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1.
Summary The authors have succeeded in isolating alliin in a pure, crystalline form and in defining its properties. Alliin is characteristic for certain kinds of garlic; it contains sulphur and nitrogen and represents the initial substance of garlic oil. Alliin itself has no bactericidal action. Upon decomposition—caused by a specific concomitant enzyme, alliinase—the highly bactericidal substance, allicin, is produced. Further decomposition yields the volatile, sharply-odorous allyl-sulphides.  相似文献   

2.
采用绿色环保超级电容器作为储能器件,开发出了一套带MPPT功能的太阳能照明控制器。控制器以入门级ARM7芯片LPC2103为控制核心;用MAX16834设计LED驱动电路;采用固定电压法结合变步长的扰动观察法对太阳能电池板进行最大功率跟踪,提高利用效率;通过软件设计的优化,获得更长的照明时间。通过实地测试发现,该控制器比传统的照明控制器拥有更好的利用率,具有实用价值。  相似文献   

3.
已有研究表明与普通水泥砂浆相比,采用相同水灰比的聚氨酯水泥砂浆可以获得较好的耐久性。本文把聚氨酯作为混凝土改性材料,经初步研究发现,掺入聚氨酯的混凝土坍落度损失增大,向混凝土中加入聚羧酸减水剂解决了这一问题。本文通过试验以抗压强度为指标初步优化了聚氨酯改性混凝土的养护条件和加料顺序。此外,加入到混凝土中的匀泡剂由于对聚氨酯有极优异的乳化能力,有可能形成了极细的泡孔和狭窄的孔径分布以及极高的闭孔率,可以提高聚氨酯混凝土的耐久性。本文选择了不同厂家提供的甲、乙两种匀泡剂并进行强度试验,以抗压强度为指标选择强度较高一种的应用于聚氨酯改性混凝土。  相似文献   

4.
Conclusions Some of the papers to follow in the present series of communications on toxinology will show that in the field of chemistry, physiology, pharmacology and immunology, as well as molecular biology, animal venoms provide us with some particularly useful models. Obviously, this is one of the main reasons for the growing interest shown by numerous scientists in animal toxins.With reference to medicine, more research is needed in the field just mentioned with the aim of improving medical care. In addition, however, it is postulated that research on the behaviour of venomous animals towards man, and research into the quantities of venom actually applied to man, be intensified. Also, on the basis of results in this context, people most exposed could be provided with more and better information about prevention.Work of this sort requests the collaboration of biologists, who observe toxic animals in their natural habitat and who investigate in particular when, and under what prerogatives, the animals make use of toxins in their natural surroundings. Thus we end up with what has been said in the introduction to these notes: toxic animals are to be studied as entities and toxicity has to be looked at from all aspects essential for life, possibly including parasite and population control.Should the very last point prove valid, fascinating links could be established between toxinology and ecology and in turn migt become important for nature conservation. Thus, toxinology is but a budding field, the limits of which, can yet only be assumed.  相似文献   

5.
This paper discusses Leibniz’s interpretation and criticism of Hobbesian materialism in the period 1698-1705. Leibniz had continued to be interested in Hobbes’s work, despite not engaging with it as intensively as he did earlier (around 1670). Leibniz offers an interpretation of Hobbes that explains Hobbes’s materialism as derived from his imagistic theory of ideas. Leibniz then criticizes Hobbes’s view as being based on a faulty theory of ideas, and as having problematic consequences, particularly with regard to what one says about God. Some of this criticism is found in the New essays, but equally significant is Leibniz’s correspondence with Damaris Masham, who proposed an argument for materialism very much like that which Leibniz attributed to Hobbes. The paper concludes by discussing the suggestion that Leibniz at this time, particularly in the New essays, himself adopted Hobbesian ideas. Though Leibniz did use some of Hobbes’s examples, and did think at this time that all souls were associated with bodies, the resulting position is still rather distant from Hobbesian materialism.  相似文献   

6.
目前分布式电网的潮流优化算法主要面对三相功率平衡系统,对于三相不平衡系统进行分析的算法介绍较少.文中利用内点法,结合美国电科院的开放式配电仿真系统分析(OpenDSS)平台,提出了三相不平衡分布式电网潮流优化算法的研究.该算法以网损和变压器三相潮流不平衡度最小为目标,以系统潮流、发电机和线路极限容量为约束,以变压器分接头和电容器投切为控制变量,建立了优化函数,利用内点法作为优化算法,以 OpenDSS为计算平台.文中最后以 IEEE123测试节点和 IEEE9500测试节点为例,验证了文中算法的有效性和实用性  相似文献   

7.
以若干个连续交叉口构成的关联交叉口序列为单位,对平面信号交叉口相位的禁/放行状态进行优化建模;建立以减少延误时间和平均排队长度为目标,同时考虑驾驶员的主观心理一生理因素,寻求平面信号最优控制交叉口配时参数为最终目标的三层路网优化控制模型;最后构造出与驾驶加速度紧密关联的、三层模型架构下的目标策略函数。  相似文献   

