排序方式: 共有18条查询结果,搜索用时 375 毫秒
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Benharrat BELAIDI 《系统科学与复杂性》2007,20(1):41-46
In this paper, we investigate the growth of meromorphic solutions of higher order linear differential equation f^(k) +Ak-1 (z)e^Pk-1^(z) f^(k-1) +…+A1 (z)e^P1(z) f′ +Ao(z)e^Po(z) f = 0 (k ≤ 2), where Pj(z) (j = 0, 1,..., k - 1) are nonconstant polynomials such that deg Pj = n (j = 0, 1,..., k - 1) and Aj(z)(≠ 0) (j = 0, 1,..., k - 1) are meromorphic functions with order p(Aj) 〈 n (j = 0, 1,..., k - 1). 相似文献
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Bela H. Banathy 《Systemic Practice and Action Research》1988,1(2):193-212
The aim of this paper is to highlight the current inadequacies of contemporary education and then to outline a methodological approach by which we can redesign and implement an educational system that is more appropriate to the postindustrial/information age in which we now live. A brief discussion of an application is given in order to exemplify the proposed systemic approach. 相似文献
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Alpha-helical coiled coils in muscle exemplify simplicity and economy of protein design: small variations in sequence lead to remarkable diversity in cellular functions. Myosin II is the key protein in muscle contraction, and the molecule's two-chain alpha-helical coiled-coil rod region--towards the carboxy terminus of the heavy chain--has unusual structural and dynamic features. The amino-terminal subfragment-2 (S2) domains of the rods can swing out from the thick filament backbone at a hinge in the coiled coil, allowing the two myosin 'heads' and their motor domains to interact with actin and generate tension. Most of the S2 rod appears to be a flexible coiled coil, but studies suggest that the structure at the N-terminal region is unstable, and unwinding or bending of the alpha-helices near the head-rod junction seems necessary for many of myosin's functional properties. Here we show the physical basis of a particularly weak coiled-coil segment by determining the 2.5-A-resolution crystal structure of a leucine-zipper-stabilized fragment of the scallop striated-muscle myosin rod adjacent to the head-rod junction. The N-terminal 14 residues are poorly ordered; the rest of the S2 segment forms a flexible coiled coil with poorly packed core residues. The unusual absence of interhelical salt bridges here exposes apolar core atoms to solvent. 相似文献
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T. Várkonyi A. Antal M. Gábor S. Benkő 《Cellular and molecular life sciences : CMLS》1971,27(8):936-937
Zusammenfassung Eine erhöhte Permeabilität der Blut-Hirn-Schranke für Evans-Blau wurde bei Ratten nach einer Flavon-Mangeldiät festgestellt. 相似文献
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在过去的20年,科研工作者已经在分子肿瘤领域取得了划时代的重大发现,这很大程度上归功于免疫组织化学方法的应用。这一方法在脑肿瘤研究中也已经从试验阶段走向了成熟。 相似文献
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The Hill equation and the origin of quantitative pharmacology 总被引:1,自引:0,他引:1
Rudolf Gesztelyi Judit Zsuga Adam Kemeny-Beke Balazs Varga Bela Juhasz Arpad Tosaki 《Archive for History of Exact Sciences》2012,66(4):427-438
This review addresses the 100-year-old Hill equation (published in January 22, 1910), the first formula relating the result
of a reversible association (e.g., concentration of a complex, magnitude of an effect) to the variable concentration of one
of the associating substances (the other being present in a constant and relatively low concentration). In addition, the Hill
equation was the first (and is the simplest) quantitative receptor model in pharmacology. Although the Hill equation is an
empirical receptor model (its parameters have only physico-chemical meaning for a simple ligand binding reaction), it requires
only minor a priori knowledge about the mechanism of action for the investigated agonist to reliably fit concentration-response
curve data and to yield useful results (in contrast to most of the advanced receptor models). Thus, the Hill equation has
remained an important tool for physiological and pharmacological investigations including drug discovery, moreover it serves
as a theoretical basis for the development of new pharmacological models. 相似文献