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1.
Wine aroma 总被引:2,自引:0,他引:2
Conclusions The progress made in the analysis of volatile wine constituents has led to a better understanding of the complexity of wine aroma.Now many factors influencing wine aroma are not only characterized by their sensory impact, but also by chemical data which in many cases allow a more differentiated approach. By correlating sensory and analytical data headway has been made, especially in the field of wine off-odors. Successful analytical cultivar differentiation based on wine volatiles indicates the importance and possibilities of wine aroma for quality control. 相似文献
2.
准确诊断作物氮素营养状况是实现氮肥优化管理的前提.遥感可全覆盖、大面积同步监测作物多种形态和理化参数.将其应用于氮素营养诊断,对指导施肥管理具有重要意义.基于遥感手段开展作物氮素营养诊断研究已有几十年,将其成果加以总结,并分析存在的问题,有利于更好地促进遥感技术在该领域中应用.本文综述了基于遥感的作物氮素营养诊断技术发展现状,分析提炼了科学问题,在此基础上提出了本领域若干研究方向,期望能对相关领域研究者有所启发. 相似文献
3.
Differential display technology: a general guide 总被引:12,自引:0,他引:12
The 10 years since the invention of differential display technology (DD) has produced a massive amount of literature detailing
problems and improvements to the technique, successful gene expression studies and studies done using genes found through
the use of DD. In this review we summarise the results of 10 years of research that has focussed on improving DD and discuss
how some of the problems associated with DD can be resolved or minimised. In addition to discussing DD, we address issues
related to other differential gene expression analysis techniques and try to illustrate how these techniques can be used to
complement one's use of DD. This review also serves as an introduction to the taxa-specific DD review articles that are found
in this issue. 相似文献
4.
俄罗斯科技对外合作态势与中国当前对俄科技合作对策 总被引:2,自引:0,他引:2
科技全球化伴随着经济全球化而来,已经成为不可阻挡的时代潮流,迫切要求中国与俄罗斯加大科技合作力度,为此首先要研究俄罗斯科技对外合作态势,主要表现为:适应国内外科学技术发展的实际情况,确定对外科技合作的长期战略目标;积极加强对外科技合作的政策安排,采取有效形式推进对外科技合作事业;对外科技合作事业全面展开,注重依据利益原则分层次地加以推进。我们掌握俄罗斯对外科技合作进程,才能使中国及早采取相应的操作对策,把对俄科技合作放在重要位置,采取激励政策提高对俄罗斯科技合作水平,按照国际规则来加强科技合作,在分配知识产权时保障创造性利益,切实加强企业之间的科技交流与合作,从而推动科技合作与经贸合作紧密地结合起来。 相似文献
5.
H. Schellekens 《Cellular and molecular life sciences : CMLS》1989,45(6):558-562
Conclusions Concepts about interferon have changed dramatically over the years. Initially it was considered to be an antiviral protein which selectively inhibited the replication of viruses24. Over the years we have discovered an increasing number of interferons and many different biological activities. Other regulatory proteins have been detected and the interferons have become part of an interacting family of biological response-modifying proteins. Because of the complexity of these systems, animal experiments are the only way to assess the clinical potential of interferons (and interferon-like molecules). It is important that the animal experiments should not be too restricted in scope, because interferon has now proved to have activity in conditions other than viral infections, for example against tumors and infections other than those caused by viruses. 相似文献
6.
国内外运载火箭POGO抑制技术研究进展 总被引:2,自引:0,他引:2
本文描述了美国、前苏联、欧洲、日本和中国等国内外运载火箭跷振(POGO)抑制技术研究的发展历程及进展,并总结出国内外火箭POGO抑制技术的特点,以及在小POGO和气蚀动力学等方面带来的启示.美国的POGO抑制技术研究经历了大力神2——土星V——航天飞机——具体问题具体分析等4个阶段的发展历程,中国的POGO抑制技术研究也类似经历了331工程——载人航天工程——新一代火箭——40 Hz问题等4个阶段.由此可知,POGO振动抑制呈现出"事前理论预示难度大、事后危害后果严重、解决过程漫长曲折"的特点,必须在重大航天工程实施前开展研究. 相似文献
7.
