Abstract:
:It is found that the addition of hexamethylphosphoramide to the solution of an alkyne, Et(2)Zn, and (S)-1,1'-bi-2-naphthol in methylene chloride allows the generation of an alkynylzinc at room temperature and shows highly enantioselective additions to aldehydes. The mild condition for the formation of the alkynylzinc reagent enables the use of functional alkynes in this asymmetric reaction with excellent enantioselectivity. It avoids the reflux of the toluene solutions of the alkynes and Et(2)Zn as previously reported.
journal_name
Proc Natl Acad Sci U S Aauthors
Gao G,Xie RG,Pu Ldoi
10.1073/pnas.0307136101keywords:
subject
Has Abstractpub_date
2004-04-13 00:00:00pages
5417-20issue
15eissn
0027-8424issn
1091-6490pii
0307136101journal_volume
101pub_type
杂志文章abstract::Somatic fungal hyphae are generally assumed to elongate at steady linear rates when grown under constant environmental conditions with ample nutrients. However, patterns of pulsed hyphal elongation were detected during apparent steady growth of hyphal tips in fungi from several major taxonomic groups (Oomycetes, Pythi...
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.91.25.12228
更新日期:1994-12-06 00:00:00
abstract::The p21(WAF1) (p21) cyclin-dependent kinase inhibitor plays a major role in regulating cell cycle arrest. It was recently reported that the p53-independent elevation of p21 protein levels is essential in mediating the G(1) arrest resulting from signal transduction events initiated by the crosslinking of membrane IgM 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.96.15.8711
更新日期:1999-07-20 00:00:00
abstract::Recent anatomical tracing studies have yielded substantial amounts of data on the areal connectivity underlying distributed processing in cortex, yet the fundamental principles that govern the large-scale organization of cortex remain unknown. Here we show that functional similarity between areas as defined by the pat...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
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abstract::Glioblastoma multiforme (GBM) is one of the most intractable of human cancers, principally because of the highly infiltrative nature of these neoplasms. Tracking and eradicating infiltrating GBM cells and tumor microsatellites is of utmost importance for the treatment of this devastating disease, yet effective strateg...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
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更新日期:2016-11-29 00:00:00
abstract::Protein tyrosine phosphatase (PTP)σ (PTPRS) was shown previously to be associated with susceptibility to inflammatory bowel disease (IBD). PTPσ(-/-) mice exhibit an IBD-like phenotype in the intestine and show increased susceptibility to acute models of murine colitis. However, the function of PTPσ in the intestine is...
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.1315017111
更新日期:2014-01-14 00:00:00
abstract::We have shown previously that hydroxyl radicals (HO*) can be produced by H2O2 and halogenated quinones, independent of transition metal ions; however, the underlying molecular mechanism is still unclear. In the present study, using the electron spin resonance secondary radical spin-trapping method, we found that tetra...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
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doi:10.1073/pnas.0704030104
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abstract::Alzheimer's disease (AD) and other neurodegenerative disorders are associated with the cytoplasmic aggregation of microtubule-associated protein tau. Recent evidence supports transcellular transfer of tau misfolding (seeding) as the mechanism of spread within an affected brain, a process reminiscent of viral infection...
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abstract::A potential new approach for gene therapy against human immunodeficiency virus type 1 (HIV-1) infection is the design of a nonstructural gene-based virion-specific inhibitory molecule that is packaged with virus to destroy its infectivity. We tested this approach for HIV-1 by using Vpx, a virion-associated protein of ...
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.90.8.3544
更新日期:1993-04-15 00:00:00
abstract::On illuminating chloroplasts with "short-wavelength" monochromatic light that supports oxygen evolution, spectral evidence was obtained for a new photoreactive chloroplast component, provisionally designated C550, which shows a reversible decrease of absorbance with a maximum at 550 mmu. The light-induced absorbance c...
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.63.3.963
更新日期:1969-07-01 00:00:00
abstract::The concentration of urea in renal medullary cells is high enough to affect enzymes seriously by reducing Vmax or raising Km, yet the cells survive and function. The usual explanation is that the methylamines found in the renal medulla, namely glycerophosphocholine and betaine, have actions opposite to those of urea a...
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.96.11.6517
更新日期:1999-05-25 00:00:00
abstract::DNA damage leads to a halt in proliferation owing to apoptosis or senescence, which prevents transmission of DNA alterations. This cellular response depends on the tumor suppressor p53 and functions as a powerful barrier to tumor development. Adult stem cells are resistant to DNA damage-induced apoptosis or senescence...
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.1213394110
更新日期:2013-03-05 00:00:00
abstract::The mechanisms that cause aging are not well understood. The oxidative stress hypothesis proposes that the changes associated with aging are a consequence of random oxidative damage to biomolecules. We hypothesized that oxidation of specific proteins is critical in controlling the rate of the aging process. Utilizing ...
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.94.21.11168
更新日期:1997-10-14 00:00:00
abstract::We report here on the isolation and characterization of a serotonin (5HT) transporter from Drosophila melanogaster. A 3.1-kb complementary DNA clone (dSERT) was found to encode a protein of 622 amino acid residues with a predicted molecular mass of approximately 69 kDa and a putative transmembrane topology characteris...
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.91.11.5158
更新日期:1994-05-24 00:00:00
abstract::During the late summer to fall of 1987, Caribbean reef corals experienced an intense and widespread discoloration event described as bleaching. Contrary to initial predictions, most bleached corals did not die. However, energy input from zooxanthellae decreased, as estimated from: (i) delta(13)C values, a measure of 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.86.23.9342
更新日期:1989-12-01 00:00:00
abstract::Platelet-derived growth factors (PDGFs) and their receptors (PDGFRs) are prototypic growth factors and receptor tyrosine kinases which have critical functions in development. We show that PDGFs share a conserved region in their prodomain sequences which can remain noncovalently associated with the mature cystine-knot ...