8.
针对我国事业单位人力资源管理改革面临着管理者角色重新定位、人才流动性加快、员工忠诚度降低等的挑战,本文从组织支持感知角度,构建事业单位人力资源管理模型。通过结构方程研究发现,我国事业单位员工的薪酬满意度、对LMX的理解、对于单位职业发展机会的理解、员工认为单位的工作家庭支持以及工作绩效与POS水平正相关;与离职意愿负相关。结论有利于事业单位制定正确的人力资源管理战略。  相似文献   

9.
A number of recent studies from as diverse fields as plant–pollinator interactions, analyses of caffeine as an environmental pollutant, and the ability of caffeine to provide protection against neurodegenerative diseases have generated interest in understanding the actions of caffeine in invertebrates. This review summarizes what is currently known about the effects of caffeine on behavior and its molecular mechanisms in invertebrates. Caffeine appears to have similar effects on locomotion and sleep in both invertebrates and mammals. Furthermore, as in mammals, caffeine appears to have complex effects on learning and memory. However, the underlying mechanisms for these effects may differ between invertebrates and vertebrates. While caffeine’s ability to cause release of intracellular calcium stores via ryanodine receptors and its actions as a phosphodiesterase inhibitor have been clearly established in invertebrates, its ability to interact with invertebrate adenosine receptors remains an important open question. Initial studies in insects and mollusks suggest an interaction between caffeine and the dopamine signaling pathway; more work needs to be done to understand the mechanisms by which caffeine influences signaling via biogenic amines. As of yet, little is known about whether other actions of caffeine in vertebrates, such as its effects on GABAA and glycine receptors, are conserved. Furthermore, the pharmacokinetics of caffeine remains to be elucidated. Overall behavioral responses to caffeine appear to be conserved amongst organisms; however, we are just beginning to understand the mechanisms underlying its effects across animal phyla.  相似文献   

10.
针对传统的按职能分工部门之间的壁垒造成产品开发过程中的信息传输迟滞,以及流程活动冗余造成的流程运行时间长的问题,从时间的维度进行产品开发活动的协同管理,建立流程活动间信息交互模型,以实现流程活动间信息传递的量化和无量纲化。根据流程活动间信息依赖关系,建立基于设计结构矩阵(Design Structure Matrix,DSM)的产品协同开发流程结构矩阵,用模糊聚类方法对流程进行优化,并建立了流程优化算法,通过实例验证该方法的可行性。  相似文献   

11.
由于可再生能源开发利用的快速发展,世界各国面临着可再生能源如何接入及充分利用等一系列问题,而智能电网则是应对这些挑战的有效战略措施.智能电网具有强大的功能、显著的综合效益和广阔的发展前景,是世界电网发展的趋势.但是智能电网不是一个单纯的技术问题,它涉及许多重要的基本理念.厘清这些理念对于科学高效地实施智能电网、对于技术创新和产业发展至关重要.为此本文从智能电网的特点、智能电网的总体设想和技术内涵、与智能电网相关的技术、智能电网的近期与远期目标以及在实施智能电网时需要注意的事项等方面阐释了智能电网的基本理念.  相似文献   

12.
A residual influence of males and females on oviposition has been examined in 7 drosophilids. There was evidence for oviposition deterrence in Drosophila funebris, with males as well as females producing the inhibitory effect. In contrast, male residues stimulated oviposition in Zaprionus tuberculatus. Male residues also stimulated oviposition and appeared to serve as an aggregation cue in D. melanogaster.  相似文献   

13.
This paper attempts a critical reappraisal of Nagel's (1961, 1970) model of reduction taking into account both traditional criticisms and recent defenses. This model treats reduction as a type of explanation in which a reduced theory is explained by a reducing theory after their relevant representational items have been suitably connected. In accordance with the deductive-nomological model, the explanation is supposed to consist of a logical deduction. Nagel was a pluralist about both the logical form of the connections between the reduced and reducing theories (which could be conditionals or biconditionals) and their epistemological status (as analytic connections, conventions, or synthetic claims). This paper defends Nagel's pluralism on both counts and, in the process, argues that the multiple realizability objection to reductionism is misplaced. It also argues that the Nagel model correctly characterizes reduction as a type of explanation. However, it notes that logical deduction must be replaced by a broader class of inferential techniques that allow for different types of approximation. Whereas Nagel (1970), in contrast to his earlier position (1961), recognized the relevance of approximation, he did not realize its full import for the model. Throughout the paper two case studies are used to illustrate the arguments: the putative reduction of classical thermodynamics to the kinetic theory of matter and that of classical genetics to molecular biology.  相似文献   