This essay considers the development of the nuclear science programme in Malaysia from a transnational perspective by examining the interactions between state agents and other external nuclear-knowledge/technology related actors and agents. Going beyond the model of knowledge diffusion that brings together concerns articulated in Harris’s (2011) geographies of long distance knowledge and Reinhardt's (2011) role of the expert in knowledge transfer, the proposed three-phase model of knowledge transfer theorises the pathways undertaken by a late-blooming participant of modern science and technology as the latter moves from epistemic dependency to increasing independence despite the hurdles encountered, and the underdevelopment of many areas of its technoscientific economy. The model considers tensions stemming from the pressures of expediency for meeting national developmental goals on the one side, and the call to support the objectives of basic science on the other. The three phases of the model are epistemic transition, epistemic transplantation and localisation, and epistemic generation (ETTLG). As additional support for the proposed model, three arguments are proffered as deeper explanations of the epistemic goal by using Malaysia as a case study: knowledge transfer for political legitimization, knowledge transfer for countering agnotology, and knowledge transfer for social engineering and science diplomacy. 相似文献
8.
组合体热管理是优化交会对接载人组合体热控设计,实现长期载人热环境控制的重要手段.在对目标飞行器和载人飞船组合体热特性分析的基础上,提出了以舱段间通风为技术手段的交会对接载人组合体热管理方案,并结合热平衡试验数据,建立了组合体热管理系统分析模型.仿真结果、地面热平衡试验数据和在轨飞行数据表明,组合体密封舱内空气流速分布满足要求,温度在19~26°C可调,空气相对湿度在30%~70%范围内,验证了交会对接载人组合体热管理设计的正确性.最后对空间站等复杂组合体热管理设计提出了建议. 相似文献
9.
In this study we introduce a new indicator for private consumption based on search query time series provided by Google Trends. The indicator is based on factors extracted from consumption‐related search categories of the Google Trends application Insights for Search. The forecasting performance of the new indicator is assessed relative to the two most common survey‐based indicators: the University of Michigan Consumer Sentiment Index and the Conference Board Consumer Confidence Index. The results show that in almost all conducted in‐sample and out‐of‐sample forecasting experiments the Google indicator outperforms the survey‐based indicators. This suggests that incorporating information from Google Trends may offer significant benefits to forecasters of private consumption. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
10.
Allingham JS Klenchin VA Rayment I 《Cellular and molecular life sciences : CMLS》2006,63(18):2119-2134
Natural small-molecule inhibitors of actin cytoskeleton dynamics have long been recognized as valuable molecular probes for
dissecting complex mechanisms of cellular function. More recently, their potential use as chemotherapeutic drugs has become
a focus of scientific investigation. The primary focus of this review is the molecular mechanism by which different actin-targeting
natural products function, with an emphasis on structural considerations of toxins for which high-resolution structural information
of their interaction with actin is available. By comparing the molecular interactions made by different toxin families with
actin, the structural themes of those that alter filament dynamics in similar ways can be understood. This provides a framework
for novel synthetic-compound designs with tailored functional properties that could be applied in both research and clinical
settings.
Received 6 April 2006; received after revision 31 May 2006; accepted 19 June 2006 相似文献
11.
A. Viarengo L. Canesi M. Pertica D. R. Livingstone M. Orunesu 《Cellular and molecular life sciences : CMLS》1991,47(5):454-457
Summary The main cellular defence systems against free radical-mediated oxidative stress are significantly reduced in the dige+ive gland of aged (>10 years old) compared to younger (2–4 years old) mussels (Mytilus edulis L.). Moreover, the concentration of lipid peroxidation products (malondialdehyde) is increased in the same age group with respect to younger animals. The obtained data indicate that an impairment of the antioxidant defence systems would render the older animals more susceptible to peroxidative stress, thus supporting the general significance of the free radical theory of aging. 相似文献
12.
