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Theoretical studies of adaptation have exploded over the past decade. This work has been inspired by recent, surprising findings in the experimental study of adaptation. For example, morphological evolution sometimes involves a modest number of genetic changes, with some individual changes having a large effect on the phenotype or fitness. Here I survey the history of adaptation theory, focusing on the rise and fall of various views over the past century and the reasons for the slow development of a mature theory of adaptation. I also discuss the challenges that face contemporary theories of adaptation.  相似文献   

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Over the past two decades, molecular and cell biologists have made important progress in characterizing the components and compartments of the cell. New visualization methods have also revealed cellular dynamics. This has raised complex issues about the organization principles that underlie the emergence of coherent dynamical cell shapes and functions. Self-organization concepts that were first developed in chemistry and physics and then applied to various morphogenetic problems in biology over the past century are now beginning to be applied to the organization of the living cell.  相似文献   

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Jack D. Rogers 《Mycopathologia》1968,35(3-4):249-255
Summary The haploid chromosome number ofHypoxylon deustum is 4. Ascospores are uninucleate when formed, becoming binucleate shortly thereafter. One of the two nuclei disappears in maturing ascospores. Mature ascospores are apparently uninucleate. The significance of these and other findings to the taxonomy of the fungus is discussed.Scientific Paper No. 3008. College of Agriculture, Washington State University. Project 3767.This study was supported in part by National Science Foundation Grant GB-5219.  相似文献   

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This article describes the history of melatonin's transformation, in the perception of the biomedical community, from a skin-lightening agent in amphibians to a hormone in mammals, which may also exert important behavioral--and physiological--effects in humans.  相似文献   

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Progressive supranuclear palsy (PSP) was originally described in 1964. Although some contended it was merely a variant of Parkinson's disease, a specific electron microscopic finding of straight, rather than twisted, filaments in the neurofibrillary tangles established PSP as a distinct entity. The almost pathognomonic early clinical finding of paralysis of downward gaze is due to lesions involving the lateral portions of the rostral interstitial nucleus of the medial longitudinal fasciculus. Recent neurochemical studies have identified both a decrease in central dopamine and acetylcholine. The etiology of PSP is unknown, and the therapy is generally ineffective.  相似文献   

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Religion has been a widely present feature of human beings. This review explores developments in the evolutionary cognitive psychology of religion and provides critical evaluation of the different theoretical positions. Generally scholars have either believed religion is adaptive, a by-product of adaptive psychological features or maladaptive and varying amounts of empirical evidence supports each position. The adaptive position has generated the costly signalling theory of religious ritual and the group selection theory. The by-product position has identified psychological machinery that has been co-opted by religion. The maladaptive position has generated the meme theory of religion. The review concludes that the by-product camp enjoys the most support in the scientific community and suggests ways forward for an evolutionarily significant study of religion.  相似文献   

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Pressure as a thermodynamical parameter was successively introduced in physics, hydrometallurgy, geochemistry, and biology. In all cases, the main objective was to recreate a natural phenomenon (gas or liquid compressibility, synthesis or crystal growth of minerals, survival of deep sea microorganisms…). The introduction of high hydrostatic pressure (HHP) in Biology was an important scientific feature over the last hundred years. This paper describes the different steps that have led to the spreading of pressure in biology and the opening of new frontiers either in basic and applied researches due to the specific characteristics of the pressure parameter. Because of the low energy conveyed by this parameter, leading to the preservation of most organoleptic properties of foods, and its ability to inactivate many pathogens, the use of HHP began to spread at the end of the twentieth century into the food industry, in particular for the development of pathogen inactivation processes. Today, even if this field is still the first application domain for HHP, more and more research works have shown that this parameter could be of great interest in health and medicine sciences.  相似文献   

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D. A. McCann  P. Batterham 《Genetica》1993,90(2-3):81-114
Although Australia has a productive history in plant and animal breeding, fundamental genetics was late in becoming established. Before the 1950s there was no separate department of genetics in any university in the country. Reasons for the delay include geographical isolation, Australian and British colonial science policy, and the lack of a critical mass of researchers. Through the efforts of Ian Clunies Ross and the CSIR several prominent scientists were induced to come from overseas to set up the framework for an Australian-based genetics community. Since that time fundamental genetics in Australia has flourished with high quality graduates in genetics being produced at a number of universities, and many local research programs being initiated. This period has seen the gradual internationalisation of Australian genetics and increased collaboration with overseas researchers taking place. This paper provides an historical overview of the origins and progress of genetics in Australia beginning with plant breeding in the first decades of this century to the present era of molecular genetics. Significant personalities, institutions, policies, reports and publications are discussed in order to make sense of the current structures.  相似文献   

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The hormonal responses to repetitive brief maximal exercise in humans   总被引:4,自引:0,他引:4  
The responses of nine men and nine women to brief repetitive maximal exercise have been studied. The exercise involved a 6-s sprint on a non-motorised treadmill repeated 10 times with 30 s recovery between each sprint. The total work done during the ten sprints was 37,693 +/- 3,956 J by the men and 26,555 +/- 4,589 J by the women (M greater than F, P less than 0.01). This difference in performance was not associated with higher blood lactate concentrations in the men (13.96 +/- 1.70 mmol.l-1) than the women (13.09 +/- 3.04 mmol.l-1). An 18-fold increase in plasma adrenaline (AD) occurred with the peak concentration observed after five sprints. The peak AD concentration in the men was larger than that seen in the women (9.2 +/- 7.3 and 3.7 +/- 2.4 nmol.l-1 respectively, P less than 0.05). The maximum noradrenaline (NA) concentration occurred after ten sprints in the men (31.6 +/- 10.9 nmol.l-1) and after five sprints in the women (27.4 +/- 20.8 nmol.l-1). Plasma cardiodilatin (CDN) and atrial natriuretic peptide (ANP) concentrations were elevated in response to the exercise. The peak ANP concentration occurred immediately post-exercise and the response of the women (10.8 +/- 4.5 pmol.l-1) was greater than that of the men (5.1 +/- 2.6 pmol.l-1, P less than 0.05). The peak CDN concentrations were 163 +/- 61 pmol.l-1 for the women and 135 +/- 61 pmol.l-1 for the men. No increases in calcitonin gene related peptide (CGRP) were detected in response to the exercise. These results indicate differences between men and women in performance and hormonal responses. There was no evidence for a role of CGRP in the control of the cardiovascular system after brief intermittent maximal exercise.  相似文献   

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Karplus M 《Biopolymers》2003,68(3):350-358
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This communication describes the invention and further development of the first 96-well solid-phase extraction system and the original purposes to which it was put. We also describe the adaption of this system for bioanalysis of pharmaceutically active small molecules and the needs underlying it. The system has become a world-wide standard for high-throughput bioanalysis and has been extended by others to include, for example, disk-phase extraction and supported liquid-liquid extraction, as well as 384-well systems. The factors that enabled this leap forward in productivity are discussed.  相似文献   

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