排序方式: 共有69条查询结果,搜索用时 31 毫秒
51.
基于BONeS设计系统的多媒体互联网通讯仿真 总被引:1,自引:1,他引:0
BONeS是美国Cadence公司Alta Group开发出的一套用于网络通讯仿真和计算机结构分析的系统设计自动化工具。介绍利用该工具进行多媒体互联网通讯仿真设计,并根据TCP/IP的确认重发和滑动窗口流量控制机制,分析TCP/IP协议的不同重发延迟和窗口设置方案对多媒通讯QoS的影响。 相似文献
52.
Eric J. R. Jansen Nick H. M. van Bakel Anthon J. M. Coenen Sander H. van Dooren Hermina A. M. van Lith Gerard J. M. Martens 《Cellular and molecular life sciences : CMLS》2010,67(4):629-640
The vacuolar (H+)-ATPase (V-ATPase) is the main regulator of intraorganellar pH and in neuroendocrine cells is controlled by its accessory
subunit, Ac45. Here, we report the discovery of the first isoform of a V-ATPase accessory subunit, namely an Ac45-like protein,
denoted Ac45LP. Phylogenetic analysis revealed a lineage-dependent evolutionary history: Ac45 is absent in birds, and Ac45LP
is absent in placental mammals, whereas all other tetrapod species contain both genes. In contrast to Ac45, Ac45LP is not
proteolytically cleaved, a prerequisite for proper Ac45 routing. Intriguingly, Xenopus Ac45LP mRNA was expressed in developing neural tissue and in neural crest cells. In adult Xenopus, Ac45 mRNA is widely expressed mostly in neuroendocrine tissues, while Ac45LP mRNA expression was found to be restricted
to the kidney and the lung. This novel Ac45LP may provide additional possibilities for V-ATPase regulation during neurodevelopment
as well as in kidney and lung cells. 相似文献
53.
The tetracycline resistome 总被引:2,自引:0,他引:2
Maulik Thaker Peter Spanogiannopoulos Gerard D. Wright 《Cellular and molecular life sciences : CMLS》2010,67(3):419-431
Resistance to tetracycline emerged soon after its discovery six decades ago. Extensive clinical and non-clinical uses of this
class of antibiotic over the years have combined to select for a large number of resistant determinants, collectively termed
the tetracycline resistome. In order to impart resistance, microbes use different molecular mechanisms including target protection,
active efflux, and enzymatic degradation. A deeper understanding of the structure, mechanism, and regulation of the genes
and proteins associated with tetracycline resistance will contribute to the development of tetracycline derivatives that overcome
resistance. Newer generations of tetracyclines derived from engineering of biosynthetic genetic programs, semi-synthesis,
and in particular recent developments in their chemical synthesis, together with a growing understanding of resistance, will
serve to retain this class of antibiotic to combat pathogens. 相似文献
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55.
't Hooft G Susskind L Witten E Fukugita M Randall L Smolin L Stachel J Rovelli C Ellis G Weinberg S Penrose R 《Nature》2005,433(7023):257-259
56.
Dumitrescu AM Liao XH Abdullah MS Lado-Abeal J Majed FA Moeller LC Boran G Schomburg L Weiss RE Refetoff S 《Nature genetics》2005,37(11):1247-1252
Incorporation of selenocysteine (Sec), through recoding of the UGA stop codon, creates a unique class of proteins. Mice lacking tRNA(Sec) die in utero, but the in vivo role of other components involved in selenoprotein synthesis is unknown, and Sec incorporation defects have not been described in humans. Deiodinases (DIOs) are selenoproteins involved in thyroid hormone metabolism. We identified three of seven siblings with clinical evidence of abnormal thyroid hormone metabolism. Their fibroblasts showed decreased DIO2 enzymatic activity not linked to the DIO2 locus. Systematic linkage analysis of genes involved in DIO2 synthesis and degradation led to the identification of an inherited Sec incorporation defect, caused by a homozygous missense mutation in SECISBP2 (also called SBP2). An unrelated child with a similar phenotype was compound heterozygous with respect to mutations in SECISBP2. Because SBP2 is epistatic to selenoprotein synthesis, these defects had a generalized effect on selenoproteins. Incomplete loss of SBP2 function probably causes the mild phenotype. 相似文献
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58.
Gerard H. Fairtlough 《Systemic Practice and Action Research》1991,4(6):547-563
The philosophical basis for Jurgen Habermas' later work is a communicative one: our ability to understand nature, society, and even ourselves arises from our communication with each other. Lifeworld is a key concept in this work, elaborated well beyond the lifeworld concept in the work of, e.g., Schutz. This paper describes Habermas' theory, relating it to his theories of communicative action and of societal steering media. It also suggests some parallels with the work of Vickers and makes proposals for the practical use of Habermas' lifeworld concept. 相似文献
59.
介绍了基于GPS全球定位系统和Internet/Intranet实现的便携式负荷预估系统,包括硬件的开发和系统结构。基于此,一种利用残差白噪声的新算法已经成功地用于提取系统的模态信息,即震荡频率和震荡阻尼度的信息。该测量系统已经应用于澳大利亚电力系统,并成功地提取出了系统的震荡信息。分析结果表明,新算法能够完全提取出系统的震荡情况,包括震荡频率和震荡阻尼,并具有较好的稳定性和可靠性。 相似文献
60.
对用过滤法制备的介电梯度功能材料的介电特性作了阐述,并用计算机模拟的方法研究了其对电场分布的影响,进而对其在工程实际中的应用作了讨论. 相似文献