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.1000806107
更新日期:2010-06-22 00:00:00
abstract::The inability to perceive and coordinate both internal and external signals that function to regulate cellular growth and proliferation is a hallmark of oncogenic transformation. To examine the effects of the v-mos oncogene on distinct signal transduction pathways, the 6m2 cell line was used, in which expression of th...
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.86.2.597
更新日期:1989-01-01 00:00:00
abstract::We have investigated the interaction of human cytomegalovirus (CMV) with cultured primary granulocyte-macrophage progenitors, a suspected natural site of viral latency, and have established conditions for latent infection and reactivation in this cell population. Progenitor cells from human fetal liver or bone marrow ...
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.91.25.11879
更新日期:1994-12-06 00:00:00
abstract::Complement membrane attack complexes (MACs) promote inflammatory functions in endothelial cells (ECs) by stabilizing NF-κB-inducing kinase (NIK) and activating noncanonical NF-κB signaling. Here we report a novel endosome-based signaling complex induced by MACs to stabilize NIK. We found that, in contrast to cytokine-...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
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abstract::Genetic analysis for group selection is developed for the case of a biallelic locus (A, a) undergoing group selection of founder populations only. By contrast to R. Levins"E = E(x) models, extinction now depends on genetics at the propagule stage but acts uniformly on larger populations. Biological evidence supports 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.75.4.1909
更新日期:1978-04-01 00:00:00
abstract::Cystic fibrosis (CF) is an autosomal recessive disorder, the most common lethal genetic disease in Caucasians. Respiratory disease is the major cause of morbidity and mortality. Indeed, 95% of CF patients die of respiratory failure. Pseudomonas aeruginosa, an opportunistic pathogen, chronically infects the lungs of ov...
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.95.10.5718
更新日期:1998-05-12 00:00:00
abstract::The two internal transcribed spacers (ITS1 and ITS2) of rDNA of three members of the Ixodes ricinus "complex" (Acari: Ixodidae) were sequenced. Sequence variation was assessed for the North American species I. scapularis, I. dammini, and I. pacificus at three levels: within individual/population, between individuals 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.90.21.10221
更新日期:1993-11-01 00:00:00
abstract::The effect of combining hormonal treatment consisting of long-acting microcapsules of the agonist [D-Trp6]LH-RH (the D-tryptophan-6 analog of luteinizing hormone-releasing hormone) with the chemotherapeutic agent cyclophosphamide was investigated in the Dunning R-3327H rat prostate cancer model. Microcapsules of [D-Tr...
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.82.8.2498
更新日期:1985-04-01 00:00:00
abstract::The explosive growth in citizen science combined with a recalcitrance on the part of mainstream science to fully embrace this data collection technique demands a rigorous examination of the factors influencing data quality and project efficacy. Patterns of contributor effort and task performance have been well reviewe...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章,meta分析
doi:10.1073/pnas.1807186115
更新日期:2019-02-05 00:00:00
abstract::Although much of the brain's functional organization is genetically predetermined, it appears that some noninnate functions can come to depend on dedicated and segregated neural tissue. In this paper, we describe a series of experiments that have investigated the neural development and organization of one such noninna...
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.95.3.847
更新日期:1998-02-03 00:00:00
abstract::Many thylakoid lumen proteins are synthesized outside the chloroplast as larger molecular weight precursors and then processed to their mature size during transport to the lumenal space. We have examined the post-translational processing of thylakoid lumen proteins in vivo by pulse-radiolabeling experiments with Chlam...
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.90.5.1862
更新日期:1993-03-01 00:00:00
abstract::The nucleotide cyclic di-3',5'- adenosine monophosphate (c-di-AMP) was recently identified as an essential and widespread second messenger in bacterial signaling. Among c-di-AMP-producing bacteria, altered nucleotide levels result in several physiological defects and attenuated virulence. Thus, a detailed molecular un...
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.1416485112
更新日期:2015-02-17 00:00:00
abstract::Cytochrome c peroxidase reacts with peroxide to form compound I, which contains an oxyferryl heme and an indolyl radical at Trp-191. The indolyl free radical has a half-life of several hours at room temperature, and this remarkable stability is essential for the catalytic function of cytochrome c peroxidase. To probe ...
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.91.23.11118
更新日期:1994-11-08 00:00:00
abstract::Cultures were prepared of embryonic cells from Drosophila melanogaster. Neurons and myocytes differentiated in vitro from their respective stem cells. Electron microscopy showed that neuromuscular junctions formed where axons contacted myocytes. Electrical stimuli were applied to axons and these caused contractions of...
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.69.3.566
更新日期:1972-03-01 00:00:00
abstract::Mosquitoes transmit devastating human diseases because they need vertebrate blood for egg development. Metabolism in female mosquitoes is tightly coupled with blood meal-mediated reproduction, which requires an extremely high level of energy consumption. Functional analysis has shown that major genes encoding for enzy...
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.1619326114
更新日期:2017-03-28 00:00:00
abstract::Most current gene transfer methods function satisfactorily in specialized systems involving established cell lines but are often not applicable with nonadherent, primary hematopoietic cells, which are notoriously difficult to transfect. To approach this problem, we have investigated an alternative method of gene trans...
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.87.10.3655
更新日期:1990-05-01 00:00:00