted with high speed bolus injections of different contrast agents. VAMP-induced artifacts were assessed using a micro-CT and a small animal MRI (9.4T) scanner ex vivo. Repeated contrast administration was performed in vivo.Results
With the VAMP there was no evidence of leakage with repeated punctures, high speed bolus contrast injections, and drawing of blood samples. In contrast to the tested commercially available ports, the VAMP did not cause artifacts with MRI or CT imaging.Conclusions
The VAMP is an alternative to commercially available mini-ports and has useful applications in animal research involving imaging procedures and contrast agent testing. 相似文献6.
Stephan Zindel Vera Ehret Marina Ehret Madeleine Hentschel Samantha Witt Andreas Kr?mer David Fiebig Norbert Jüttner Sabrina Fr?ls Felicitas Pfeifer Hans-Lothar Fuchsbauer 《PloS one》2016,11(2)
Streptomyces mobaraensis DSM 40847 secretes transglutaminase that cross-links proteins via γ-glutamyl-ε-lysine isopeptide bonds. Characterized substrates are inhibitory proteins acting against various serine, cysteine and metalloproteases. In the present study, the bacterial secretome was examined to uncover additional transglutaminase substrates. Fractional ethanol precipitation of the exported proteins at various times of culture growth, electrophoresis of the precipitated proteins, and sequencing of a 39 kDa protein by mass spectrometry revealed the novel beta-lactamase Sml-1. As indicated by biotinylated probes, Sml-1, produced in E. coli, exhibits glutamine and lysine residues accessible for transglutaminase. The chromogenic cephalosporin analogue, nitrocefin, was hydrolyzed by Sml-1 with low velocity. The obtained Km and kcat values of the recombinant enzyme were 94.3±1.8 μM and 0.39±0.03 s-1, respectively. Penicillin G and ampicillin proved to be weak inhibitors of nitrocefin hydrolysis (Ki of 0.1 mM and 0.18 mM). Negligible influence of metals on β-lactamase activity ruled out that Sml-1 is a Zn2+-dependent class B beta-lactamase. Rather, sequence motifs such as SITK, YSN, and HDG forming the active core in a hypothetical structure may be typical for class C beta-lactamases. Based on the results, we assume that the novel transglutaminase substrate ensures undisturbed growth of aerial hyphae in Streptomyces mobaraensis by trapping and inactivating hostile beta-lactam antibiotics. 相似文献
7.
Chloroplast RNA editing proceeds by C-to-U transitions at highly specific sites. Here, we provide a phylogenetic analysis of RNA editing in a small plastid gene, petL, encoding subunit VI of the cytochrome b6f complex. Analyzing representatives from most major groups of seed plants, we find an unexpectedly high frequency and dynamics of RNA editing. High-frequency editing has previously been observed in plastid ndh genes, which are remarkable in that their mutational inactivation does not produce an obvious mutant phenotype. In order to test the idea that reduced functional constraints allow for more flexible evolution of RNA editing sites, we have created petL knockout plants by tobacco chloroplast transformation. We find that, in the higher plant tobacco, targeted inactivation of petL does not impair plant growth under a variety of conditions markedly contrasting the important role of petL in photosynthesis in the green alga Chlamydomonas reinhardtii. Together with a low number of editing sites in plastid genes that are essential to gene expression and photosynthetic activity, these data suggest that RNA editing sites may evolve more readily in those genes whose transitory loss of function can be tolerated. Accumulated evidence for this ‘relative neutrality hypothesis for the evolution of plastid editing sites’ is discussed. 相似文献
8.
Ikegami T Verdier L Sakhaii P Grimme S Pescatore B Saxena K Fiebig KM Griesinger C 《Journal of biomolecular NMR》2004,29(3):339-349
A molecule with an anisotropic magnetic susceptibility is spontaneously aligned in a static magnetic field. Alignment of such a molecule yields residual dipolar couplings and pseudocontact shifts. Lanthanide ions have recently been successfully used to provide an anisotropic magnetic susceptibility in target molecules either by replacing a calcium ion with a lanthanide ion in calcium-binding proteins or by attaching an EDTA derivative to a cysteine residue via a disulfide bond. Here we describe a novel enantiomerically pure EDTA derived tag that aligns stronger due to its shorter linker and does not suffer from stereochemical diversity upon lanthanide complexation. We observed residual (15)N,(1)H-dipolar couplings of up to 8 Hz at 800 MHz induced by a single alignment tensor from this tag. 相似文献
9.
Vogtherr M Jacobs DM Parac TN Maurer M Pahl A Saxena K Rüterjans H Griesinger C Fiebig KM 《Journal of molecular biology》2002,318(4):1097-1115
We have solved the solution structure of the peptidyl-prolyl cis-trans isomerase (PPIase) domain of the trigger factor from Mycoplasma genitalium by homo- and heteronuclear NMR spectroscopy. Our results lead to a well-defined structure with a backbone rmsd of 0.23 A. As predicted, the PPIase domain of the trigger factor adopts the FK506 binding protein (FKBP) fold. Furthermore, our NMR relaxation data indicate that the dynamic behavior of the trigger factor PPIase domain and of FKBP are similar. Structural variations when compared to FKBP exist in the flap region and within the bulges of strand 5 of the beta sheet. Although the active-site crevice is similar to that of FKBP, subtle steric variations in this region can explain why FK506 does not bind to the trigger factor. Sequence variability (27% identity) between trigger factor and FKBP results in significant differences in surface charge distribution and the absence of the first strand of the central beta sheet. Our data indicate, however, that this strand may be partially structured as "nascent" beta strand. This makes the trigger factor PPIase domain the most minimal representative of the FKBP like protein family of PPIases. 相似文献
10.
Suck R Weber B Schäffer B Diedrich E Kamionka T Fiebig H Cromwell O 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》2003,787(2):357-368
The recombinant major grass pollen allergen Phl p 6 has been expressed with a N-terminal 6 x His-tag sequence and subsequently purified using nickel-chelating Sepharose. After cleavage of the tag-sequence, a second pass over the affinity chromatography revealed that even untagged rPhl p 6 bound tightly. In order to determine if that property is typical for Phl p 6, the natural allergen was purified in the same way starting with a grass pollen extract. Indeed, nPhl p 6 could be highly enriched in one step using nickel-chelating Sepharose. In addition to this new powerful purification method, the results provide further information in that the recombinant and natural allergens share a lot of properties, since biochemical characteristics are reflected in the purification strategies. The preparations of natural and recombinant Phl p 6 were used for comparative electrophoretic, chromatographic and immunological analysis which demonstrated high similarity. 相似文献