排序方式: 共有114条查询结果,搜索用时 15 毫秒
91.
Erler J Birge N Kortelainen M Nazarewicz W Olsen E Perhac AM Stoitsov M 《Nature》2012,486(7404):509-512
In 2011, 100 new nuclides were discovered. They joined the approximately 3,000 stable and radioactive nuclides that either occur naturally on Earth or are synthesized in the laboratory. Every atomic nucleus, characterized by a specific number of protons and neutrons, occupies a spot on the chart of nuclides, which is bounded by 'drip lines' indicating the values of neutron and proton number at which nuclear binding ends. The placement of the neutron drip line for the heavier elements is based on theoretical predictions using extreme extrapolations, and so is uncertain. However, it is not known how uncertain it is or how many protons and neutrons can be bound in a nucleus. Here we estimate these limits of the nuclear 'landscape' and provide statistical and systematic uncertainties for our predictions. We use nuclear density functional theory, several Skyrme interactions and high-performance computing, and find that the number of bound nuclides with between 2 and 120 protons is around 7,000. We find that extrapolations for drip-line positions and selected nuclear properties, including neutron separation energies relevant to astrophysical processes, are very consistent between the models used. 相似文献
92.
Beatriz Domingo María Gasset Mario Durán-Prado Justo P. Castaño Antonio Serrano Thierry Fischer Juan Llopis 《Cellular and molecular life sciences : CMLS》2010,67(19):3345-3354
Membrane protein function is determined by the relative organization of the protein domains with respect to the membrane.
We have experimentally verified the topology of a protein with diverse orientations arising from a single primary sequence
(the cellular prion protein, PrPC), a novel somatostatin truncated receptor, and the Golgi-associated protein GPBP91. Tagging with fluorescent proteins (FP) allows location of their expression at the plasma membrane or at endomembranes, but
does not inform about their orientation. Exploiting the pH dependency of some FPs, we developed a pH exchange assay in which
extracellularly exposed FPs are quenched by application of low pH buffer. We constructed standards to demonstrate and calibrate
the assay, and the method was adapted for acidic organelle membrane proteins. This method can serve as a proof of concept,
experimentally confirming and/or discriminating in living cells among theoretical topology predictions, providing the proportion
of inside/outside orientation for proteins with multiple forms. 相似文献
93.
Hanns Ulrich Zeilhofer Mario A. Acuña Jacinthe Gingras Gonzalo E. Yévenes 《Cellular and molecular life sciences : CMLS》2018,75(3):447-465
Glycinergic neurotransmission has long been known for its role in spinal motor control. During the last two decades, additional functions have become increasingly recognized—among them is a critical contribution to spinal pain processing. Studies in rodent pain models provide proof-of-concept evidence that enhancing inhibitory glycinergic neurotransmission reduces chronic pain symptoms. Apparent strategies for pharmacological intervention include positive allosteric modulators of glycine receptors and modulators or inhibitors of the glial and neuronal glycine transporters GlyT1 and GlyT2. These prospects have led to drug discovery efforts in academia and in industry aiming at compounds that target glycinergic neurotransmission with high specificity. Available data show promising analgesic efficacy. Less is currently known about potential unwanted effects but the presence of glycinergic innervation in CNS areas outside the nociceptive system prompts for a careful evaluation not only of motor function, but also of potential respiratory impairment and addictive properties. 相似文献
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95.
M.卢塞提尼 《国外科技新书评介》2006,(7):9-10
这是一本介绍现代工程系统演化过程中的技术概念和数学模型的书,包括控制、管理、组织等方面内容。二战后工业时代的生产模式使得工程师们开始考虑信息、决策、质量这些抽象的概念。过程技术强调的重点就是实物和信息的计划与控制,随着大生产方式、自动化、控制、通讯与信息技术的改革和发展,工程技术已经成为现代工程的显著特点。 相似文献
96.