14.
Like many virtuosi in his day, the English philosopher John Locke maintained an active interest in metrology. Yet for Locke, this was no mere hobby: questions concerning measurement were also implicated in his ongoing philosophical project to develop an account of human understanding. This paper follows Locke's treatment of four problems of measurement from the early Drafts A and B of the Essay concerning Human Understanding to the publication of this famous book and its aftermath. It traces Locke's attempt to develop a natural or universal standard for the measure of length, his attempts to grapple with the measurement of duration, as well as the problems of determining comparative measures for secondary qualities, and the problem of discriminating small differences in the conventional measures of his day. It is argued that the salient context for Locke's treatment of these problems is the new experimental philosophy and its method of experimental natural history.  相似文献   

15.
利用粒子群优化(eso)算法全局寻优、快速收敛的特点,结合模糊C-均值(FCM)图像分割算法提出一种新算法,用PSO算法代替了FCM算法的基于梯度下降的迭代过程,使算法具有很强的全局搜索能力,很大程度上避免了FCM算法易陷入局部极小的缺陷;同时也降低了FCM算法对初始值的敏感度。实验结果表明,与FCM相比该算法聚类更准确,效率更高,具有较高的分割速度和良好的抑制噪声的能力。  相似文献   

16.
HIV/AIDS remains a major public health issue. In 2014, it was estimated that 36.9 million people are living with HIV worldwide, including 2.6 million children. Since the advent of combination antiretroviral therapy (cART), in the 1990s, treatment has been so successful that in many parts of the world, HIV has become a chronic condition in which progression to AIDS has become increasingly rare. However, while people with HIV can expect to live a normal life span with cART, lifelong medication is required and cardiovascular, renal, liver, and neurologic diseases are still possible, which continues to prompt research for a cure for HIV. Infected reservoir cells, such as CD4+?T cells and myeloid cells, allow persistence of HIV as an integrated DNA provirus and serve as a potential source for the re-emergence of virus. Attempts to eradicate HIV from these cells have focused mainly on the so-called “shock and kill” approach, where cellular reactivation is induced so as to trigger the purging of virus-producing cells by cytolysis or immune attack. This approach has several limitations and its usefulness in clinical applications remains to be assessed. Recent advances in gene-editing technology have allowed the use of this approach for inactivating integrated proviral DNA in the genome of latently infected cells or knocking out HIV receptors. Here, we review this strategy and its potential to eliminate the latent HIV reservoir resulting in a sterile cure of AIDS.  相似文献   

17.
Summary A residual influence of males and females on oviposition has been examined in 7 drosophilids. There was evidence for oviposition deterrence inDrosophila funebris, with males as well as females producing the inhibitory effect. In contrast, male residues stimulated oviposition inZaprionus tuberculatus. Male residues also stimulated oviposition and appeared to serve as an aggregation cue inD. melanogaster.  相似文献   

18.
Social environmental conditions, particularly the experience of social adversity, have long been connected with health and mortality in humans and other social mammals. Efforts to identify the physiological basis for these effects have historically focused on their neurological, endocrinological, and immunological consequences. Recently, this search has been extended to understanding the role of gene regulation in sensing, mediating, and determining susceptibility to social environmental variation. Studies in laboratory rodents, captive primates, and human populations have revealed correlations between social conditions and the regulation of a large number of genes, some of which are likely causal. Gene expression responses to the social environment are, in turn, mediated by a set of underlying regulatory mechanisms, of which epigenetic marks are the best studied to date. Importantly, a number of genes involved in the response to the social environment are also associated with susceptibility to other external stressors, as well as certain diseases. Hence, gene regulatory studies are a promising avenue for understanding, and potentially developing strategies to address, the effects of social adversity on health.  相似文献   

19.
结合嵌入式软件的实时性、与硬件紧密结合等特点,采用UML对系统建模,引入场景技术描述系统预期的执行流程,提出了基于二叉树场景模型的测试用例生成方法。改善了人工设计测试用例时易发生的纰漏,如遗漏或冗余的测试用例、工作量大、效率低等问题,缩短了软件的开发周期。  相似文献   

20.
John Norton's The Material Theory of Induction bristles with fresh insights and provocative ideas that provide a much needed stimulus to a stodgy if not moribund field. I use quantum mechanics (QM) as a medium for exploring some of these ideas. First, I note that QM offers more predictability than Newtonian mechanics for the Norton dome and other cases where classical determinism falters. But this ability of QM to partially cure the ills of classical determinism depends on facts about the quantum Hamiltonian operator that vary from case to case, providing an illustration of Norton's theme of the importance of contingent facts for inductive reasoning. Second, I agree with Norton that Bayesianism as developed for classical probability theory does not constitute a universal inference machine, and I use QM to explain the sense in which this is so. But at the same time I defend a brand of quantum Bayesianism as providing an illuminating account of how physicists' reasoning about quantum events. Third, I argue that if the probabilities induced by quantum states are regarded as objective chances then there are strong reasons to think that fair infinite lotteries are impossible in a quantum world.  相似文献   

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