Abstract:
:The superparamagnetic behavior of very small particles of metallic iron (ca 1.5 nm), with about half of their atoms at the surface, is changed reversibly by adsorption and desorption of hydrogen below the superparamagnetic transition temperature. The change after adsorption implies a lowering of the anisotropy energy barrier for the magnetic relaxation of iron and is ascribed to a change in crystalline shape. No such changes are observed for larger particles of iron (ca 8 nm) with about 10% of their atoms at the surface.
journal_name
Proc Natl Acad Sci U S Aauthors
Boudart M,Dumesic JA,Topsøe Hdoi
10.1073/pnas.74.3.806subject
Has Abstractpub_date
1977-03-01 00:00:00pages
806-10issue
3eissn
0027-8424issn
1091-6490journal_volume
74pub_type
杂志文章abstract::TCL1 and TCL1b genes on human chromosome 14q23.1 are activated in T cell leukemias by translocations and inversions at 14q32.1, juxtaposing them to regulatory elements of T cell receptor genes. In this report we present the cloning, mapping, and expression analysis of the human and murine TCL1/Tcl1 locus. In addition ...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.96.25.14418
更新日期:1999-12-07 00:00:00
abstract::Ribonuclease H (EC 3.1.4.34) has been used to remove selectively much of the 3'-terminal poly(adenylic acid) [poly(A)] from poliovirus RNA by treating the RNA with the enzyme in the presence of poly(dT). Over 80% of the poly(A) could be removed and the residuum was found as oligo(A) stretches attached to many or all o...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.71.8.2983
更新日期:1974-08-01 00:00:00
abstract::The chloroplast coupling factor 1 consists of five nonidentical subunits, three of which (alpha, beta, and epsilon subunits) have been shown in several laboratories to be synthesized within chloroplasts. The site of synthesis of the remaining two (gamma and delta subunits) was investigated by analyzing products direct...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.79.20.6304
更新日期:1982-10-01 00:00:00
abstract::In a medium without Na+, gamma-aminobutyric acid (GABA) binds at 0 degrees to freshly prepared crude synaptic membranes from rat cerebral cortex with an apparent dissociation constant of 218 nM. An endogenous inhibitor of the Na+-independent GABA binding was removed from these membranes by freezing and thawing and by ...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.75.8.4024
更新日期:1978-08-01 00:00:00
abstract::In facultative photoperiodic flowering plants, noninductive photoperiods result in a delay in flowering, but such plants eventually flower, illustrating plasticity in an important developmental transition, flowering. The model plant, Arabidopsis, has a facultative photoperiod response. Although the inductive flowering...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1010834107
更新日期:2010-09-28 00:00:00
abstract::Cancer therapies using genes and other macromolecules might realize their full clinical potential if they could be delivered to tumor tissue in optimal quantities. Unfortunately, the compromised circulation within tumors poses a formidable resistance to adequate and uniform penetration of these agents. Previously, we ...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.96.6.3137
更新日期:1999-03-16 00:00:00
abstract::Chemokines play a key role in inflammation. They are expressed not only in neuroinflammatory conditions, but also constitutively by different cell types, including neurons in the normal brain, suggesting that they may act as modulators of neuronal functions. Here, we investigated a possible neuroendocrine role of the ...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.0602620103
更新日期:2006-05-23 00:00:00
abstract::Pentamidine, diminazene aceturate (Berenil), isometamidium chloride (Samorin), and ethidium bromide, which are important antitrypanosomal drugs, promote linearization of Trypanosoma equiperdum minicircle DNA (the principal component of kinetoplast DNA, the mitochondrial DNA in these parasites). This effect occurs at t...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.87.3.950
更新日期:1990-02-01 00:00:00
abstract::Conflicts of interest between the community and its members are at the core of human social dilemmas. If observed selfishness has future costs, individuals may hide selfish acts but display altruistic ones, and peers aim at identifying the most selfish persons to avoid them as future social partners. An interaction in...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1108996108
更新日期:2011-11-08 00:00:00
abstract::MuB is an ATP-dependent nonspecific DNA-binding protein that regulates the activity of the MuA transposase and captures target DNA for transposition. Mechanistic understanding of MuB function has previously been hindered by MuB's poor solubility. Here we combine bioinformatic, mutagenic, biochemical, and electron micr...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1309499110
更新日期:2013-07-02 00:00:00
abstract::The restoration of planar cell polarity is an essential but poorly understood step toward physiological recovery during sensory-organ regeneration. Investigating this issue in the lateral line of the zebrafish, we found that hair cells regenerate in pairs along a single axis established by the restricted localization ...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.0608536103
更新日期:2006-12-05 00:00:00
abstract::I summarize recent computational and experimental work that addresses the inherent variability in the synaptic and intrinsic conductances in normal healthy brains and shows that multiple solutions (sets of parameters) can produce similar circuit performance. I then discuss a number of issues raised by this observation...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章,评审
doi:10.1073/pnas.1010674108
更新日期:2011-09-13 00:00:00
abstract::Although it is accepted that regulatory T cells (T regs) contribute to cancer progression, most studies in the field consider nonantigen-specific suppression. Here, we show the presence of tumor antigen-specific CD4(+) T regs in the blood of patients with metastatic melanoma. These CD4(+) T regs recognize a broad rang...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.0710557105
更新日期:2007-12-26 00:00:00
abstract::Collective intelligence refers to the ability of groups to outperform individual decision makers when solving complex cognitive problems. Despite its potential to revolutionize decision making in a wide range of domains, including medical, economic, and political decision making, at present, little is known about the ...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1601827113
更新日期:2016-08-02 00:00:00