Lynnette Khong 《Studies in history and philosophy of science》2003,34(4):579-704
A central issue in the philosophy of technology concerns the relationship between technology and the conditions under which technology develops. Traditionally, two main accounts are given of this relationship. The social constructivist approach considers technology to be largely determined by “social” factors (e.g. military interests, economic policy). By contrast, technological determinism describes technology as self-determinative, and as following its own independent aim of greater efficiency. This paper discusses two alternatives to these conceptions of technology, namely, the accounts offered by Bruno Latour and Martin Heidegger. It examines their common theses that our present misunderstanding of technology is due to a continued commitment to the subject–object distinction. The paper further compares their accounts, which attempt to overcome this distinction, and argues that ultimately both authors fail to find a role for human beings that is consistent with their contention that we need to develop a less anthropocentric understanding of the world. 相似文献
13.
Kerry Patterson 《Journal of forecasting》2002,21(4):245-264
Much published data is subject to a process of revision due, for example, to additional source data, which generates multiple vintages of data on the same generic variable, a process termed the data measurement process or DMP. This article is concerned with several interrelated aspects of the DMP for UK Gross National Product. Relevant questions include the following. Is the DMP well behaved in the sense of providing a single stochastic trend in the vector time series of vintages? Is one of the vintages of data, for example the ‘final’, the sole vintage generating the long‐memory component? Does the multivariate framework proposed here add to the debate on the existence of a unit root in GNP? The likely implicit assumptions of users (that the DMP is well behaved and the final vintage is ‘best’) can be cast in terms of testable hypotheses; and we show that these ‘standard’ assumptions have not always been empirically founded. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献
14.
Comparative genome analyses reveal that most functional domains of human genes have homologs in widely divergent species.
These shared functional domains, however, are differentially shuffled among evolutionary lineages to produce an increasing
number of domain architectures. Combined with duplication and adaptive evolution, domain shuffling is responsible for the
great phenotypic complexity of higher eukaryotes. Although the domain-shuffling hypothesis is generally accepted, determining
the molecular mechanisms that lead to domain shuffling and novel gene creation has been challenging, as sequence features
accompanying the formation of known genes have been obscured by accumulated mutations. The growing availability of genome
sequences and EST databases allows us to study the characteristics of newly emerged genes. Here we review recent genome-wide
DNA and EST analyses, and discuss the three major molecular mechanisms of gene formation: (1) atypical spicing, both within
and between genes, followed by adaptation, (2) tandem and interspersed segmental duplications, and (3) retrotransposition
events.
Received 18 October 2006; received after revision 18 November 2006; accepted 28 November 2006 相似文献
15.
Compatible solutes of halophilic eubacteria: molecular principles,water-solute interaction,stress protection 总被引:20,自引:0,他引:20
E. A. Galinski 《Cellular and molecular life sciences : CMLS》1993,49(6-7):487-496
Compatible solutes are best described as organic osmolytes responsible for osmotic balance and at the same time compatible with the cells' metabolism. A comprehensive survey (using HPLC and NMR methods) on halophilic/halotolerant eubacteria has revealed the full diversity of compatible solutes employed in nature. Molecular principles derived from the spectrum of compounds found in the bacterial world may be summarized as follows. Compatible solutes are polar, highly soluble molecules and uncharged at physiological pH. With the exception of proline (a proteinogenic amino acid) they are characterized as amino acid derivatives of the following types: betaines, ectoines, N-acetylated diamino acids and N-derivatized carboxamides of glutamine. Using nearinfrared spectroscopy we have also been able to demonstrate that compatible solutes are strong water-structure formers and as such probably excluded from the hydration shell of proteins. This preferential exclusion probably explains their function as effective stabilizers of the hydration shell of native proteins (protection against heating freezing and drying). Hence these typical products of halophilic eubacteria have a considerable potential as stabilizing/protecting agents on both molecular and whole-cell level. Thorough understanding of common structural principles and fundamental water-solute interactions will ultimately enable us to design novel highly efficient stress protectants and stabilizers of biomolecules. 相似文献
16.