A truncating mutation of HDAC2 in human cancers confers resistance to histone deacetylase inhibition 总被引:1,自引:0,他引:1
Ropero S Fraga MF Ballestar E Hamelin R Yamamoto H Boix-Chornet M Caballero R Alaminos M Setien F Paz MF Herranz M Palacios J Arango D Orntoft TF Aaltonen LA Schwartz S Esteller M 《Nature genetics》2006,38(5):566-569
Disruption of histone acetylation patterns is a common feature of cancer cells, but very little is known about its genetic basis. We have identified truncating mutations in one of the primary human histone deacetylases, HDAC2, in sporadic carcinomas with microsatellite instability and in tumors arising in individuals with hereditary nonpolyposis colorectal cancer syndrome. The presence of the HDAC2 frameshift mutation causes a loss of HDAC2 protein expression and enzymatic activity and renders these cells more resistant to the usual antiproliferative and proapoptotic effects of histone deacetylase inhibitors. As such drugs may serve as therapeutic agents for cancer, our findings support the use of HDAC2 mutational status in future pharmacogenetic treatment of these individuals. 相似文献
97.
Toward simpler and faster genome-wide mutagenesis in mice 总被引:8,自引:0,他引:8
Here we describe a practical Cre-loxP and piggyBac transposon-based mutagenesis strategy to systematically mutate coding sequences and/or the vast noncoding regions of the mouse genome for large-scale functional genomic analysis. To illustrate this approach, we first created loxP-containing loss-of-function alleles in the protocadherin alpha, beta and gamma gene clusters (Pcdha, Pcdhb and Pcdhg). Using these alleles, we show that, under proper guidance, Cre-loxP site-specific recombination can mediate efficient trans-allelic recombination in vivo, facilitating the generation of large germline deletions and duplications including deletions of Pcdha, and Pcdha to Pcdhb, simply by breeding (that is, at frequencies of 5.5%-21.6%). The same breeding method can also generate designed germline translocations between nonhomologous chromosomes at unexpected frequencies of greater than 1%. By incorporating a piggyBac transposon to insert and to distribute loxP sites randomly throughout the mouse genome, we present a simple but comprehensive method for generating genome-wide deletions and duplications, in addition to insertional loss-of-function and conditional rescue alleles, again simply by breeding. 相似文献
98.
The ability to accurately characterize projects is essential to good project management. Therefore, a novel project characteristic is developed that reflects the value accrue within a project. This characteristic, called project regularity, is expressed in terms of the newly introduced regular/irregular-indicator RI. The widely accepted management system of earned value management (EVM) forms the basis for evaluation of the new characteristic. More concretely, the influence of project regularity on EVM forecasting accuracy is assessed, and is shown to be significant for both time and cost forecasting. Moreover, this effect appears to be stronger than that of the widely used characteristic of project seriality expressed by the serial/parallel-indicator SP. Therefore, project regularity could also be useful as an input parameter for project network generators. Furthermore, the introduction of project regularity can provide project managers with a more accurate indication of the time and cost forecasting accuracy that is to be expected for a certain project and, correspondingly, of how a project should be built up in order to obtain more reliable forecasts during project control. 相似文献
99.
Mario Bunge 《Foundations of Science》2017,22(4):695-707
Axiomatization is uncommon outside mathematics, partly for being often viewed as embalming, partly because the best-known axiomatizations have serious shortcomings, and partly because it has had only one eminent champion, namely David Hilbert (Math Ann 78:405–415, 1918). The aims of this paper are (a) to describe what will be called dual axiomatics, for it concerns not just the formalism, but also the meaning (reference and sense) of the key concepts; and (b) to suggest that every instance of dual axiomatics presupposes some philosophical view or other. To illustrate these points, a theory of solidarity will be crafted and axiomatized, and certain controversies in both classical and quantum physics, as well as in the philosophy of mind, will be briefly discussed. The upshot of this paper is that dual axiomatics, unlike the purely formal axiomatics favored by the structuralists school, is not a luxury but a tool helping resolve some scientific controversies. 相似文献
100.