abstract::Kinesin-1 is a molecular motor protein that transports cargo along microtubules. Inside cells, the vast majority of kinesin-1 is regulated to conserve ATP and to ensure its proper intracellular distribution and coordination with other molecular motors. Regulated kinesin-1 folds in half at a hinge in its coiled-coil st...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.0803575105
更新日期:2008-07-01 00:00:00
abstract::A number of eukaryotic viruses have evolved mechanisms to downregulate activity of the interferon-induced, double-stranded RNA-activated protein kinase (referred to as P68 based on its Mr of 68,000 in human cells). This control is essential because once activated, the P68 kinase phosphorylates its natural substrate, t...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.87.16.6208
更新日期:1990-08-01 00:00:00
abstract::Active center fractions have been prepared from Rhodopseudomonas spheroides strain Y. (de Klerk) using the cationic detergent cetyltrimethyl ammonium bromide and light particles from bacteria grown in two media differing in iron content. Spectral properties and composition of the fractions are presented. ...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.64.2.650
更新日期:1969-10-01 00:00:00
abstract::Chorismate mutase acts at the first branch-point of aromatic amino acid biosynthesis and catalyzes the conversion of chorismate to prephenate. The results of molecular dynamics simulations of the substrate in solution and in the active site of chorismate mutase are reported. Two nonreactive conformers of chorismate ar...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.141230998
更新日期:2001-07-31 00:00:00
abstract::We have recently determined that high calcium concentrations, in parallel with their suppressive effects on parathyroid hormone (PTH) secretion, reversibly and specifically decrease preproPTH mRNA in cultured bovine parathyroid cells. In order to determine whether vitamin D metabolites also regulate the content of pre...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.82.12.4270
更新日期:1985-06-01 00:00:00
abstract::Ionizing radiation (IR) induces a variety of DNA lesions among which DNA double-strand breaks (DSBs) are the biologically most significant. It is currently unclear if DSB repair is equally efficient after low and high doses. Here, we use gamma-H2AX, phospho-ATM (pATM), and 53BP1 foci analysis to monitor DSB repair. We...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1002213107
更新日期:2010-08-10 00:00:00
abstract::The effect of carlorie intake on the development of spontaneous mammary tumors in virgin C3H mice was studied. Only about 10% of the mice fed a low-calorie diet [10 kcal/day (1 kcal = 4.184 kJ)] since weaning developed mammary tumors, compared to about 60% of those mice that were reared on high-calorie diets (16 kcal/...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.79.24.7758
更新日期:1982-12-01 00:00:00
abstract::Electrical coupling between pyramidal cell axons, and between interneuron dendrites, have both been described in the hippocampus. What are the functional roles of the two types of coupling? Interneuron gap junctions enhance synchrony of gamma oscillations (25-70 Hz) in isolated interneuron networks and also in network...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.0337529100
更新日期:2003-02-04 00:00:00
abstract::"Head-to-head" terpene synthases catalyze the first committed steps in sterol and carotenoid biosynthesis: the condensation of two isoprenoid diphosphates to form cyclopropylcarbinyl diphosphates, followed by ring opening. Here, we report the structures of Staphylococcus aureus dehydrosqualene synthase (CrtM) complexe...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1010907107
更新日期:2010-12-14 00:00:00
abstract::Several nonclassical major histocompatibilty antigens (class Ib molecules) have emerged as key players in the early immune response to pathogens or stress. Class Ib molecules activate subsets of T cells that mount effector responses before the adaptive immune system, and thus are called innate T cells. MR1 is a novel ...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.0903196106
更新日期:2009-05-19 00:00:00
abstract::Social bees harbor a simple and specialized microbiota that is spatially organized into different gut compartments. Recent results on the potential involvement of bee gut communities in pathogen protection and nutritional function have drawn attention to the impact of the microbiota on bee health. However, the contrib...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1701819114
更新日期:2017-05-02 00:00:00
abstract::We have cloned a murine cDNA encoding a tyrosine kinase receptor with about 90% similarity to the chicken fibroblast growth factor (FGF) receptor and the human fms-like gene (FLG) tyrosine kinase. This mouse receptor lacks 88 amino acids in the extracellular portion, leaving only two immunoglobulin-like domains compar...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.87.11.4378
更新日期:1990-06-01 00:00:00
abstract::An electrophoretic karyotype of Aspergillus nidulans has been obtained using contour-clamped homogeneous electric field gel electrophoresis. Six chromosomal bands were separated, with two of the bands migrating as doublets. Using the Schizosaccharomyces pombe and Saccharomyces cerevisiae chromosomes as size standards,...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.86.16.6260
更新日期:1989-08-01 00:00:00
abstract::The formation of myelin by Schwann cells (SCs) occurs via a series of orchestrated molecular events. We previously used global expression profiling to examine peripheral nerve myelination and identified the NAD(+)-dependent deacetylase Sir-two-homolog 2 (Sirt2) as a protein likely to be involved in myelination. Here, ...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1104969108
更新日期:2011-10-25 00:00:00
abstract::There is a hypothesis that dangerous diseases such as bovine spongiform encephalopathy, Creutzfeldt-Jakob, Alzheimer's, fatal familial insomnia, and several others are induced by propagation of wrong or misfolded conformations of some vital proteins. If for some reason the misfolded conformations were acquired by many...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.0409389102
更新日期:2005-05-31 00:00:00
abstract::Eye-opening represents a turning point in the function of the visual cortex. Before eye-opening, the visual cortex is largely devoid of sensory inputs and neuronal activities are generated intrinsically. After eye-opening, the cortex starts to integrate visual information. Here we used in vivo two-photon calcium imagi...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.0907660106
更新日期:2009-09-01 00:00:00