During the last decade we have learned much on physiological changes in the secretion of the pineal hormone melatonin (MLT) in man. Reportedly, there is little or no MLT secreted before age 3 months. Then MLT production commences, becmes circadian, and reaches highest nocturnal levels at the age of 1–3 years. During all of childhood nocturnal peak levles drop progressively by 80% until adult levels are reached. This alteration appears to be the consequence of increasing body size in face of constant MLT production during childhood. The biological significance of this MLT alteration is presently unknown. Because of conceptual considerations, major depressive syndrome (MDS) and seasonal affective disorder (SAD) have been in the focus of pineal research for several years. Although in these disorders alterations in MLT levels could not be substantiated, light therapy, a consequence of this research, was discovered as an effective treatment for SAD and perhaps for MDS. In addition, there is some recent evidence for low MLT levels in schizophrenia. Finally, the potential effect of MLT in neuroimmunoendocrine interactions is presently explored. Reportedly, in vitro studies and animal experiments give evidence for a modulatory role of MLT in the immune response. However, the exact way of this possible action of MLT remains to be clarified. Clinical studies are too scant for a meaningful estimation of MLT's involvement in human neuroimmunoendocrine interactions. 相似文献
17.
Social situations, the object of the social sciences, are complex and unique: they contain so many variable aspects that they cannot be reproduced, and it is even difficult to experience two situations that are alike in many respects. The social scientists' past experiences that serve as their background knowledge to intervene in an existent situation is poor compared to what a traditional epistemologist would consider ideal. A way of dealing with the variable and insufficient background of social scientists is by means of models. But, then, how should we characterize social scientific models? This paper examines Otto Neurath's scientific utopianism as an attempt to deal with this problem. Neurath proposes that social scientists work with utopias: broad imaginative plans that coordinate a multitude of features of a social situation. This notion can be used in current debates in philosophy of science because we notice that utopias, in Neurath's sense, are comparable to models and nomological machines in Nancy Cartwright's conception. A model-based view of science lays emphasis on the fact that scientists learn from the repeated operation of such abstract entities, just as they learn from the repetition of experiments in a laboratory. Hence this approach suggests an approximation between the natural and the social sciences, as well as between science and utopian literature. This is exemplified by analyzing the literary dystopia We, written by Yevgeny Zamyatin, to show that reasoning from and debating about utopian writings, even if fictional and pessimistic, creates phenomena of valuation, which are fundamental for constituting a background of experiences in the social sciences. 相似文献
18.
国防风险投资:美国的探索与启示 总被引:1,自引:0,他引:1
为更迅速地利用工商业界的技术成果,促进国防科技创新,降低国防科技发展成本,美国在国防科研投入不断下降的背景下,对国防风险投资进行了探索。本文对美国国防风险投资兴起的动因和实践探索进行了分析,并对美国对风险投资在国防科研领域的尝试进行了追溯;综述了美国理论界对国防风险投资的研究成果,并对我国借鉴风险投资发展武器装备提出了建议。 相似文献
19.
The burgeoning field of studies in expertise and experience (SEE) is a useful theoretical approach to complex problems. In light of SEE, examination of the controversial and well known case study of dolphin bycatch in the US tuna fishery, reveals that effective problem-solving was hindered by institutional tensions in respect of decision-making authority and difficulties with the integration of different expertises. Comparing the profiles of four individuals, who played distinct roles in the problem-solving process, I show that (1) to address a complex problem, a suite of contributory expertises—rarely found in one individual—may be required; (2) formal credentials are not a reliable indicator of who possesses these necessary expertises; (3) interactional expertise and interactive ability are useful tools in combining the contributory expertises of others to yield a desirable collective outcome; and (4) the concepts of contributory expertise and no expertise are useful tools for understanding the actual contribution of various parties to the problem-solving process. 相似文献
20.
I analyse the case of three Japanese-Portuguese interpreters who have given support to technology transfer from a steel company in Japan to one in Brazil for more than thirty years. Their job requires them to be ‘interactional experts’ in steel-making. The Japanese–Portuguese interpreters are immersed in more than the language of steel-making as their job involves a great deal of ‘physical contiguity’ with steel-making practice. Physical contiguity undoubtedly makes the acquisition of interactional expertise easier. This draws attention to the lack of empirical work on the exact way that the physical and the linguistic interact in the acquisition of interactional expertise, or any other kind of expertise. 相似文献